Develop Reference

How to add setSelection method logic to custom listview in Android

I have developed a custom 3D ListView by following this tutorial. I am able to create the listview successfully. However, now I wish to scroll down and up in the listview by using Button events. I have created following functions for scrolling down and up in the listview.
//scroll list down
public void scrollListDown(){
int count = 20;
int currentSelected = mListView.getSelectedItemPosition();
if (currentSelected != (count -1) && currentSelected < (count - 1)) {
int count1 = currentSelected + 1;
mListView.setSelection(count1);
}
}
However, in this example, they have not written any implementation for the setSelection method. Due to this the scrolling does not work. I wish to move the selection from one item to another when a button is clicked. My function works on a normal ListView in Android
Currently, I have written a logic for the setSelection method as follows:
#Override
public void setSelection(int position) {
if (mAdapter == null) {
return;
}
if (!isInTouchMode()) {
position = lookForSelectablePosition(position, true);
if (position >= 0) {
setNextSelectedPositionInt(position);
}
} else {
mResurrectToPosition = position;
}
if (position >= 0) {
mLayoutMode = LAYOUT_SPECIFIC;
mSpecificTop = 10;
if (mNeedSync) {
mSyncPosition = position;
mSyncRowId = mAdapter.getItemId(position);
}
requestLayout();
}
}
This is not working as expected. Can anyone suggest how I should use the setSelection method in this case?
My Adapter class
/**
* A simple list view that displays the items as 3D blocks
*/
public class MyListView extends AdapterView<ListAdapter> {
/** Width of the items compared to the width of the list */
private static final float ITEM_WIDTH = 0.85f;
/** Space occupied by the item relative to the height of the item */
private static final float ITEM_VERTICAL_SPACE = 1.45f;
/** Ambient light intensity */
private static final int AMBIENT_LIGHT = 55;
/** Diffuse light intensity */
private static final int DIFFUSE_LIGHT = 200;
/** Specular light intensity */
private static final float SPECULAR_LIGHT = 70;
/** Shininess constant */
private static final float SHININESS = 200;
/** The max intensity of the light */
private static final int MAX_INTENSITY = 0xFF;
/** Amount of down scaling */
private static final float SCALE_DOWN_FACTOR = 0.15f;
/** Amount to rotate during one screen length */
private static final int DEGREES_PER_SCREEN = 270;
/** Represents an invalid child index */
private static final int INVALID_INDEX = -1;
/** Distance to drag before we intercept touch events */
private static final int TOUCH_SCROLL_THRESHOLD = 10;
/** Children added with this layout mode will be added below the last child */
private static final int LAYOUT_MODE_BELOW = 0;
/** Children added with this layout mode will be added above the first child */
private static final int LAYOUT_MODE_ABOVE = 1;
/** User is not touching the list */
private static final int TOUCH_STATE_RESTING = 0;
/** User is touching the list and right now it's still a "click" */
private static final int TOUCH_STATE_CLICK = 1;
/** User is scrolling the list */
private static final int TOUCH_STATE_SCROLL = 2;
/** The adapter with all the data */
private ListAdapter mAdapter;
/** Current touch state */
private int mTouchState = TOUCH_STATE_RESTING;
/** X-coordinate of the down event */
private int mTouchStartX;
/** Y-coordinate of the down event */
private int mTouchStartY;
/**
* The top of the first item when the touch down event was received
*/
private int mListTopStart;
/** The current top of the first item */
private int mListTop;
/**
* The offset from the top of the currently first visible item to the top of
* the first item
*/
private int mListTopOffset;
/** Current rotation */
private int mListRotation;
/** The adaptor position of the first visible item */
private int mFirstItemPosition;
/** The adaptor position of the last visible item */
private int mLastItemPosition;
/** A list of cached (re-usable) item views */
private final LinkedList<View> mCachedItemViews = new LinkedList<View>();
/** Used to check for long press actions */
private Runnable mLongPressRunnable;
/** Reusable rect */
private Rect mRect;
/** Camera used for 3D transformations */
private Camera mCamera;
/** Re-usable matrix for canvas transformations */
private Matrix mMatrix;
/** Paint object to draw with */
private Paint mPaint;
/** true if rotation of the items is enabled */
private boolean mRotationEnabled = true;
/** true if lighting of the items is enabled */
private boolean mLightEnabled = true;
int mSyncPosition;
long mSyncRowId = INVALID_ROW_ID;
long mNextSelectedRowId;
boolean mNeedSync = false;
int mLayoutHeight;
private boolean mAreAllItemsSelectable = true;
private int mResurrectToPosition;
private int mLayoutMode, mSpecificTop,mNextSelectedPosition;
static final int SYNC_SELECTED_POSITION = 0;
int mSyncMode;
static final int LAYOUT_SPECIFIC = 4;
/**
* Constructor
*
* #param context The context
* #param attrs Attributes
*/
public MyListView(final Context context, final AttributeSet attrs) {
super(context, attrs);
}
#Override
public void setAdapter(ListAdapter adapter) {
mAdapter = adapter;
removeAllViewsInLayout();
requestLayout();
}
#Override
public ListAdapter getAdapter() {
return mAdapter;
}
#Override
public void setSelection(int position) {
//throw new UnsupportedOperationException("Not supported");
if (mAdapter == null) {
return;
}
if (!isInTouchMode()) {
position = lookForSelectablePosition(position, true);
if (position >= 0) {
setNextSelectedPositionInt(position);
}
} else {
mResurrectToPosition = position;
}
if (position >= 0) {
mLayoutMode = LAYOUT_SPECIFIC;
mSpecificTop = 10;
if (mNeedSync) {
mSyncPosition = position;
mSyncRowId = mAdapter.getItemId(position);
}
requestLayout();
}
}
public void setNextSelectedPositionInt(int position) {
mNextSelectedPosition = position;
mNextSelectedRowId = getItemIdAtPosition(position);
// If we are trying to sync to the selection, update that too
if (mNeedSync && mSyncMode == SYNC_SELECTED_POSITION && position >= 0) {
mSyncPosition = position;
mSyncRowId = mNextSelectedRowId;
}
}
/**
* Find a position that can be selected (i.e., is not a separator).
*
* #param position The starting position to look at.
* #param lookDown Whether to look down for other positions.
* #return The next selectable position starting at position and then searching either up or
* down. Returns {#link #INVALID_POSITION} if nothing can be found.
*/
public int lookForSelectablePosition(int position, boolean lookDown) {
final ListAdapter adapter = mAdapter;
if (adapter == null || isInTouchMode()) {
return INVALID_POSITION;
}
final int count = adapter.getCount();
if (!mAreAllItemsSelectable) {
if (lookDown) {
position = Math.max(0, position);
while (position < count && !adapter.isEnabled(position)) {
position++;
}
} else {
position = Math.min(position, count - 1);
while (position >= 0 && !adapter.isEnabled(position)) {
position--;
}
}
if (position < 0 || position >= count) {
return INVALID_POSITION;
}
return position;
} else {
if (position < 0 || position >= count) {
return INVALID_POSITION;
}
return position;
}
}
/* #Override
public View getSelectedView() {
throw new UnsupportedOperationException("Not supported");
}*/
/**
* Enables and disables individual rotation of the items.
*
* #param enable If rotation should be enabled or not
*/
public void enableRotation(final boolean enable) {
mRotationEnabled = enable;
if (!mRotationEnabled) {
mListRotation = 0;
}
invalidate();
}
/**
* Checks whether rotation is enabled
*
* #return true if rotation is enabled
*/
public boolean isRotationEnabled() {
return mRotationEnabled;
}
/**
* Enables and disables lighting of the items.
*
* #param enable If lighting should be enabled or not
*/
public void enableLight(final boolean enable) {
mLightEnabled = enable;
if (!mLightEnabled) {
mPaint.setColorFilter(null);
} else {
mPaint.setAlpha(0xFF);
}
invalidate();
}
/**
* Checks whether lighting is enabled
*
* #return true if rotation is enabled
*/
public boolean isLightEnabled() {
return mLightEnabled;
}
#Override
public boolean onInterceptTouchEvent(final MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
startTouch(event);
return false;
case MotionEvent.ACTION_MOVE:
return startScrollIfNeeded(event);
default:
endTouch();
return false;
}
}
#Override
public boolean onTouchEvent(final MotionEvent event) {
if (getChildCount() == 0) {
return false;
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
startTouch(event);
break;
case MotionEvent.ACTION_MOVE:
if (mTouchState == TOUCH_STATE_CLICK) {
startScrollIfNeeded(event);
}
if (mTouchState == TOUCH_STATE_SCROLL) {
scrollList((int)event.getY() - mTouchStartY);
}
break;
case MotionEvent.ACTION_UP:
if (mTouchState == TOUCH_STATE_CLICK) {
clickChildAt((int)event.getX(), (int)event.getY());
}
endTouch();
break;
default:
endTouch();
break;
}
return true;
}
#Override
protected void onLayout(final boolean changed, final int left, final int top, final int right,
final int bottom) {
super.onLayout(changed, left, top, right, bottom);
// if we don't have an adapter, we don't need to do anything
if (mAdapter == null) {
return;
}
if (getChildCount() == 0) {
mLastItemPosition = -1;
fillListDown(mListTop, 0);
} else {
final int offset = mListTop + mListTopOffset - getChildTop(getChildAt(0));
removeNonVisibleViews(offset);
fillList(offset);
}
positionItems();
invalidate();
}
#Override
protected boolean drawChild(final Canvas canvas, final View child, final long drawingTime) {
// get the bitmap
final Bitmap bitmap = child.getDrawingCache();
if (bitmap == null) {
// if the is null for some reason, default to the standard
// drawChild implementation
return super.drawChild(canvas, child, drawingTime);
}
// get top left coordinates
final int top = child.getTop();
final int left = child.getLeft();
// get centerX and centerY
final int childWidth = child.getWidth();
final int childHeight = child.getHeight();
final int centerX = childWidth / 2;
final int centerY = childHeight / 2;
// get scale
final float halfHeight = getHeight() / 2;
final float distFromCenter = (top + centerY - halfHeight) / halfHeight;
final float scale = (float)(1 - SCALE_DOWN_FACTOR * (1 - Math.cos(distFromCenter)));
// get rotation
float childRotation = mListRotation - 20 * distFromCenter;
childRotation %= 90;
if (childRotation < 0) {
childRotation += 90;
}
// draw the item
if (childRotation < 45) {
drawFace(canvas, bitmap, top, left, centerX, centerY, scale, childRotation - 90);
drawFace(canvas, bitmap, top, left, centerX, centerY, scale, childRotation);
} else {
drawFace(canvas, bitmap, top, left, centerX, centerY, scale, childRotation);
drawFace(canvas, bitmap, top, left, centerX, centerY, scale, childRotation - 90);
}
return false;
}
/**
* Draws a face of the 3D block
*
* #param canvas The canvas to draw on
* #param view A bitmap of the view to draw
* #param top Top placement of the view
* #param left Left placement of the view
* #param centerX Center x-coordinate of the view
* #param centerY Center y-coordinate of the view
* #param scale The scale to draw the view in
* #param rotation The rotation of the view
*/
private void drawFace(final Canvas canvas, final Bitmap view, final int top, final int left,
final int centerX, final int centerY, final float scale, final float rotation) {
// create the camera if we haven't before
if (mCamera == null) {
mCamera = new Camera();
}
// save the camera state
mCamera.save();
// translate and then rotate the camera
mCamera.translate(0, 0, centerY);
mCamera.rotateX(rotation);
mCamera.translate(0, 0, -centerY);
// create the matrix if we haven't before
if (mMatrix == null) {
mMatrix = new Matrix();
}
// get the matrix from the camera and then restore the camera
mCamera.getMatrix(mMatrix);
mCamera.restore();
// translate and scale the matrix
mMatrix.preTranslate(-centerX, -centerY);
mMatrix.postScale(scale, scale);
mMatrix.postTranslate(left + centerX, top + centerY);
// create and initialize the paint object
if (mPaint == null) {
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setFilterBitmap(true);
}
// set the light
if (mLightEnabled) {
mPaint.setColorFilter(calculateLight(rotation));
} else {
mPaint.setAlpha(0xFF - (int)(2 * Math.abs(rotation)));
}
// draw the bitmap
canvas.drawBitmap(view, mMatrix, mPaint);
}
/**
* Calculates the lighting of the item based on rotation.
*
* #param rotation The rotation of the item
* #return A color filter to use
*/
private LightingColorFilter calculateLight(final float rotation) {
final double cosRotation = Math.cos(Math.PI * rotation / 180);
int intensity = AMBIENT_LIGHT + (int)(DIFFUSE_LIGHT * cosRotation);
int highlightIntensity = (int)(SPECULAR_LIGHT * Math.pow(cosRotation, SHININESS));
if (intensity > MAX_INTENSITY) {
intensity = MAX_INTENSITY;
}
if (highlightIntensity > MAX_INTENSITY) {
highlightIntensity = MAX_INTENSITY;
}
final int light = Color.rgb(intensity, intensity, intensity);
final int highlight = Color.rgb(highlightIntensity, highlightIntensity, highlightIntensity);
return new LightingColorFilter(light, highlight);
}
/**
* Sets and initializes all things that need to when we start a touch
* gesture.
*
* #param event The down event
*/
private void startTouch(final MotionEvent event) {
// save the start place
mTouchStartX = (int)event.getX();
mTouchStartY = (int)event.getY();
mListTopStart = getChildTop(getChildAt(0)) - mListTopOffset;
// start checking for a long press
startLongPressCheck();
// we don't know if it's a click or a scroll yet, but until we know
// assume it's a click
mTouchState = TOUCH_STATE_CLICK;
}
/**
* Resets and recycles all things that need to when we end a touch gesture
*/
private void endTouch() {
// remove any existing check for longpress
removeCallbacks(mLongPressRunnable);
// reset touch state
mTouchState = TOUCH_STATE_RESTING;
}
/**
* Scrolls the list. Takes care of updating rotation (if enabled) and
* snapping
*
* #param scrolledDistance The distance to scroll
*/
public void scrollList(final int scrolledDistance) {
mListTop = mListTopStart + scrolledDistance;
//mRotationEnabled = false;
if (mRotationEnabled) {
mListRotation = -(DEGREES_PER_SCREEN * mListTop) / getHeight();
}
requestLayout();
}
public void scrollListViewUp(final int scrolledDistance) {
mListTop = mListTopStart + scrolledDistance;
//mRotationEnabled = false;
if (mRotationEnabled) {
mListRotation = -(DEGREES_PER_SCREEN * mListTop) / getHeight();
}
requestLayout();
}
public void scrollListViewDown(final int scrolledDistance) {
mListTop = mListTopStart + scrolledDistance;
//mRotationEnabled = false;
if (mRotationEnabled) {
mListRotation = -(DEGREES_PER_SCREEN * mListTop) / getHeight();
}
requestLayout();
}
/**
* Posts (and creates if necessary) a runnable that will when executed call
* the long click listener
*/
private void startLongPressCheck() {
// create the runnable if we haven't already
if (mLongPressRunnable == null) {
mLongPressRunnable = new Runnable() {
public void run() {
if (mTouchState == TOUCH_STATE_CLICK) {
final int index = getContainingChildIndex(mTouchStartX, mTouchStartY);
if (index != INVALID_INDEX) {
longClickChild(index);
}
}
}
};
}
// then post it with a delay
postDelayed(mLongPressRunnable, ViewConfiguration.getLongPressTimeout());
}
/**
* Checks if the user has moved far enough for this to be a scroll and if
* so, sets the list in scroll mode
*
* #param event The (move) event
* #return true if scroll was started, false otherwise
*/
public boolean startScrollIfNeeded(final MotionEvent event) {
final int xPos = (int)event.getX();
final int yPos = (int)event.getY();
if (xPos < mTouchStartX - TOUCH_SCROLL_THRESHOLD
|| xPos > mTouchStartX + TOUCH_SCROLL_THRESHOLD
|| yPos < mTouchStartY - TOUCH_SCROLL_THRESHOLD
|| yPos > mTouchStartY + TOUCH_SCROLL_THRESHOLD) {
// we've moved far enough for this to be a scroll
removeCallbacks(mLongPressRunnable);
mTouchState = TOUCH_STATE_SCROLL;
return true;
}
return false;
}
/**
* Returns the index of the child that contains the coordinates given.
*
* #param x X-coordinate
* #param y Y-coordinate
* #return The index of the child that contains the coordinates. If no child
* is found then it returns INVALID_INDEX
*/
private int getContainingChildIndex(final int x, final int y) {
if (mRect == null) {
mRect = new Rect();
}
for (int index = 0; index < getChildCount(); index++) {
getChildAt(index).getHitRect(mRect);
if (mRect.contains(x, y)) {
return index;
}
}
return INVALID_INDEX;
}
/**
* Calls the item click listener for the child with at the specified
* coordinates
*
* #param x The x-coordinate
* #param y The y-coordinate
*/
private void clickChildAt(final int x, final int y) {
final int index = getContainingChildIndex(x, y);
if (index != INVALID_INDEX) {
final View itemView = getChildAt(index);
final int position = mFirstItemPosition + index;
final long id = mAdapter.getItemId(position);
performItemClick(itemView, position, id);
}
}
/**
* Calls the item long click listener for the child with the specified index
*
* #param index Child index
*/
private void longClickChild(final int index) {
final View itemView = getChildAt(index);
final int position = mFirstItemPosition + index;
final long id = mAdapter.getItemId(position);
final OnItemLongClickListener listener = getOnItemLongClickListener();
if (listener != null) {
listener.onItemLongClick(this, itemView, position, id);
}
}
/**
* Removes view that are outside of the visible part of the list. Will not
* remove all views.
*
* #param offset Offset of the visible area
*/
private void removeNonVisibleViews(final int offset) {
// We need to keep close track of the child count in this function. We
// should never remove all the views, because if we do, we loose track
// of were we are.
int childCount = getChildCount();
// if we are not at the bottom of the list and have more than one child
if (mLastItemPosition != mAdapter.getCount() - 1 && childCount > 1) {
// check if we should remove any views in the top
View firstChild = getChildAt(0);
while (firstChild != null && getChildBottom(firstChild) + offset < 0) {
// remove the top view
removeViewInLayout(firstChild);
childCount--;
mCachedItemViews.addLast(firstChild);
mFirstItemPosition++;
// update the list offset (since we've removed the top child)
mListTopOffset += getChildHeight(firstChild);
// Continue to check the next child only if we have more than
// one child left
if (childCount > 1) {
firstChild = getChildAt(0);
} else {
firstChild = null;
}
}
}
// if we are not at the top of the list and have more than one child
if (mFirstItemPosition != 0 && childCount > 1) {
// check if we should remove any views in the bottom
View lastChild = getChildAt(childCount - 1);
while (lastChild != null && getChildTop(lastChild) + offset > getHeight()) {
// remove the bottom view
removeViewInLayout(lastChild);
childCount--;
mCachedItemViews.addLast(lastChild);
mLastItemPosition--;
// Continue to check the next child only if we have more than
// one child left
if (childCount > 1) {
lastChild = getChildAt(childCount - 1);
} else {
lastChild = null;
}
}
}
}
/**
* Fills the list with child-views
*
* #param offset Offset of the visible area
*/
private void fillList(final int offset) {
final int bottomEdge = getChildBottom(getChildAt(getChildCount() - 1));
fillListDown(bottomEdge, offset);
final int topEdge = getChildTop(getChildAt(0));
fillListUp(topEdge, offset);
}
/**
* Starts at the bottom and adds children until we've passed the list bottom
*
* #param bottomEdge The bottom edge of the currently last child
* #param offset Offset of the visible area
*/
private void fillListDown(int bottomEdge, final int offset) {
while (bottomEdge + offset < getHeight() && mLastItemPosition < mAdapter.getCount() - 1) {
mLastItemPosition++;
final View newBottomchild = mAdapter.getView(mLastItemPosition, getCachedView(), this);
addAndMeasureChild(newBottomchild, LAYOUT_MODE_BELOW);
bottomEdge += getChildHeight(newBottomchild);
}
}
/**
* Starts at the top and adds children until we've passed the list top
*
* #param topEdge The top edge of the currently first child
* #param offset Offset of the visible area
*/
private void fillListUp(int topEdge, final int offset) {
while (topEdge + offset > 0 && mFirstItemPosition > 0) {
mFirstItemPosition--;
final View newTopCild = mAdapter.getView(mFirstItemPosition, getCachedView(), this);
addAndMeasureChild(newTopCild, LAYOUT_MODE_ABOVE);
final int childHeight = getChildHeight(newTopCild);
topEdge -= childHeight;
// update the list offset (since we added a view at the top)
mListTopOffset -= childHeight;
}
}
/**
* Adds a view as a child view and takes care of measuring it
*
* #param child The view to add
* #param layoutMode Either LAYOUT_MODE_ABOVE or LAYOUT_MODE_BELOW
*/
private void addAndMeasureChild(final View child, final int layoutMode) {
LayoutParams params = child.getLayoutParams();
if (params == null) {
params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
}
final int index = layoutMode == LAYOUT_MODE_ABOVE ? 0 : -1;
child.setDrawingCacheEnabled(true);
addViewInLayout(child, index, params, true);
final int itemWidth = (int)(getWidth() * ITEM_WIDTH);
child.measure(MeasureSpec.EXACTLY | itemWidth, MeasureSpec.UNSPECIFIED);
}
/**
* Positions the children at the "correct" positions
*/
private void positionItems() {
int top = mListTop + mListTopOffset;
for (int index = 0; index < getChildCount(); index++) {
final View child = getChildAt(index);
final int width = child.getMeasuredWidth();
final int height = child.getMeasuredHeight();
final int left = (getWidth() - width) / 2;
final int margin = getChildMargin(child);
final int childTop = top + margin;
child.layout(left, childTop, left + width, childTop + height);
top += height + 2 * margin;
}
}
/**
* Checks if there is a cached view that can be used
*
* #return A cached view or, if none was found, null
*/
private View getCachedView() {
if (mCachedItemViews.size() != 0) {
return mCachedItemViews.removeFirst();
}
return null;
}
/**
* Returns the margin of the child view taking into account the
* ITEM_VERTICAL_SPACE
*
* #param child The child view
* #return The margin of the child view
*/
private int getChildMargin(final View child) {
return (int)(child.getMeasuredHeight() * (ITEM_VERTICAL_SPACE - 1) / 2);
}
/**
* Returns the top placement of the child view taking into account the
* ITEM_VERTICAL_SPACE
*
* #param child The child view
* #return The top placement of the child view
*/
private int getChildTop(final View child) {
return child.getTop() - getChildMargin(child);
}
/**
* Returns the bottom placement of the child view taking into account the
* ITEM_VERTICAL_SPACE
*
* #param child The child view
* #return The bottom placement of the child view
*/
private int getChildBottom(final View child) {
return child.getBottom() + getChildMargin(child);
}
/**
* Returns the height of the child view taking into account the
* ITEM_VERTICAL_SPACE
*
* #param child The child view
* #return The height of the child view
*/
private int getChildHeight(final View child) {
return child.getMeasuredHeight() + 2 * getChildMargin(child);
}
#Override
public View getSelectedView() {
// TODO Auto-generated method stub
return null;
}

how to fill adapter to viewpage fully without going aside?

I am trying to change viewpage rotation 90 to get vertical swapping. but my adapter going aside. i am unable fix it. help me to fit layout correctly.
Here is my view pager
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_alignParentTop="true"
android:layout_width="800dp"
android:layout_height="480dp"
android:background="#a07fe0">
</android.support.v4.view.ViewPager>
Here is my layout of adapter
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ff0000"
android:layout_centerInParent="true"
android:orientation="horizontal"
android:rotation="270">
<ImageView
android:id="#+id/screen"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="start"
android:src="#drawable/makescr1"/>
</LinearLayout>

Use This class.
public class VerticalPager extends ViewGroup {
public static final String TAG = "VerticalPager";
private static final int INVALID_SCREEN = -1;
public static final int SPEC_UNDEFINED = -1;
private static final int TOP = 0;
private static final int BOTTOM = 1;
/**
* The velocity at which a fling gesture will cause us to snap to the next screen
*/
private static final int SNAP_VELOCITY = 1000;
private int pageHeight;
private int measuredHeight;
private boolean mFirstLayout = true;
private int mCurrentPage;
private int mNextPage = INVALID_SCREEN;
private Scroller mScroller;
private VelocityTracker mVelocityTracker;
private int mTouchSlop;
private int mMaximumVelocity;
private float mLastMotionY;
private float mLastMotionX;
private final static int TOUCH_STATE_REST = 0;
private final static int TOUCH_STATE_SCROLLING = 1;
private int mTouchState = TOUCH_STATE_REST;
private boolean mAllowLongPress;
private Set<OnScrollListener> mListeners = new HashSet<OnScrollListener>();
VerticalPageChange mpageChangeListener;
/**
* Used to inflate the Workspace from XML.
*
* #param context The application's context.
* #param attrs The attribtues set containing the Workspace's customization values.
*/
public VerticalPager(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public VerticalPager(Context context, AttributeSet attrs,
VerticalPageChange mpageChangeListener) {
this(context, attrs, 0);
this.mpageChangeListener=mpageChangeListener;
}
/**
* Used to inflate the Workspace from XML.
*
* #param context The application's context.
* #param attrs The attribtues set containing the Workspace's customization values.
* #param defStyle Unused.
*/
public VerticalPager(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
//TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.com_deezapps_widget_HorizontalPager);
//pageHeightSpec = a.getDimensionPixelSize(R.styleable.com_deezapps_widget_HorizontalPager_pageWidth, SPEC_UNDEFINED);
//a.recycle();
init(context);
}
/**
* Initializes various states for this workspace.
*/
private void init(Context context) {
mScroller = new Scroller(getContext(), new DecelerateInterpolator());
mCurrentPage = 0;
final ViewConfiguration configuration = ViewConfiguration.get(getContext());
mTouchSlop = configuration.getScaledTouchSlop();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
}
/**
* Returns the index of the currently displayed page.
*
* #return The index of the currently displayed page.
*/
int getCurrentPage() {
return mCurrentPage;
}
/**
* Sets the current page.
*
* #param currentPage
*/
public void setCurrentPage(int currentPage) {
mCurrentPage = Math.max(0, Math.min(currentPage, getChildCount()));
scrollTo(getScrollYForPage(mCurrentPage), 0);
invalidate();
}
public int getPageHeight() {
return pageHeight;
}
// public void setPageHeight(int pageHeight) {
// this.pageHeightSpec = pageHeight;
// }
/**
* Gets the value that getScrollX() should return if the specified page is the current page (and no other scrolling is occurring).
* Use this to pass a value to scrollTo(), for example.
* #param whichPage
* #return
*/
private int getScrollYForPage(int whichPage) {
int height = 0;
for(int i = 0; i < whichPage; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
height += child.getHeight();
}
}
return height - pageHeightPadding();
}
#Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
} else if (mNextPage != INVALID_SCREEN) {
mCurrentPage = mNextPage;
mNextPage = INVALID_SCREEN;
clearChildrenCache();
}
}
#Override
protected void dispatchDraw(Canvas canvas) {
// ViewGroup.dispatchDraw() supports many features we don't need:
// clip to padding, layout animation, animation listener, disappearing
// children, etc. The following implementation attempts to fast-track
// the drawing dispatch by drawing only what we know needs to be drawn.
final long drawingTime = getDrawingTime();
// todo be smarter about which children need drawing
final int count = getChildCount();
for (int i = 0; i < count; i++) {
drawChild(canvas, getChildAt(i), drawingTime);
}
for (OnScrollListener mListener : mListeners) {
int adjustedScrollY = getScrollY() + pageHeightPadding();
mListener.onScroll(adjustedScrollY);
if (adjustedScrollY % pageHeight == 0) {
mListener.onViewScrollFinished(adjustedScrollY / pageHeight);
}
}
}
int pageHeightPadding() {
return ((getMeasuredHeight() - pageHeight) / 2);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
pageHeight = getMeasuredHeight();
final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(MeasureSpec.makeMeasureSpec(getMeasuredWidth(), MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(pageHeight, MeasureSpec.UNSPECIFIED));
}
if (mFirstLayout) {
scrollTo(getScrollYForPage(mCurrentPage), 0);
mFirstLayout = false;
}
}
#Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
measuredHeight = 0;
final int count = getChildCount();
int height;
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
if(i == 0) {
child.getHeight();
child.layout(0, measuredHeight, right - left, measuredHeight + (int)(pageHeight*.96));
measuredHeight += (pageHeight*.96);
} else {
height = pageHeight * (int)Math.ceil((double)child.getMeasuredHeight()/(double)pageHeight);
height = Math.max(pageHeight, height);
child.layout(0, measuredHeight, right - left, measuredHeight + height);
measuredHeight += height;
}
}
}
}
#Override
public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) {
int screen = indexOfChild(child);
if (screen != mCurrentPage || !mScroller.isFinished()) {
return true;
}
return false;
}
#Override
protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) {
int focusableScreen;
try
{
if (mNextPage != INVALID_SCREEN) {
focusableScreen = mNextPage;
} else {
focusableScreen = mCurrentPage;
}
getChildAt(focusableScreen).requestFocus(direction, previouslyFocusedRect);
}
catch(Exception e)
{
e.printStackTrace();
}
return false;
}
#Override
public boolean dispatchUnhandledMove(View focused, int direction) {
if (direction == View.FOCUS_LEFT) {
if (getCurrentPage() > 0) {
snapToPage(getCurrentPage() - 1);
return true;
}
} else if (direction == View.FOCUS_RIGHT) {
if (getCurrentPage() < getChildCount() - 1) {
snapToPage(getCurrentPage() + 1);
return true;
}
}
return super.dispatchUnhandledMove(focused, direction);
}
#Override
public void addFocusables(ArrayList<View> views, int direction) {
getChildAt(mCurrentPage).addFocusables(views, direction);
if (direction == View.FOCUS_LEFT) {
if (mCurrentPage > 0) {
getChildAt(mCurrentPage - 1).addFocusables(views, direction);
}
} else if (direction == View.FOCUS_RIGHT){
if (mCurrentPage < getChildCount() - 1) {
getChildAt(mCurrentPage + 1).addFocusables(views, direction);
}
}
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
//Log.d(TAG, "onInterceptTouchEvent::action=" + ev.getAction());
/*
* This method JUST determines whether we want to intercept the motion.
* If we return true, onTouchEvent will be called and we do the actual
* scrolling there.
*/
/*
* Shortcut the most recurring case: the user is in the dragging
* state and he is moving his finger. We want to intercept this
* motion.
*/
final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != TOUCH_STATE_REST)) {
//Log.d(TAG, "onInterceptTouchEvent::shortcut=true");
return true;
}
final float y = ev.getY();
final float x = ev.getX();
switch (action) {
case MotionEvent.ACTION_MOVE:
/*
* mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
* whether the user has moved far enough from his original down touch.
*/
if (mTouchState == TOUCH_STATE_REST) {
checkStartScroll(x, y);
}
break;
case MotionEvent.ACTION_DOWN:
// Remember location of down touch
mLastMotionX = x;
mLastMotionY = y;
mAllowLongPress = true;
/*
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
*/
mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
// Release the drag
clearChildrenCache();
mTouchState = TOUCH_STATE_REST;
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mTouchState != TOUCH_STATE_REST;
}
private void checkStartScroll(float x, float y) {
/*
* Locally do absolute value. mLastMotionX is set to the y value
* of the down event.
*/
final int xDiff = (int) Math.abs(x - mLastMotionX);
final int yDiff = (int) Math.abs(y - mLastMotionY);
boolean xMoved = xDiff > mTouchSlop;
boolean yMoved = yDiff > mTouchSlop;
if (xMoved || yMoved) {
if (yMoved) {
// Scroll if the user moved far enough along the X axis
mTouchState = TOUCH_STATE_SCROLLING;
enableChildrenCache();
}
// Either way, cancel any pending longpress
if (mAllowLongPress) {
mAllowLongPress = false;
// Try canceling the long press. It could also have been scheduled
// by a distant descendant, so use the mAllowLongPress flag to block
// everything
final View currentScreen = getChildAt(mCurrentPage);
currentScreen.cancelLongPress();
}
}
}
void enableChildrenCache() {
setChildrenDrawingCacheEnabled(true);
setChildrenDrawnWithCacheEnabled(true);
}
void clearChildrenCache() {
setChildrenDrawnWithCacheEnabled(false);
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
final int action = ev.getAction();
final float x = ev.getX();
final float y = ev.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
// Remember where the motion event started
mLastMotionY = y;
break;
case MotionEvent.ACTION_MOVE:
if (mTouchState == TOUCH_STATE_REST) {
checkStartScroll(y, x);
} else if (mTouchState == TOUCH_STATE_SCROLLING) {
// Scroll to follow the motion event
int deltaY = (int) (mLastMotionY - y);
mLastMotionY = y;
// Apply friction to scrolling past boundaries.
final int count = getChildCount();
if (getScrollY() < 0 || getScrollY() + pageHeight > getChildAt(count - 1).getBottom()) {
deltaY /= 2;
}
scrollBy(0, deltaY);
}
break;
case MotionEvent.ACTION_UP:
if (mTouchState == TOUCH_STATE_SCROLLING) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int velocityY = (int) velocityTracker.getYVelocity();
final int count = getChildCount();
// check scrolling past first or last page?
if(getScrollY() < 0) {
snapToPage(0);
} else if(getScrollY() > measuredHeight - pageHeight) {
snapToPage(count - 1, BOTTOM);
} else {
for(int i = 0; i < count; i++) {
final View child = getChildAt(i);
if(child.getTop() < getScrollY() &&
child.getBottom() > getScrollY() + pageHeight) {
// we're inside a page, fling that bitch
mNextPage = i;
mScroller.fling(getScrollX(), getScrollY(), 0, -velocityY, 0, 0, child.getTop(), child.getBottom() - getHeight());
invalidate();
break;
} else if(child.getBottom() > getScrollY() && child.getBottom() < getScrollY() + getHeight()) {
// stuck in between pages, oh snap!
if(velocityY < -SNAP_VELOCITY) {
snapToPage(i + 1);
} else if(velocityY > SNAP_VELOCITY) {
snapToPage(i, BOTTOM);
} else if(getScrollY() + pageHeight/2 > child.getBottom()) {
snapToPage(i + 1);
} else {
snapToPage(i, BOTTOM);
}
break;
}
}
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
mTouchState = TOUCH_STATE_REST;
}
return true;
}
private void snapToPage(final int whichPage, final int where) {
enableChildrenCache();
boolean changingPages = whichPage != mCurrentPage;
mNextPage = whichPage;
View focusedChild = getFocusedChild();
if (focusedChild != null && changingPages && focusedChild == getChildAt(mCurrentPage)) {
focusedChild.clearFocus();
}
final int delta;
if(getChildAt(whichPage).getHeight() <= pageHeight || where == TOP) {
delta = getChildAt(whichPage).getTop() - getScrollY();
} else {
delta = getChildAt(whichPage).getBottom() - pageHeight - getScrollY();
}
mScroller.startScroll(0, getScrollY(), 0, delta, 400);
invalidate();
mpageChangeListener.onPageChange(whichPage);
}
public void snapToPage(final int whichPage) {
snapToPage(whichPage, TOP);
// mpageChangeListener.onPageChange(whichPage);
}
#Override
protected Parcelable onSaveInstanceState() {
final SavedState state = new SavedState(super.onSaveInstanceState());
state.currentScreen = mCurrentPage;
return state;
}
#Override
protected void onRestoreInstanceState(Parcelable state) {
SavedState savedState = (SavedState) state;
super.onRestoreInstanceState(savedState.getSuperState());
if (savedState.currentScreen != INVALID_SCREEN) {
mCurrentPage = savedState.currentScreen;
}
}
public void scrollUp() {
if (mNextPage == INVALID_SCREEN && mCurrentPage > 0 && mScroller.isFinished()) {
snapToPage(mCurrentPage - 1);
}
}
public void scrollDown() {
if (mNextPage == INVALID_SCREEN && mCurrentPage < getChildCount() - 1 && mScroller.isFinished()) {
snapToPage(mCurrentPage + 1);
}
}
public int getScreenForView(View v) {
int result = -1;
if (v != null) {
ViewParent vp = v.getParent();
int count = getChildCount();
for (int i = 0; i < count; i++) {
if (vp == getChildAt(i)) {
return i;
}
}
}
return result;
}
/**
* #return True is long presses are still allowed for the current touch
*/
public boolean allowLongPress() {
return mAllowLongPress;
}
public static class SavedState extends BaseSavedState {
int currentScreen = -1;
SavedState(Parcelable superState) {
super(superState);
}
private SavedState(Parcel in) {
super(in);
currentScreen = in.readInt();
}
#Override
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
out.writeInt(currentScreen);
}
public static final Parcelable.Creator<SavedState> CREATOR =
new Parcelable.Creator<SavedState>() {
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
public void addOnScrollListener(OnScrollListener listener) {
mListeners.add(listener);
}
public void removeOnScrollListener(OnScrollListener listener) {
mListeners.remove(listener);
}
/**
* Implement to receive events on scroll position and page snaps.
*/
public static interface OnScrollListener {
/**
* Receives the current scroll X value. This value will be adjusted to assume the left edge of the first
* page has a scroll position of 0. Note that values less than 0 and greater than the right edge of the
* last page are possible due to touch events scrolling beyond the edges.
* #param scrollX Scroll X value
*/
void onScroll(int scrollX);
/**
* Invoked when scrolling is finished (settled on a page, centered).
* #param currentPage The current page
*/
void onViewScrollFinished(int currentPage);
}
public interface VerticalPageChange
{
public void onPageChange(int position);
}
}
i have add page dynamically. inside getView() of BaseAdapter.
final VerticalPager verticalPage = new VerticalPager(Act_ItemView.this, null, mVerticalPagechangeListener);
// setDotIndicatorView(p.arr_images.size());
for (int i = 0; i < p.arr_images.size(); i++)
{
final String image_url = p.arr_images.get(i).image_method;
PhotoView imageView = new PhotoView(Act_ItemView.this);
imageView.setLayoutParams(new ViewGroup.LayoutParams(width, height));
imageView.setAllowParentInterceptOnEdge(true);
// imageView.setScaleType(ScaleType.CENTER_CROP);
imageLoader1.displayImage(image_url, imageView, options1, animateFirstListener1);
verticalPage.setHorizontalScrollBarEnabled(false);
verticalPage.addView(imageView);
verticalPage.setTag(i);
}
linearLayoutMain.addView(verticalPage);
here is listner implemented
VerticalPager.VerticalPageChange mVerticalPagechangeListener = new VerticalPager.VerticalPageChange()
{
#Override
public void onPageChange(int position)
{
try
{
int pagePosition1 = viewPager.getCurrentItem();
setindicator(position);
array_index[pagePosition1] = position;
} catch (Exception e)
{
e.printStackTrace();
}
}
};

Drag GridView items Up and Down

I am working on Drag Grid item up and down module.
Drag grid item Up = DoUPFunction();
Drag grid item Down = DoDownFunction();
At that time, remove the dragged item from the gridlist and rearrange the remaining views.
I tried lot of examples.
Please guide me to do this.
Forgive me for my bad english.

Here is a Drag and drop for List View,you will have to change it according to your needs to convert it into gridview...in the code you may get errors because i have used a custom object called "song details" replace it with any other data type or class.....
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.animation.TypeEvaluator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.ListView;
import java.util.ArrayList;
import source.justanothermusicplayer.adapters.Adapter_ListView;
/**
* The dynamic listview is an extension of listview that supports cell dragging
* and swapping.
*
* This layout is in charge of positioning the hover cell in the correct location
* on the screen in response to user touch events. It uses the position of the
* hover cell to determine when two cells should be swapped. If two cells should
* be swapped, all the corresponding data set and layout changes are handled here.
*
* If no cell is selected, all the touch events are passed down to the listview
* and behave normally. If one of the items in the listview experiences a
* long press event, the contents of its current visible state are captured as
* a bitmap and its visibility is set to INVISIBLE. A hover cell is then created and
* added to this layout as an overlaying BitmapDrawable above the listview. Once the
* hover cell is translated some distance to signify an item swap, a data set change
* accompanied by animation takes place. When the user releases the hover cell,
* it animates into its corresponding position in the listview.
*
* When the hover cell is either above or below the bounds of the listview, this
* listview also scrolls on its own so as to reveal additional content.
*/
public class DynamicListView extends ListView {
private final int SMOOTH_SCROLL_AMOUNT_AT_EDGE = 15;
private final int MOVE_DURATION = 150;
private final int LINE_THICKNESS = 15;
public ArrayList<SongDetails> mCheeseList;
private int mLastEventY = -1;
private int mDownY = -1;
private int mDownX = -1;
private int mTotalOffset = 0;
private boolean mCellIsMobile = false;
private boolean mIsMobileScrolling = false;
private int mSmoothScrollAmountAtEdge = 0;
private final int INVALID_ID = -1;
private long mAboveItemId = INVALID_ID;
private long mMobileItemId = INVALID_ID;
private long mBelowItemId = INVALID_ID;
private BitmapDrawable mHoverCell;
private Rect mHoverCellCurrentBounds;
private Rect mHoverCellOriginalBounds;
private final int INVALID_POINTER_ID = -1;
private int mActivePointerId = INVALID_POINTER_ID;
private boolean mIsWaitingForScrollFinish = false;
private int mScrollState = OnScrollListener.SCROLL_STATE_IDLE;
public DynamicListView(Context context) {
super(context);
init(context);
}
public DynamicListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public DynamicListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public void init(Context context) {
setOnItemLongClickListener(mOnItemLongClickListener);
setOnScrollListener(mScrollListener);
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
mSmoothScrollAmountAtEdge = (int)(SMOOTH_SCROLL_AMOUNT_AT_EDGE / metrics.density);
}
/**
* Listens for long clicks on any items in the listview. When a cell has
* been selected, the hover cell is created and set up.
*/
private AdapterView.OnItemLongClickListener mOnItemLongClickListener =
new AdapterView.OnItemLongClickListener() {
public boolean onItemLongClick(AdapterView<?> arg0, View arg1, int pos, long id) {
mTotalOffset = 0;
int position = pointToPosition(mDownX, mDownY);
int itemNum = position - getFirstVisiblePosition();
View selectedView = getChildAt(itemNum);
mMobileItemId = getAdapter().getItemId(position);
mHoverCell = getAndAddHoverView(selectedView);
selectedView.setVisibility(INVISIBLE);
mCellIsMobile = true;
updateNeighborViewsForID(mMobileItemId);
return true;
}
};
/**
* Creates the hover cell with the appropriate bitmap and of appropriate
* size. The hover cell's BitmapDrawable is drawn on top of the bitmap every
* single time an invalidate call is made.
*/
private BitmapDrawable getAndAddHoverView(View v) {
int w = v.getWidth();
int h = v.getHeight();
int top = v.getTop();
int left = v.getLeft();
Bitmap b = getBitmapWithBorder(v);
BitmapDrawable drawable = new BitmapDrawable(getResources(), b);
mHoverCellOriginalBounds = new Rect(left, top, left + w, top + h);
mHoverCellCurrentBounds = new Rect(mHoverCellOriginalBounds);
drawable.setBounds(mHoverCellCurrentBounds);
return drawable;
}
/** Draws a black border over the screenshot of the view passed in. */
private Bitmap getBitmapWithBorder(View v) {
Bitmap bitmap = getBitmapFromView(v);
Canvas can = new Canvas(bitmap);
Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
Paint paint = new Paint();
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(LINE_THICKNESS);
paint.setColor(Color.BLACK);
can.drawBitmap(bitmap, 0, 0, null);
can.drawRect(rect, paint);
return bitmap;
}
/** Returns a bitmap showing a screenshot of the view passed in. */
private Bitmap getBitmapFromView(View v) {
Bitmap bitmap = Bitmap.createBitmap(v.getWidth(), v.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas (bitmap);
v.draw(canvas);
return bitmap;
}
/**
* Stores a reference to the views above and below the item currently
* corresponding to the hover cell. It is important to note that if this
* item is either at the top or bottom of the list, mAboveItemId or mBelowItemId
* may be invalid.
*/
private void updateNeighborViewsForID(long itemID) {
int position = getPositionForID(itemID);
Adapter_ListView adapter = ((Adapter_ListView)getAdapter());
mAboveItemId = adapter.getItemId(position - 1);
mBelowItemId = adapter.getItemId(position + 1);
}
/** Retrieves the view in the list corresponding to itemID */
public View getViewForID (long itemID) {
int firstVisiblePosition = getFirstVisiblePosition();
Adapter_ListView adapter = ((Adapter_ListView)getAdapter());
for(int i = 0; i < getChildCount(); i++) {
View v = getChildAt(i);
int position = firstVisiblePosition + i;
long id = adapter.getItemId(position);
if (id == itemID) {
return v;
}
}
return null;
}
/** Retrieves the position in the list corresponding to itemID */
public int getPositionForID (long itemID) {
View v = getViewForID(itemID);
if (v == null) {
return -1;
} else {
return getPositionForView(v);
}
}
/**
* dispatchDraw gets invoked when all the child views are about to be drawn.
* By overriding this method, the hover cell (BitmapDrawable) can be drawn
* over the listview's items whenever the listview is redrawn.
*/
#Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (mHoverCell != null) {
mHoverCell.draw(canvas);
}
}
#Override
public boolean onTouchEvent (MotionEvent event) {
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
mDownX = (int)event.getX();
mDownY = (int)event.getY();
mActivePointerId = event.getPointerId(0);
break;
case MotionEvent.ACTION_MOVE:
if (mActivePointerId == INVALID_POINTER_ID) {
break;
}
int pointerIndex = event.findPointerIndex(mActivePointerId);
mLastEventY = (int) event.getY(pointerIndex);
int deltaY = mLastEventY - mDownY;
if (mCellIsMobile) {
mHoverCellCurrentBounds.offsetTo(mHoverCellOriginalBounds.left,
mHoverCellOriginalBounds.top + deltaY + mTotalOffset);
mHoverCell.setBounds(mHoverCellCurrentBounds);
invalidate();
handleCellSwitch();
mIsMobileScrolling = false;
handleMobileCellScroll();
return false;
}
break;
case MotionEvent.ACTION_UP:
touchEventsEnded();
break;
case MotionEvent.ACTION_CANCEL:
touchEventsCancelled();
break;
case MotionEvent.ACTION_POINTER_UP:
/* If a multitouch event took place and the original touch dictating
* the movement of the hover cell has ended, then the dragging event
* ends and the hover cell is animated to its corresponding position
* in the listview. */
pointerIndex = (event.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = event.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
touchEventsEnded();
}
break;
default:
break;
}
return super.onTouchEvent(event);
}
/**
* This method determines whether the hover cell has been shifted far enough
* to invoke a cell swap. If so, then the respective cell swap candidate is
* determined and the data set is changed. Upon posting a notification of the
* data set change, a layout is invoked to place the cells in the right place.
* Using a ViewTreeObserver and a corresponding OnPreDrawListener, we can
* offset the cell being swapped to where it previously was and then animate it to
* its new position.
*/
private void handleCellSwitch() {
final int deltaY = mLastEventY - mDownY;
int deltaYTotal = mHoverCellOriginalBounds.top + mTotalOffset + deltaY;
View belowView = getViewForID(mBelowItemId);
View mobileView = getViewForID(mMobileItemId);
View aboveView = getViewForID(mAboveItemId);
boolean isBelow = (belowView != null) && (deltaYTotal > belowView.getTop());
boolean isAbove = (aboveView != null) && (deltaYTotal < aboveView.getTop());
if (isBelow || isAbove) {
final long switchItemID = isBelow ? mBelowItemId : mAboveItemId;
View switchView = isBelow ? belowView : aboveView;
final int originalItem = getPositionForView(mobileView);
if (switchView == null) {
updateNeighborViewsForID(mMobileItemId);
return;
}
swapElements(mCheeseList, originalItem, getPositionForView(switchView));
((BaseAdapter) getAdapter()).notifyDataSetChanged();
mDownY = mLastEventY;
final int switchViewStartTop = switchView.getTop();
mobileView.setVisibility(View.VISIBLE);
switchView.setVisibility(View.INVISIBLE);
updateNeighborViewsForID(mMobileItemId);
final ViewTreeObserver observer = getViewTreeObserver();
observer.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
public boolean onPreDraw() {
observer.removeOnPreDrawListener(this);
View switchView = getViewForID(switchItemID);
mTotalOffset += deltaY;
int switchViewNewTop = switchView.getTop();
int delta = switchViewStartTop - switchViewNewTop;
switchView.setTranslationY(delta);
ObjectAnimator animator = ObjectAnimator.ofFloat(switchView,
View.TRANSLATION_Y, 0);
animator.setDuration(MOVE_DURATION);
animator.start();
return true;
}
});
}
}
private void swapElements(ArrayList arrayList, int indexOne, int indexTwo) {
Object temp = arrayList.get(indexOne);
arrayList.set(indexOne, arrayList.get(indexTwo));
arrayList.set(indexTwo, temp);
}
/**
* Resets all the appropriate fields to a default state while also animating
* the hover cell back to its correct location.
*/
private void touchEventsEnded () {
final View mobileView = getViewForID(mMobileItemId);
if (mCellIsMobile|| mIsWaitingForScrollFinish) {
mCellIsMobile = false;
mIsWaitingForScrollFinish = false;
mIsMobileScrolling = false;
mActivePointerId = INVALID_POINTER_ID;
// If the autoscroller has not completed scrolling, we need to wait for it to
// finish in order to determine the final location of where the hover cell
// should be animated to.
if (mScrollState != OnScrollListener.SCROLL_STATE_IDLE) {
mIsWaitingForScrollFinish = true;
return;
}
mHoverCellCurrentBounds.offsetTo(mHoverCellOriginalBounds.left, mobileView.getTop());
ObjectAnimator hoverViewAnimator = ObjectAnimator.ofObject(mHoverCell, "bounds",
sBoundEvaluator, mHoverCellCurrentBounds);
hoverViewAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
invalidate();
}
});
hoverViewAnimator.addListener(new AnimatorListenerAdapter() {
#Override
public void onAnimationStart(Animator animation) {
setEnabled(false);
}
#Override
public void onAnimationEnd(Animator animation) {
mAboveItemId = INVALID_ID;
mMobileItemId = INVALID_ID;
mBelowItemId = INVALID_ID;
mobileView.setVisibility(VISIBLE);
mHoverCell = null;
setEnabled(true);
invalidate();
}
});
hoverViewAnimator.start();
} else {
touchEventsCancelled();
}
}
/**
* Resets all the appropriate fields to a default state.
*/
private void touchEventsCancelled () {
View mobileView = getViewForID(mMobileItemId);
if (mCellIsMobile) {
mAboveItemId = INVALID_ID;
mMobileItemId = INVALID_ID;
mBelowItemId = INVALID_ID;
mobileView.setVisibility(VISIBLE);
mHoverCell = null;
invalidate();
}
mCellIsMobile = false;
mIsMobileScrolling = false;
mActivePointerId = INVALID_POINTER_ID;
}
/**
* This TypeEvaluator is used to animate the BitmapDrawable back to its
* final location when the user lifts his finger by modifying the
* BitmapDrawable's bounds.
*/
private final static TypeEvaluator<Rect> sBoundEvaluator = new TypeEvaluator<Rect>() {
public Rect evaluate(float fraction, Rect startValue, Rect endValue) {
return new Rect(interpolate(startValue.left, endValue.left, fraction),
interpolate(startValue.top, endValue.top, fraction),
interpolate(startValue.right, endValue.right, fraction),
interpolate(startValue.bottom, endValue.bottom, fraction));
}
public int interpolate(int start, int end, float fraction) {
return (int)(start + fraction * (end - start));
}
};
/**
* Determines whether this listview is in a scrolling state invoked
* by the fact that the hover cell is out of the bounds of the listview;
*/
private void handleMobileCellScroll() {
mIsMobileScrolling = handleMobileCellScroll(mHoverCellCurrentBounds);
}
/**
* This method is in charge of determining if the hover cell is above
* or below the bounds of the listview. If so, the listview does an appropriate
* upward or downward smooth scroll so as to reveal new items.
*/
public boolean handleMobileCellScroll(Rect r) {
int offset = computeVerticalScrollOffset();
int height = getHeight();
int extent = computeVerticalScrollExtent();
int range = computeVerticalScrollRange();
int hoverViewTop = r.top;
int hoverHeight = r.height();
if (hoverViewTop <= 0 && offset > 0) {
smoothScrollBy(-mSmoothScrollAmountAtEdge, 0);
return true;
}
if (hoverViewTop + hoverHeight >= height && (offset + extent) < range) {
smoothScrollBy(mSmoothScrollAmountAtEdge, 0);
return true;
}
return false;
}
public void setCheeseList(ArrayList<SongDetails> cheeseList) {
mCheeseList = cheeseList;
}
/**
* This scroll listener is added to the listview in order to handle cell swapping
* when the cell is either at the top or bottom edge of the listview. If the hover
* cell is at either edge of the listview, the listview will begin scrolling. As
* scrolling takes place, the listview continuously checks if new cells became visible
* and determines whether they are potential candidates for a cell swap.
*/
private AbsListView.OnScrollListener mScrollListener = new AbsListView.OnScrollListener () {
private int mPreviousFirstVisibleItem = -1;
private int mPreviousVisibleItemCount = -1;
private int mCurrentFirstVisibleItem;
private int mCurrentVisibleItemCount;
private int mCurrentScrollState;
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
int totalItemCount) {
mCurrentFirstVisibleItem = firstVisibleItem;
mCurrentVisibleItemCount = visibleItemCount;
mPreviousFirstVisibleItem = (mPreviousFirstVisibleItem == -1) ? mCurrentFirstVisibleItem
: mPreviousFirstVisibleItem;
mPreviousVisibleItemCount = (mPreviousVisibleItemCount == -1) ? mCurrentVisibleItemCount
: mPreviousVisibleItemCount;
checkAndHandleFirstVisibleCellChange();
checkAndHandleLastVisibleCellChange();
mPreviousFirstVisibleItem = mCurrentFirstVisibleItem;
mPreviousVisibleItemCount = mCurrentVisibleItemCount;
}
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
mCurrentScrollState = scrollState;
mScrollState = scrollState;
isScrollCompleted();
}
/**
* This method is in charge of invoking 1 of 2 actions. Firstly, if the listview
* is in a state of scrolling invoked by the hover cell being outside the bounds
* of the listview, then this scrolling event is continued. Secondly, if the hover
* cell has already been released, this invokes the animation for the hover cell
* to return to its correct position after the listview has entered an idle scroll
* state.
*/
private void isScrollCompleted() {
if (mCurrentVisibleItemCount > 0 && mCurrentScrollState == SCROLL_STATE_IDLE) {
if (mCellIsMobile && mIsMobileScrolling) {
handleMobileCellScroll();
} else if (mIsWaitingForScrollFinish) {
touchEventsEnded();
}
}
}
/**
* Determines if the listview scrolled up enough to reveal a new cell at the
* top of the list. If so, then the appropriate parameters are updated.
*/
public void checkAndHandleFirstVisibleCellChange() {
if (mCurrentFirstVisibleItem != mPreviousFirstVisibleItem) {
if (mCellIsMobile && mMobileItemId != INVALID_ID) {
updateNeighborViewsForID(mMobileItemId);
handleCellSwitch();
}
}
}
/**
* Determines if the listview scrolled down enough to reveal a new cell at the
* bottom of the list. If so, then the appropriate parameters are updated.
*/
public void checkAndHandleLastVisibleCellChange() {
int currentLastVisibleItem = mCurrentFirstVisibleItem + mCurrentVisibleItemCount;
int previousLastVisibleItem = mPreviousFirstVisibleItem + mPreviousVisibleItemCount;
if (currentLastVisibleItem != previousLastVisibleItem) {
if (mCellIsMobile && mMobileItemId != INVALID_ID) {
updateNeighborViewsForID(mMobileItemId);
handleCellSwitch();
}
}
}
};
}

Viewgroup not Drawing its Children

I have an activity that gets a bitmap from the sdcard. Its view is set to a custom viewgroup. i have dynamically added a view containing the bitmap to the viewgroup and used a handler to update the viewgroup in the UI thread, but to no avail. The viewgroup doesn't show the bitmap. The viewgroup code I have not written myself but ought to allow the user to swipe the screen to load different views/bitmaps.
i have checked to see if the bitmap is not null and placed log statements in various places in both files. Any ideas as to why the viewgroup's children are not being drawn?
The activity
public class HorizontalPagerActivity extends Activity {
private static final String TAG = "*********hpActivity";
private Context mContext = this;
File tempFile;
byte [] imageArray;
private Bitmap b = null;
private Handler handler;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.hpview);
final ViewGroup viewgroup = (ViewGroup)findViewById(R.id.hpview);
handler = new Handler();
tempFile = new File(Environment.getExternalStorageDirectory().
getAbsolutePath() + "/"+"image.jpeg");
Log.e(TAG, "image length = "+tempFile.length());
imageArray = new byte[(int)tempFile.length()];
try{
InputStream is = new FileInputStream(tempFile);
BufferedInputStream bis = new BufferedInputStream(is);
DataInputStream dis = new DataInputStream(bis);
int i = 0;
while (dis.available() > 0 ) {
imageArray[i] = dis.readByte();
i++;
}
dis.close();
} catch (Exception e) {
e.printStackTrace();
}
Bitmap bm = BitmapFactory.decodeByteArray(imageArray, 0, imageArray.length);
// Bitmap b = Bitmap.createBitmap(bm.getWidth(), bm.getHeight(), Bitmap.Config.ARGB_8888);
b = bm.copy(bm.getConfig(), true);
if(b == null){
Log.e(TAG, "b = null");
}else{
Log.e(TAG, "b = not null");
}
Canvas canvas = new Canvas(b);
Log.e(TAG, "canvas created");
final View view = new View(this);
Log.e(TAG, "view created");
// LayoutParams lp = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
// view.setLayoutParams(lp);
view.draw(canvas);
viewgroup.addView(view);
Log.e(TAG, "view added to viewgroup");
Runnable runnable = new Runnable() {
#Override
public void run() {
handler.post(new Runnable() {
#Override
public void run() {
Log.e(TAG, "about to inval viewgroup");
viewgroup.invalidate();
Log.e(TAG, "finished inval viewgroup");
}
});
}
};
new Thread(runnable).start();
Log.e(TAG, "finished handler");
/*
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
Log.e(TAG, "about to inval viewgroup");
viewgroup.postInvalidate();
Log.e(TAG, "finished inval viewgroup");
}
});
*/
Log.e(TAG, "no of chidren = "+viewgroup.getChildCount());
}
}
The viewgroup
/**
* A view group that allows users to switch between multiple screens (layouts) in the same way as
* the Android home screen (Launcher application).
* <p>
* You can add and remove views using the normal methods {#link ViewGroup#addView(View)},
* {#link ViewGroup#removeView(View)} etc. You may want to listen for updates by calling
* {#link HorizontalPager#setOnScreenSwitchListener(OnScreenSwitchListener)} in order to perform
* operations once a new screen has been selected.
*
* Modifications from original version (ysamlan): Animate argument in setCurrentScreen and duration
* in snapToScreen; onInterceptTouchEvent handling to support nesting a vertical Scrollview inside
* the RealViewSwitcher; allowing snapping to a view even during an ongoing scroll; snap to
* next/prev view on 25% scroll change; density-independent swipe sensitivity; width-independent
* pager animation durations on scrolling to properly handle large screens without excessively
* long animations.
*
* Other modifications:
* (aveyD) Handle orientation changes properly and fully snap to the right position.
*
* #author Marc Reichelt, http://www.marcreichelt.de/
* #version 0.1.0
*/
public final class HorizontalPager extends ViewGroup {
/*
* How long to animate between screens when programmatically setting with setCurrentScreen using
* the animate parameter
*/
private static final int ANIMATION_SCREEN_SET_DURATION_MILLIS = 500;
// What fraction (1/x) of the screen the user must swipe to indicate a page change
private static final int FRACTION_OF_SCREEN_WIDTH_FOR_SWIPE = 4;
private static final int INVALID_SCREEN = -1;
/*
* Velocity of a swipe (in density-independent pixels per second) to force a swipe to the
* next/previous screen. Adjusted into mDensityAdjustedSnapVelocity on init.
*/
private static final int SNAP_VELOCITY_DIP_PER_SECOND = 600;
// Argument to getVelocity for units to give pixels per second (1 = pixels per millisecond).
private static final int VELOCITY_UNIT_PIXELS_PER_SECOND = 1000;
private static final int TOUCH_STATE_REST = 0;
private static final int TOUCH_STATE_HORIZONTAL_SCROLLING = 1;
private static final int TOUCH_STATE_VERTICAL_SCROLLING = -1;
private int mCurrentScreen;
private int mDensityAdjustedSnapVelocity;
private boolean mFirstLayout = true;
private float mLastMotionX;
private float mLastMotionY;
private OnScreenSwitchListener mOnScreenSwitchListener;
private int mMaximumVelocity;
private int mNextScreen = INVALID_SCREEN;
private Scroller mScroller;
private int mTouchSlop;
private int mTouchState = TOUCH_STATE_REST;
private VelocityTracker mVelocityTracker;
private int mLastSeenLayoutWidth = -1;
private static final String TAG = "*********horizontalpager";
private Bitmap bm = null;
/**
* Simple constructor to use when creating a view from code.
*
* #param context The Context the view is running in, through which it can
* access the current theme, resources, etc.
*/
public HorizontalPager(final Context context) {
super(context);
Log.e(TAG, "inside hp standard constructor");
init();
}
/**
* Constructor that is called when inflating a view from XML. This is called
* when a view is being constructed from an XML file, supplying attributes
* that were specified in the XML file. This version uses a default style of
* 0, so the only attribute values applied are those in the Context's Theme
* and the given AttributeSet.
*
* <p>
* The method onFinishInflate() will be called after all children have been
* added.
*
* #param context The Context the view is running in, through which it can
* access the current theme, resources, etc.
* #param attrs The attributes of the XML tag that is inflating the view.
* #see #View(Context, AttributeSet, int)
*/
public HorizontalPager(final Context context, final AttributeSet attrs) {
super(context, attrs);
Log.e(TAG, "inside hp constructor for xml inflation");
init();
}
/**
* Sets up the scroller and touch/fling sensitivity parameters for the pager.
*/
private void init() {
mScroller = new Scroller(getContext());
// Calculate the density-dependent snap velocity in pixels
DisplayMetrics displayMetrics = new DisplayMetrics();
((WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay()
.getMetrics(displayMetrics);
mDensityAdjustedSnapVelocity =
(int) (displayMetrics.density * SNAP_VELOCITY_DIP_PER_SECOND);
final ViewConfiguration configuration = ViewConfiguration.get(getContext());
mTouchSlop = configuration.getScaledTouchSlop();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
}
#Override
protected void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final int width = MeasureSpec.getSize(widthMeasureSpec);
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
if (widthMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("ViewSwitcher can only be used in EXACTLY mode.");
}
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("ViewSwitcher can only be used in EXACTLY mode.");
}
// The children are given the same width and height as the workspace
final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
if (mFirstLayout) {
scrollTo(mCurrentScreen * width, 0);
mFirstLayout = false;
}
else if (width != mLastSeenLayoutWidth) { // Width has changed
/*
* Recalculate the width and scroll to the right position to be sure we're in the right
* place in the event that we had a rotation that didn't result in an activity restart
* (code by aveyD). Without this you can end up between two pages after a rotation.
*/
Display display =
((WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay();
int displayWidth = display.getWidth();
mNextScreen = Math.max(0, Math.min(getCurrentScreen(), getChildCount() - 1));
final int newX = mNextScreen * displayWidth;
final int delta = newX - getScrollX();
mScroller.startScroll(getScrollX(), 0, delta, 0, 0);
}
mLastSeenLayoutWidth = width;
}
#Override
protected void onLayout(final boolean changed, final int l, final int t, final int r,
final int b) {
int childLeft = 0;
final int count = getChildCount();
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
final int childWidth = child.getMeasuredWidth();
child.layout(childLeft, 0, childLeft + childWidth, child.getMeasuredHeight());
childLeft += childWidth;
}
}
}
#Override
public boolean onInterceptTouchEvent(final MotionEvent ev) {
/*
* By Yoni Samlan: Modified onInterceptTouchEvent based on standard ScrollView's
* onIntercept. The logic is designed to support a nested vertically scrolling view inside
* this one; once a scroll registers for X-wise scrolling, handle it in this view and don't
* let the children, but once a scroll registers for y-wise scrolling, let the children
* handle it exclusively.
*/
final int action = ev.getAction();
boolean intercept = false;
switch (action) {
case MotionEvent.ACTION_MOVE:
/*
* If we're in a horizontal scroll event, take it (intercept further events). But if
* we're mid-vertical-scroll, don't even try; let the children deal with it. If we
* haven't found a scroll event yet, check for one.
*/
if (mTouchState == TOUCH_STATE_HORIZONTAL_SCROLLING) {
/*
* We've already started a horizontal scroll; set intercept to true so we can
* take the remainder of all touch events in onTouchEvent.
*/
intercept = true;
} else if (mTouchState == TOUCH_STATE_VERTICAL_SCROLLING) {
// Let children handle the events for the duration of the scroll event.
intercept = false;
} else { // We haven't picked up a scroll event yet; check for one.
/*
* If we detected a horizontal scroll event, start stealing touch events (mark
* as scrolling). Otherwise, see if we had a vertical scroll event -- if so, let
* the children handle it and don't look to intercept again until the motion is
* done.
*/
final float x = ev.getX();
final int xDiff = (int) Math.abs(x - mLastMotionX);
boolean xMoved = xDiff > mTouchSlop;
if (xMoved) {
// Scroll if the user moved far enough along the X axis
mTouchState = TOUCH_STATE_HORIZONTAL_SCROLLING;
mLastMotionX = x;
}
final float y = ev.getY();
final int yDiff = (int) Math.abs(y - mLastMotionY);
boolean yMoved = yDiff > mTouchSlop;
if (yMoved) {
mTouchState = TOUCH_STATE_VERTICAL_SCROLLING;
}
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
// Release the drag.
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_DOWN:
/*
* No motion yet, but register the coordinates so we can check for intercept at the
* next MOVE event.
*/
mLastMotionY = ev.getY();
mLastMotionX = ev.getX();
break;
default:
break;
}
return intercept;
}
#Override
public boolean onTouchEvent(final MotionEvent ev) {
Log.e(TAG, "inside hp ontouchEvent");
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
final int action = ev.getAction();
final float x = ev.getX();
switch (action) {
case MotionEvent.ACTION_DOWN:
/*
* If being flinged and user touches, stop the fling. isFinished will be false if
* being flinged.
*/
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
// Remember where the motion event started
mLastMotionX = x;
if (mScroller.isFinished()) {
mTouchState = TOUCH_STATE_REST;
} else {
mTouchState = TOUCH_STATE_HORIZONTAL_SCROLLING;
}
break;
case MotionEvent.ACTION_MOVE:
final int xDiff = (int) Math.abs(x - mLastMotionX);
boolean xMoved = xDiff > mTouchSlop;
if (xMoved) {
// Scroll if the user moved far enough along the X axis
mTouchState = TOUCH_STATE_HORIZONTAL_SCROLLING;
}
if (mTouchState == TOUCH_STATE_HORIZONTAL_SCROLLING) {
// Scroll to follow the motion event
final int deltaX = (int) (mLastMotionX - x);
mLastMotionX = x;
final int scrollX = getScrollX();
if (deltaX < 0) {
if (scrollX > 0) {
scrollBy(Math.max(-scrollX, deltaX), 0);
}
} else if (deltaX > 0) {
final int availableToScroll =
getChildAt(getChildCount() - 1).getRight() - scrollX - getWidth();
if (availableToScroll > 0) {
scrollBy(Math.min(availableToScroll, deltaX), 0);
}
}
}
break;
case MotionEvent.ACTION_UP:
if (mTouchState == TOUCH_STATE_HORIZONTAL_SCROLLING) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(VELOCITY_UNIT_PIXELS_PER_SECOND,
mMaximumVelocity);
int velocityX = (int) velocityTracker.getXVelocity();
if (velocityX > mDensityAdjustedSnapVelocity && mCurrentScreen > 0) {
// Fling hard enough to move left
snapToScreen(mCurrentScreen - 1);
} else if (velocityX < -mDensityAdjustedSnapVelocity
&& mCurrentScreen < getChildCount() - 1) {
// Fling hard enough to move right
snapToScreen(mCurrentScreen + 1);
} else {
snapToDestination();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
mTouchState = TOUCH_STATE_REST;
break;
default:
break;
}
return true;
}
#Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
} else if (mNextScreen != INVALID_SCREEN) {
mCurrentScreen = Math.max(0, Math.min(mNextScreen, getChildCount() - 1));
// Notify observer about screen change
if (mOnScreenSwitchListener != null) {
mOnScreenSwitchListener.onScreenSwitched(mCurrentScreen);
}
mNextScreen = INVALID_SCREEN;
}
}
/**
* Returns the index of the currently displayed screen.
*
* #return The index of the currently displayed screen.
*/
public int getCurrentScreen() {
return mCurrentScreen;
}
/**
* Sets the current screen.
*
* #param currentScreen The new screen.
* #param animate True to smoothly scroll to the screen, false to snap instantly
*/
public void setCurrentScreen(final int currentScreen, final boolean animate) {
mCurrentScreen = Math.max(0, Math.min(currentScreen, getChildCount() - 1));
if (animate) {
snapToScreen(currentScreen, ANIMATION_SCREEN_SET_DURATION_MILLIS);
} else {
scrollTo(mCurrentScreen * getWidth(), 0);
}
invalidate();
}
/**
* Sets the {#link OnScreenSwitchListener}.
*
* #param onScreenSwitchListener The listener for switch events.
*/
public void setOnScreenSwitchListener(final OnScreenSwitchListener onScreenSwitchListener) {
mOnScreenSwitchListener = onScreenSwitchListener;
}
/**
* Snaps to the screen we think the user wants (the current screen for very small movements; the
* next/prev screen for bigger movements).
*/
private void snapToDestination() {
final int screenWidth = getWidth();
int scrollX = getScrollX();
int whichScreen = mCurrentScreen;
int deltaX = scrollX - (screenWidth * mCurrentScreen);
// Check if they want to go to the prev. screen
if ((deltaX < 0) && mCurrentScreen != 0
&& ((screenWidth / FRACTION_OF_SCREEN_WIDTH_FOR_SWIPE) < -deltaX)) {
whichScreen--;
// Check if they want to go to the next screen
} else if ((deltaX > 0) && (mCurrentScreen + 1 != getChildCount())
&& ((screenWidth / FRACTION_OF_SCREEN_WIDTH_FOR_SWIPE) < deltaX)) {
whichScreen++;
}
snapToScreen(whichScreen);
}
/**
* Snap to a specific screen, animating automatically for a duration proportional to the
* distance left to scroll.
*
* #param whichScreen Screen to snap to
*/
private void snapToScreen(final int whichScreen) {
snapToScreen(whichScreen, -1);
}
/**
* Snaps to a specific screen, animating for a specific amount of time to get there.
*
* #param whichScreen Screen to snap to
* #param duration -1 to automatically time it based on scroll distance; a positive number to
* make the scroll take an exact duration.
*/
private void snapToScreen(final int whichScreen, final int duration) {
/*
* Modified by Yoni Samlan: Allow new snapping even during an ongoing scroll animation. This
* is intended to make HorizontalPager work as expected when used in conjunction with a
* RadioGroup used as "tabbed" controls. Also, make the animation take a percentage of our
* normal animation time, depending how far they've already scrolled.
*/
mNextScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
final int newX = mNextScreen * getWidth();
final int delta = newX - getScrollX();
if (duration < 0) {
// E.g. if they've scrolled 80% of the way, only animation for 20% of the duration
mScroller.startScroll(getScrollX(), 0, delta, 0, (int) (Math.abs(delta)
/ (float) getWidth() * ANIMATION_SCREEN_SET_DURATION_MILLIS));
} else {
mScroller.startScroll(getScrollX(), 0, delta, 0, duration);
}
Log.e(TAG, "about to call inval****************** on viewgroup");
invalidate();
}
/**
* Listener for the event that the HorizontalPager switches to a new view.
*/
public static interface OnScreenSwitchListener {
/**
* Notifies listeners about the new screen. Runs after the animation completed.
*
* #param screen The new screen index.
*/
void onScreenSwitched(int screen);
}
#Override
public void onDraw(Canvas canvas){
super.onDraw(canvas);
Log.e(TAG, "inside hp ondraw()");
}
output:
01-13 14:52:00.290: ERROR/*********horizontalpager(9206): inside hp constructor for xml inflation
01-13 14:52:00.295: ERROR/*********hpActivity(9206): image length = 13215
01-13 14:52:00.295: INFO/global(9206): Default buffer size used in BufferedInputStream constructor. It would be better to be explicit if an 8k buffer is required.
01-13 14:52:00.730: DEBUG/dalvikvm(9206): GC freed 353 objects / 40040 bytes in 58ms
01-13 14:52:00.740: ERROR/*********hpActivity(9206): b = not null
01-13 14:52:00.740: ERROR/*********hpActivity(9206): canvas created
01-13 14:52:00.740: ERROR/*********hpActivity(9206): view created
01-13 14:52:00.740: ERROR/*********hpActivity(9206): view added to viewgroup
01-13 14:52:00.740: ERROR/*********hpActivity(9206): finished handler
01-13 14:52:00.740: ERROR/*********hpActivity(9206): no of chidren = 1
01-13 14:52:00.775: ERROR/*********hpActivity(9206): about to inval viewgroup
01-13 14:52:00.775: ERROR/*********hpActivity(9206): finished inval viewgroup

Lose the Canvas, unless you intend to draw into the image you do not need it.
Your image loading code is horrific. Use BitmapFactory.decodeFile(..) instead.
The Bitmap object you get from BitmapFactory.decodeFile(..) should go inside an ImageView, not a View.
File file = new File(Environment.getExternalStorageDirectory(), "image.jpeg");
if (file.exists() && file.canRead()) {
Bitmap bitmap = BitmapFactory.decodeFile(file.toString());
if (bitmap != null) {
ImageView view = new ImageView(this);
view.setImageBitmap(bitmap);
viewgroup.addView(view);
}
}

which would be the best to do make a horizontal scrolling app in android?

I have to make an application in which the user moves around a screen, which is like our android home screen.
There is a list of images that come, and we can scroll through the images in a horizontal scroll er.
The user cannot change the location of images, it's just like a few thumbnails arranged over a horizontal screen
This is like the paging control in iPhone app development.
I have tried to find ways to do this, but I am fairly new to android and I wanted to know the best way to achieve the above?
I have heard of the gallery control, but I am not sure if it will suit my purposes.
Also if you can give links to the answers you suggest.. it would be great as if there is a new controller involved , I will be able to understand it better as I am still a fresher.
Thank you in advance.
Edit: For those who are unfamiliar with the iPhone paging view,here is a video example.

In my search to implement this, I found many implementation like below
http://www.codeshogun.com/blog/2009/04/16/how-to-implement-swipe-action-in-android/
https://github.com/ysamlan/horizontalpager
http://code.google.com/p/deezapps-widgets/

Well, you could look at the source code for the android homescreen, since it's open source. Maybe you can get some ideas from there.

The GreenDroid library (a collection of useful Android components) recently added a PagedView class that does exactly what you're looking for. It also includes a PageIndicator that works like the iOS dots.
It uses a Adapter system, similar to ListView (with efficient View re-use, etc), which I haven't seen in any of the other implementations of this pattern.
Source code:
https://github.com/cyrilmottier/GreenDroid
Demo application:
https://market.android.com/details?id=com.cyrilmottier.android.gdcatalog

You could use a HorizontalScrollView to hold a LinearLayout containing all your image views.

I think you want like the paging control in iphone app development, in android this functionality is available by using ViewFlipper. It may help you that you want to implement.

Like dmon said you can try something with the android homescreen app OR try this http://code.google.com/p/deezapps-widgets/
This seems to me like a custom implementation of the homescreen from android.. and has the page control as well jus like the iphone.. I think this is what you are looking for...

I have hacked around with items posted here: Horizontal "tab"ish scroll between views
I had good luck replicating a horizontal scrolling type navigation that your describing.

Here is a solution to this problem with a lot of helpful code.

I posted code to do something like the Android homescreen before : Developing an Android Homescreen
Note that will make the whole screen flip between pages, it will not work if you want to flip only part of the screen like shown on the video you linked to.
First the source code
package com.matthieu.launcher;
import android.content.Context;
import android.util.Log;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewConfiguration;
import android.widget.Scroller;
public class DragableSpace extends ViewGroup {
private Scroller mScroller;
private VelocityTracker mVelocityTracker;
private int mScrollX = 0;
private int mCurrentScreen = 0;
private float mLastMotionX;
private static final String LOG_TAG = "DragableSpace";
private static final int SNAP_VELOCITY = 1000;
private final static int TOUCH_STATE_REST = 0;
private final static int TOUCH_STATE_SCROLLING = 1;
private int mTouchState = TOUCH_STATE_REST;
private int mTouchSlop = 0;
public DragableSpace(Context context) {
super(context);
mScroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
this.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.FILL_PARENT));
}
public DragableSpace(Context context, AttributeSet attrs) {
super(context, attrs);
mScroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
this.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT ,
ViewGroup.LayoutParams.FILL_PARENT));
TypedArray a=getContext().obtainStyledAttributes(attrs,R.styleable.DragableSpace);
mCurrentScreen = a.getInteger(R.styleable.DragableSpace_default_screen, 0);
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
/*
* This method JUST determines whether we want to intercept the motion.
* If we return true, onTouchEvent will be called and we do the actual
* scrolling there.
*/
/*
* Shortcut the most recurring case: the user is in the dragging state
* and he is moving his finger. We want to intercept this motion.
*/
final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE)
&& (mTouchState != TOUCH_STATE_REST)) {
return true;
}
final float x = ev.getX();
switch (action) {
case MotionEvent.ACTION_MOVE:
/*
* mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
* whether the user has moved far enough from his original down touch.
*/
/*
* Locally do absolute value. mLastMotionX is set to the y value
* of the down event.
*/
final int xDiff = (int) Math.abs(x - mLastMotionX);
boolean xMoved = xDiff > mTouchSlop;
if (xMoved) {
// Scroll if the user moved far enough along the X axis
mTouchState = TOUCH_STATE_SCROLLING;
}
break;
case MotionEvent.ACTION_DOWN:
// Remember location of down touch
mLastMotionX = x;
/*
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
*/
mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
// Release the drag
mTouchState = TOUCH_STATE_REST;
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mTouchState != TOUCH_STATE_REST;
}
#Override
public boolean onTouchEvent(MotionEvent event) {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);
final int action = event.getAction();
final float x = event.getX();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.i(LOG_TAG, "event : down");
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
// Remember where the motion event started
mLastMotionX = x;
break;
case MotionEvent.ACTION_MOVE:
// Log.i(LOG_TAG,"event : move");
// if (mTouchState == TOUCH_STATE_SCROLLING) {
// Scroll to follow the motion event
final int deltaX = (int) (mLastMotionX - x);
mLastMotionX = x;
//Log.i(LOG_TAG, "event : move, deltaX " + deltaX + ", mScrollX " + mScrollX);
if (deltaX < 0) {
if (mScrollX > 0) {
scrollBy(Math.max(-mScrollX, deltaX), 0);
}
} else if (deltaX > 0) {
final int availableToScroll = getChildAt(getChildCount() - 1)
.getRight()
- mScrollX - getWidth();
if (availableToScroll > 0) {
scrollBy(Math.min(availableToScroll, deltaX), 0);
}
}
// }
break;
case MotionEvent.ACTION_UP:
Log.i(LOG_TAG, "event : up");
// if (mTouchState == TOUCH_STATE_SCROLLING) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) velocityTracker.getXVelocity();
if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) {
// Fling hard enough to move left
snapToScreen(mCurrentScreen - 1);
} else if (velocityX < -SNAP_VELOCITY
&& mCurrentScreen < getChildCount() - 1) {
// Fling hard enough to move right
snapToScreen(mCurrentScreen + 1);
} else {
snapToDestination();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
// }
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
Log.i(LOG_TAG, "event : cancel");
mTouchState = TOUCH_STATE_REST;
}
mScrollX = this.getScrollX();
return true;
}
private void snapToDestination() {
final int screenWidth = getWidth();
final int whichScreen = (mScrollX + (screenWidth / 2)) / screenWidth;
Log.i(LOG_TAG, "from des");
snapToScreen(whichScreen);
}
public void snapToScreen(int whichScreen) {
Log.i(LOG_TAG, "snap To Screen " + whichScreen);
mCurrentScreen = whichScreen;
final int newX = whichScreen * getWidth();
final int delta = newX - mScrollX;
mScroller.startScroll(mScrollX, 0, delta, 0, Math.abs(delta) * 2);
invalidate();
}
public void setToScreen(int whichScreen) {
Log.i(LOG_TAG, "set To Screen " + whichScreen);
mCurrentScreen = whichScreen;
final int newX = whichScreen * getWidth();
mScroller.startScroll(newX, 0, 0, 0, 10);
invalidate();
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childLeft = 0;
final int count = getChildCount();
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
final int childWidth = child.getMeasuredWidth();
child.layout(childLeft, 0, childLeft + childWidth, child
.getMeasuredHeight());
childLeft += childWidth;
}
}
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final int width = MeasureSpec.getSize(widthMeasureSpec);
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
if (widthMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("error mode.");
}
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("error mode.");
}
// The children are given the same width and height as the workspace
final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
Log.i(LOG_TAG, "moving to screen "+mCurrentScreen);
scrollTo(mCurrentScreen * width, 0);
}
#Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
mScrollX = mScroller.getCurrX();
scrollTo(mScrollX, 0);
postInvalidate();
}
}
}
And the layout file :
<?xml version="1.0" encoding="utf-8"?>
<com.matthieu.launcher.DragableSpace xmlns:app="http://schemas.android.com/apk/res/com.matthieu.launcher"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/space"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
app:default_screen="1"
>
<include android:id="#+id/left" layout="#layout/left_screen" />
<include android:id="#+id/center" layout="#layout/initial_screen" />
<include android:id="#+id/right" layout="#layout/right_screen" />
</com.matthieu.launcher.DragableSpace>
To be able to have the extra attribute in the xml file, you want to save this in res/values/attrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="DragableSpace">
<attr name="default_screen" format="integer"/>
</declare-styleable>
</resources>
The original SO post also has a few comments to make it work correctly...

If you're specifically interested in duplicating the home screen-style paging control, take a look at this, with source at Github. It even includes code to do the little page dots on the bottom.