How should I give images rounded corners in Android?

Question

I would like to change an image I loaded to have round corners.

Any hints, tutorials, best practices you know of?

Answer 1

How about creating a NinePatchDrawable image that has just rounded corners and has a transparent body. Overlay your image with an appropriately re-sized version of your NinePatchDrawable.

Answer 2

For a more controlled method draw a rounded rectangle and mask it onto your image using the porter-duff Xfer mode of the paint.

First setup the Xfer paint and the rounded bitmap:

Bitmap myCoolBitmap = ... ; // <-- Your bitmap you want rounded    
int w = myCoolBitmap.getWidth(), h = myCoolBitmap.getHeight();

// We have to make sure our rounded corners have an alpha channel in most cases
Bitmap rounder = Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(rounder);    

// We're going to apply this paint eventually using a porter-duff xfer mode.
// This will allow us to only overwrite certain pixels. RED is arbitrary. This
// could be any color that was fully opaque (alpha = 255)
Paint xferPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
xferPaint.setColor(Color.RED);

// We're just reusing xferPaint to paint a normal looking rounded box, the 20.f
// is the amount we're rounding by.
canvas.drawRoundRect(new RectF(0,0,w,h), 20.0f, 20.0f, xferPaint);     

// Now we apply the 'magic sauce' to the paint  
xferPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));

Now apply this bitmap ontop of your image:

canvas.drawBitmap(myCoolBitmap, 0,0, null);
canvas.drawBitmap(rounder, 0, 0, xferPaint);

Note: this is not the same canvas as before, it is a canvas to whatever buffer you're drawing to.

Answer 3

try this!

public class BitmapUtils {
private static final int ROUND_DIPS = 10;

public static Bitmap getRoundedCornerBitmap(Context context, Bitmap bitmap) {
    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 = convertDipsToPixels(context, ROUND_DIPS);

    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;
}

public static int convertDipsToPixels(Context context, int dips) {
    final float scale = context.getResources().getDisplayMetrics().density;
    return (int) (dips * scale + 0.5f);
}

}