I am using custom listview to zoom in and out, this is listview:
public class CustomListView extends ListView {
private static final int INVALID_POINTER_ID = -1;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private float maxWidth = 0.0f;
private float maxHeight = 0.0f;
private float mLastTouchX;
private float mLastTouchY;
private float mPosX;
private float mPosY;
private float width;
private float height;
public CustomListView(Context context) {
super(context);
mScaleDetector = new ScaleGestureDetector(getContext(),
new ScaleListener());
}
public CustomListView(Context context, AttributeSet attrs) {
super(context, attrs);
mScaleDetector = new ScaleGestureDetector(getContext(),
new ScaleListener());
}
public CustomListView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mScaleDetector = new ScaleGestureDetector(getContext(),
new ScaleListener());
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
width = MeasureSpec.getSize(widthMeasureSpec);
height = MeasureSpec.getSize(heightMeasureSpec);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
#Override
public boolean onTouchEvent(#NonNull MotionEvent ev) {
super.onTouchEvent(ev);
final int action = ev.getAction();
mScaleDetector.onTouchEvent(ev);
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
if (mPosX > 0.0f)
mPosX = 0.0f;
else if (mPosX < maxWidth)
mPosX = maxWidth;
if (mPosY > 0.0f)
mPosY = 0.0f;
else if (mPosY < maxHeight)
mPosY = maxHeight;
mLastTouchX = x;
mLastTouchY = y;
invalidate();
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (action & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save(Canvas.MATRIX_SAVE_FLAG);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
canvas.restore();
}
#Override
protected void dispatchDraw(#NonNull Canvas canvas) {
canvas.save(Canvas.MATRIX_SAVE_FLAG);
if (mScaleFactor == 1.0f) {
mPosX = 0.0f;
mPosY = 0.0f;
}
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
super.dispatchDraw(canvas);
canvas.restore();
invalidate();
}
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
mScaleFactor = Math.max(1.0f, Math.min(mScaleFactor, 4.0f));
maxWidth = width - (width * mScaleFactor);
maxHeight = height - (height * mScaleFactor);
invalidate();
return true;
}
}
With this, listview can pinch to zoom in and out.
and I want one more thing, double tap to zoom in and double tap again to zoom out listview.
How to do it?
i use custom listview for zoom in and out.
this is custom listview:
public class CustomListView1 extends ListView {
private static final int INVALID_POINTER_ID = -1;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private float maxWidth = 0.0f;
private float maxHeight = 0.0f;
private float mLastTouchX;
private float mLastTouchY;
private float mPosX;
private float mPosY;
private float width;
private float height;
public CustomListView1(Context context) {
super(context);
mScaleDetector = new ScaleGestureDetector(getContext(),
new ScaleListener());
}
public CustomListView1(Context context, AttributeSet attrs) {
super(context, attrs);
mScaleDetector = new ScaleGestureDetector(getContext(),
new ScaleListener());
}
public CustomListView1(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mScaleDetector = new ScaleGestureDetector(getContext(),
new ScaleListener());
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
width = MeasureSpec.getSize(widthMeasureSpec);
height = MeasureSpec.getSize(heightMeasureSpec);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
#Override
public boolean onTouchEvent(#NonNull MotionEvent ev) {
super.onTouchEvent(ev);
final int action = ev.getAction();
mScaleDetector.onTouchEvent(ev);
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
if (mPosX > 0.0f)
mPosX = 0.0f;
else if (mPosX < maxWidth)
mPosX = maxWidth;
if (mPosY > 0.0f)
mPosY = 0.0f;
else if (mPosY < maxHeight)
mPosY = maxHeight;
mLastTouchX = x;
mLastTouchY = y;
invalidate();
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (action & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save(Canvas.MATRIX_SAVE_FLAG);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
canvas.restore();
}
#Override
protected void dispatchDraw(#NonNull Canvas canvas) {
canvas.save(Canvas.MATRIX_SAVE_FLAG);
if (mScaleFactor == 1.0f) {
mPosX = 0.0f;
mPosY = 0.0f;
}
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
super.dispatchDraw(canvas);
canvas.restore();
invalidate();
}
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
mScaleFactor = Math.max(1.0f, Math.min(mScaleFactor, 4.0f));
maxWidth = width - (width * mScaleFactor);
maxHeight = height - (height * mScaleFactor);
invalidate();
return true;
}
}
}
this listview can zoom in and out.
but this listview just zoom in the top left corner.
how to fix it to zoom in the center of the pinch?
I took the code from that other ZoomLayout thing and adapted it to your code. Just replace the ScaleListener class at the bottom with this code:
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
float prevScaleFactor = mScaleFactor;
mScaleFactor *= detector.getScaleFactor();
mScaleFactor = Math.max(1.0f, Math.min(mScaleFactor, 4.0f));
maxWidth = width - (width * mScaleFactor);
maxHeight = height - (height * mScaleFactor);
float adjustedScaleFactor = mScaleFactor / prevScaleFactor;
float focusX = detector.getFocusX();
float focusY = detector.getFocusY();
mPosX += (mPosX - focusX) * (adjustedScaleFactor - 1);
mPosY += (mPosY - focusY) * (adjustedScaleFactor - 1);
invalidate();
return true;
}
}
package com.example.demo;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.RelativeLayout;
public class MyLayout extends RelativeLayout {
private static final int INVALID_POINTER_ID = -1;
private Drawable mIcon;
private float mPosX;
private float mPosY;
MyLayout temp;
private float mLastTouchX;
private float mLastTouchY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
public MyLayout(Context context) {
this(context, null, 0);
temp = this;
}
public MyLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
temp = this;
}
public MyLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mIcon = context.getResources()
.getDrawable(R.drawable.ic_launcher);
mIcon.setBounds(0, 0, mIcon.getIntrinsicWidth(),
mIcon.getIntrinsicHeight());
temp = this;
mScaleDetector = new ScaleGestureDetector(context,
new ScaleListener());
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
// Let the ScaleGestureDetector inspect all events.
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev
.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
// Only move if the ScaleGestureDetector isn't processing a
// gesture.
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a
// new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1
: 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int count = getChildCount();
Log.d("onLayout", "" + count);
for (int i = 0; i < count; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) child
.getLayoutParams();
child.layout((int) (params.leftMargin * mScaleFactor),
(int) (params.topMargin * mScaleFactor),
(int) ((params.leftMargin + child
.getMeasuredWidth()) * mScaleFactor),
(int) ((params.topMargin + child
.getMeasuredHeight()) * mScaleFactor));
child.setLayoutParams(params);
}
}
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save(Canvas.MATRIX_SAVE_FLAG);
// canvas.translate(mLastTouchX, mLastTouchY);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
System.out.println("onDraw");
int count = getChildCount();
for (int i = 0; i < count; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.draw(canvas);
Log.d("onDraw", "" + mScaleFactor);
}
}
canvas.restore();
}
#Override
protected void dispatchDraw(Canvas canvas) {
canvas.save(Canvas.MATRIX_SAVE_FLAG);
System.out.println("dispatchDraw");
System.out.println("x :: " + mPosX + " :: X2 :: " + mLastTouchX);
System.out.println("y :: " + mPosY + " :: Y2 :: " + mLastTouchY);
System.out.println("Scale factor :: " + mScaleFactor);
canvas.translate(
mPosX
- ((mLastTouchX * mScaleFactor) - mLastTouchX),
mPosY
- ((mLastTouchY * mScaleFactor) - mLastTouchY));
canvas.scale(mScaleFactor, mScaleFactor);
super.dispatchDraw(canvas);
canvas.restore();
}
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math
.max(1.0f, Math.min(mScaleFactor, 5.0f));
// Log.d("onScale", ""+mScaleFactor);
temp.invalidate();
invalidate();
return true;
}
}
}
Above code is for custom relative layout for pinch zoom and move with finger on screen.
But, above code is working properly. but problem is that I unable to implement zoom from where I pinch on screen.
Please help me for this.
I took a references from below link.
Zoom and Pinch RelativeLayout
I am arranging my views inside HorizontalScrollView and my each view(DrawView.java) contains rectangle. When the activity only contain this view, pinch zoom functionality is working fine(See Code 1 and respective image 1) but when I am arranging multiple of these views in HorizontalScrollView, it's not working properly because touch events of this view are messing up with touch events of HorizontalScrollView(Code 2 and Image 2).
Someone please help me to fix this bug.
This is a code for activity in which pinch zoom is working fine.
public class MainActivity extends Activity {
DrawView drawView;
public class DrawView extends View {
Paint paint = new Paint();
public int recog=-1; // this variable will tell if onDraw is called for first time or is called by listener usinf invalidate()
boolean listener=false;
int data[] = new int[] {200,200,200,200,200,200,200,200,200,200,200,200};
private float MIN_ZOOM = 0.1f;
private float MAX_ZOOM = 10f;
private float mPosX;
private float mPosY;
boolean zoom=false;
private ScaleGestureDetector detector;
float width=200;
private float mLastTouchX;
private float mLastTouchY;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private static final int INVALID_POINTER_ID = -1;
// The ‘active pointer’ is the one currently moving our object.
private int mActivePointerId = INVALID_POINTER_ID;
public DrawView(Context context) {
this(context, null);
}
public DrawView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public DrawView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
#Override
public void onDraw(Canvas canvas) {
paint.setColor(Color.GREEN);
canvas.save();
if(listener ==true)
mScaleFactor+=0.4;
Log.e("Ronak","Listener"+listener);
Log.e("Ronak","ScaleFactor"+mScaleFactor);
canvas.scale(mScaleFactor, 1);
canvas.drawRect(0.0f, 0.0f, 300.0f, 100.0f, paint);
makeLinesinRange(0,100,300,100,200, 5, canvas,100);
width=mScaleFactor*300;
canvas.restore();
requestLayout();
}
public boolean onTouchEvent(MotionEvent ev) {
// Let the ScaleGestureDetector inspect all events.
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
#Override protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
// int width = MeasureSpec.getSize(widthMeasureSpec);
//int height = (int)(width * 0.5f);
setMeasuredDimension((int)width, 350);
}
private void makeLinesinRange(int x1, int y1, int x2, int y2, int size, int divisions, Canvas canvas,int width)
{
paint.setStrokeWidth(6);
paint.setColor(Color.DKGRAY);
float kk=(x2-x1)/(divisions-1);
for(int i=0;i<divisions;i++)
{
canvas.drawLine(x1+i*kk, y1, x1+i*kk, y2+size, paint);
}
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
Log.e("Ronak","scale "+mScaleFactor);
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.3f, Math.min(mScaleFactor, 5.0f));
invalidate();
return true;
}
}
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
drawView = new DrawView(this);
drawView.setBackgroundColor(Color.WHITE);
setContentView(drawView);
}
}
DrawView.java. This is a code of single view. I am arranging multiple of these views in HorizontalScrollView
public class DrawView extends View {
Paint paint = new Paint();
public int recog=-1; // this variable will tell if onDraw is called for first time or is called by listener usinf invalidate()
boolean listener=false;
int view_number=0;
int data[] = new int[] {200,200,200,200,200,200,200,200,200,200,200,200};
int lines[] = new int[] {4,5,7,8,2,6,6,3,2,1,1,6};
String[] type=new String[]{"Song","Music","Magazine","Audible","Videos","Apps","Other"};
private static float MIN_ZOOM = 0.1f;
private static float MAX_ZOOM = 10f;
private float mPosX;
private float mPosY;
boolean zoom=false;
private ScaleGestureDetector detector;
float width=700;
float height=500;
private float mLastTouchX;
private float mLastTouchY;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private static final int INVALID_POINTER_ID = -1;
// The ‘active pointer’ is the one currently moving our object.
private int mActivePointerId = INVALID_POINTER_ID;
public DrawView(Context context) {
this(context, null);
}
public DrawView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public DrawView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
#Override
public void onDraw(Canvas canvas) {
paint.setColor(Color.BLUE);
canvas.save();
if(listener ==true)
mScaleFactor+=0.4;
Log.e("Ronak","Listener"+listener);
Log.e("Ronak","ScaleFactor"+mScaleFactor);
canvas.scale(mScaleFactor, 1);
canvas.drawRect(0.0f, 0.0f, 300.0f, 70.0f, paint);
makeLinesinRange(0,70,300,70,200, lines[view_number], canvas,100);
width=mScaleFactor*300;
height=mScaleFactor*100;
/*int start=0;
int temp=(int)width/lines[view_number];
for(int i=0;i<lines[view_number];i++)
{
canvas.drawText(type[i], 50, 100, paint);
start=temp;
temp+=temp;
}*/
canvas.restore();
requestLayout();
}
public boolean onTouchEvent(MotionEvent ev) {
// Let the ScaleGestureDetector inspect all events.
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
// invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
public boolean onInterceptTouchEvent(MotionEvent event) {
/* switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
mIsBeingDragged = false;
break;
case MotionEvent.ACTION_MOVE:
float x = event.getX();
float y = event.getY();
float xDelta = Math.abs(x - mLastX);
float yDelta = Math.abs(y - mLastY);
float yDeltaTotal = y - mStartY;
if (yDelta > xDelta && Math.abs(yDeltaTotal) > mTouchSlop) {
mIsBeingDragged = true;
mStartY = y;
return true;
}
break;
}*/
Log.e("Ronak","Here");
return false;
}
#Override protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
// int width = MeasureSpec.getSize(widthMeasureSpec);
//int height = (int)(width * 0.5f);
setMeasuredDimension((int)width, 350);
}
private void makeLinesinRange(int x1, int y1, int x2, int y2, int size, int total_events, Canvas canvas,int width)
{
paint.setStrokeWidth(6);
paint.setColor(Color.MAGENTA);
if(total_events<1)
{
return;
}
if(total_events==1)
{
canvas.drawLine(((x1+x2)/2), y1, (x1+x2)/2, y2+size, paint);
}
else if(total_events==2)
{
canvas.drawLine(((x1+x2)/3), y1, (x1+x2)/3, y2+size, paint);
canvas.drawLine((2*(x1+x2)/3), y1, 2*(x1+x2)/3, y2+size, paint);
}
else
{
paint.setStrokeWidth(6);
paint.setColor(Color.MAGENTA);
float kk=(x2-x1)/(total_events-1);
for(int i=0;i<total_events;i++)
{
canvas.drawLine(x1+i*kk, y1, x1+i*kk, y2+size, paint);
}
}
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
Log.e("Ronak","scale "+mScaleFactor);
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
invalidate();
return true;
}
}
}
I also have a class which is extending HorizontalScrollView and is calling the above class(DrawView.java) for fitting multiple of these view in horizontal scrolling. Is there ant need to override the onTouch function of this class?
First: YIKES! Don't call requestLayout() from onDraw() -- or you'll get 100% load, all it's ever going to do is relayout and redraw itself.
Second: Remove onInterceptTouchEvent() from DrawView. Since it extends View -- and Views don't have this method -- it'll not get called as part of the touch dispatch process anyway.
Third: which one's not working -- scrolling or scaling?
Read this thread, it's got some insights on how to handle multiple gesture-consuming components
I'm trying a simple CustomView with canvas. This custom view simply change the position of an icon picture on the screen randomly when is invoked updatePosition(), and in my intention should move the image on drag, scale on pinch... and when I touch a position in the screen should appear in the clicked position.
My try is the follow
public class CustomView extends View {
Bitmap mBmp;
Random mRnd;
Paint mPaint;
private static final int INVALID_POINTER_ID = -1;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
int w, h, bw, bh;
int px = -1, py = -1;
public CustomView(Context context) {
this(context, null, 0);
mBmp = BitmapFactory.decodeResource(context.getResources(),
R.drawable.icon);
}
public CustomView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs, 0);
mBmp = BitmapFactory.decodeResource(context.getResources(),
R.drawable.icon);
bw = mBmp.getWidth();
bh = mBmp.getHeight();
mPaint = new Paint();
mPaint.setColor(Color.CYAN);
mPaint.setAntiAlias(true);
mRnd = new Random();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
Log.d("DEBUG", "X: " + mPosX + " Y: " + mPosY);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
if (px == -1 && py == -1) {
px = w / 2 - bw / 2;
py = h / 2 - bh / 2;
}
canvas.drawCircle(px + (bw / 2), py + (bh / 2), 70, mPaint);
canvas.drawBitmap(mBmp, px, py, null);
canvas.restore();
}
public void updatePosition() {
px = mRnd.nextInt(w - bw);
py = mRnd.nextInt(h - bh);
invalidate();
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
w = MeasureSpec.getSize(widthMeasureSpec);
h = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(w, h);
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 10.0f));
invalidate();
return true;
}
}
}
updatePosition() listener works while onTouchListener cause crash of the application with a NullPointerException if I try to drag the image or touch any position of the screen
Could someone help me? Thanks
It looks like mScaleDetector is only initialized in one of the constructor. It should be initialized in all constructors. A common pattern is to create an init() method and place all you initializing in there then call that method from all constructors.
Note: It's always helpful to post a StackTrace... You should be able to see which constructor got called.