I have a nested LinearLayout (or other type of layout), and I would just like to sum up all the horizontal values of margins/paddings of this view and its parent and potentially grandparents and so on.
I just need the clean width of this Layout which will be window width minus all horizontal margins/paddings.
I've started like that:
private int sumMargins(View view) {
LayoutParams params = (LayoutParams) view.getLayoutParams();
int margins = params.leftMargin + params.rightMargin + view.getPaddingStart() + view.getPaddingEnd();
ViewParent parent = view.getParent();
while (parent != null) {
// here I need to recursively gather all nested parents margins/paddings
// (add them to the `margins` variable)
}
return margins;
}
ViewGroup.MarginLayoutParams will give you access to the margins of a view. The following code will follow the hierarchy of views up to the top-level DecorView and sum left/right margins and padding.
private int sumMargins(View view) {
ViewGroup.MarginLayoutParams marginParams;
int margins = 0;
View decorView = getWindow().getDecorView();
while (view != null && view != decorView) {
marginParams = (ViewGroup.MarginLayoutParams) view.getLayoutParams();
if (marginParams != null) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
margins += marginParams.getMarginStart() + marginParams.getMarginEnd() +
view.getPaddingStart() + view.getPaddingEnd();
} else {
margins += marginParams.leftMargin + marginParams.rightMargin +
view.getPaddingLeft() + view.getPaddingRight();
}
}
view = (View) view.getParent();
}
return margins;
}
I have a gridlayout who's size I want to check before displaying anything in the activity, because I want to check if an image needs to be resized. Can't do it OnStart() because apparently it hasn't been loaded yet. Adding a listener doesn't work due to synchronization issues with the rest of the code. It would be nice if I could just manually generate the value, by using the dimensions of the device, but I for the life of me can't find the exact value of those stupid margins Android places automatically. Any suggestions? Essentially in the code below I need to have height/width of the GridLayout BEFORE SplitImage() is called.
XML
<GridLayout
android:id="#+id/grid_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:useDefaultMargins="false" >
</GridLayout>
Relevant JAVA
public class GamePlay extends Activity {
int difficulty = 0;
int image = 0;
int widthView = 0;
int heightView = 0;
int boardW;
int boardH;
int nSqr;
Bitmap[][] gameBoard;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
Intent intent = getIntent();
difficulty = intent.getIntExtra("DIFFICULTY_KEY_DMIROU246", 0);
image = intent.getIntExtra("LEVEL_KEY_DMIROU246", 0);
setContentView(R.layout.activity_game_play);
Log.w("Derp", "1");
}
#Override
protected void onStart() {
super.onStart();
View view = (View) findViewById(R.id.grid_layout);
Log.w("Derp", "2");
heightView = view.getHeight();
widthView = view.getWidth();
Log.w("Derp", "3");
gameBoard = SplitImage();
Log.w("Derp", "9");
}
You won't get the height or width of the view until it is drawn on the screen.
For this purpose you'll have two ways to get the hight and width of a layout:-
1) ViewTreeObserver--Doc
View view = (View) findViewById(R.id.grid_layout);
ViewTreeObserver vto = view.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
this.layout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
gameBoard = SplitImage();
Log.w("Derp", "9");
}
});
2) Handler.postDelayed--Doc
View view = (View) findViewById(R.id.grid_layout);
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
gameBoard = SplitImage();
Log.w("Derp", "9");
}
}, 500);
The easiest solution is to do this asynchronously, use view.getViewTreeObserver then add a OnGlobalLayoutListener that will get the size of your view and call splitImage().
Take care that your listener is not called to often, the best is to remove it after it has been triggered once.
Try This One
Problem:I have some data show as list (Expandable view).
Main list view Show i am Using List View and show Child view Display another inner listview used.so child view can not calculate cell heigt.
1) i have both UI TABLAT and PHONE
2) if any user any problem implement time this code so contact me i will help you."rp1741995#gmail.com"
public static int getListViewHeightBasedOnChildren(ListView listView,Context context) {
ListAdapter listAdapter = listView.getAdapter();
if (listAdapter != null)
{
int totalHeight = 0;
int size = listAdapter.getCount();
Log.e(TAG, "getListViewHeightBasedOnChildren: >>"+size);
for (int i = 0; i < size; i++)
{
View listItem = listAdapter.getView(i, null, listView);
listItem.measure(0, 0);
totalHeight += listItem.getMeasuredHeight();
}
totalHeight = totalHeight + (listView.getDividerHeight() * (listAdapter.getCount()-1));
if(listAdapter.getCount()!=0) {
if (MyApplication.isTablet(context)) {
Float height = convertDpToPixel(10);
totalHeight = (totalHeight / listAdapter.getCount()) + Math.round(height);
}else {
Float height = convertDpToPixel(80);
totalHeight = (totalHeight / listAdapter.getCount()) + Math.round(height);
}
}
ViewGroup.LayoutParams params = listView.getLayoutParams();
params.height = totalHeight;
//params.height;
Log.e(TAG, "getListViewSize: "+String.valueOf(totalHeight));
listView.setLayoutParams(params);
return totalHeight;
}
return 0;
}
I need to get width and height of Relative layout, however I do not know when the Relative Layout is ready to provide me these two attributes. My activity has several tabs and I call the getWidth() and getHeight() in onCreateView() after inflater.inflate(R.layout.fragment_pizza, container, false);, however it returns 0 for both of them, so they are not apparently ready. Is there some kind of event like afterCreateView() or something similar where I can call these two methods and get the actual width and height?
Code:
public class PizzaFragment extends Fragment {
private static final String TAG = "PizzaFragment";
private Controller controller;
private static final int BUTTON_WIDTH = 70;
private static final int BUTTON_HEIGHT = 20;
private static final int MARGIN_LEFT = 80;
private static final int MARGIN_BOTTOM = 30;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
controller = Controller.getInstance();
controller.loadProducts("pizza", getActivity().getApplicationContext());
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_pizza, container, false);
RelativeLayout layout = (RelativeLayout) view.findViewById(R.id.rl_order_pizza);
Log.d(TAG, "Width: " + layout.getWidth());
Log.d(TAG, "Height: " + layout.getHeight());
int currentX = 10;
int currentY = 10;
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(BUTTON_WIDTH, BUTTON_HEIGHT);
for (Product product: controller.getProducts("pizza")){
Button tempButton = new Button(getActivity());
tempButton.setId(product.getId());
tempButton.setText(product.getName());
if (layout.getWidth() < currentX + MARGIN_LEFT){
currentX = 10;
currentY = MARGIN_BOTTOM;
}
else{
currentX += MARGIN_LEFT;
}
Log.d(TAG, "CurrentY: " + currentY);
Log.d(TAG, "CurrentX: " + currentX);
layoutParams.leftMargin = currentX;
layoutParams.bottomMargin = currentY;
tempButton.setLayoutParams(layoutParams);
layout.addView(tempButton);
}
return view;
}
}
My suggestion is to use a global layout listener like this in onCreateView:
YOUR_LAYOUT_INSTANCE = view.findViewById(R.id.YOUR_LAYOUT_ID);
...
YOUR_LAYOUT_INSTANCE.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener()
{
#Override
public void onGlobalLayout()
{
// gets called after layout has been done but before display.
if (Build.VERSION.SDK_INT < 16) {
YOUR_LAYOUT_INSTANCE.getViewTreeObserver().removeGlobalOnLayoutListener(this);
} else {
YOUR_LAYOUT_INSTANCE.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
// get width and height
}
});
addOnGlobalLayoutListener is deprecated use removeOnGlobalLayoutListener .For better handling extending the solution provided above by #fasteque
YOUR_LAYOUT_INSTANCE.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener()
{
#Override
public void onGlobalLayout()
{
// gets called after layout has been done but before display.
if (Build.VERSION.SDK_INT < 16) {
YOUR_LAYOUT_INSTANCE.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
else {
YOUR_LAYOUT_INSTANCE.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
// get width and height
}
});
Hi I'm using the TouchListView control from here: https://github.com/commonsguy/cwac-touchlist
and I've added some buttons to add to the list in the footer:
mFooter = getLayoutInflater().inflate(R.layout.edit_homepage_footer_layout, null);
mListView = (TouchListView) findViewById(R.id.sectionList);
mListView.addFooterView(mFooter);
It all seems to be working fine until I drag an item in the list, at which point the footer collapses (to the height of one list item I think) obscuring the buttons I have added.
Can anyone suggest a fix/workaround for this?
I actually worked this out shortly after asking it (always the way...)
The issue is in the doExpansion() and unExpandViews() methods which were modifying every item in the list including the footer. To fix it I created a method to check whether we are dealing with a draggable item or the footer:
private boolean isDraggableItem(View view) {
View dragger = view.findViewById(grabberId);
return dragger != null;
}
And then modified the methods mentioned as follows:
private void unExpandViews(boolean deletion) {
for (int i = 0; ; i++) {
View v = getChildAt(i);
if (v == null) {
if (deletion) {
// HACK force update of mItemCount
int position = getFirstVisiblePosition();
int y = getChildAt(0).getTop();
setAdapter(getAdapter());
setSelectionFromTop(position, y);
// end hack
}
layoutChildren(); // force children to be recreated where needed
v = getChildAt(i);
if (v == null) {
break;
}
}
if (isDraggableItem(v)) { //check this view isn't the footer
ViewGroup.LayoutParams params = v.getLayoutParams();
params.height = mItemHeightNormal;
v.setLayoutParams(params);
v.setVisibility(View.VISIBLE);
}
}
}
private void doExpansion() {
Log.d(logTag, "Doing expansion");
int childnum = mDragPos - getFirstVisiblePosition();
if (mDragPos > mFirstDragPos) {
childnum++;
}
View first = getChildAt(mFirstDragPos - getFirstVisiblePosition());
for (int i = 0; ; i++) {
View vv = getChildAt(i);
if (vv == null) {
break;
}
int height = mItemHeightNormal;
int visibility = View.VISIBLE;
if (vv.equals(first)) {
// processing the item that is being dragged
if (mDragPos == mFirstDragPos) {
// hovering over the original location
visibility = View.INVISIBLE;
} else {
// not hovering over it
height = 1;
}
} else if (i == childnum) {
if (mDragPos < getCount() - 1) {
height = mItemHeightExpanded;
}
}
if (isDraggableItem(vv)) { //check this view isn't the footer
ViewGroup.LayoutParams params = vv.getLayoutParams();
params.height = height;
vv.setLayoutParams(params);
vv.setVisibility(visibility);
}
}
}
Would be worth updating the github project to include this I think.
I have a ScrollView which holds a series of Views. I would like to be able to determine if a view is currently visible (if any part of it is currently displayed by the ScrollView). I would expect the below code to do this, surprisingly it does not:
Rect bounds = new Rect();
view.getDrawingRect(bounds);
Rect scrollBounds = new Rect(scroll.getScrollX(), scroll.getScrollY(),
scroll.getScrollX() + scroll.getWidth(), scroll.getScrollY() + scroll.getHeight());
if(Rect.intersects(scrollBounds, bounds))
{
//is visible
}
This works:
Rect scrollBounds = new Rect();
scrollView.getHitRect(scrollBounds);
if (imageView.getLocalVisibleRect(scrollBounds)) {
// Any portion of the imageView, even a single pixel, is within the visible window
} else {
// NONE of the imageView is within the visible window
}
Use View#getHitRect instead of View#getDrawingRect on the view you're testing. You can use View#getDrawingRect on the ScrollView instead of calculating explicitly.
Code from View#getDrawingRect:
public void getDrawingRect(Rect outRect) {
outRect.left = mScrollX;
outRect.top = mScrollY;
outRect.right = mScrollX + (mRight - mLeft);
outRect.bottom = mScrollY + (mBottom - mTop);
}
Code from View#getHitRect:
public void getHitRect(Rect outRect) {
outRect.set(mLeft, mTop, mRight, mBottom);
}
If you want to detect that the view is FULLY visible:
private boolean isViewVisible(View view) {
Rect scrollBounds = new Rect();
mScrollView.getDrawingRect(scrollBounds);
float top = view.getY();
float bottom = top + view.getHeight();
if (scrollBounds.top < top && scrollBounds.bottom > bottom) {
return true;
} else {
return false;
}
}
This extension help detect view fully visible.
It also work if your View is a child of child of ... of ScrollView (eg: ScrollView -> LinearLayout -> ContraintLayout -> ... -> YourView).
fun ScrollView.isViewVisible(view: View): Boolean {
val scrollBounds = Rect()
this.getDrawingRect(scrollBounds)
var top = 0f
var temp = view
while (temp !is ScrollView){
top += (temp).y
temp = temp.parent as View
}
val bottom = top + view.height
return scrollBounds.top < top && scrollBounds.bottom > bottom
}
Note
1) view.getY() and view.getX() return the x,y value to FIRST PARENT.
2) Here is example about how getDrawingRect will return
Link
My Solution is use NestedScrollView Scroll element:
final Rect scrollBounds = new Rect();
scroller.getHitRect(scrollBounds);
scroller.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
#Override
public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
if (myBtn1 != null) {
if (myBtn1.getLocalVisibleRect(scrollBounds)) {
if (!myBtn1.getLocalVisibleRect(scrollBounds)
|| scrollBounds.height() < myBtn1.getHeight()) {
Log.i(TAG, "BTN APPEAR PARCIALY");
} else {
Log.i(TAG, "BTN APPEAR FULLY!!!");
}
} else {
Log.i(TAG, "No");
}
}
}
});
}
To expand a bit on Bill Mote's answer using getLocalVisibleRect, you may want to check if the view is only partially visible:
Rect scrollBounds = new Rect();
scrollView.getHitRect(scrollBounds);
if (!imageView.getLocalVisibleRect(scrollBounds)
|| scrollBounds.height() < imageView.getHeight()) {
// imageView is not within or only partially within the visible window
} else {
// imageView is completely visible
}
public static int getVisiblePercent(View v) {
if (v.isShown()) {
Rect r = new Rect();
v.getGlobalVisibleRect(r);
double sVisible = r.width() * r.height();
double sTotal = v.getWidth() * v.getHeight();
return (int) (100 * sVisible / sTotal);
} else {
return -1;
}
}
I faced the same problem today. While Googling and reading Android reference I found this post and a method I ended up using instead;
public final boolean getLocalVisibleRect (Rect r)
Nice of them not to only providing Rect but also boolean indicating if View visible at all. On negative side this method is undocumented :(
I you want to detect if your View is fully visible, try with this method:
private boolean isViewVisible(View view) {
Rect scrollBounds = new Rect();
mScrollView.getDrawingRect(scrollBounds);
float top = view.getY();
float bottom = top + view.getHeight();
if (scrollBounds.top < top && scrollBounds.bottom > bottom) {
return true; //View is visible.
} else {
return false; //View is NOT visible.
}
}
Strictly speaking you can get the visibility of a view with:
if (myView.getVisibility() == View.VISIBLE) {
//VISIBLE
} else {
//INVISIBLE
}
The posible constant values of the visibility in a View are:
VISIBLE
This view is visible. Use with setVisibility(int) and android:visibility.
INVISIBLE
This view is invisible, but it still takes up space for layout purposes. Use with setVisibility(int) and android:visibility.
GONE
This view is invisible, and it doesn't take any space for layout purposes. Use with setVisibility(int) and android:visibility.
Kotlin way;
An extension for listing scroll view's scroll and get an action if child view visible on screen.
#SuppressLint("ClickableViewAccessibility")
fun View.setChildViewOnScreenListener(view: View, action: () -> Unit) {
val visibleScreen = Rect()
this.setOnTouchListener { _, motionEvent ->
if (motionEvent.action == MotionEvent.ACTION_MOVE) {
this.getDrawingRect(visibleScreen)
if (view.getLocalVisibleRect(visibleScreen)) {
action()
}
}
false
}
}
Use this extension function for any scrollable view
nestedScrollView.setChildViewOnScreenListener(childView) {
action()
}
You can use the FocusAwareScrollView which notifies when view becomes visible :
FocusAwareScrollView focusAwareScrollView = (FocusAwareScrollView) findViewById(R.id.focusAwareScrollView);
if (focusAwareScrollView != null) {
ArrayList<View> viewList = new ArrayList<>();
viewList.add(yourView1);
viewList.add(yourView2);
focusAwareScrollView.registerViewSeenCallBack(viewList, new FocusAwareScrollView.OnViewSeenListener() {
#Override
public void onViewSeen(View v, int percentageScrolled) {
if (v == yourView1) {
// user have seen view1
} else if (v == yourView2) {
// user have seen view2
}
}
});
}
Here is class :
import android.content.Context;
import android.graphics.Rect;
import android.support.v4.widget.NestedScrollView;
import android.util.AttributeSet;
import android.view.View;
import java.util.ArrayList;
import java.util.List;
public class FocusAwareScrollView extends NestedScrollView {
private List<OnScrollViewListener> onScrollViewListeners = new ArrayList<>();
public FocusAwareScrollView(Context context) {
super(context);
}
public FocusAwareScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public FocusAwareScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public interface OnScrollViewListener {
void onScrollChanged(FocusAwareScrollView v, int l, int t, int oldl, int oldt);
}
public interface OnViewSeenListener {
void onViewSeen(View v, int percentageScrolled);
}
public void addOnScrollListener(OnScrollViewListener l) {
onScrollViewListeners.add(l);
}
public void removeOnScrollListener(OnScrollViewListener l) {
onScrollViewListeners.remove(l);
}
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
for (int i = onScrollViewListeners.size() - 1; i >= 0; i--) {
onScrollViewListeners.get(i).onScrollChanged(this, l, t, oldl, oldt);
}
super.onScrollChanged(l, t, oldl, oldt);
}
#Override
public void requestChildFocus(View child, View focused) {
super.requestChildFocus(child, focused);
}
private boolean handleViewSeenEvent(View view, int scrollBoundsBottom, int scrollYOffset,
float minSeenPercentage, OnViewSeenListener onViewSeenListener) {
int loc[] = new int[2];
view.getLocationOnScreen(loc);
int viewBottomPos = loc[1] - scrollYOffset + (int) (minSeenPercentage / 100 * view.getMeasuredHeight());
if (viewBottomPos <= scrollBoundsBottom) {
int scrollViewHeight = this.getChildAt(0).getHeight();
int viewPosition = this.getScrollY() + view.getScrollY() + view.getHeight();
int percentageSeen = (int) ((double) viewPosition / scrollViewHeight * 100);
onViewSeenListener.onViewSeen(view, percentageSeen);
return true;
}
return false;
}
public void registerViewSeenCallBack(final ArrayList<View> views, final OnViewSeenListener onViewSeenListener) {
final boolean[] viewSeen = new boolean[views.size()];
FocusAwareScrollView.this.postDelayed(new Runnable() {
#Override
public void run() {
final Rect scrollBounds = new Rect();
FocusAwareScrollView.this.getHitRect(scrollBounds);
final int loc[] = new int[2];
FocusAwareScrollView.this.getLocationOnScreen(loc);
FocusAwareScrollView.this.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
boolean allViewsSeen = true;
#Override
public void onScrollChange(NestedScrollView v, int x, int y, int oldx, int oldy) {
for (int index = 0; index < views.size(); index++) {
//Change this to adjust criteria
float viewSeenPercent = 1;
if (!viewSeen[index])
viewSeen[index] = handleViewSeenEvent(views.get(index), scrollBounds.bottom, loc[1], viewSeenPercent, onViewSeenListener);
if (!viewSeen[index])
allViewsSeen = false;
}
//Remove this if you want continuous callbacks
if (allViewsSeen)
FocusAwareScrollView.this.setOnScrollChangeListener((NestedScrollView.OnScrollChangeListener) null);
}
});
}
}, 500);
}
}
I ended up implementing a combination of two of the Java answers ( #bill-mote https://stackoverflow.com/a/12428154/3686125 and #denys-vasylenko https://stackoverflow.com/a/25528434/3686125 ) in my project as a set of Kotlin extensions, which support either standard vertial ScrollView or HorizontalScrollView controls.
I just tossed these in a Kotlin file named Extensions.kt, no class, just methods.
I used these to determine which item to snap to when a user stops scrolling in various scrollviews in my project:
fun View.isPartiallyOrFullyVisible(horizontalScrollView: HorizontalScrollView) : Boolean {
val scrollBounds = Rect()
horizontalScrollView.getHitRect(scrollBounds)
return getLocalVisibleRect(scrollBounds)
}
fun View.isPartiallyOrFullyVisible(scrollView: ScrollView) : Boolean {
val scrollBounds = Rect()
scrollView.getHitRect(scrollBounds)
return getLocalVisibleRect(scrollBounds)
}
fun View.isFullyVisible(horizontalScrollView: HorizontalScrollView) : Boolean {
val scrollBounds = Rect()
horizontalScrollView.getDrawingRect(scrollBounds)
val left = x
val right = left + width
return scrollBounds.left < left && scrollBounds.right > right
}
fun View.isFullyVisible(scrollView: ScrollView) : Boolean {
val scrollBounds = Rect()
scrollView.getDrawingRect(scrollBounds)
val top = y
val bottom = top + height
return scrollBounds.top < top && scrollBounds.bottom > bottom
}
fun View.isPartiallyVisible(horizontalScrollView: HorizontalScrollView) : Boolean = isPartiallyOrFullyVisible(horizontalScrollView) && !isFullyVisible(horizontalScrollView)
fun View.isPartiallyVisible(scrollView: ScrollView) : Boolean = isPartiallyOrFullyVisible(scrollView) && !isFullyVisible(scrollView)
Example usage, iterating through scrollview's LinearLayout children and logging outputs:
val linearLayoutChild: LinearLayout = getChildAt(0) as LinearLayout
val scrollView = findViewById(R.id.scroll_view) //Replace with your scrollview control or synthetic accessor
for (i in 0 until linearLayoutChild.childCount) {
with (linearLayoutChild.getChildAt(i)) {
Log.d("ScrollView", "child$i left=$left width=$width isPartiallyOrFullyVisible=${isPartiallyOrFullyVisible(scrollView)} isFullyVisible=${isFullyVisible(scrollView)} isPartiallyVisible=${isPartiallyVisible(scrollView)}")
}
}
My way:
scrollView.viewTreeObserver?.addOnScrollChangedListener {
scrollView.getDrawingRect(Rect())
myViewInsideScrollView.getLocalVisibleRect(Rect())
}
I know its very late. But i have a good solution. Below is the code snippet for getting view visibility percentage in scroll view.
First of all set touch listener on scroll view for getting callback for scroll stop.
#Override
public boolean onTouch(View v, MotionEvent event) {
switch ( event.getAction( ) ) {
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
if(mScrollView == null){
mScrollView = (ScrollView) findViewById(R.id.mScrollView);
}
int childCount = scrollViewRootChild.getChildCount();
//Scroll view location on screen
int[] scrollViewLocation = {0,0};
mScrollView.getLocationOnScreen(scrollViewLocation);
//Scroll view height
int scrollViewHeight = mScrollView.getHeight();
for (int i = 0; i < childCount; i++){
View child = scrollViewRootChild.getChildAt(i);
if(child != null && child.getVisibility() == View.VISIBLE){
int[] viewLocation = new int[2];
child.getLocationOnScreen(viewLocation);
int viewHeight = child.getHeight();
getViewVisibilityOnScrollStopped(scrollViewLocation, scrollViewHeight,
viewLocation, viewHeight, (String) child.getTag(), (childCount - (i+1)));
}
}
}
}, 150);
break;
}
return false;
}
In above code snippet, we are getting call backs for scroll view touch events and post a runnable after 150 millis(Not mandatory) after getting the callback for scroll stopped. In that runnable we will get location of scroll view on the screen and scroll view height. Then get the direct child viewgroup instance of scroll view and get the child counts. In my case direct child of scroll view is LinearLayout named scrollViewRootChild. Then iterate all the child views of scrollViewRootChild. In above code snippet you can see I am getting the location of the child on the screen in a integer array named viewLocation, get height of view in variable name viewHeight. Then i called a private method getViewVisibilityOnScrollStopped. You can get the understanding of the internal working of this method by reading documentation.
/**
* getViewVisibilityOnScrollStopped
* #param scrollViewLocation location of scroll view on screen
* #param scrollViewHeight height of scroll view
* #param viewLocation location of view on screen, you can use the method of view claas's getLocationOnScreen method.
* #param viewHeight height of view
* #param tag tag on view
* #param childPending number of views pending for iteration.
*/
void getViewVisibilityOnScrollStopped(int[] scrollViewLocation, int scrollViewHeight, int[] viewLocation, int viewHeight, String tag, int childPending) {
float visiblePercent = 0f;
int viewBottom = viewHeight + viewLocation[1]; //Get the bottom of view.
if(viewLocation[1] >= scrollViewLocation[1]) { //if view's top is inside the scroll view.
visiblePercent = 100;
int scrollBottom = scrollViewHeight + scrollViewLocation[1]; //Get the bottom of scroll view
if (viewBottom >= scrollBottom) { //If view's bottom is outside from scroll view
int visiblePart = scrollBottom - viewLocation[1]; //Find the visible part of view by subtracting view's top from scrollview's bottom
visiblePercent = (float) visiblePart / viewHeight * 100;
}
}else{ //if view's top is outside the scroll view.
if(viewBottom > scrollViewLocation[1]){ //if view's bottom is outside the scroll view
int visiblePart = viewBottom - scrollViewLocation[1]; //Find the visible part of view by subtracting scroll view's top from view's bottom
visiblePercent = (float) visiblePart / viewHeight * 100;
}
}
if(visiblePercent > 0f){
visibleWidgets.add(tag); //List of visible view.
}
if(childPending == 0){
//Do after iterating all children.
}
}
If you feel any improvement in this code please contribute.
Using #Qberticus answer which was to the point but great btw, I compined a bunch of codes to check if whenever a scrollview is called and got scrolled it trigger the #Qberticus answer and you can do whatever you want, in my case I have a social network containing videos so when the view is drawed on the screen I play the video same idea like facebook and Instagram.
Here's the code:
mainscrollview.getViewTreeObserver().addOnScrollChangedListener(new OnScrollChangedListener() {
#Override
public void onScrollChanged() {
//mainscrollview is my scrollview that have inside it a linearlayout containing many child views.
Rect bounds = new Rect();
for(int xx=1;xx<=postslayoutindex;xx++)
{
//postslayoutindex is the index of how many posts are read.
//postslayoutchild is the main layout for the posts.
if(postslayoutchild[xx]!=null){
postslayoutchild[xx].getHitRect(bounds);
Rect scrollBounds = new Rect();
mainscrollview.getDrawingRect(scrollBounds);
if(Rect.intersects(scrollBounds, bounds))
{
vidPreview[xx].startPlaywithoutstoppping();
//I made my own custom video player using textureview and initialized it globally in the class as an array so I can access it from anywhere.
}
else
{
}
}
}
}
});