DrawBitmap with Matrix not Accurate

Question

I'm trying to use Canvas.drawBitmap(...) to draw Bitmaps onto a Canvas but it's not appearing in the correct position or size.

Below is an example on how I'm attempting to achieve this:

Canvas canvas = new Canvas();
Matrix matrix = new Matrix();

/// scale = 0.5
/// image.getX() = 250
/// image.getY() = 250
matrix.setTranslate(
        imageView.getX() * scale,
        imageView.getY() * scale
);

matrix.setScale(
        scale,
        scale
);

matrix.postRotate(imageView.getRotation(), imageView.getX() * scale, imageView.getY() * scale);

canvas.drawBitmap(bitmap, matrix, null);

The result that I'm getting is that the image is at the original size at 0x0 position.
The expected result is for the image to be half-size and in the center of the canvas.

NOTE: I'm using matrix.postRotate(...) to draw the bitmap rotated to the same angle as the ImageView.

Answer 1

Can you give this a shot, I have tried to explain the logic in the comments:

// as you wanted Half size so reduced width and height to half

  Bitmap dstBitmap = Bitmap.createScaledBitmap(srcbitmap,(srcbitmap.getWidth()/2 ),(srcbitmap.getHeight()/2),true);

                // Here I calculate screen size
                DisplayMetrics displayMetrics = new DisplayMetrics();
                getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
                int height = displayMetrics.heightPixels;
                int width = displayMetrics.widthPixels;

   //Create screen size bitmap to position image at center easily
                Bitmap bitmap = Bitmap.createBitmap(
                        width, 
                        height, 
                        Bitmap.Config.ARGB_8888 
                );

                // Initialize a new Canvas  with above bitmap
                Canvas canvas = new Canvas(bitmap);


             
           Matrix matrix = new Matrix();


            // Rotating about center of image
            matrix.setRotate(
                    45, // your angle
                    dstBitmap.getWidth() / 2, 
                    dstBitmap.getHeight() / 2 
            );

  
            matrix.postTranslate(
                    (width  - dstBitmap.getWidth()) / 2,
                    (height - dstBitmap.getHeight() )/ 2
            );

           

            canvas.drawBitmap(dstBitmap, matrix, null);

Now you should be good to proceed , this should give you correct output