Android 截屏

最近做了一个截屏的功能，需要每个页面在跳转的时候截屏然后上传到后台，后台管理系统上就可以看到用户当前在哪个页面
截屏的时候遇到了两种情况 一个是页面还没渲染完，另一种是页面渲染完了

• 1、如果是页面已经渲染完了（只是布局UI加载完，并不是指网络请求的数据也加载完），我们直接截屏是没有问题的，因为我们需要拿到 DecorView 布局加载到Activity上时 DecorView 是可以拿到宽高的

    // 开始截屏
    public static void screenshotView(Activity activity) {
        WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);
        //获取到DecorView
        View view = activityWeakReference.get().getWindow().getDecorView();
        LogUtil.e("height:" + view.getHeight() + "  width:" + view.getWidth());
        Bitmap bitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_4444);
        Canvas canvas = new Canvas(bitmap);
        view.draw(canvas);
        view.setDrawingCacheEnabled(false); // 清空缓存，可用于实时截图
    }

• 2 、如果页面还没有加载出来怎么办，拿到的 DecorView 宽高是0，就会导致Bitmap是null，这时候我们需要监听一下页面布局的变化，通过 view.getViewTreeObserver().addOnGlobalLayoutListener();
  下面是完整的代码：

public class ScreenUtils {
    private static final String TAG = "ScreenUtils";

    private static MyListener myListener;

    // 开始截屏
    public static void screenshotView(Activity activity) {
        WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);

        View view = activityWeakReference.get().getWindow().getDecorView();
        LogUtil.e("height:" + view.getHeight() + "  width:" + view.getWidth());
        if (view.getHeight() > 0 && view.getHeight() > 0) {
            LogUtil.e("直接上传");
            captureScreen(view);
        } else {
            LogUtil.e("观察变化上传");
            myListener = new MyListener(view);
            view.getViewTreeObserver().addOnGlobalLayoutListener(myListener);
        }
    }

    //将Bitmap保存成图片到本地
    public static void saveBitmapToJPG(Bitmap bitmap, File file) throws IOException {
        Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(),
                bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(newBitmap);
        canvas.drawColor(Color.WHITE);
        canvas.drawBitmap(bitmap, 0, 0, null);
        OutputStream stream = new FileOutputStream(file);
        //压缩图片
        newBitmap.compress(Bitmap.CompressFormat.JPEG, 10, stream);
        stream.close();
    }

    //截屏
    private static void captureScreen(View view) {
        Log.e(TAG, "高：" + view.getHeight());
        Bitmap bitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_4444);
        Canvas canvas = new Canvas(bitmap);
        view.draw(canvas);
        view.setDrawingCacheEnabled(false); // 清空缓存，可用于实时截图
        if (bitmap == null) {
            Log.e(TAG, "screenshotView: 截屏失败");
        } else {
            Log.e(TAG, "screenshotView: 截屏成功");
        }
        //获取到本地存储路径
        File file = new File(FileUtils.getFileStorageRootPath() + "/screen.jpeg");

        Observable.create((ObservableOnSubscribe<File>) emitter -> {
                    try {
                        saveBitmapToJPG(bitmap, file);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    //发射
                    emitter.onNext(file);
                    emitter.onComplete();
                }).subscribeOn(Schedulers.newThread())
                .observeOn(Schedulers.io())
                .subscribe(new Observer<File>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(File file) {
                        Log.e(TAG, "onNext: " + file.getAbsolutePath());
                        //在此上传图片到服务器
                    }

                    @Override
                    public void onError(Throwable e) {
                        LogUtil.e("报错：" + e.toString());
                    }

                    @Override
                    public void onComplete() {
                        LogUtil.e("完成");
                    }
                });
    }

    static class MyListener implements ViewTreeObserver.OnGlobalLayoutListener {
        private final View view;

        public MyListener(View view) {
            this.view = view;
        }

        @Override
        public void onGlobalLayout() {
            view.getViewTreeObserver().removeOnGlobalLayoutListener(myListener);
            captureScreen(view);
        }
    }
}