创build自定义ImageView

我通过扩展ImageView来创build一个自定义的图像视图,只是在屏幕上绘制一些文本,但是我没有在模拟器屏幕上看到任何内容,但日志消息和printlns被打印在日志控制台中。 我没有做什么?

这是我的活动

public class HelloAndroidActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // setContentView(R.layout.main); CustomImageView myView = new CustomImageView(getApplicationContext()); System.out.println("Setting the view"); myView.invalidate(); setContentView(myView); System.out.println("Calling invalidate"); } } 

这是我的CustomImageView

 public class CustomImageView extends ImageView { /** * @param context */ public CustomImageView(Context context) { super(context); // TODO Auto-generated constructor stub setBackgroundColor(0xFFFFFF); } /** * @param context * @param attrs */ public CustomImageView(Context context, AttributeSet attrs) { super(context, attrs); // TODO Auto-generated constructor stub } /** * @param context * @param attrs * @param defStyle */ public CustomImageView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); // TODO Auto-generated constructor stub } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); System.out.println("Painting content"); Paint paint = new Paint(Paint.LINEAR_TEXT_FLAG); paint.setColor(0x0); paint.setTextSize(12.0F); System.out.println("Drawing text"); canvas.drawText("Hello World in custom view", 100, 100, paint); } @Override public boolean onTouchEvent(MotionEvent event) { // TODO Auto-generated method stub Log.d("Hello Android", "Got a touch event: " + event.getAction()); return super.onTouchEvent(event); } } 

即使在onTouchEvent()的日志消息被打印,但没有任何东西被绘制。

这是我的main.xml有布局

 <?xml version="1.0" encoding="utf-8"?> <AbsoluteLayout android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/AbsoluteLayout"> </AbsoluteLayout> 

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