Android 执行invalidate（）时未绘制TextView

我试图显示屏幕上的坐标取决于传感器数据的视图。我按照中的说明显示了一个文本，现在我尝试显示一些文本视图，但是在我的文本视图上调用invalidate时，它们并没有被绘制出来

有人能帮忙吗

谢谢

ARView.java

ARActivity.java

在这里，我将ARView添加到其父视图中

public class ARActivity extends Activity{

    private ARLayout ar;
    private CBCameraView cv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);

            ar = new ARLayout(getApplicationContext());

            cv = new CBCameraView(this.getApplicationContext());

            FrameLayout rl = new FrameLayout(this.getApplicationContext());

            rl.addView(cv, GlobalVars.screenWidth, GlobalVars.screenHeight); 
            rl.addView(ar, GlobalVars.screenWidth, GlobalVars.screenHeight); 

            setContentView(rl);

            Location location = new Location("me");
            location.setLatitude(41.371974);
            location.setLongitude(2.166978);

            ARView fs = new ARView(this.getApplicationContext());
            fs.azimuth = 0;
            fs.inclination = 0;
            fs.location = location;
            fs.name="Bar seco";
            ar.addARView(fs);                    
    }
}

ARLayout.java

在这里，我获取传感器数据，更新我的ARViews坐标，并希望绘制它们

public class ARLayout extends View implements LocationListener, SensorEventListener
{

    // ...

    @Override
    public void onSensorChanged(SensorEvent event) {

        // here I get sensors data and update my views

        for(int i=0; i<nArViews; i++)
        {

            ARView view = arViews.get(i);            

            int x = ...; // new x coordinate of my ARView
            int y = ...; // new y coordinate of my ARView

            view.layout(x, y, view.getBottom(), view.getRight());  // set new coordinates to my ARViews

        }

        invalidate(); // draw my ARLayout       
    }

    public void onDraw(Canvas c)
    {
        for(int i=0; i<nArViews; i++)
        {                
            ARView view = arViews.get(i);
            view.invalidate();  // I thought it would draw my ARViews, but it doesn't :(
        }
    }

    // more stuff   

}

---

我不知道这是否是具体问题的解决方案，但我知道这是另一个问题

删除onDraw方法中的invalidate调用。每次绘制只需调用invalidate一次。将其从onDraw中删除将确保屏幕仅在您有新传感器数据时更新。在onDraw离开之前，屏幕实际上不会绘制

---

或者，您可以将调用移动到onDraw中for循环之后的invalidate，并将其完全从onSensorChanged中删除。这将使屏幕不断地重新绘制，无论您是否有传感器数据。

看起来您只是在更改视图的位置。您不必调用invalidate，也不必否决onDraw。对于这类事情，操作系统知道何时重新绘制。无效和onDraw仅用于自定义图形

public class ARLayout extends View implements LocationListener, SensorEventListener
{

    // ...

    @Override
    public void onSensorChanged(SensorEvent event) {

        // here I get sensors data and update my views

        for(int i=0; i<nArViews; i++)
        {

            ARView view = arViews.get(i);            

            int x = ...; // new x coordinate of my ARView
            int y = ...; // new y coordinate of my ARView

            view.layout(x, y, view.getBottom(), view.getRight());  // set new coordinates to my ARViews

        }

        invalidate(); // draw my ARLayout       
    }

    public void onDraw(Canvas c)
    {
        for(int i=0; i<nArViews; i++)
        {                
            ARView view = arViews.get(i);
            view.invalidate();  // I thought it would draw my ARViews, but it doesn't :(
        }
    }

    // more stuff   

}