召回/更新视图onDraw()

Question

我对用java编程相当陌生。现在我正在为课堂写一个小小的平台游戏。我面临的问题是:我画了一个男人的小bitmap到我的canvas。如果你触摸屏幕的右半部分，他应该向右移动。屏幕的左边也是一样的。我试图回忆一下单独的"CanvasClass“中的CanvasClass方法，它扩展了View Class，每次都更改绘制的bitmap的变量。帮助我使用失效/事后验证方法，我似乎无法理解它！谢谢:) GameActivity：

public class GameActivity extends Activity implements OnTouchListener{

CanvasClass ourView;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);            
    ourView = new CanvasClass(this);
    setContentView(ourView);     
}   

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onTouch(View v, MotionEvent me) {
    return false;
}

}

CanvasClass:

public class CanvasClass extends View implements OnTouchListener {

Bitmap mBackground, BackScaled,bobOri, bobScale;
int width, height,bobWidth = 33, bobHeight = 93;
float meX = 20,meY = 400;
Canvas canvas;

public CanvasClass(Context context) {
    super(context);
    ((Activity) getContext()).requestWindowFeature(Window.FEATURE_NO_TITLE);
    ((Activity) getContext()).getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

    DisplayMetrics displaymetrics = getResources().getDisplayMetrics();
    height =displaymetrics.heightPixels;
    width = displaymetrics.widthPixels;
    mBackground = BitmapFactory.decodeResource(getResources(), R.drawable.background); 
    ((Activity) getContext()).getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
    BackScaled = Bitmap.createScaledBitmap(mBackground, width, height,true);

    bobOri = BitmapFactory.decodeResource(getResources(),R.drawable.bobertfront);
    bobScale = Bitmap.createScaledBitmap(bobOri, bobWidth,bobHeight, true);

}
@Override
protected void onDraw(Canvas canvas){
    super.onDraw(canvas);
    canvas.drawBitmap(BackScaled,0,0,null);
    canvas.drawBitmap(bobScale,20,410,null);

}

@Override
public boolean onTouch(View v, MotionEvent me) {

    return true;
}

}

如果你还需要什么，请问！我将每5-10分钟查看一次回复，谢谢:)

Answer 1

你的问题到底是什么？

要使onDraw()再次被调用，您需要调用失效()。失效和postInvalidate的区别在于，需要从UI线程调用无效，而postInvalidate可以从其他线程调用.

在您的情况下，无效应该能起作用。

参考文献

http://developer.android.com/reference/android/view/View.html#invalidate()和http://developer.android.com/reference/android/view/View.html#postInvalidate()

Answer 2

在我看来，您需要刷新onDraw实现onPause方法