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My application draws to the canvas in a continuous loop and on each loop re-evaluates the positions of the drawables and cycles them to animate. My question is which of the following 2 methods is superior and why? I'm a beginner so I have no idea how to benchmark methods and that kinda stuff, so if you can, or you already have, i'd appreciate the input.

The first method, (the one i'm using) is to assign the png resource a Handle as a Drawable. then every time I want to draw the object I call:

Drawable.setBounds(x,y,x,y);
Drawable.draw(canvas);

My question is would it be faster to (in the constructor), decode the resource as a BitMap, and then scale it it to the appropriate size. Then on each loop Draw the resource via:

canvas.drawBitmap(DrawableName, 0, 0, null);

The reason I ask is that my app draws hundreds of resources, so changing a few doesn't do enough to tell a difference, and i'd like to know whether it would be significantly faster doing it this way before I overhaul the code. Regardless, I need to increase the performance somehow so any other good ideas are also welcome.

cody
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  • By using canvas.drawBitmap you can have quite a big performance boost. Look at this: http://stackoverflow.com/questions/4296441/android-canvas-drawbitmap-vs-drawable-draw-huge-performance-boost – MetalRain Nov 28 '11 at 19:14

1 Answers1

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In general, drawing bitmaps is faster than drawing as with the right preparation, drawing a bitmap is just dumping memory to the screen. If you need to draw a scaled bitmap, then draw it as one using createScaledBitmap rather than creating it then scaling it. You can achieve this by:

Bitmap myBitmap = BitmapFactory.decodeFile(myFile.getPath());
myBitmap = myBitmap.createScaledBitmap(myBitmap, width, height, true);

The Android developers documentation on the above function

Calculating and drawing primitives while running takes calculations and when drawing many of them will decrease performance, so use more bitmaps where you can - but be careful of doing premature optimisation - there's no point creating lots of bitmaps if there's no need as there will not be a significance (i.e. noticable) performance increase.

Deco
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  • Thanks for the help, and thanks for the comment above. I think I may have to do this. I created a fps counter and found that I was bottoming out at under 20 fps in certain places and by eliminating the drawing from the main loop, the fps went up to over 5000, tells me that drawing is HEAVY in my app and needs to be optimized. Because the physics calculation is only done after the last frame is drawn, I've limited the loop to only do the next iteration after 33 ms have past. Meaning I've limited the animation to 30 fps, regardless of how fast the device can finish the draw sequence.... – cody Nov 28 '11 at 21:20
  • ... This keeps the physics consistent across every device provided that the device is capable of finishing a single loop in 33 ms. If it's not the entire game simply lags until the processor can catch up. I was thinking of adding a frames skipping feature to help curb the problem on slower devices, but that might be avoided by speeding up the drawing significantly. – cody Nov 28 '11 at 21:22