Android subpixel rendering

Question

I have a line that should get thinner the longer it gets. The problem is, that you can clearly see a jump when it gets a pixel thinner. Is there a way to do subpixel rendering/antialiasing on Android?

canvas.drawRect() takes float values, but it's ignoring those. Here's the code:

@Override
protected void onDraw(Canvas canvas) {
    float width = getMeasuredWidth() / (float) getMeasuredHeight()  * getMinimumHeight();
    float left = (getMeasuredWidth() - width) / 2.0f;
    canvas.drawRect(left, 0, left + width, getMeasuredHeight(), paint);
    super.onDraw(canvas);
}

The paint object has ANTI_ALIAS_FLAG enabled and contains a solid color.

This is the default line:

This is when it gets longer and thinner. It should have some anti aliasing on the sides, though to make the whole transition seems smoother.

Eade

Have you tried setAntiAlias( true )? It's easy to accidentally override a flag using setFlags(). – Ratan

No, it's not working either. I'm not setting any other flags :/ – Eade

Could you post a screenshot? – Pinch

I've edited my post and added screenshots, thanks! – Eade

Actually drawLine with the strokeWidth set seems to do the job! – Eade

Answer 1

This seems to do a better job:

@Override
protected void onDraw(Canvas canvas) {
    float width = getMeasuredWidth() / (float) getMeasuredHeight()  * getMinimumHeight();
    float left = (getMeasuredWidth() - width) / 2.0f;
    paint.setStrokeWidth(width * getResources().getDisplayMetrics().density);
    canvas.drawLine(left, 0, left, getMeasuredHeight(), paint);
    super.onDraw(canvas);
}

Eade