为什么TextView.onDraw会被调用???
main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:id="@+id/title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="----"
/>
<com.myTextViewDemo.MyTextView
android:id="@+id/text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:id="@+id/btn"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="change"
/>
</LinearLayout>
public class MyTextViewDemo extends Activity {
private MyTextView mt;
private Button btn;
private TextView tv;
private int i = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mt = (MyTextView) findViewById(R.id.text);
tv = (TextView) findViewById(R.id.title);
btn = (Button) findViewById(R.id.btn);
btn.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View v) {
tv.setText("adsf:" + i++);
}
});
}
}
自定义TextView
public class MyTextView extends TextView {
public MyTextView(Context context) {
super(context);
}
public MyTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
protected void onDraw(Canvas canvas) {
System.out.println("--------------- onDraw --------------");
super.onDraw(canvas);
}
}
现在的问题是,当点击button时,会改变tv的值,但是(MyTextView)mt .onDraw也会被调用,而且点击几次就调用几次,这是为什么??