Why is setColor so slow on Android

Question

I'm benchmarking some of our code on an OPO device that's normally pretty fast and I'm seeing a lot of "weird" performance oddities. Before digging deeper into the Android native code I thought I'd ask here.

What I'm seeing is that a call for paint.setColor(argbInt) takes roughly 5 times longer to execute than the following calls:

paint.setStyle(Paint.Style.FILL);
paint.setAntiAlias(false);
canvas.drawRect(x, y, x + w, y + h, paint);
paint.setAntiAlias(antialias);

Now draw rect happens on the GPU so I'm guessing I don't see any overhead for that. But why should I get overhead for the paint color?

And as a natural followup, how do I reduce said overhead?

I'm also seeing quite a bit of overhead for canvas.restore() (roughly 4 times slower than the code above) but I guess that would make sense as it could be a complex operation. I just don't see why setColor would be slow?

For the record I tested the performance on an OPO with System.nanoTime() and its pretty consistent in terms of performance (not a sudden GC fluke or something).

Answer 1

I could find no real answer for "why" this is happening even after digging thru the code. My solution was to cache Paint objects for every style in our theme so repainting the component with similar settings can reuse a previously set value. This did seem to have a positive impact on performance.