【发布时间】：2020-04-02 04:03:34
【问题描述】：
我有一个自定义的相机应用程序，它有一个居中的矩形视图，如下所示：
当我拍照时，我想忽略矩形之外的所有内容。这是我的 XML 布局：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/black_50">
<TextureView
android:id="@+id/viewFinder"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<View
android:layout_width="match_parent"
android:layout_height="250dp"
android:layout_margin="16dp"
android:background="@drawable/rectangle"
app:layout_constraintBottom_toTopOf="@+id/cameraBottomView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<View
android:id="@+id/cameraBottomView"
android:layout_width="match_parent"
android:layout_height="130dp"
android:background="@color/black_50"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<ImageButton
android:id="@+id/cameraCaptureImageButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@android:color/transparent"
android:src="@drawable/ic_capture_image"
app:layout_constraintBottom_toBottomOf="@id/cameraBottomView"
app:layout_constraintEnd_toEndOf="@id/cameraBottomView"
app:layout_constraintStart_toStartOf="@id/cameraBottomView"
app:layout_constraintTop_toTopOf="@id/cameraBottomView"
tools:ignore="ContentDescription" />
</androidx.constraintlayout.widget.ConstraintLayout>
这是我用于 cameraX 预览的 kotlin 代码：
class CameraFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_camera, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewFinder.post { setupCamera() }
}
private fun setupCamera() {
CameraX.unbindAll()
CameraX.bindToLifecycle(
this,
buildPreviewUseCase(),
buildImageCaptureUseCase(),
buildImageAnalysisUseCase()
)
}
private fun buildPreviewUseCase(): Preview {
val preview = Preview(
UseCaseConfigBuilder.buildPreviewConfig(
viewFinder.display
)
)
preview.setOnPreviewOutputUpdateListener { previewOutput ->
updateViewFinderWithPreview(previewOutput)
correctPreviewOutputForDisplay(previewOutput.textureSize)
}
return preview
}
private fun updateViewFinderWithPreview(previewOutput: Preview.PreviewOutput) {
val parent = viewFinder.parent as ViewGroup
parent.removeView(viewFinder)
parent.addView(viewFinder, 0)
viewFinder.surfaceTexture = previewOutput.surfaceTexture
}
/**
* Corrects the camera/preview's output to the display, by scaling
* up/down and/or rotating the camera/preview's output.
*/
private fun correctPreviewOutputForDisplay(textureSize: Size) {
val matrix = Matrix()
val centerX = viewFinder.width / 2f
val centerY = viewFinder.height / 2f
val displayRotation = getDisplayRotation()
val (dx, dy) = getDisplayScalingFactors(textureSize)
matrix.postRotate(displayRotation, centerX, centerY)
matrix.preScale(dx, dy, centerX, centerY)
// Correct preview output to account for display rotation and scaling
viewFinder.setTransform(matrix)
}
private fun getDisplayRotation(): Float {
val rotationDegrees = when (viewFinder.display.rotation) {
Surface.ROTATION_0 -> 0
Surface.ROTATION_90 -> 90
Surface.ROTATION_180 -> 180
Surface.ROTATION_270 -> 270
else -> throw IllegalStateException("Unknown display rotation ${viewFinder.display.rotation}")
}
return -rotationDegrees.toFloat()
}
private fun getDisplayScalingFactors(textureSize: Size): Pair<Float, Float> {
val cameraPreviewRation = textureSize.height / textureSize.width.toFloat()
val scaledWidth: Int
val scaledHeight: Int
if (viewFinder.width > viewFinder.height) {
scaledHeight = viewFinder.width
scaledWidth = (viewFinder.width * cameraPreviewRation).toInt()
} else {
scaledHeight = viewFinder.height
scaledWidth = (viewFinder.height * cameraPreviewRation).toInt()
}
val dx = scaledWidth / viewFinder.width.toFloat()
val dy = scaledHeight / viewFinder.height.toFloat()
return Pair(dx, dy)
}
private fun buildImageCaptureUseCase(): ImageCapture {
val capture = ImageCapture(
UseCaseConfigBuilder.buildImageCaptureConfig(
viewFinder.display
)
)
cameraCaptureImageButton.setOnClickListener {
capture.takePicture(
FileCreator.createTempFile(JPEG_FORMAT),
Executors.newSingleThreadExecutor(),
object : ImageCapture.OnImageSavedListener {
override fun onImageSaved(file: File) {
requireActivity().runOnUiThread {
launchGalleryFragment(file.absolutePath)
}
}
override fun onError(
imageCaptureError: ImageCapture.ImageCaptureError,
message: String,
cause: Throwable?
) {
Toast.makeText(requireContext(), "Error: $message", Toast.LENGTH_LONG)
.show()
Log.e("CameraFragment", "Capture error $imageCaptureError: $message", cause)
}
})
}
return capture
}
private fun buildImageAnalysisUseCase(): ImageAnalysis {
val analysis = ImageAnalysis(
UseCaseConfigBuilder.buildImageAnalysisConfig(
viewFinder.display
)
)
analysis.setAnalyzer(
Executors.newSingleThreadExecutor(),
ImageAnalysis.Analyzer { image, rotationDegrees ->
Log.d(
"CameraFragment",
"Image analysis: $image - Rotation degrees: $rotationDegrees"
)
})
return analysis
}
private fun launchGalleryFragment(path: String) {
val action = CameraFragmentDirections.actionLaunchGalleryFragment(path)
findNavController().navigate(action)
}
}
当我拍摄照片并将其发送到新页面（GalleryPage）时，它会显示相机预览中的所有屏幕，如下所示：
这是从 cameraX 预览中获取图片并将其显示到 ImageView 中的 kotlin 代码：
class GalleryFragment : Fragment() {
private lateinit var imageView: ImageView
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_gallery, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
imageView = view.findViewById(R.id.img)
val imageFilePath = GalleryFragmentArgs.fromBundle(arguments!!).data
val bitmap = BitmapFactory.decodeFile(imageFilePath)
val rotatedBitmap = bitmap.rotate(90)
if (imageFilePath.isBlank()) {
Log.i(
"GalleryFragment",
"Image is Null or Empty"
)
} else {
Glide.with(activity!!)
.load(rotatedBitmap)
.into(imageView)
}
}
private fun Bitmap.rotate(degree:Int):Bitmap{
// Initialize a new matrix
val matrix = Matrix()
// Rotate the bitmap
matrix.postRotate(degree.toFloat())
// Resize the bitmap
val scaledBitmap = Bitmap.createScaledBitmap(
this,
width,
height,
true
)
// Create and return the rotated bitmap
return Bitmap.createBitmap(
scaledBitmap,
0,
0,
scaledBitmap.width,
scaledBitmap.height,
matrix,
true
)
}
}
有人可以帮我如何正确裁剪图像吗？因为我已经搜索并研究了如何做到这一点，但仍然感到困惑并且不适合我。
【问题讨论】：
标签： kotlin crop android-camerax