EditPageScreen: fix visual glitch when loading the same page twice

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

@@ -182,7 +182,6 @@ class MainActivity : ComponentActivity() {
                     is Screen.Main.EditImage -> {
                         EditPageScreen(
                             pageId = documentUiState.currentPage?.key?.pageId ?: "",
-                            onLoad = { id -> viewModel.loadCropInitialState(id)},
                             initState = cropInitialState,
                             navigation = navigation,
                             onUpdatePageQuad = { quad -> viewModel.setCurrentPageUserQuad(quad) },
@@ -196,6 +195,7 @@ class MainActivity : ComponentActivity() {
                             onDeleteImage =  { viewModel.deleteCurrentPage() },
                             onRotateImage = { clockwise -> viewModel.rotateCurrentPage(clockwise) },
                             onToggleColorMode = { viewModel.toggleCurrentPageColorMode() },
+                            onCropClick = { viewModel.onClickOnCropButton() },
                             onPageReorder = { id, newIndex -> viewModel.movePage(id, newIndex) },
                             onPageSelected = viewModel::onPageSelected
                         )

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

@@ -242,13 +242,12 @@ class MainViewModel(val imageRepository: ImageRepository): ViewModel() {
     val cropInitState: StateFlow<CropInitState> = _cropInitState
 
     private var cropInitialStateJob: Job? = null
-    fun loadCropInitialState(pageId: String) {
+    fun onClickOnCropButton() {
         cropInitialStateJob?.cancel()
         cropInitialStateJob = viewModelScope.launch {
             _cropInitState.value = CropInitState.Loading
 
-            val page = _pages.value.find { it.id == pageId }
+            val page = currentPage()
-                ?: return@launch
 
             val metadata = page.metadata
             val rotation = page.totalRotation()
@@ -277,6 +276,8 @@ class MainViewModel(val imageRepository: ImageRepository): ViewModel() {
                 CropInitState.Error
             else
                 CropInitState.Ready(page.id, bitmap, quad)
+            navigateTo(Screen.Main.EditImage)
         }
+
     }
 }

app/src/main/java/org/fairscan/app/ui/screens/document/DocumentScreen.kt

@@ -99,6 +99,7 @@ fun DocumentScreen(
     onDeleteImage: () -> Unit,
     onRotateImage: (Boolean) -> Unit,
     onToggleColorMode: () -> Unit,
+    onCropClick: () -> Unit,
     onPageReorder: (String, Int) -> Unit,
     onPageSelected: (Int) -> Unit,
 ) {
@@ -132,7 +133,7 @@ fun DocumentScreen(
             { showDeletePageDialog.value = true },
             onRotateImage,
             onToggleColorMode,
-            navigation,
+            onCropClick,
             modifier
         )
         if (showDeletePageDialog.value) {
@@ -151,7 +152,7 @@ private fun DocumentPreview(
     onDeleteImage: () -> Unit,
     onRotateImage: (Boolean) -> Unit,
     onToggleColorMode: () -> Unit,
-    navigation: Navigation,
+    onCropClick: () -> Unit,
     modifier: Modifier,
 ) {
     val currentPageIndex = uiState.currentPageIndex
@@ -199,7 +200,7 @@ private fun DocumentPreview(
             EditButtons(
                 uiState,
                 onToggleColorMode,
-                navigation,
+                onCropClick,
                 modifier = Modifier.align(Alignment.BottomStart)
             )
             RotationButtons(onRotateImage, Modifier.align(Alignment.BottomCenter))
@@ -256,7 +257,7 @@ fun RotationButtons(
 fun EditButtons(
     uiState: DocumentUiState,
     onToggleColorMode: () -> Unit,
-    navigation: Navigation,
+    onCropClick: () -> Unit,
     modifier: Modifier
 ) {
     Row(modifier = modifier.padding(8.dp)) {
@@ -271,7 +272,7 @@ fun EditButtons(
             SecondaryActionButton(
                 icon = Icons.Default.Crop,
                 contentDescription = "Crop", // TODO externalize string
-                onClick = navigation.toEditImageScreen,
+                onClick = onCropClick,
             )
         }
     }
@@ -378,6 +379,7 @@ fun DocumentScreenPreview() {
             onDeleteImage = { },
             onRotateImage = { _ -> },
             onToggleColorMode = { },
+            onCropClick = { },
             onPageReorder = { _,_ -> },
             onPageSelected = { _ -> },
         )

app/src/main/java/org/fairscan/app/ui/screens/edit/EditPageScreen.kt

@@ -66,25 +66,20 @@ import org.fairscan.imageprocessing.Quad
 @Composable
 fun EditPageScreen(
     pageId: String,
-    onLoad: (String) -> Unit,
     initState: CropInitState,
     navigation: Navigation,
     onUpdatePageQuad: (Quad) -> Unit,
 ) {
-    val state = remember { EditPageScreenState() }
+    val state = remember(pageId) { EditPageScreenState() }
     val quadHandler = remember { QuadEditingHandler() }
 
-    if (initState is CropInitState.Ready && initState.pageId == pageId) {
+    if (initState is CropInitState.Ready && initState.pageId == pageId && state.bitmap == null) {
         state.bitmap = initState.bitmap
         state.setInitialQuad(initState.quad)
     }
 
     BackHandler { navigation.back() }
 
-    LaunchedEffect(pageId) {
-        onLoad(pageId)
-    }
-
     val isLandscape = isLandscape(LocalConfiguration.current)
 
     MyScaffold(
@@ -321,7 +316,6 @@ fun EditPageScreenPreview() {
         val quad = Quad(Point(.1, .1), Point(.9, .1), Point(.9, .9), Point(.1, .9))
         EditPageScreen(
             pageId = "123",
-            onLoad = {},
             initState = CropInitState.Ready("123",dummyImage, quad),
             navigation = dummyNavigation(),
             onUpdatePageQuad = { _ -> },