【安卓笔记】wallpaper设置系统主页墙纸的一种方法

一.可实现代码：

因为这几天逛csdn搜了好多"Wallpaper设置墙纸"的内容，
所以也找不到reference在哪里了，就不写了，有觉得侵权的就告诉我。
总之就记录下copy&paste之后能直接用的方法，为以后我再需要做个记录。

1. 创建一个自定义WallpaperService

public class LiveWallpaper extends WallpaperService {
    private Bitmap bitmap;

    // 实现动态壁纸必须要实现的抽象方法
    @Override
    public Engine onCreateEngine() {
        bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ac_eco_on);
        return new MyEngine();
    }

    class MyEngine extends Engine {
        private boolean mVisible; // 根据visibleChange的回调保存的visible状态

        // 记录当前用户动作发生的位置
        private float mTouchX = -1;

        private float mTouchY = -1;

        // 记录要绘制的矩形的数量
        private int count = 1;

        // 记录第一个矩形所需坐标变换的X、Y坐标的偏移

        private int originX = 50, originY = 50;

        // 定义画笔
        private Paint mPaint = new Paint();

        Handler mHandler = new Handler();

        private final Runnable drawTarget = () -> drawFrame();

        @Override
        public void onCreate(SurfaceHolder surfaceHolder) {
            super.onCreate(surfaceHolder);
            // 初始化画笔
            mPaint.setARGB(76, 0, 0, 255);
            mPaint.setAntiAlias(true);
            mPaint.setStyle(Paint.Style.FILL);

            // 设置壁纸的触碰事件为true
            setTouchEventsEnabled(true);
        }

        @Override
        public void onVisibilityChanged(boolean visible) {
            super.onVisibilityChanged(visible);
            mVisible = visible;
            if (visible) {
                drawFrame();
            } else {
                // 如果界面不可见，删除回调
                mHandler.removeCallbacks(drawTarget);
            }
        }

        @Override
        public void onOffsetsChanged(float xOffset, float yOffset, float xOffsetStep, float yOffsetStep, int xPixelOffset, int yPixelOffset) {
            super.onOffsetsChanged(xOffset, yOffset, xOffsetStep, yOffsetStep, xPixelOffset, yPixelOffset);
            drawFrame();
        }

        @Override
        public void onDestroy() {
            super.onDestroy();
            // 删除回调
            mHandler.removeCallbacks(drawTarget);
        }

        @Override
        public void onTouchEvent(MotionEvent event) {
            // 检测到滑动操作
            if (event.getAction() == MotionEvent.ACTION_MOVE) {
                mTouchX = event.getX();
                mTouchY = event.getY();
            } else {
                mTouchX = -1;
                mTouchY = -1;
            }
            super.onTouchEvent(event);
        }

        private void drawFrame() {
            final SurfaceHolder holder = getSurfaceHolder();
            Canvas canvas = holder.lockCanvas();
            if (canvas != null) {
                canvas.drawColor(0xFFAADD);
                // 在触碰点绘制图像
                drawTouchPoint(canvas);
                mPaint.setAlpha(76);

                canvas.translate(originX, originY);

                // 采用循环绘制count个图形
                for (int i = 0; i < count; i++) {
                    canvas.translate(80, 0);
                    canvas.scale(0.95f, 0.95f);
                    canvas.rotate(20f);
                    canvas.drawRect(0, 0, 150, 75, mPaint);
                }
                holder.unlockCanvasAndPost(canvas);
                // 调度下一次重绘
                mHandler.removeCallbacks(drawTarget);
                if (mVisible) {
                    count++;
                    if (count >= 50) {
                        Random rand = new Random();
                        count = 1;
                        originX += (rand.nextInt(60) - 30);
                        originY += (rand.nextInt(60) - 30);
                        try {
                            Thread.sleep(500);
                        } catch (InterruptedException e) {
                            e.printStackTrace();

                        }
                    }
                    // 每隔0.1秒执行drawTarget一次
                    mHandler.postDelayed(drawTarget, 100);
                }
            }
        }

        private void drawTouchPoint(Canvas canvas) {
            if (mTouchX >= 0 && mTouchY >= 0) {
                // 设置画笔的透明度
                mPaint.setAlpha(255);
                canvas.drawBitmap(bitmap, mTouchX, mTouchY, mPaint);
            }
        }
    }
}

这个动画绘制就是直接用了别的文章里的算法，后面再慢慢细化成我想要的样子的。总之，在这里谢谢那位dalao啦。

2. 在manifest中application标签下添加一个service配置

		<service
            android:name=".LiveWallpaper"
            android:enabled="true"
            android:permission="android.permission.BIND_WALLPAPER"
            android:exported="true">
            <intent-filter>
                <action android:name="android.service.wallpaper.WallpaperService"/>
            </intent-filter>
            <meta-data
                android:name="android.service.wallpaper"
                android:resource="@xml/wallpaper_file" />
        </service>

这个service的android:name就是刚刚自定义的WallpaperService的类名（可能安卓用久了对Service了解多了自然而然就知道了吧，我认识安卓刚满一年，是第一次直接应用service，还有很多不足呢）

3.通过intent启动这个自定义的service

就直接在Activity里面启动了，后面放到点击事件里也可以直接用来着。

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView(){
        findViewById(R.id.setting_button).setOnClickListener(clickListener -> {
            Intent intent = new Intent(WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER);
            intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT,
                    new ComponentName(this, LiveWallpaper.class));
            startActivity(intent);

        });
    }
}