kotlin调用摄像头拍照

Question

第一行代码第三版，学习到调用摄像头拍照，由于startActivityForResult一弃用，改用TakePicturePreview这个Contract,到了这段就写不对了。

书的代码

---

MainActivity.kt

package android.example.cameraalbumtest

import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.graphics.Matrix
import android.media.ExifInterface
import android.net.Uri
import android.os.Build
import android.os.Bundle
import android.widget.Button
import android.widget.ImageView
import androidx.activity.result.contract.ActivityResultContracts
import androidx.appcompat.app.AppCompatActivity
import androidx.core.content.FileProvider
import java.io.File

class MainActivity : AppCompatActivity() {

    val takePhoto = 1
    private val imageView: ImageView = findViewById(R.id.imageView)
    private lateinit var imageUri: Uri
    private lateinit var outputImage: File
    private val takePictureLauncher = registerForActivityResult(
        ActivityResultContracts.TakePicturePreview()
    ) {
        val bitmap = BitmapFactory.decodeStream(contentResolver.openInputStream(imageUri))
        imageView.setImageBitmap(rotateIfRequired(bitmap))

    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val takePhotoBtn: Button = findViewById(R.id.takePhotoBtn)
        takePhotoBtn.setOnClickListener {
            outputImage = File(externalCacheDir, "output_image.jpg")
            if (outputImage.exists()) {
                outputImage.delete()
            }
            outputImage.createNewFile()
            imageUri = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                FileProvider.getUriForFile(
                    this, "android.example.bicameralism.file-provider",
                    outputImage
                )
            } else {
                Uri.fromFile(outputImage)
            }

            takePictureLauncher.launch(null)
        }
    }

    private fun rotateIfRequired(bitmap: Bitmap?): Bitmap? {
        val exif = ExifInterface(outputImage.path)
        val orientation = exif.getAttributeInt(
            ExifInterface.TAG_ORIENTATION,
            ExifInterface.ORIENTATION_NORMAL
        )
        return when (orientation) {
            ExifInterface.ORIENTATION_ROTATE_90 -> rotateBitmap(bitmap, 90)
            ExifInterface.ORIENTATION_ROTATE_180 -> rotateBitmap(bitmap, 180)
            ExifInterface.ORIENTATION_ROTATE_270 -> rotateBitmap(bitmap, 270)
            else -> bitmap
        }
    }

    private fun rotateBitmap(bitmap: Bitmap?, degree: Int): Bitmap? {
        val matrix = Matrix()
        matrix.postRotate(degree.toFloat())
        val rotateBitmap = bitmap?.let {
            Bitmap.createBitmap(
                bitmap, 0, 0, bitmap.width, bitmap.height,
                matrix, true
            )
        }
        bitmap?.recycle()
        return rotateBitmap
    }
}

---

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/takePhotoBtn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/take_photo"/>

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:contentDescription="@string/todo" />

</LinearLayout>

---

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.CameraAlbumTest"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>

        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="android.example.bicameralism.file-provider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths" />
        </provider>
    </application>
</manifest>

Answer 1

相机和存储权限呢