Rounding Only ONE Image Corner - not all four

Question

I am using this very common class to round corners:

   public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, int pixels) {
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap
                .getHeight(), Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        final RectF rectF = new RectF(rect);
        final float roundPx = pixels;

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);

        return output;
    }

I'd like to modify it so that only Top Left corner is rounded. I can't find the parameter in the code that does this? Can someone assist?

Answer 1

It's probably not the most efficient way to do this, but you could fill in the rounded off corners by painting on top of your current mask. You could start with the current code then use canvas.drawRect (right after the call to canvas.drawRoundRect) on the appropriate regions (the corners). I imagine something like this would round only the top left corner:

public static Bitmap getRoundedTopLeftCornerBitmap(Bitmap bitmap, int pixels) {
    Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap
            .getHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(output);

    final int color = 0xff424242;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
    final RectF rectF = new RectF(rect);
    final float roundPx = pixels;
    final Rect topRightRect = new Rect(bitmap.getWidth()/2, 0, bitmap.getWidth(), bitmap.getHeight()/2);
    final Rect bottomRect = new Rect(0, bitmap.getHeight()/2, bitmap.getWidth(), bitmap.getHeight());

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
    // Fill in upper right corner
    canvas.drawRect(topRightRect, paint);
    // Fill in bottom corners
    canvas.drawRect(bottomRect, paint);

    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rect, paint);

    return output;
}

There's a bit of optimization you could do here if you feel like it, but I think it should work. The general idea definitely should. I haven't tried or tested this code though and it won't look right if pixels > bitmap.getWidth()/2 or pixels > bitmap.getHeight()/2. Then again, that was probably true before too.

Answer 2

public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, int topLeftX, int topLeftY, int topRightX, int topRightY, int bottomRightX, int bottomRightY, int bottomLeftX, int bottomLeftY) {
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        // the float array passed to this function defines the x/y values of the corners
        // it starts top-left and works clockwise
        // so top-left-x, top-left-y, top-right-x etc
        RoundRectShape rrs = new RoundRectShape(new float[]{topLeftX, topLeftY, topRightX, topRightY, bottomRightX, bottomRightY, bottomLeftX, bottomLeftY}, null, null);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setAntiAlias(true);
        paint.setColor(0xFF000000);
        rrs.resize(bitmap.getWidth(), bitmap.getHeight());
        rrs.draw(canvas, paint);
        paint.setXfermode(new PorterDuffXfermode(android.graphics.PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;
    }

Or you can see RoundRects.java source code - example that show how to produce round corners, available in SDK samples: http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android-apps/4.3_r2.1/com/example/android/apis/graphics/RoundRects.java/