在相机应用中支持可调整大小的 Surface

git clone https://github.com/googlecodelabs/android-camera2-preview.git

<activity
    android:name=".CameraActivity"
    android:exported="true"
    android:resizeableActivity="true">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

<activity
    android:name=".CameraActivity"
    android:exported="true"
    android:configChanges="keyboard|keyboardHidden|orientation|screenSize|screenLayout|smallestScreenSize|uiMode"
    android:resizeableActivity="true">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

override fun onSurfaceTextureSizeChanged(
    surface: SurfaceTexture,
    width: Int,
    height: Int
) {
    createCaptureSession()
}

/** DisplayManager to listen to display changes */
private val displayManager: DisplayManager by lazy {
    applicationContext.getSystemService(DISPLAY_SERVICE) as DisplayManager
}

/** Keeps track of display rotations */
private var displayRotation = 0

...

override fun onAttachedToWindow() {
    super.onAttachedToWindow()
    displayManager.registerDisplayListener(displayListener, mainLooperHandler)
}

override fun onDetachedFromWindow() {
    super.onDetachedFromWindow()
    displayManager.unregisterDisplayListener(displayListener)
}

private val displayListener = object : DisplayManager.DisplayListener {
    override fun onDisplayAdded(displayId: Int) {}
    override fun onDisplayRemoved(displayId: Int) {}
    override fun onDisplayChanged(displayId: Int) {
        val difference = displayManager.getDisplay(displayId).rotation - displayRotation
        displayRotation = displayManager.getDisplay(displayId).rotation

        if (difference == 2 || difference == -2) {
            createCaptureSession()
        }
    }
}

fun buildTargetTexture(
    containerView: TextureView,
    characteristics: CameraCharacteristics,
    surfaceRotation: Int
): SurfaceTexture? {

    val previewSize = findBestPreviewSize(Size(containerView.width, containerView.height), characteristics)

    val surfaceRotationDegrees = surfaceRotation * 90

    val halfWidth = containerView.width / 2f
    val halfHeight = containerView.height / 2f

    val matrix = Matrix()

    // Rotate to compensate display rotation
    matrix.postRotate(
        -surfaceRotationDegrees.toFloat(),
        halfWidth,
        halfHeight
    )

    containerView.setTransform(matrix)

    return containerView.surfaceTexture?.apply {
        setDefaultBufferSize(previewSize.width, previewSize.height)
    }
}

val targetTexture = CameraUtils.buildTargetTexture(
textureView, cameraManager.getCameraCharacteristics(cameraID))

/**
 * Computes the relative rotation between the sensor orientation and the display rotation.
 */
private fun computeRelativeRotation(
    characteristics: CameraCharacteristics,
    deviceOrientationDegrees: Int
): Int {
    val sensorOrientationDegrees =
        characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION) ?: 0

    // Reverse device orientation for front-facing cameras
    val sign = if (characteristics.get(CameraCharacteristics.LENS_FACING) ==
        CameraCharacteristics.LENS_FACING_FRONT
    ) 1 else -1

    return (sensorOrientationDegrees - (deviceOrientationDegrees * sign) + 360) % 360
}

val isRotationRequired =
        computeRelativeRotation(characteristics, surfaceRotationDegrees) % 180 != 0

fun buildTargetTexture(
        containerView: TextureView,
        characteristics: CameraCharacteristics,
        surfaceRotation: Int
    ): SurfaceTexture? {

        val surfaceRotationDegrees = surfaceRotation * 90
        val windowSize = Size(containerView.width, containerView.height)
        val previewSize = findBestPreviewSize(windowSize, characteristics)
        val sensorOrientation =
            characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION) ?: 0
        val isRotationRequired =
            computeRelativeRotation(characteristics, surfaceRotationDegrees) % 180 != 0

        /* Scale factor required to scale the preview to its original size on the x-axis */
        var scaleX = 1f
        /* Scale factor required to scale the preview to its original size on the y-axis */
        var scaleY = 1f

        if (sensorOrientation == 0) {
            scaleX =
                if (!isRotationRequired) {
                    windowSize.width.toFloat() / previewSize.height
                } else {
                    windowSize.width.toFloat() / previewSize.width
                }

            scaleY =
                if (!isRotationRequired) {
                    windowSize.height.toFloat() / previewSize.width
                } else {
                    windowSize.height.toFloat() / previewSize.height
                }
        } else {
            scaleX =
                if (isRotationRequired) {
                    windowSize.width.toFloat() / previewSize.height
                } else {
                    windowSize.width.toFloat() / previewSize.width
                }

            scaleY =
                if (isRotationRequired) {
                    windowSize.height.toFloat() / previewSize.width
                } else {
                    windowSize.height.toFloat() / previewSize.height
                }
        }

        /* Scale factor required to fit the preview to the TextureView size */
        val finalScale = max(scaleX, scaleY)
        val halfWidth = windowSize.width / 2f
        val halfHeight = windowSize.height / 2f

        val matrix = Matrix()

        if (isRotationRequired) {
            matrix.setScale(
                1 / scaleX * finalScale,
                1 / scaleY * finalScale,
                halfWidth,
                halfHeight
            )
        } else {
            matrix.setScale(
                windowSize.height / windowSize.width.toFloat() / scaleY * finalScale,
                windowSize.width / windowSize.height.toFloat() / scaleX * finalScale,
                halfWidth,
                halfHeight
            )
        }

        // Rotate to compensate display rotation
        matrix.postRotate(
            -surfaceRotationDegrees.toFloat(),
            halfWidth,
            halfHeight
        )

        containerView.setTransform(matrix)

        return containerView.surfaceTexture?.apply {
            setDefaultBufferSize(previewSize.width, previewSize.height)
        }
    }

val windowParams: WindowManager.LayoutParams = window.attributes
windowParams.rotationAnimation = WindowManager.LayoutParams.ROTATION_ANIMATION_JUMPCUT
window.attributes = windowParams