改一个版

app/src/main/java/com/example/studentfaceregistry/ImageUtils.kt

@@ -1,63 +1,72 @@
 package com.example.studentfaceregistry
 
 import android.graphics.Bitmap
-import android.graphics.BitmapFactory
-import android.graphics.ImageFormat
 import android.graphics.Matrix
-import android.graphics.Rect
-import android.graphics.YuvImage
 import android.media.Image
+import androidx.camera.core.ExperimentalGetImage
 import androidx.camera.core.ImageProxy
-import java.io.ByteArrayOutputStream
-import kotlin.math.min
 
+@ExperimentalGetImage
 object ImageUtils {
     fun imageProxyToBitmap(imageProxy: ImageProxy): Bitmap {
         val image = imageProxy.image ?: error("ImageProxy does not contain an image.")
-        val nv21 = yuv420ToNv21(image)
-        val yuvImage = YuvImage(nv21, ImageFormat.NV21, image.width, image.height, null)
-        val output = ByteArrayOutputStream()
-        yuvImage.compressToJpeg(Rect(0, 0, image.width, image.height), 90, output)
-        val bitmap = BitmapFactory.decodeByteArray(output.toByteArray(), 0, output.size())
+        val bitmap = yuv420ToBitmap(image)
+        if (imageProxy.imageInfo.rotationDegrees == 0) {
+            return bitmap
+        }
         val matrix = Matrix().apply {
             postRotate(imageProxy.imageInfo.rotationDegrees.toFloat())
         }
         return Bitmap.createBitmap(bitmap, 0, 0, bitmap.width, bitmap.height, matrix, true)
     }
 
-    private fun yuv420ToNv21(image: Image): ByteArray {
+    private fun yuv420ToBitmap(image: Image): Bitmap {
         val width = image.width
         val height = image.height
-        val ySize = width * height
-        val chromaSize = width * height / 4
-        val nv21 = ByteArray(ySize + chromaSize * 2)
-        copyPlane(image.planes[0], width, height, nv21, 0, 1)
-        copyPlane(image.planes[2], width / 2, height / 2, nv21, ySize, 2)
-        copyPlane(image.planes[1], width / 2, height / 2, nv21, ySize + 1, 2)
-        return nv21
-    }
+        val yPlane = image.planes[0]
+        val uPlane = image.planes[1]
+        val vPlane = image.planes[2]
 
-    private fun copyPlane(
-        plane: Image.Plane,
-        width: Int,
-        height: Int,
-        output: ByteArray,
-        offset: Int,
-        outputPixelStride: Int
-    ) {
-        val buffer = plane.buffer
-        val row = ByteArray(plane.rowStride)
-        var outputIndex = offset
-        for (rowIndex in 0 until height) {
-            val bytesToRead = min(plane.rowStride, buffer.remaining())
-            buffer.get(row, 0, bytesToRead)
-            for (colIndex in 0 until width) {
-                val inputIndex = colIndex * plane.pixelStride
-                if (inputIndex < bytesToRead && outputIndex < output.size) {
-                    output[outputIndex] = row[inputIndex]
-                }
-                outputIndex += outputPixelStride
+        val yBuffer = yPlane.buffer
+        val uBuffer = uPlane.buffer
+        val vBuffer = vPlane.buffer
+        val pixels = IntArray(width * height)
+
+        val yRowStride = yPlane.rowStride
+        val yPixelStride = yPlane.pixelStride
+        val uRowStride = uPlane.rowStride
+        val uPixelStride = uPlane.pixelStride
+        val vRowStride = vPlane.rowStride
+        val vPixelStride = vPlane.pixelStride
+
+        var pixelIndex = 0
+        for (row in 0 until height) {
+            val yRow = row * yRowStride
+            val uvRow = (row shr 1) * uRowStride
+            val vvRow = (row shr 1) * vRowStride
+            for (col in 0 until width) {
+                val y = (yBuffer.get(yRow + col * yPixelStride).toInt() and 0xFF) - 16
+                val u = (uBuffer.get(uvRow + (col shr 1) * uPixelStride).toInt() and 0xFF) - 128
+                val v = (vBuffer.get(vvRow + (col shr 1) * vPixelStride).toInt() and 0xFF) - 128
+
+                val y1192 = 1192 * y.coerceAtLeast(0)
+                var r = y1192 + 1634 * v
+                var g = y1192 - 833 * v - 400 * u
+                var b = y1192 + 2066 * u
+
+                r = r.coerceIn(0, 262143)
+                g = g.coerceIn(0, 262143)
+                b = b.coerceIn(0, 262143)
+
+                pixels[pixelIndex++] = -0x1000000 or
+                    ((r shl 6) and 0x00FF0000) or
+                    ((g shr 2) and 0x0000FF00) or
+                    ((b shr 10) and 0x000000FF)
             }
         }
+
+        return Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888).apply {
+            setPixels(pixels, 0, width, 0, 0, width, height)
+        }
     }
 }