android - 使用动画 gif 的动态壁纸(使用 centercrop scaletype)

Question

如何使用动画 .gif 图像创建简单的动态壁纸？我得到的 .gif 图像与屏幕不成比例。如何使它居中？

Answer 1

你的 Activity 文件

public class GIFWallpaperService extends WallpaperService {

@Override
public WallpaperService.Engine onCreateEngine() {
    try {
        Movie movie = Movie.decodeStream(
                getResources().getAssets().open("owlinsnow.gif"));

        return new GIFWallpaperEngine(movie);
    }catch(IOException e){
        Log.d("GIF", "Could not load asset");
        return null;
    }
}

private class GIFWallpaperEngine extends WallpaperService.Engine {

    private final int frameDuration = 20;

    private SurfaceHolder holder;
    private Movie movie;
    private boolean visible;
    private Handler handler;

    public GIFWallpaperEngine(Movie movie) {
        this.movie = movie;
        handler = new Handler();
    }

    @Override
    public void onCreate(SurfaceHolder surfaceHolder) {
        super.onCreate(surfaceHolder);
        this.holder = surfaceHolder;
    }

    private Runnable drawGIF = new Runnable() {
        public void run() {
            draw();
        }
    };


    private void draw() {
        if (visible) {
            Canvas canvas = holder.lockCanvas();
            canvas.save();
            // Adjust size and position so that
            // the image looks good on your screen
            canvas.scale(2f, 2f);
            movie.draw(canvas, -100, 0);
            canvas.restore();
            holder.unlockCanvasAndPost(canvas);
            movie.setTime((int) (System.currentTimeMillis() % movie.duration()));

            handler.removeCallbacks(drawGIF);
            handler.postDelayed(drawGIF, frameDuration);
        }
    }

    @Override
    public void onVisibilityChanged(boolean visible) {
        this.visible = visible;
        if (visible) {
            handler.post(drawGIF);
        } else {
            handler.removeCallbacks(drawGIF);
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        handler.removeCallbacks(drawGIF);
    }
}
}

list 文件

<application android:allowBackup="true" android:label="@string/app_name"
    android:icon="@drawable/owl" android:theme="@style/AppTheme">

    <service
        android:name=".GIFWallpaperService"
        android:enabled="true"
        android:label="Owl in Snow"
        android:permission="android.permission.BIND_WALLPAPER" >
        <intent-filter>
            <action android:name="android.service.wallpaper.WallpaperService"/>
        </intent-filter>
        <meta-data
            android:name="android.service.wallpaper"
            android:resource="@xml/wallpaper" >
        </meta-data>
    </service>

</application>

<uses-feature
    android:name="android.software.live_wallpaper"
    android:required="true" >
</uses-feature>

在res下创建xml目录，里面有wallpaper.xml。

<?xml version="1.0" encoding="UTF-8"?>
<wallpaper
xmlns:android="http://schemas.android.com/apk/res/android"
android:label="GIF Wallpaper"
android:thumbnail="@drawable/owl">
</wallpaper>

确保将 gif 图像放在 assets 文件夹中。要创建 Assets 文件夹，请单击文件->新建->文件夹-> Assets