I am using code sample from Making Sense of Multitouch
for zooming image view. On ScaleListener I added ScaleGestureDetector.getFocusX() and getFocusY()
for content to zoom about the focal point of the gesture. It is working fine.
The problem is, on first multitouch the entire Image drawing position is changing to the current touch point and zooming it from there. Could you help me to resolve this issue?
Here is My Code Sample For TouchImageView.
public class TouchImageViewSample extends ImageView {
private Paint borderPaint = null;
private Paint backgroundPaint = null;
private float mPosX = 0f;
private float mPosY = 0f;
private float mLastTouchX;
private float mLastTouchY;
private static final int INVALID_POINTER_ID = -1;
private static final String LOG_TAG = "TouchImageView";
// The ‘active pointer’ is the one currently moving our object.
private int mActivePointerId = INVALID_POINTER_ID;
public TouchImageViewSample(Context context) {
this(context, null, 0);
}
public TouchImageViewSample(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
// Existing code ...
public TouchImageViewSample(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// Create our ScaleGestureDetector
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
borderPaint = new Paint();
borderPaint.setARGB(255, 255, 128, 0);
borderPaint.setStyle(Paint.Style.STROKE);
borderPaint.setStrokeWidth(4);
backgroundPaint = new Paint();
backgroundPaint.setARGB(32, 255, 255, 255);
backgroundPaint.setStyle(Paint.Style.FILL);
}
@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;
}
/*
* (non-Javadoc)
*
* @see android.view.View#draw(android.graphics.Canvas)
*/
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
canvas.drawRect(0, 0, getWidth() - 1, getHeight() - 1, borderPaint);
}
@Override
public void onDraw(Canvas canvas) {
canvas.drawRect(0, 0, getWidth() - 1, getHeight() - 1, backgroundPaint);
if (this.getDrawable() != null) {
canvas.save();
canvas.translate(mPosX, mPosY);
Matrix matrix = new Matrix();
matrix.postScale(mScaleFactor, mScaleFactor, pivotPointX,
pivotPointY);
// canvas.setMatrix(matrix);
canvas.drawBitmap(
((BitmapDrawable) this.getDrawable()).getBitmap(), matrix,
null);
// this.getDrawable().draw(canvas);
canvas.restore();
}
}
/*
* (non-Javadoc)
*
* @see
* android.widget.ImageView#setImageDrawable(android.graphics.drawable.Drawable
* )
*/
@Override
public void setImageDrawable(Drawable drawable) {
// Constrain to given size but keep aspect ratio
int width = drawable.getIntrinsicWidth();
int height = drawable.getIntrinsicHeight();
mLastTouchX = mPosX = 0;
mLastTouchY = mPosY = 0;
int borderWidth = (int) borderPaint.getStrokeWidth();
mScaleFactor = Math.min(((float) getLayoutParams().width - borderWidth)
/ width, ((float) getLayoutParams().height - borderWidth)
/ height);
pivotPointX = (((float) getLayoutParams().width - borderWidth) - (int) (width * mScaleFactor)) / 2;
pivotPointY = (((float) getLayoutParams().height - borderWidth) - (int) (height * mScaleFactor)) / 2;
super.setImageDrawable(drawable);
}
float pivotPointX = 0f;
float pivotPointY = 0f;
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
pivotPointX = detector.getFocusX();
pivotPointY = detector.getFocusY();
Log.d(LOG_TAG, "mScaleFactor " + mScaleFactor);
Log.d(LOG_TAG, "pivotPointY " + pivotPointY + ", pivotPointX= "
+ pivotPointX);
mScaleFactor = Math.max(0.05f, mScaleFactor);
invalidate();
return true;
}
}
And here how I used it within my activity.
ImageView imageView = (ImageView) findViewById(R.id.imgView);
int hMargin = (int) (displayMetrics.widthPixels * .10);
int vMargin = (int) (displayMetrics.heightPixels * .10);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(displayMetrics.widthPixels - (hMargin * 2), (int)(displayMetrics.heightPixels - btnCamera.getHeight()) - (vMargin * 2));
params.leftMargin = hMargin;
params.topMargin = vMargin;
imageView.setLayoutParams(params);
imageView.setImageDrawable(drawable);
This question is related to
android
android-layout
android-intent
android-widget
I made my own custom imageview with pinch to zoom. There is no limits/borders on Chirag Ravals code, so user can drag the image off the screen. This will fix it.
Here is the CustomImageView class:
public class CustomImageVIew extends ImageView implements OnTouchListener {
private Matrix matrix = new Matrix();
private Matrix savedMatrix = new Matrix();
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
private int mode = NONE;
private PointF mStartPoint = new PointF();
private PointF mMiddlePoint = new PointF();
private Point mBitmapMiddlePoint = new Point();
private float oldDist = 1f;
private float matrixValues[] = {0f, 0f, 0f, 0f, 0f, 0f, 0f, 0f, 0f};
private float scale;
private float oldEventX = 0;
private float oldEventY = 0;
private float oldStartPointX = 0;
private float oldStartPointY = 0;
private int mViewWidth = -1;
private int mViewHeight = -1;
private int mBitmapWidth = -1;
private int mBitmapHeight = -1;
private boolean mDraggable = false;
public CustomImageVIew(Context context) {
this(context, null, 0);
}
public CustomImageVIew(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomImageVIew(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.setOnTouchListener(this);
}
@Override
public void onSizeChanged (int w, int h, int oldw, int oldh){
super.onSizeChanged(w, h, oldw, oldh);
mViewWidth = w;
mViewHeight = h;
}
public void setBitmap(Bitmap bitmap){
if(bitmap != null){
setImageBitmap(bitmap);
mBitmapWidth = bitmap.getWidth();
mBitmapHeight = bitmap.getHeight();
mBitmapMiddlePoint.x = (mViewWidth / 2) - (mBitmapWidth / 2);
mBitmapMiddlePoint.y = (mViewHeight / 2) - (mBitmapHeight / 2);
matrix.postTranslate(mBitmapMiddlePoint.x, mBitmapMiddlePoint.y);
this.setImageMatrix(matrix);
}
}
@Override
public boolean onTouch(View v, MotionEvent event){
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
mStartPoint.set(event.getX(), event.getY());
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
if(oldDist > 10f){
savedMatrix.set(matrix);
midPoint(mMiddlePoint, event);
mode = ZOOM;
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
if(mode == DRAG){
drag(event);
} else if(mode == ZOOM){
zoom(event);
}
break;
}
return true;
}
public void drag(MotionEvent event){
matrix.getValues(matrixValues);
float left = matrixValues[2];
float top = matrixValues[5];
float bottom = (top + (matrixValues[0] * mBitmapHeight)) - mViewHeight;
float right = (left + (matrixValues[0] * mBitmapWidth)) -mViewWidth;
float eventX = event.getX();
float eventY = event.getY();
float spacingX = eventX - mStartPoint.x;
float spacingY = eventY - mStartPoint.y;
float newPositionLeft = (left < 0 ? spacingX : spacingX * -1) + left;
float newPositionRight = (spacingX) + right;
float newPositionTop = (top < 0 ? spacingY : spacingY * -1) + top;
float newPositionBottom = (spacingY) + bottom;
boolean x = true;
boolean y = true;
if(newPositionRight < 0.0f || newPositionLeft > 0.0f){
if(newPositionRight < 0.0f && newPositionLeft > 0.0f){
x = false;
} else{
eventX = oldEventX;
mStartPoint.x = oldStartPointX;
}
}
if(newPositionBottom < 0.0f || newPositionTop > 0.0f){
if(newPositionBottom < 0.0f && newPositionTop > 0.0f){
y = false;
} else{
eventY = oldEventY;
mStartPoint.y = oldStartPointY;
}
}
if(mDraggable){
matrix.set(savedMatrix);
matrix.postTranslate(x? eventX - mStartPoint.x : 0, y? eventY - mStartPoint.y : 0);
this.setImageMatrix(matrix);
if(x)oldEventX = eventX;
if(y)oldEventY = eventY;
if(x)oldStartPointX = mStartPoint.x;
if(y)oldStartPointY = mStartPoint.y;
}
}
public void zoom(MotionEvent event){
matrix.getValues(matrixValues);
float newDist = spacing(event);
float bitmapWidth = matrixValues[0] * mBitmapWidth;
float bimtapHeight = matrixValues[0] * mBitmapHeight;
boolean in = newDist > oldDist;
if(!in && matrixValues[0] < 1){
return;
}
if(bitmapWidth > mViewWidth || bimtapHeight > mViewHeight){
mDraggable = true;
} else{
mDraggable = false;
}
float midX = (mViewWidth / 2);
float midY = (mViewHeight / 2);
matrix.set(savedMatrix);
scale = newDist / oldDist;
matrix.postScale(scale, scale, bitmapWidth > mViewWidth ? mMiddlePoint.x : midX, bimtapHeight > mViewHeight ? mMiddlePoint.y : midY);
this.setImageMatrix(matrix);
}
/** Determine the space between the first two fingers */
private float spacing(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return (float)Math.sqrt(x * x + y * y);
}
/** Calculate the mid point of the first two fingers */
private void midPoint(PointF point, MotionEvent event) {
float x = event.getX(0) + event.getX(1);
float y = event.getY(0) + event.getY(1);
point.set(x / 2, y / 2);
}
}
This is how you can use it in your activity:
CustomImageVIew mImageView = (CustomImageVIew)findViewById(R.id.customImageVIew1);
mImage.setBitmap(your bitmap);
And layout:
<your.package.name.CustomImageVIew
android:id="@+id/customImageVIew1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginBottom="15dp"
android:layout_marginLeft="15dp"
android:layout_marginRight="15dp"
android:layout_marginTop="15dp"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:scaleType="matrix"/> // important
When learning a new concept I don't like using libraries or code dumps. I found a good description here and in the documentation of how to resize an image by pinching. This answer is a slightly modified summary. You will probably want to add more functionality later, but it will help you get started.
The ImageView
just uses the app logo since it is already available. You can replace it with any image you like, though.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/imageView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="@mipmap/ic_launcher"
android:layout_centerInParent="true"/>
</RelativeLayout>
We use a ScaleGestureDetector
on the activity to listen to touch events. When a scale (ie, pinch) gesture is detected, then the scale factor is used to resize the ImageView
.
public class MainActivity extends AppCompatActivity {
private ScaleGestureDetector mScaleGestureDetector;
private float mScaleFactor = 1.0f;
private ImageView mImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// initialize the view and the gesture detector
mImageView = findViewById(R.id.imageView);
mScaleGestureDetector = new ScaleGestureDetector(this, new ScaleListener());
}
// this redirects all touch events in the activity to the gesture detector
@Override
public boolean onTouchEvent(MotionEvent event) {
return mScaleGestureDetector.onTouchEvent(event);
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
// when a scale gesture is detected, use it to resize the image
@Override
public boolean onScale(ScaleGestureDetector scaleGestureDetector){
mScaleFactor *= scaleGestureDetector.getScaleFactor();
mImageView.setScaleX(mScaleFactor);
mImageView.setScaleY(mScaleFactor);
return true;
}
}
}
You can limit the size of the scaling with something like
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
Thanks again to Pinch-to-zoom with multi-touch gestures In Android
You will probably want to do other things like panning and scaling to some focus point. You can develop these things yourself, but if you would like to use a pre-made custom view, copy TouchImageView.java
into your project and use it like a normal ImageView
. It worked well for me and I only ran into one bug. I plan to further edit the code to remove the warning and the parts that I don't need. You can do the same.
Add bellow line in build.gradle:
compile 'com.commit451:PhotoView:1.2.4'
or
compile 'com.github.chrisbanes:PhotoView:1.3.0'
In Java file:
PhotoViewAttacher photoAttacher;
photoAttacher= new PhotoViewAttacher(Your_Image_View);
photoAttacher.update();
You can use this class : TouchImageView
Custom zoom view in Kotlin
import android.content.Context
import android.graphics.Matrix
import android.graphics.PointF
import android.util.AttributeSet
import android.util.Log
import android.view.MotionEvent
import android.view.ScaleGestureDetector
import android.view.ScaleGestureDetector.SimpleOnScaleGestureListener
import androidx.appcompat.widget.AppCompatImageView
class ZoomImageview : AppCompatImageView {
var matri: Matrix? = null
var mode = NONE
// Remember some things for zooming
var last = PointF()
var start = PointF()
var minScale = 1f
var maxScale = 3f
lateinit var m: FloatArray
var viewWidth = 0
var viewHeight = 0
var saveScale = 1f
protected var origWidth = 0f
protected var origHeight = 0f
var oldMeasuredWidth = 0
var oldMeasuredHeight = 0
var mScaleDetector: ScaleGestureDetector? = null
var contex: Context? = null
constructor(context: Context) : super(context) {
sharedConstructing(context)
}
constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {
sharedConstructing(context)
}
private fun sharedConstructing(context: Context) {
super.setClickable(true)
this.contex= context
mScaleDetector = ScaleGestureDetector(context, ScaleListener())
matri = Matrix()
m = FloatArray(9)
imageMatrix = matri
scaleType = ScaleType.MATRIX
setOnTouchListener { v, event ->
mScaleDetector!!.onTouchEvent(event)
val curr = PointF(event.x, event.y)
when (event.action) {
MotionEvent.ACTION_DOWN -> {
last.set(curr)
start.set(last)
mode = DRAG
}
MotionEvent.ACTION_MOVE -> if (mode == DRAG) {
val deltaX = curr.x - last.x
val deltaY = curr.y - last.y
val fixTransX = getFixDragTrans(deltaX, viewWidth.toFloat(), origWidth * saveScale)
val fixTransY = getFixDragTrans(deltaY, viewHeight.toFloat(), origHeight * saveScale)
matri!!.postTranslate(fixTransX, fixTransY)
fixTrans()
last[curr.x] = curr.y
}
MotionEvent.ACTION_UP -> {
mode = NONE
val xDiff = Math.abs(curr.x - start.x).toInt()
val yDiff = Math.abs(curr.y - start.y).toInt()
if (xDiff < CLICK && yDiff < CLICK) performClick()
}
MotionEvent.ACTION_POINTER_UP -> mode = NONE
}
imageMatrix = matri
invalidate()
true // indicate event was handled
}
}
fun setMaxZoom(x: Float) {
maxScale = x
}
private inner class ScaleListener : SimpleOnScaleGestureListener() {
override fun onScaleBegin(detector: ScaleGestureDetector): Boolean {
mode = ZOOM
return true
}
override fun onScale(detector: ScaleGestureDetector): Boolean {
var mScaleFactor = detector.scaleFactor
val origScale = saveScale
saveScale *= mScaleFactor
if (saveScale > maxScale) {
saveScale = maxScale
mScaleFactor = maxScale / origScale
} else if (saveScale < minScale) {
saveScale = minScale
mScaleFactor = minScale / origScale
}
if (origWidth * saveScale <= viewWidth || origHeight * saveScale <= viewHeight) matri!!.postScale(mScaleFactor, mScaleFactor, viewWidth / 2.toFloat(), viewHeight / 2.toFloat()) else matri!!.postScale(mScaleFactor, mScaleFactor, detector.focusX, detector.focusY)
fixTrans()
return true
}
}
fun fixTrans() {
matri!!.getValues(m)
val transX = m[Matrix.MTRANS_X]
val transY = m[Matrix.MTRANS_Y]
val fixTransX = getFixTrans(transX, viewWidth.toFloat(), origWidth * saveScale)
val fixTransY = getFixTrans(transY, viewHeight.toFloat(), origHeight * saveScale)
if (fixTransX != 0f || fixTransY != 0f) matri!!.postTranslate(fixTransX, fixTransY)
}
fun getFixTrans(trans: Float, viewSize: Float, contentSize: Float): Float {
val minTrans: Float
val maxTrans: Float
if (contentSize <= viewSize) {
minTrans = 0f
maxTrans = viewSize - contentSize
} else {
minTrans = viewSize - contentSize
maxTrans = 0f
}
if (trans < minTrans) return -trans + minTrans
if (trans > maxTrans) return -trans + maxTrans
return 0f
}
fun getFixDragTrans(delta: Float, viewSize: Float, contentSize: Float): Float {
if (contentSize <= viewSize) {
return 0f
} else {
return delta
}
}
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec)
viewWidth = MeasureSpec.getSize(widthMeasureSpec)
viewHeight = MeasureSpec.getSize(heightMeasureSpec)
//
// Rescales image on rotation
//
if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight || viewWidth == 0 || viewHeight == 0) return
oldMeasuredHeight = viewHeight
oldMeasuredWidth = viewWidth
if (saveScale == 1f) {
//Fit to screen.
val scale: Float
val drawable = drawable
if (drawable == null || drawable.intrinsicWidth == 0 || drawable.intrinsicHeight == 0) return
val bmWidth = drawable.intrinsicWidth
val bmHeight = drawable.intrinsicHeight
Log.d("bmSize", "bmWidth: $bmWidth bmHeight : $bmHeight")
val scaleX = viewWidth.toFloat() / bmWidth.toFloat()
val scaleY = viewHeight.toFloat() / bmHeight.toFloat()
scale = Math.min(scaleX, scaleY)
matri!!.setScale(scale, scale)
// Center the image
var redundantYSpace = viewHeight.toFloat() - scale * bmHeight.toFloat()
var redundantXSpace = viewWidth.toFloat() - scale * bmWidth.toFloat()
redundantYSpace /= 2.toFloat()
redundantXSpace /= 2.toFloat()
matri!!.postTranslate(redundantXSpace, redundantYSpace)
origWidth = viewWidth - 2 * redundantXSpace
origHeight = viewHeight - 2 * redundantYSpace
imageMatrix = matri
}
fixTrans()
}
companion object {
// We can be in one of these 3 states
const val NONE = 0
const val DRAG = 1
const val ZOOM = 2
const val CLICK = 3
}
}
I made code for imageview with pinch to zoom using zoomageview. so user can drag the image off the screen and zoom-In , zoom-out the image.
You can follow this link
to get the Step By Step
Code and also given Output Screenshot.
Source: Stackoverflow.com