android截屏功能

前言
安卓的截图开发是一个很简单的功能，但是我的需求是在视频的过程中进行 截屏，如果普通截屏操作视频的部分会是黑色的，根本就不符合当前需求。所以记录下怎么能够截取视频画面。
点击截图按钮事件

 MediaProjectionManager mMediaProjectionManager =  null;
 private int REQUEST_MEDIA_PROJECTION  =  1;
startActivityForResult(
                        mMediaProjectionManager.createScreenCaptureIntent(),
                        REQUEST_MEDIA_PROJECTION);

回调监听

 private String  mImageName  =  "";
private MediaProjection mMediaProjection;
private VirtualDisplay  mVirtualDisplay;

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_MEDIA_PROJECTION) {
            if (resultCode != Activity.RESULT_OK) {
                Toast.makeText(this, "用户取消了", Toast.LENGTH_SHORT).show();
                return;
            }
            final ImageReader mImageReader = ImageReader.newInstance(ScreenUtils.getScreenWidth(), ScreenUtils.getScreenHeight(), 0x1, 2);
            mMediaProjection = mMediaProjectionManager.getMediaProjection(resultCode, data);
            mVirtualDisplay = mMediaProjection.createVirtualDisplay("ScreenCapture",
                    ScreenUtils.getScreenWidth(), ScreenUtils.getScreenHeight(), getResources().getDisplayMetrics().densityDpi,
                    DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
                    mImageReader.getSurface(), null, null);

            mImageName = System.currentTimeMillis() + ".png";
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    Image image = null;
                    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
                        image = mImageReader.acquireLatestImage();
                    }
                    if (image == null) {
                        return;
                    }
                    int width = 0;
                    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
                        width = image.getWidth();
                        int height = image.getHeight();
                        final Image.Plane[] planes = image.getPlanes();
                        final ByteBuffer buffer = planes[0].getBuffer();
                        int pixelStride = planes[0].getPixelStride();
                        int rowStride = planes[0].getRowStride();
                        int rowPadding = rowStride - pixelStride * width;
                        Bitmap mBitmap;
                        mBitmap = Bitmap.createBitmap(width + rowPadding / pixelStride, height, Bitmap.Config.ARGB_8888);
                        mBitmap.copyPixelsFromBuffer(buffer);
                        mBitmap = Bitmap.createBitmap(mBitmap, 0, 0, width, height);
                        image.close();

                        if (mBitmap != null) {
                            //拿到mitmap
                            final Bitmap finalMBitmap = mBitmap;
                        }
                    }

                }
            }, 300);
        }
    }