android - Bitmap not drawn anti-aliased

Question

I have a custom View that always draws a Bitmap at a certain rotation. I overwrite the onDraw method, rotate the Canvas and draw the bitmap with an anti-aliased Paint.

public RotatedImageView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    someBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.placeholder);
}

@Override
protected void onDraw(Canvas canvas) {

    // Save and rotate canvas
    canvas.save();
    canvas.rotate(3F, getWidth() / 2, getHeight());

    // Draw the icon
    Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
    canvas.drawBitmap(someBitmap, 0, 0, p);
    canvas.drawRoundRect(new RectF(75, 50, 225, 200), 10, 10, p);

    // All done; restore canvas
    canvas.restore();
}

However, I always get jagged edges on the Bitmap. Note that the roudned rectangle gets nicely anti-aliased edges. Also, when I apply p.setFilterBitmap(true); this works (the bitmap surface gets filtered/smoothed) correctly. Am I missing something?

Here's a minimal Android project with isolated example of one screen that shows the View that draws the non-anti-aliased Bitmap, loaded from a resource: https://bitbucket.org/erickok/antialiastest

UPDATE: I have also tried the following:

    Paint p = new Paint();
    p.setAntiAlias(true);
    p.setFilterBitmap(true);
    p.setDither(true);
    canvas.drawBitmap(someBitmap, 0, 0, p);

But this doesn't help as setFilterBitmap filters the surface; it does not anti-alias the edges. Also, setAntiAlias does the same as directly setting the flag in the Paint constructor. If in doubt, please try my minimal test project. Thanks so much for any help!

Answer 1

Use setFilterBitmap(true).

paint_object.setFilterBitmap(true);

it works for me too.. I got it from this question

Drawing rotated bitmap with anti alias

set both the AntiAlias flag and FilterBitmap flag to true, they together shall make bitmap's edges smooth, I have tested it on Samsung Galaxy Ace , android 2.2 ...

My Testing Code is

Paint p = new Paint();
p.setAntiAlias(true);
p.setFilterBitmap(true);
canvas.drawBitmap(someBitmap, new Matrix(), p);