Android: bitmap rotation leads to black background

Question

I\'m facing an issue related to Bitmap rotation, issue is follow code rotates the bitmap fine but with a back background when draw rotated bitmap on canvas, I see this only

Answer 1

I also get this issue. After Goolge, I find that if you use BitmapFactory.decodeResource，this issue can't be fixed at some devices. So I use these code instead of BitmapFactory.decodeResource:

Bitmap bitmap = yourBitmap;
Matrix matrix = new Matrix();
matrix.postRotate(angle);

Rect srcR = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
RectF dstR = new RectF(0, 0, bitmap.getWidth(), bitmap.getHeight());
RectF deviceR = new RectF();
matrix.mapRect(deviceR, dstR);

int neww = Math.round(deviceR.width());
int newh = Math.round(deviceR.height());

Bitmap result = Bitmap.createBitmap(neww, newh, Bitmap.Config.ARGB_8888);
result.eraseColor(Color.TRANSPARENT);
Canvas canvas = new Canvas();
canvas.translate(-deviceR.left, -deviceR.top);
canvas.concat(matrix);

Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
canvas.setBitmap(result);
canvas.drawBitmap(bitmap, srcR, dstR, paint);
canvas.setBitmap(null);

the 'result' Bitmap is your rotated bitmap with transparent BG.