CircleBitmapDrawable.java

    class CircleBitmapDrawable extends Drawable {
        Bitmap bitmap;
        Paint maskPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        Paint borderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        float side;
        float radius;

        public CircleBitmapDrawable(Bitmap wrappedBitmap, float borderWidth, int borderColor) {
            bitmap = wrappedBitmap;
            borderPaint.setStyle(Paint.Style.STROKE);
            borderPaint.setStrokeWidth(borderWidth);
            borderPaint.setColor(borderColor);
            side = Math.min(bitmap.getWidth(), bitmap.getHeight());
        }

        @Override
        protected void onBoundsChange(Rect bounds) {
            Matrix matrix = new Matrix();
            RectF src = new RectF(0, 0, side, side);
            src.offset((bitmap.getWidth() - side) / 2, (bitmap.getHeight() - side) / 2);
            RectF dst = new RectF(bounds);
            dst.inset(borderPaint.getStrokeWidth(), borderPaint.getStrokeWidth());
            matrix.setRectToRect(src, dst, Matrix.ScaleToFit.CENTER);

            Shader shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
            shader.setLocalMatrix(matrix);
            maskPaint.setShader(shader);
            matrix.mapRect(src);
            radius = src.width() / 2;
        }

        @Override
        public void draw(Canvas canvas) {
            Rect b = getBounds();
            canvas.drawCircle(b.exactCenterX(), b.exactCenterY(), radius, maskPaint);
            canvas.drawCircle(b.exactCenterX(), b.exactCenterY(), radius + borderPaint.getStrokeWidth() / 2, borderPaint);
        }

        @Override public void setAlpha(int alpha) {}
        @Override public void setColorFilter(ColorFilter cf) {}
        @Override public int getOpacity() {return PixelFormat.TRANSLUCENT;}
    }