Bex Bex - 3 months ago 60
Android Question

Android View.getDrawingCache returns null, only null

Would anyone please try to explain to me why

public void addView(View child) {
child.setDrawingCacheEnabled(true);
child.setWillNotCacheDrawing(false);
child.setWillNotDraw(false);
child.buildDrawingCache();
if(child.getDrawingCache() == null) { //TODO Make this work!
Log.w("View", "View child's drawing cache is null");
}
setImageBitmap(child.getDrawingCache()); //TODO MAKE THIS WORK!!!
}


ALWAYS logs that the drawing cache is null, and sets the bitmap to null?

Do I have to actually draw the view before the cache is set?

Thanks!

Answer

I was having this problem also and found this answer:

v.setDrawingCacheEnabled(true);

// this is the important code :)  
// Without it the view will have a dimension of 0,0 and the bitmap will be null          
v.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight()); 

v.buildDrawingCache(true);
Bitmap b = Bitmap.createBitmap(v.getDrawingCache());
v.setDrawingCacheEnabled(false); // clear drawing cache
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