canvas.drawRect doesn't draw a rectangle on the image

Krishna

Here canvas.drawRect will be different when using different bitmaps. I want to draw a rectangle over the top image and want the part of the image outside the rectangle to be darkened or blurred. please help me.

draw.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeWidth(2);

            Bitmap bitmap=((BitmapDrawable)image.getDrawable()).getBitmap();
            Bitmap mutableBitmap = bitmap.copy(Bitmap.Config.RGB_565, true);

            Bitmap bitmap1 = Bitmap.createBitmap(600,400, Bitmap.Config.RGB_565);

            Rect r = new Rect();
            r.set(100,100,500,300);

            Canvas canvas = new Canvas(mutableBitmap);
            Canvas canvas1 = new Canvas(bitmap1);

            canvas.drawRect(r,paint);
            canvas1.drawRect(r,paint);

            image.setImageBitmap(mutableBitmap);
            image1.setImageBitmap(bitmap1);

        }
 });

enter image description here

Venkata

If you want to draw a rectangle and darken the outside, do it this way. Create a bitmap and draw a full-sized semi-transparent rectangle, and then draw another rectangle with a full-transparent color inside it. Then put that bitmap on the image.

Try the following code:

            Bitmap bitmap = Bitmap.createBitmap(600,400,Bitmap.Config.ARGB_8888);
            Canvas canvas = new Canvas(bitmap);

            RectF outerRectangle = new RectF(0, 0, 600, 400);
            RectF innerRectangle = new RectF(100, 100, 500, 300);

            Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
            paint.setColor(Color.BLACK);
            paint.setAlpha(80);
            canvas.drawRect(outerRectangle, paint);

            paint.setColor(Color.TRANSPARENT);
            paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OUT));
            canvas.drawRect(innerRectangle, paint);

            paint.setColor(Color.RED);
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeWidth(2);
            canvas.drawRect(innerRectangle, paint);

            image1.setImageBitmap(bitmap);

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