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我正在使用androidx组件中的CameraView，当我使用takePicutre方法时，在ImageCapture.OnImageSavedListener监听器中调用onImageSaved方法大约需要2秒，这让用户感觉有问题。

这是我的代码：

private fun takePicture() {
    Log.d("ThreadRunning", Thread.currentThread().name)
    val file = File(filesDir, UUID.randomUUID().toString())
    val executor = Executors.newSingleThreadExecutor()
    val startTime = System.currentTimeMillis()
    cameraView?.takePicture(file, executor,
            object : ImageCapture.OnImageSavedListener {
                override fun onError(
                        error: ImageCapture.ImageCaptureError,
                        message: String,
                        exc: Throwable?
                ) {
                    runOnUiThread {
                        captureButton.visibility = View.VISIBLE
                        cameraView.visibility = View.VISIBLE
                    }
                    Log.d("CaptureClicked", "{$message}")
                }

                override fun onImageSaved(file: File) {

                    val bmOptions = BitmapFactory.Options()
                    var bitmap = BitmapFactory.decodeFile(file.absolutePath, bmOptions)
                    val displayMetrics = DisplayMetrics()
                    windowManager?.defaultDisplay?.getMetrics(displayMetrics)
                    //val width = displayMetrics.widthPixels
                    //val height = displayMetrics.heightPixels
                    val width = cameraView.width
                    val height = cameraView.height
                    val numratorValue = (height.toDouble() / width.toDouble()).roundToInt()
                    bitmap = Bitmap.createScaledBitmap(bitmap, width, height, true)
                    bitmap = if (cameraView.cameraLensFacing == CameraX.LensFacing.FRONT) {
                        bitmap.rotate(270F).mirror()
                    } else {
                        bitmap.rotate(90F)
                    }
                    runOnUiThread{
                        capturedImageView.setImageBitmap(bitmap)
                        capturedImageView.visibility = View.VISIBLE
                        cancelButton.visibility = View.VISIBLE
                        captureButton.visibility = View.INVISIBLE

                    }


                    Log.d("TestDelay", "${System.currentTimeMillis() - startTime}")
                }
            }
    )

}

private fun Bitmap.rotate(degrees: Float): Bitmap {
    val matrix = Matrix().apply {
        postRotate(degrees)
    }
    return Bitmap.createBitmap(this, 0, 0, width, height, matrix, true)
}

private fun Bitmap.mirror(): Bitmap {
    val matrix = Matrix().apply {
        preScale(-1F, 1F)
    }
    return Bitmap.createBitmap(this, 0, 0, width, height, matrix, true)
}

这是cameraView的xml元素

<androidx.camera.view.CameraView
    android:id="@+id/cameraView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:captureMode="image"/>

另一个问题，当我在Fragment中使用takePicture方法时，我得到了 0.5 秒的黑屏，我认为是因为生命周期管理器对象，但我不知道应该将绑定方法放在哪里以及在哪里取消绑定。

所以我有两个问题

1 - 为什么相机视图需要太多时间来捕捉图片以及如何减少这个时间？

2 - 为什么我在使用Fragment时调用takePicutre方法后会出现黑屏？

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0 回答 0