Question

代码：

public class MainActivity extends AppCompatActivity implements GestureDetector.OnGestureListener,
GestureDetector.OnDoubleTapListener {

    DrawView drawView;
    private GestureDetectorCompat g1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        drawView = new DrawView(this);
        drawView.setBackgroundColor(Color.TRANSPARENT);
        setContentView(drawView);
        g1 = new GestureDetectorCompat(this,this);
        g1.setOnDoubleTapListener(this);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        g1.onTouchEvent(event);
        return super.onTouchEvent(event);
    }

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        DrawView.x_touch = e.getX();
        DrawView.y_touch = e.getY();
        Log.v("id2","message2");
        return false;
    }

绘图代码：

public class DrawView extends View {
    Paint paint = new Paint();
    static float x_touch = -1;
    static float y_touch = -1;
    public DrawView(Context context) {
        super(context);
        super.setWillNotDraw(false);
        paint.setColor(Color.BLACK);
    }
    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Display mdisp = ((WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
        Point mdispSize = new Point();
        mdisp.getSize(mdispSize);
        int maxX = mdispSize.x;
        int maxY = mdispSize.y;
        canvas.drawLine(maxX/3, 0, maxX/3, maxY, paint);
        canvas.drawLine(maxX*2/3, 0, maxX*2/3, maxY, paint);
        canvas.drawLine(0, maxY/3, maxX, maxY/3, paint);
        canvas.drawLine(0, maxY*2/3, maxX, maxY*2/3, paint);
        Log.v("id1","message1");
        if (x_touch>0 && y_touch > 0)
            canvas.drawText("X",x_touch,y_touch,paint);
    }
}

在做一些研究时，我发现需要在覆盖setWillNotDraw(false)或使用onDraw()时调用dispatchDraw()。我已经尝试了两种，但只有一次调用Draw函数。

我是Android开发的新手。

Answer 1

更改您的代码如下：

public class DrawView extends View {
Paint paint = new Paint();
float x_touch = -1;
float y_touch = -1;
public DrawView(Context context) {
    super(context);
    super.setWillNotDraw(false);
    paint.setColor(Color.BLACK);
}
@Override
public void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Display mdisp = ((WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
    Point mdispSize = new Point();
    mdisp.getSize(mdispSize);
    int maxX = mdispSize.x;
    int maxY = mdispSize.y;
    canvas.drawLine(maxX/3, 0, maxX/3, maxY, paint);
    canvas.drawLine(maxX*2/3, 0, maxX*2/3, maxY, paint);
    canvas.drawLine(0, maxY/3, maxX, maxY/3, paint);
    canvas.drawLine(0, maxY*2/3, maxX, maxY*2/3, paint);
    Log.v("id1","message1");
    if (x_touch>0 && y_touch > 0)
        canvas.drawText("X",x_touch,y_touch,paint);
}

public void setXandY(float x, float y) {
  x_touch = x;
  y_touch = y;
  this.invalidate();
}

}

并且：

@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
    drawView.setXandY(e.getX(), e.getY());
    return (true);
}

onDraw（）或dispatchDraw（）没有被触摸调用

1 个答案: