定时关键游戏的Android触摸输入延迟问题。 在调用onTouchEvent之前是否有延迟？

Question

So we're working on the android version of the iPhone game Snake Race (it's a cool game). However, we seem to be getting a delay on the touch inputs just big enough to make a difference. (The snake might turn a step later than you intended) After getting almost used to the android version, the iPhone version feels like a blessing.

The question is whether there is a delay from androids side in calling the onTouchEvent() method? (I'm using Samsung Galaxy S2) If so, is there any neat tricks to circumvent the issue?(Even if it means using the NDK)

This is the current implementation touch handling:

public boolean onTouchEvent(final MotionEvent event) {      
    int action = event.getAction();
    if(action == MotionEvent.ACTION_DOWN || 
            (action & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_POINTER_DOWN){     
        Run run = GameVars.run;

        if(run != null){
            if(run.paused){
                run.paused = false;
            }else{
                if(event.getX(action >> MotionEvent.ACTION_POINTER_ID_SHIFT) < GameVars.width/2){
                    run.addTap(-1);

                }else{
                    run.addTap(1);

                }
            }
        }
        return true;
    }
    return false;
}

This is the addTap method:

public void addTap(int newDir) {
    if(newDir == -tapDir){
        taps++;
        tapDir *= -1;
    }
}

And then every frame, taps is checked, and if it's greater than zero (and we're allowed to turn atm) we turn.

It all works fine and is reliable, but there is a consistent delay (maybe 2-3 frames, which is enough to make the iPhone snake seriously more maneuverable).

Any feedback is apprieciated!

Answer 1

I've come to realize that it is indeed a delay from the side of the device. It is not big but it is there, and it varies quite a lot between different android phones. My Galaxy S2 has a bigger delay than most of the newer HTC models I've tested. I've also made new project where a touch switch background / play a sound (I know that has an additional delay) etc. And I can't seem to find anything that circumvents the problem.

Answer 2

I think this is Android or device issue. I have same problems with Galaxy Tab 10.1, Galaxy Note and Galaxy S II devices when develop NDK and GLES based apps, ie in contrast to iOS devices, lags between actual touch and receiving event on all "galaxies" depends to current gpu/cpu utilization, even if main (event processing) thread is do nothing, except processing theses events and all rendering and other things are performed in separated thread...

Answer 3

This is not a solution, but a direct answer to you question: no, there is no delay on android's side for a touch event.

Somewhere in your code is the source of the problem. It could be a variety of things.

For example, java is a multi-threaded language, so code does not necessarily run in a linear fashion. The Android UI thread will run on a different thread than your Surface, so they may not be syncing the way you expect.

Another possibility is that your controls are not getting touched. Are the touch areas small? iPhone has an excellent and responsive touch screen, but not all android devices are built to the same quality.

I wish I knew the specific cause, but i can let you safely eliminate the "its just freakin android" possibility. There is no delay caused by the OS.

Answer 4

Make sure the garbage collector doesn't run when you are handling the click event. If so, disable garbage collecting when your game is running. Otherwise, you are doing something expensive in your ui cycle that is causing stutter. Profiling your app should reveal the problem.