[android-developers] Incorrect clip rect in onDraw()?

[Leisuresuit Larry]

Hi all,

We came across a strange behavior. The clip rect of our custom view is
getting reset to its entire visible region, if we change the value of
another view.

Below is a sample app to demonstrate the behavior:

main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/
android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

<com.test.MyView
    android:id="@+id/view"
    android:layout_width="fill_parent"
    android:layout_height="100px" />

<TextView
    android:id="@+id/text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />

</LinearLayout>

ClipTest.java:
package com.test;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.widget.TextView;

public class ClipTest extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        TextView tv = (TextView)findViewById(R.id.text);
        tv.setText("Test");

        findViewById(R.id.view).invalidate(100, 0, 150, 75);
        return true;
    }
}

MyView.java:
package com.test;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;

public class MyView extends View {

    public MyView(Context context) {
        super(context);
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        Rect clip = canvas.getClipBounds();
        System.out.println("clip " + clip);
    }
}

If you run the above app, MyView.onDraw() prints "clip Rect(0, 0, 320,
100)". If you comment out "tv.setText("Test");", then MyView.onDraw()
prints "clip Rect(100, 0, 150, 75)".

Why does setting the TextView's text affect MyView's clip rect? How
can we get the correct clip rect in MyView.onDraw()? Thanks for any
help!

Larry

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