How to create a partially-rounded-corners-rectangular drawable with center-crop and without creating new bitmap?

Question

Background

I've already seen how to create a drawable that's circular out of a bitmap, and also how to add an outline (AKA stroke) around it, here.

The problem

I can't find out how to do a similar task for rounding only some of the corners of the bitmap, inside the drawable, without creating a new bitmap, and still do it for a center-crop ImageView.

What I've found

This is what I've found, but it does create a new bitmap, and when using it in an imageView with center-crop (source here):

/**
 * Create rounded corner bitmap from original bitmap.
 *
 * @param input                               Original bitmap.
 * @param cornerRadius                        Corner radius in pixel.
 * @param squareTL,squareTR,squareBL,squareBR where to use square corners instead of rounded ones.
 */
public static Bitmap getRoundedCornerBitmap(final Bitmap input, final float cornerRadius, final int w, final int h,
                                            final boolean squareTL, final boolean squareTR, final boolean squareBL, final boolean squareBR) {
    final Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);
    final Canvas canvas = new Canvas(output);
    final int color = 0xff424242;
    final Rect rect = new Rect(0, 0, w, h);
    final RectF rectF = new RectF(rect);
    // make sure that our rounded corner is scaled appropriately
    Paint paint = new Paint();
    paint.setXfermode(null);
    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawRoundRect(rectF, cornerRadius, cornerRadius, paint);
    // draw rectangles over the corners we want to be square
    if (squareTL) 
        canvas.drawRect(0, 0, w / 2, h / 2, paint);
    if (squareTR) 
        canvas.drawRect(w / 2, 0, w, h / 2, paint);
    if (squareBL) 
        canvas.drawRect(0, h / 2, w / 2, h, paint);
    if (squareBR) 
        canvas.drawRect(w / 2, h / 2, w, h, paint);
    paint.setXfermode(PORTER_DUFF_XFERMODE_SRC_IN);
    canvas.drawBitmap(input, 0, 0, paint);
    return output;
}

And, this is what I've found for creating a rounded corners drawable that acts on all corners:

public static class RoundedCornersDrawable extends Drawable {
    private final float mCornerRadius;
    private final RectF mRect = new RectF();
    private final BitmapShader mBitmapShader;
    private final Paint mPaint;

    public RoundedCornersDrawable(final Bitmap bitmap, final float cornerRadius) {
        mCornerRadius = cornerRadius;
        mBitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP,
                Shader.TileMode.CLAMP);
        mPaint = new Paint();
        mPaint.setAntiAlias(false);
        mPaint.setShader(mBitmapShader);
        mRect.set(0, 0, bitmap.getWidth(), bitmap.getHeight());
    }

    @Override
    protected void onBoundsChange(final Rect bounds) {
        super.onBoundsChange(bounds);
        mRect.set(0, 0, bounds.width(), bounds.height());
    }

    @Override
    public void draw(final Canvas canvas) {
        canvas.drawRoundRect(mRect, mCornerRadius, mCornerRadius, mPaint);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }

    @Override
    public void setAlpha(final int alpha) {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(final ColorFilter cf) {
        mPaint.setColorFilter(cf);
    }
}

But this solution only works well if the imageView shows the content while maintaining the same aspect ratio as the bitmap, and also has its size pre-determined.

The question

How to create a center-cropped drawable, that shows a bitmap, has rounded corners for specific corners, and also be able to show an outline/stroke around it?

I want to do it without creating a new bitmap or extending ImageView. Only use a drawable that has the bitmap as the input.

Answer 1

The SMART way is to use the PorterDuff blending mode. It's really simple and slick to create any fancy shading, blending, "crop" effect. you can find a lot of good tutorial about PorterDuff. here a good one.