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PO
 

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    <p>If I were you, I'd use the <code>Canvas.scale(float sx, float sy, float px, float py)</code> method which does exactly what you want.</p> <p>However looking at your code I think you might be messing with too many transformations at once, which is harder to debug.</p> <ol> <li><p>Always (and I mean <em>always</em>) call <code>Canvas.save()</code> and <code>Canvas.restore()</code> on the initial matrix you're getting in <code>Canvas</code> if you plan to alter it. This is because the <code>Canvas</code> that you get to draw on may be the canvas for e.g. the whole window with just clipping set to the boundaries of the control that is currently drawing itself.</p></li> <li><p>Use matrix transformation method provided by the <code>Canvas</code> method and draw bitmap using the simplest invocation.</p></li> </ol> <p>Following these two advices look at the whole <code>View</code> I have just made up, that scales the <code>bitmap</code> by a factor of <code>3</code> with point <code>(16,16)</code> set as the pivot (unchanged point - center of scaling). Tested - working.</p> <pre><code>public class DrawingView extends View { Bitmap bitmap; public DrawingView(Context context) { super(context); bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher); } @Override protected void onDraw(Canvas canvas) { float sx = 3; float sy = 3; float px = 16; float py = 16; canvas.save(); canvas.scale(sx, sy, px, py); canvas.drawBitmap(bitmap, 0, 0, null); canvas.restore(); } } </code></pre>
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    1. COThank you for the information, I have trimmed down my code significantly and believe I have it working now. I am not sure I understand what canvas.save() and restore() are doing though. Is this independant of locking and unlocking and posting?
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    2. CO`save` and `restore` push and pop current matrix that canvas has onto a stack, similar to what you have in OpenGL. the thing is, unless you're absolutely sure that nothing draws to the canvas after you, you need to restore the matrix to the state it was when you started drawing. that's because the canvas you're drawing to is most likely shared by all views in your current window. you can test this by simply calling `canvas.setMatrix(null);` to load an identity matrix and seeing the (weird) results :>
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    3. COThat makes sense. Next question, how do you set it to center on a given point and zoom in on it. If I set the pivot point to the center of the image it pivots there but the canvas is still centered on the same spot so it just flies by, if I try to translate it, then it seems to do odd things when I zoom in.
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