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POZoom & Drag an Image in android
 

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    <p>I need to drag and zoom an image. Here is my code ...</p> <pre><code>//instance variables Matrix matrix = new Matrix(); Matrix savedMatrix = new Matrix(); static final int NONE = 0; static final int DRAG = 1; static final int ZOOM = 2; int mode = NONE; PointF start = new PointF(); PointF mid = new PointF(); float oldDist = 1f; </code></pre> <p>//OnTouchListener for imageview</p> <pre><code>OnTouchListener touchAction = new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { ImageView i = (ImageView)v; dragAndZoom(i, event); return true; } }; </code></pre> <p>//performing drag&amp;zoom operations</p> <pre><code>private void dragAndZoom(View v, MotionEvent event) { ImageView view = (ImageView) v; view.setScaleType(ImageView.ScaleType.MATRIX); float scale; // Handle touch events here... switch (event.getAction() &amp; MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: // first finger down only savedMatrix.set(matrix); start.set(event.getX(), event.getY()); mode = DRAG; break; case MotionEvent.ACTION_UP: // first finger lifted case MotionEvent.ACTION_POINTER_UP: // second finger lifted mode = NONE; break; case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down oldDist = spacing(event); if (oldDist &gt; 5f) { savedMatrix.set(matrix); midPoint(mid, event); mode = ZOOM; } break; case MotionEvent.ACTION_MOVE: if (mode == DRAG) { matrix.set(savedMatrix); matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); } else if (mode == ZOOM) { // pinch zooming float newDist = spacing(event); if (newDist &gt; 5f) { matrix.set(savedMatrix); scale = newDist / oldDist; matrix.postScale(scale, scale, mid.x, mid.y); } } break; } view.setImageMatrix(matrix); // display the transformation on screen } private float spacing(MotionEvent event) { float x = event.getX(0) - event.getX(1); float y = event.getY(0) - event.getY(1); return FloatMath.sqrt(x * x + y * y); } 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); } </code></pre> <p>It works okay. but sometimes the image is going out of screen boundaries on touch of it. How can i keep the image in UI all the times? Please help me. Thanks in advance. </p>
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