无法使用 LayoutInfalter 呈现 xml 布局。我做错了什么？

Question

我需要从xml文件中显示一个布局，并在其上绘制一些基于矢量的图像。如果执行下面的代码，则显示除布局之外的所有内容。为什么?我做错了什么?

public class About extends Activity 
{
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    //setContentView(R.layout.about); 
    setContentView(new GraphicsView(this));
}
public class GraphicsView extends View
{
    public GraphicsView(Context context)
    {
        super(context);                 
    }
    @Override
    protected void onDraw(Canvas canvas)
    {
        Context context;
        context=getContext();
        View aview; 
        LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);    
        aview = inflater.inflate(R.layout.about, null);                 
        aview.draw(canvas);
        Path circle = new Path();
        Paint cPaint = new Paint(); 
        cPaint.setColor(Color.LTGRAY);
        circle.addCircle(150, 150, 100, Direction.CW);
        canvas.drawPath(circle, cPaint);
        cPaint.setColor(Color.RED);
        canvas.drawTextOnPath("Some stupid text", circle, 0, 20, cPaint);
    }
}

}

Answer 1

在对视图进行充气后，您需要对其进行测量并对其进行布局以确定其大小，以便可以正确绘制。在调用avview .draw()之前，你应该先调用avview .measure()和avview .layout()。

注意，你应该永远不要从onDraw()中膨胀视图。这是非常昂贵和浪费。同样，你不应该在onDraw()中创建油漆或路径。

Answer 2

另一个论坛的答案:

FrameLayout:

 public class About extends Activity 
 { 
    @Override 
    protected void onCreate(Bundle savedInstanceState) 
    { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.about);
       GraphicsView drawing = new GraphicsView(this);
       FrameLayout container = (FrameLayout) findViewById(R.id.container);
       container.addView(drawing);
    } 
    public class GraphicsView extends View 
    { 
       public GraphicsView(Context context) 
       { 
          super(context);                 
       } 
       @Override 
       protected void onDraw(Canvas canvas) 
       { 
          Path circle = new Path(); 
          Paint cPaint = new Paint(); 
          cPaint.setColor(Color.LTGRAY); 
          circle.addCircle(150, 150, 100, Direction.CW); 
          canvas.drawPath(circle, cPaint); 
          cPaint.setColor(Color.RED); 
          canvas.drawTextOnPath("Some stupid text", circle, 0, 20, cPaint); 
       } 
    } 
 }

然后是XML:

<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:padding="10dip" 
    android:id="@+id/container"> 
    <TextView 
        android:id="@+id/about_content" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="@string/about_text" />
</FrameLayout>