游戏编程性能

Question

I have narrowed down my slowdowns to this method

public void drawMap(Canvas canvas) {

    if (car.x > 0 && map != null) {
        clipArea = Bitmap.createBitmap(map, mapx, mapy, getWidth(),
                getHeight());
        canvas.drawBitmap(clipArea, 0, 0, null);
    }
}

This is taking about 3 seconds to run! any help would be appreciated the bitmap is about twice the size of the screen but this is key to my game so I need to keep this :) any help on optimising? thanks

Answer 1

you always wait a fixed time here, independent of how long the whole calculations and ui updates take

 frame.postDelayed(frameUpdate, FRAME_RATE);

what you want to do is: before the new "game tick" you create a timestamp variable, then you do the calculations, and then you check how much time is left until the next tick should be.

something like this:

synchronized public void run() {


    Date timestamp = new Date();

    // do your calculations
    ...

    // calculate how much time it took and when the next update should be:
    int timeToNextTick = FRAME_RATE - (new Date().getTime() - timestamp.getTime());
    frame.postDelayed(frameUpdate, timeToNextTick);

}

this way, the update ticks should always be equally timed (assumed that the device is capable of running the code within the framerate value)