android - 如何使用 Stock 相机应用程序通过 Jetpack Compose 拍照？

Question

在我使用 Jetpack Compose 的应用中，如何使用现有的图库应用拍照并存储？ Google 的文档通过使用 Intent 提到了折旧的 Camera API，但他们使用的是旧的 View 系统。似乎较新的 Camera2 和 CameraX API 都旨在直接在应用程序中创建自定义相机界面。

Answer 1

您必须使用 Activity 契约(Contract)，请参阅 this article for details

class ComposeFileProvider : FileProvider(
    R.xml.filepaths
) {
    companion object {
        fun getImageUri(context: Context): Uri {
            val directory = File(context.cacheDir, "images")
            directory.mkdirs()
            val file = File.createTempFile(
                "selected_image_",
                ".jpg",
                directory,
            )
            val authority = context.packageName + ".fileprovider"
            return getUriForFile(
                context,
                authority,
                file,
            )
        }
    }
}

@Composable
fun ImagePicker(
    modifier: Modifier = Modifier,
) {
    var hasImage by remember {
        mutableStateOf(false)
    }
    var imageUri by remember {
        mutableStateOf<Uri?>(null)
    }

    val imagePicker = rememberLauncherForActivityResult(
        contract = ActivityResultContracts.GetContent(),
        onResult = { uri ->
            hasImage = uri != null
            imageUri = uri
        }
    )

    val cameraLauncher = rememberLauncherForActivityResult(
        contract = ActivityResultContracts.TakePicture(),
        onResult = { success ->
            hasImage = success
        }
    )

    val context = LocalContext.current
    Box(
        modifier = modifier,
    ) {
        if (hasImage && imageUri != null) {
            AsyncImage(
                model = imageUri,
                modifier = Modifier.fillMaxWidth(),
                contentDescription = "Selected image",
            )
        }
        Column(
            modifier = Modifier
                .align(Alignment.BottomCenter)
                .padding(bottom = 32.dp),
            horizontalAlignment = Alignment.CenterHorizontally,
        ) {
            Button(
                onClick = {
                    imagePicker.launch("image/*")
                },
            ) {
                Text(
                    text = "Select Image"
                )
            }
            Button(
                modifier = Modifier.padding(top = 16.dp),
                onClick = {
                    val uri = ComposeFileProvider.getImageUri(context)
                    imageUri = uri
                    cameraLauncher.launch(uri)
                },
            ) {
                Text(
                    text = "Take photo"
                )
            }
        }
    }
}