Question

For my application, i have used pinch zoom feature by adapting from the tutorial and creating a custom view http://www.zdnet.com/blog/burnette/how-to-use-multi-touch-in-android-2-part-6-implementing-the-pinch-zoom-gesture/1847

Right now i’m working on capturing the zoomed image as bitmap.

Partially I was able to get the bitmap by making use of

setDrawingCacheEnabled(true);
Bitmap bm = Bitmap.createBitmap(finalView.getDrawingCache());
setDrawingCacheEnabled(false);

Using this approach, I’m getting both the zoomed image and the screen background.

Is there any way to capture only the zoomed image as a bitmap?

Answer 1

After having searched a lot, I found a ‘Temporary’ solution in the same Community & also thanks for the code from ‘weakwire’ provided in the same post.

Getting coordinates and width/height from a matrix

Idea is simple, all i have do is remove the background screen from the scaled image by cropping. Code is bit lengthy, but worked for me.

1. First get the Original Bitmap size

   float imgWidth = imgBitmap.getWidth()   
   float imgHeight = imgBitmap.getHeight()
   

2. Obtain the matrix ( pinch zoom feature used in my application uses matrix ‘trick’) values, used to scale the image and get the scaledWidth & scaledHeight of the original image.

   float[] values = new float[9];
   matrix.getValues(values);
   float globalX = values[2];
   float globalY = values[5];
   float scaledWidth = values[0]*imgWidth;
   float scaledHeight = values[4]*imgHeight;   
   
   // If zoomed Image gets out of screen, I'm trying to crop the image available in the screen by considering image from (0,0)
   
   if(globalX<0)
   globalX = 0;
   
   if(globalY<0)
   globalY = 0;
   

3. Finally capture the View and crop the background
   In my case (“finalView” is the custom View name, where pinch zooming happens)

   setDrawingCacheEnabled(false);
   destroyDrawingCache();
   finalView.setDrawingCacheEnabled(true);
   Bitmap bm = Bitmap.createBitmap(finalView.getDrawingCache());
   finalView.setDrawingCacheEnabled(false);    
   
   //Final Image Width &  Height
   
   int finalWidth = Math.min((int)width,(int)finalView.getWidth());
   int finalHeight = Math.min((int)height,(int)finalView.getHeight());        
   

   // crop to get the scaled image

    Bitmap finalBitmap = Bitmap.createBitmap(bm, (int)globalX, (int)globalY, finalWidth ,finalHeight);
   

Though this is a temporary solution, it works for me. If there is any alternate solution, please post it.