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Android example source code file (ImageWallpaper.java)

This example Android source code file (ImageWallpaper.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

android, broadcastreceiver, canvas, content, drawableengine, drawing, graphics, handlerthread, imagewallpaper, object, os, override, paint, runtimeexception, surfaceholder, ui, unable, view, wallpapermanager, wallpaperobserver

The ImageWallpaper.java Android example source code

/*
 * Copyright (C) 2009 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 com.android.internal.service.wallpaper;

import com.android.internal.view.WindowManagerPolicyThread;

import android.app.WallpaperManager;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.Region.Op;
import android.graphics.drawable.Drawable;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Process;
import android.service.wallpaper.WallpaperService;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.content.Context;
import android.content.IntentFilter;
import android.content.Intent;
import android.content.BroadcastReceiver;

/**
 * Default built-in wallpaper that simply shows a static image.
 */
public class ImageWallpaper extends WallpaperService {
    WallpaperManager mWallpaperManager;
    private HandlerThread mThread;

    @Override
    public void onCreate() {
        super.onCreate();
        mWallpaperManager = (WallpaperManager) getSystemService(WALLPAPER_SERVICE);
        Looper looper = WindowManagerPolicyThread.getLooper();
        if (looper != null) {
            setCallbackLooper(looper);
        } else {
            mThread = new HandlerThread("Wallpaper", Process.THREAD_PRIORITY_FOREGROUND);
            mThread.start();
            setCallbackLooper(mThread.getLooper());
        }
    }

    public Engine onCreateEngine() {
        return new DrawableEngine();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mThread != null) {
            mThread.quit();
        }
    }

    class DrawableEngine extends Engine {
        private final Object mLock = new Object();
        private WallpaperObserver mReceiver;
        Drawable mBackground;
        float mXOffset;
        float mYOffset;

        class WallpaperObserver extends BroadcastReceiver {
            public void onReceive(Context context, Intent intent) {
                updateWallpaper();
                drawFrame();
                // Assume we are the only one using the wallpaper in this
                // process, and force a GC now to release the old wallpaper.
                System.gc();
            }
        }

        @Override
        public void onCreate(SurfaceHolder surfaceHolder) {
            super.onCreate(surfaceHolder);
            IntentFilter filter = new IntentFilter(Intent.ACTION_WALLPAPER_CHANGED);
            mReceiver = new WallpaperObserver();
            registerReceiver(mReceiver, filter);
            updateWallpaper();
            surfaceHolder.setSizeFromLayout();
        }

        @Override
        public void onDestroy() {
            super.onDestroy();
            unregisterReceiver(mReceiver);
        }

        @Override
        public void onVisibilityChanged(boolean visible) {
            drawFrame();
        }
        
        @Override
        public void onTouchEvent(MotionEvent event) {
            super.onTouchEvent(event);
        }

        @Override
        public void onOffsetsChanged(float xOffset, float yOffset,
                float xOffsetStep, float yOffsetStep,
                int xPixels, int yPixels) {
            mXOffset = xOffset;
            mYOffset = yOffset;
            drawFrame();
        }

        @Override
        public void onSurfaceChanged(SurfaceHolder holder, int format, int width, int height) {
            super.onSurfaceChanged(holder, format, width, height);
            drawFrame();
        }

        @Override
        public void onSurfaceCreated(SurfaceHolder holder) {
            super.onSurfaceCreated(holder);
        }

        @Override
        public void onSurfaceDestroyed(SurfaceHolder holder) {
            super.onSurfaceDestroyed(holder);
        }
        
        void drawFrame() {
            SurfaceHolder sh = getSurfaceHolder();
            Canvas c = sh.lockCanvas();
            if (c != null) {
                final Rect frame = sh.getSurfaceFrame();
                synchronized (mLock) {
                    final Drawable background = mBackground;
                    final int dw = frame.width();
                    final int dh = frame.height();
                    final int bw = background != null ? background.getIntrinsicWidth() : 0;
                    final int bh = background != null ? background.getIntrinsicHeight() : 0;
                    final int availw = dw-bw;
                    final int availh = dh-bh;
                    int xPixels = availw < 0 ? (int)(availw*mXOffset+.5f) : (availw/2);
                    int yPixels = availh < 0 ? (int)(availh*mYOffset+.5f) : (availh/2);

                    c.translate(xPixels, yPixels);
                    if (availw<0 || availh<0) {
                        c.save(Canvas.CLIP_SAVE_FLAG);
                        c.clipRect(0, 0, bw, bh, Op.DIFFERENCE);
                        c.drawColor(0xff000000);
                        c.restore();
                    }
                    if (background != null) {
                        background.draw(c);
                    }
                }
                sh.unlockCanvasAndPost(c);
            }
        }

        void updateWallpaper() {
            synchronized (mLock) {
                try {
                    mBackground = mWallpaperManager.getFastDrawable();
                } catch (RuntimeException e) {
                    Log.w("ImageWallpaper", "Unable to load wallpaper!", e);
                }
            }
        }
    }
}

Other Android examples (source code examples)

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

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