Compress source JPEG during capture preview rather than later

app/src/androidTest/java/org/fairscan/app/domain/DocumentDetectionTest.kt

@@ -15,12 +15,14 @@
 package org.fairscan.app.domain
 
 import android.content.Context
-import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.util.Log
 import androidx.test.core.app.ApplicationProvider
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.platform.app.InstrumentationRegistry
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.runBlocking
 import org.fairscan.app.ui.screens.camera.extractDocumentFromBitmap
 import org.fairscan.imageprocessing.ImageSize
@@ -32,7 +34,6 @@ import org.junit.Test
 import org.junit.runner.RunWith
 import org.opencv.android.OpenCVLoader
 import java.io.File
-import java.io.FileOutputStream
 
 @RunWith(AndroidJUnit4::class)
 class DocumentDetectionTest {
@@ -45,6 +46,7 @@ class DocumentDetectionTest {
         val segmentationService = ImageSegmentationService(context) { _, _, _ -> }
         segmentationService.initialize()
         OpenCVLoader.initLocal()
+        val scope = CoroutineScope(SupervisorJob() + Dispatchers.Unconfined)
 
         listOf("img01.jpg", "img02.jpg", "img03.jpg").forEach { imageFileName ->
             val inputStream = context.assets.open("uncropped/$imageFileName")
@@ -60,7 +62,7 @@ class DocumentDetectionTest {
                 if (quad != null) {
                     val resizedQuad =
                         quad.scaledTo(mask.width, mask.height, bitmap.width, bitmap.height)
-                    outputJpeg = extractDocumentFromBitmap(bitmap, resizedQuad, 0, mask).pageJpeg
+                    outputJpeg = extractDocumentFromBitmap(bitmap, resizedQuad, 0, mask, scope).pageJpeg
                     val file = File(context.getExternalFilesDir(null), imageFileName)
                     file.writeBytes(outputJpeg)
                     Log.i("DocumentDetectionTest", "Image saved to ${file.absolutePath}")

app/src/main/java/org/fairscan/app/MainViewModel.kt

@@ -20,6 +20,7 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.toImmutableList
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.asCoroutineDispatcher
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
@@ -35,10 +36,6 @@ import org.fairscan.app.domain.PageViewKey
 import org.fairscan.app.ui.NavigationState
 import org.fairscan.app.ui.Screen
 import org.fairscan.app.ui.state.DocumentUiModel
-import org.fairscan.imageprocessing.encodeJpeg
-import org.opencv.android.Utils
-import org.opencv.core.Mat
-import org.opencv.imgproc.Imgproc
 import java.util.concurrent.Executors
 
 class MainViewModel(val imageRepository: ImageRepository, launchMode: LaunchMode): ViewModel() {
@@ -125,10 +122,13 @@ class MainViewModel(val imageRepository: ImageRepository, launchMode: LaunchMode
 
     fun handleImageCaptured(capturedPage: CapturedPage) {
         viewModelScope.launch {
+            val sourceJpeg = withContext(Dispatchers.IO) {
+                capturedPage.sourceJpeg.await()
+            }
             val pages = withContext(repositoryDispatcher) {
                 imageRepository.add(
                     capturedPage.pageJpeg,
-                    compressJpeg(capturedPage.source, 90),
+                    sourceJpeg,
                     capturedPage.metadata,
                 )
                 imageRepository.pages()
@@ -136,17 +136,4 @@ class MainViewModel(val imageRepository: ImageRepository, launchMode: LaunchMode
             _pages.value = pages
         }
     }
-
-    private fun compressJpeg(bitmap: Bitmap, quality: Int): ByteArray {
-        val rgba = Mat()
-        Utils.bitmapToMat(bitmap, rgba)
-        val bgr = Mat()
-        Imgproc.cvtColor(rgba, bgr, Imgproc.COLOR_RGBA2BGR)
-        rgba.release()
-        return try {
-            encodeJpeg(bgr, quality)
-        } finally {
-            bgr.release()
-        }
-    }
 }

app/src/main/java/org/fairscan/app/domain/CapturedPage.kt

@@ -15,10 +15,10 @@
 
 package org.fairscan.app.domain
 
-import android.graphics.Bitmap
+import kotlinx.coroutines.Deferred
 
 data class CapturedPage(
     val pageJpeg: ByteArray,
-    val source: Bitmap,
+    val sourceJpeg: Deferred<ByteArray>,
     val metadata: PageMetadata,
 )

app/src/main/java/org/fairscan/app/ui/screens/camera/CameraScreen.kt

@@ -86,6 +86,7 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import kotlinx.collections.immutable.toImmutableList
+import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.delay
 import org.fairscan.app.MainViewModel
 import org.fairscan.app.R
@@ -536,7 +537,7 @@ fun CameraScreenPreviewWithProcessedImage() {
         bitmap(debugImage("uncropped/img01.jpg")),
         CapturedPage(
             debugImage("gallica.bnf.fr-bpt6k5530456s-1.jpg"),
-            bitmap(debugImage("gallica.bnf.fr-bpt6k5530456s-1.jpg")),
+            CompletableDeferred(ByteArray(0)),
             PageMetadata(quad, R0, false))))
 }
 

app/src/main/java/org/fairscan/app/ui/screens/camera/CameraViewModel.kt

@@ -17,10 +17,11 @@ package org.fairscan.app.ui.screens.camera
 import android.graphics.Bitmap
 import android.graphics.Matrix
 import androidx.camera.core.ImageProxy
-import androidx.core.graphics.createBitmap
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.async
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -42,7 +43,6 @@ import org.fairscan.imageprocessing.extractDocument
 import org.fairscan.imageprocessing.isColoredDocument
 import org.fairscan.imageprocessing.scaledTo
 import org.opencv.android.Utils
-import org.opencv.core.CvType
 import org.opencv.core.Mat
 import org.opencv.imgproc.Imgproc
 
@@ -165,7 +165,8 @@ class CameraViewModel(appContainer: AppContainer): ViewModel() {
             val quad = detectDocumentQuad(mask, originalSize, isLiveAnalysis = false)
             if (quad != null) {
                 val resizedQuad = quad.scaledTo(mask.width, mask.height, source.width, source.height)
-                result = extractDocumentFromBitmap(source, resizedQuad, rotationDegrees, mask)
+                result = extractDocumentFromBitmap(
+                    source, resizedQuad, rotationDegrees, mask, viewModelScope)
             }
         }
         return@withContext result
@@ -196,6 +197,19 @@ class CameraViewModel(appContainer: AppContainer): ViewModel() {
     }
 }
 
+private fun compressJpeg(bitmap: Bitmap, quality: Int): ByteArray {
+    val rgba = Mat()
+    Utils.bitmapToMat(bitmap, rgba)
+    val bgr = Mat()
+    Imgproc.cvtColor(rgba, bgr, Imgproc.COLOR_RGBA2BGR)
+    rgba.release()
+    return try {
+        encodeJpeg(bgr, quality)
+    } finally {
+        bgr.release()
+    }
+}
+
 sealed class CaptureState {
     open val frozenImage: Bitmap? = null
 
@@ -209,7 +223,7 @@ sealed class CaptureState {
 }
 
 fun extractDocumentFromBitmap(
-    source: Bitmap, quad: Quad, rotationDegrees: Int, mask: Mask
+    source: Bitmap, quad: Quad, rotationDegrees: Int, mask: Mask, viewModelScope: CoroutineScope
 ): CapturedPage {
     val rgba = Mat()
     Utils.bitmapToMat(source, rgba)
@@ -226,7 +240,10 @@ fun extractDocumentFromBitmap(
     val normalizedQuad = quad.scaledTo(source.width, source.height, 1, 1)
     val baseRotation = Rotation.fromDegrees(rotationDegrees)
     val metadata = PageMetadata(normalizedQuad, baseRotation, isColored)
-    return CapturedPage(pageJpeg, source, metadata)
+    val sourceJpegDeferred = viewModelScope.async(Dispatchers.IO) {
+        compressJpeg(source, 90)
+    }
+    return CapturedPage(pageJpeg, sourceJpegDeferred, metadata)
 }
 
 fun rotateBitmap(source: Bitmap, angle: Float): Bitmap {