add sources

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

@@ -0,0 +1,63 @@
+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.ImageProxy
+import java.io.ByteArrayOutputStream
+import kotlin.math.min
+
+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 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 {
+        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
+    }
+
+    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
+            }
+        }
+    }
+}