canvas.drawBitmap（）在设备上崩溃

时间：2013-06-18 13:30:31

标签： android game-engine

我是Android游戏开发的新手。一切都在仿真器和我的一个Android设备上工作正常但在我的nexus 4中崩溃......

我正在尝试使用

获取用户的触摸 
@Override
public boolean dispatchTouchEvent(MotionEvent event) {

    if(!jump){
    first=true;
    makeajump();
    }

    return super.dispatchTouchEvent(event);
}

这是在nexus的调试模式测试中出现错误的地方：

jcanvas.drawBitmap(mytree, xtree1,height-t1.getHeight(), null);//inside makeajump() line 404

一切都有效，直到用户点击屏幕... 

jcanvas = canvas;//set in onDraw(),jcanvas is global

这是我的logcat，当出现错误时：

06-18 18:40:55.752: E/InputEventReceiver(8523): Exception dispatching input event.
06-18 18:40:55.752: E/MessageQueue-JNI(8523): Exception in MessageQueue callback: handleReceiveCallback
06-18 18:40:55.762: E/MessageQueue-JNI(8523): java.lang.NullPointerException
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.GLES20RecordingCanvas.drawBitmap(GLES20RecordingCanvas.java:105)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at lion.run.vjapps.game.animal.GameView.makeajump(GameView.java:404)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at lion.run.vjapps.game.animal.GameView.dispatchTouchEvent(GameView.java:455)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.View.dispatchPointerEvent(View.java:7426)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.os.MessageQueue.nativePollOnce(Native Method)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.os.MessageQueue.next(MessageQueue.java:125)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.os.Looper.loop(Looper.java:124)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at android.app.ActivityThread.main(ActivityThread.java:5041)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at java.lang.reflect.Method.invokeNative(Native Method)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at java.lang.reflect.Method.invoke(Method.java:511)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-18 18:40:55.762: E/MessageQueue-JNI(8523):   at dalvik.system.NativeStart.main(Native Method)
06-18 18:40:55.762: D/AndroidRuntime(8523): Shutting down VM
06-18 18:40:55.762: W/dalvikvm(8523): threadid=1: thread exiting with uncaught exception (group=0x41a8d930)
06-18 18:40:55.762: E/AndroidRuntime(8523): FATAL EXCEPTION: main
06-18 18:40:55.762: E/AndroidRuntime(8523): java.lang.NullPointerException
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.GLES20RecordingCanvas.drawBitmap(GLES20RecordingCanvas.java:105)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at lion.run.vjapps.game.animal.GameView.makeajump(GameView.java:404)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at lion.run.vjapps.game.animal.GameView.dispatchTouchEvent(GameView.java:455)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.View.dispatchPointerEvent(View.java:7426)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.os.MessageQueue.nativePollOnce(Native Method)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.os.MessageQueue.next(MessageQueue.java:125)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.os.Looper.loop(Looper.java:124)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at android.app.ActivityThread.main(ActivityThread.java:5041)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at java.lang.reflect.Method.invokeNative(Native Method)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at java.lang.reflect.Method.invoke(Method.java:511)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-18 18:40:55.762: E/AndroidRuntime(8523):     at dalvik.system.NativeStart.main(Native Method)

感谢任何帮助......非常感谢..

1 个答案:

答案 0 :(得分：1)

你应该在onDraw（）

中移动你的绘图代码 
       canvas.drawBitmap(mytree, xtree1,height-t1.getHeight(), null);

您可以在onDraw（）之外进行计算，并调用invalidate()来刷新绘图

public void invalidate ()

使整个视图无效。如果视图可见，将在某个时间点调用onDraw（android.graphics.Canvas）。必须从UI线程调用此方法。要从非UI线程调用，请调用postInvalidate（）。

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