如何通过中心裁剪和调整宽度/高度来将视频适合动态壁纸？

背景

我正在制作可以显示视频的动态壁纸。一开始我以为这会非常困难，因此有人建议使用OpenGL解决方案或其他非常复杂的解决方案（例如this）。

无论如何，为此，我发现了很多地方都在谈论它，并基于这个github库（有一些错误），终于使它工作了。

问题

成功显示视频后，与屏幕分辨率相比，我找不到控制视频显示方式的方法。

目前，它总是要扩展到屏幕尺寸，这意味着（从此处拍摄的视频）：

得到显示为：

原因是宽高比不同：560x320（视频分辨率）与1080x1920（设备分辨率）。

注意：我很清楚缩放视频的解决方案，该解决方案可在各种Github存储库（例如here）上找到，但是我在询问动态壁纸。因此，它没有View，因此它在做事上受到更多限制。更具体地说，解决方案不能具有任何类型的布局，TextureView或SurfaceView或任何其他类型的View。

我尝试过的

我尝试使用SurfaceHolder的各个领域和功能，但到目前为止还没有运气。例子：

• setVideoScalingMode - it either crashes or doesn't do anything.

• changing surfaceFrame - same.

Here's the current code I've made (full project available here) :

class MovieLiveWallpaperService : WallpaperService() {
    override fun onCreateEngine(): WallpaperService.Engine {
        return VideoLiveWallpaperEngine()
    }

    private enum class PlayerState {
        NONE, PREPARING, READY, PLAYING
    }

    inner class VideoLiveWallpaperEngine : WallpaperService.Engine() {
        private var mp: MediaPlayer? = null
        private var playerState: PlayerState = PlayerState.NONE

        override fun onSurfaceCreated(holder: SurfaceHolder) {
            super.onSurfaceCreated(holder)
            Log.d("AppLog", "onSurfaceCreated")
            mp = MediaPlayer()
            val mySurfaceHolder = MySurfaceHolder(holder)
            mp!!.setDisplay(mySurfaceHolder)
            mp!!.isLooping = true
            mp!!.setVolume(0.0f, 0.0f)
            mp!!.setOnPreparedListener { mp ->
                playerState = PlayerState.READY
                setPlay(true)
            }
            try {
                //mp!!.setDataSource(this@MovieLiveWallpaperService, Uri.parse("http://techslides.com/demos/sample-videos/small.mp4"))
                mp!!.setDataSource(this@MovieLiveWallpaperService, Uri.parse("android.resource://" + packageName + "/" + R.raw.small))
            } catch (e: Exception) {
            }
        }

        override fun onDestroy() {
            super.onDestroy()
            Log.d("AppLog", "onDestroy")
            if (mp == null)
                return
            mp!!.stop()
            mp!!.release()
            playerState = PlayerState.NONE
        }

        private fun setPlay(play: Boolean) {
            if (mp == null)
                return
            if (play == mp!!.isPlaying)
                return
            when {
                !play -> {
                    mp!!.pause()
                    playerState = PlayerState.READY
                }
                mp!!.isPlaying -> return
                playerState == PlayerState.READY -> {
                    Log.d("AppLog", "ready, so starting to play")
                    mp!!.start()
                    playerState = PlayerState.PLAYING
                }
                playerState == PlayerState.NONE -> {
                    Log.d("AppLog", "not ready, so preparing")
                    mp!!.prepareAsync()
                    playerState = PlayerState.PREPARING
                }
            }
        }

        override fun onVisibilityChanged(visible: Boolean) {
            super.onVisibilityChanged(visible)
            Log.d("AppLog", "onVisibilityChanged:" + visible + " " + playerState)
            if (mp == null)
                return
            setPlay(visible)
        }

    }

    class MySurfaceHolder(private val surfaceHolder: SurfaceHolder) : SurfaceHolder {
        override fun addCallback(callback: SurfaceHolder.Callback) = surfaceHolder.addCallback(callback)

        override fun getSurface() = surfaceHolder.surface!!

        override fun getSurfaceFrame() = surfaceHolder.surfaceFrame

        override fun isCreating(): Boolean = surfaceHolder.isCreating

        override fun lockCanvas(): Canvas = surfaceHolder.lockCanvas()

        override fun lockCanvas(dirty: Rect): Canvas = surfaceHolder.lockCanvas(dirty)

        override fun removeCallback(callback: SurfaceHolder.Callback) = surfaceHolder.removeCallback(callback)

        override fun setFixedSize(width: Int, height: Int) = surfaceHolder.setFixedSize(width, height)

        override fun setFormat(format: Int) = surfaceHolder.setFormat(format)

        override fun setKeepScreenOn(screenOn: Boolean) {}

        override fun setSizeFromLayout() = surfaceHolder.setSizeFromLayout()

        override fun setType(type: Int) = surfaceHolder.setType(type)

        override fun unlockCanvasAndPost(canvas: Canvas) = surfaceHolder.unlockCanvasAndPost(canvas)
    }
}

The questions

I'd like to know how to adjust the scale the content based on what we have for ImageView, all while keeping the aspect ratio :

1. center-crop - fits to 100% of the container (the screen in this case), cropping on sides (top&bottom or left&right) when needed. Doesn't stretch anything. This means the content seems fine, but not all of it might be shown.
2. fit-center - stretch to fit width/height
3. center-inside - set as original size, centered, and stretch to fit width/height only if too large.