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Android example source code file (PreDrawListener.java)

This example Android source code file (PreDrawListener.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

activity, android, app, attributeset, button, content, hello, mylinearlayout, onclicklistener, os, override, predrawlistener, ui, view, widget

The PreDrawListener.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewTreeObserver;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;

import com.android.frameworks.coretests.R;


/**
 * Tests views with popupWindows becoming invisible
 */
public class PreDrawListener extends Activity implements OnClickListener {
    
    private MyLinearLayout mFrame;


    static public class MyLinearLayout extends LinearLayout implements
            ViewTreeObserver.OnPreDrawListener {

        public boolean mCancelNextDraw;
        
        public MyLinearLayout(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

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

        @Override
        protected void onAttachedToWindow() {
            super.onAttachedToWindow();
            getViewTreeObserver().addOnPreDrawListener(this);
        }
        
        public boolean onPreDraw() {
            if (mCancelNextDraw) {
                Button b = new Button(this.getContext());
                b.setText("Hello");
                addView(b, new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                        LayoutParams.WRAP_CONTENT));
                mCancelNextDraw = false;
                return false;
            }
            return true;
        }
        
    }

    @Override
    protected void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.pre_draw_listener);

        mFrame = (MyLinearLayout) findViewById(R.id.frame);

        Button mGoButton = (Button) findViewById(R.id.go);
        mGoButton.setOnClickListener(this);
    }


    public void onClick(View v) {
        mFrame.mCancelNextDraw = true;
        mFrame.invalidate();
    }



}

Other Android examples (source code examples)

Here is a short list of links related to this Android PreDrawListener.java source code file:

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