New feature: Reorder pages (#20) (#38)

* Page reordering: backend * Page reordering: user interface * Improve handling of data inconsistencies
2025-09-27 10:16:18 +02:00
parent 189af12c88
commit e93cf0c3a2
13 changed files with 171 additions and 35 deletions
--- a/app/src/main/java/org/fairscan/app/ImageRepository.kt
+++ b/app/src/main/java/org/fairscan/app/ImageRepository.kt
@@ -14,6 +14,11 @@
 */
 package org.fairscan.app

+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.toImmutableList
+import kotlinx.serialization.json.Json
+import org.fairscan.app.data.DocumentMetadata
+import org.fairscan.app.data.Page
 import java.io.File

 const val SCAN_DIR_NAME = "scanned_pages"
@@ -24,19 +29,52 @@ class ImageRepository(appFilesDir: File, val transformations: ImageTransformatio
        if (!exists()) mkdirs()
    }

-    val fileNames = scanDir.listFiles()
-        ?.map { f -> f.name }?.toMutableList()
-        ?:mutableListOf()
+    private val metadataFile = File(scanDir, "document.json")

-    fun imageIds(): List<String> {
-        return fileNames.toList()
+    private var fileNames: MutableList<String> =
+        loadFileNames()
+
+    private fun loadFileNames(): MutableList<String> {
+        val filesOnDisk: Set<String> = scanDir.listFiles()
+            ?.filter { it.extension == "jpg" }
+            ?.map { it.name }
+            ?.toSet()
+            ?: emptySet()
+
+        val metadataFiles: List<String>? = loadMetadata()
+            ?.pages
+            ?.map { it.file }
+
+        return when {
+            metadataFiles != null -> metadataFiles
+                .filter { it in filesOnDisk }
+                .toMutableList()
+            else -> filesOnDisk
+                .sorted()
+                .toMutableList()
+        }
    }

+    private fun loadMetadata(): DocumentMetadata? =
+        if (metadataFile.exists()) {
+            runCatching {
+                Json.decodeFromString<DocumentMetadata>(metadataFile.readText())
+            }.getOrNull()
+        } else null
+
+    private fun saveMetadata() {
+        val metadata = DocumentMetadata(version = 1, pages = fileNames.map { id -> Page(id) })
+        metadataFile.writeText(Json.encodeToString(metadata))
+    }
+
+    fun imageIds(): ImmutableList<String> = fileNames.toImmutableList()
+
    fun add(bytes: ByteArray) {
        val fileName = "${System.currentTimeMillis()}.jpg"
        val file = File(scanDir, fileName)
        file.writeBytes(bytes)
        fileNames.add(fileName)
+        saveMetadata()
    }

    val idRegex = Regex("([0-9]+)(-(90|180|270))?\\.jpg")
@@ -57,6 +95,7 @@ class ImageRepository(appFilesDir: File, val transformations: ImageTransformatio
                val index = fileNames.indexOf(id)
                if (index >= 0) {
                    fileNames[index] = rotatedId
+                    saveMetadata()
                }
                delete(id)
            }
@@ -64,17 +103,25 @@ class ImageRepository(appFilesDir: File, val transformations: ImageTransformatio
    }

    fun getContent(id: String): ByteArray? {
-        if (fileNames.contains(id)) {
-            val file = File(scanDir, id)
+        val file = File(scanDir, id)
+        if (file.exists()) {
            return file.readBytes()
        }
        return null
    }

+    fun movePage(id: String, newIndex: Int) {
+        if (!fileNames.remove(id)) return
+        val safeIndex = newIndex.coerceIn(0, fileNames.size)
+        fileNames.add(safeIndex, id)
+        saveMetadata()
+    }
+
    fun delete(id: String) {
        val file = File(scanDir, id)
        file.delete()
        fileNames.remove(id)
+        saveMetadata()
    }

    fun clear() {
@@ -82,5 +129,6 @@ class ImageRepository(appFilesDir: File, val transformations: ImageTransformatio
        scanDir.listFiles()?.forEach {
            file -> file.delete()
        }
+        saveMetadata()
    }
 }
--- a/app/src/main/java/org/fairscan/app/MainActivity.kt
+++ b/app/src/main/java/org/fairscan/app/MainActivity.kt
@@ -122,7 +122,8 @@ class MainActivity : ComponentActivity() {
                            initialPage = screen.initialPage,
                            navigation = navigation,
                            onDeleteImage =  { id -> viewModel.deletePage(id) },
-                            onRotateImage = { id, clockwise -> viewModel.rotateImage(id, clockwise) }
+                            onRotateImage = { id, clockwise -> viewModel.rotateImage(id, clockwise) },
+                            onPageReorder = { id, newIndex -> viewModel.movePage(id, newIndex) },
                        )
                    }
                    is Screen.Main.Export -> {
--- a/app/src/main/java/org/fairscan/app/MainViewModel.kt
+++ b/app/src/main/java/org/fairscan/app/MainViewModel.kt
@@ -26,6 +26,7 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.viewModelScope
 import androidx.lifecycle.viewmodel.CreationExtras
+import kotlinx.collections.immutable.persistentListOf
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -87,7 +88,7 @@ class MainViewModel(
        }.stateIn(
            scope = viewModelScope,
            started = SharingStarted.Eagerly,
-            initialValue = DocumentUiModel(emptyList(), ::getBitmap)
+            initialValue = DocumentUiModel(persistentListOf(), ::getBitmap)
        )

    private val _captureState = MutableStateFlow<CaptureState>(CaptureState.Idle)
@@ -228,6 +229,11 @@ class MainViewModel(
        }
    }

+    fun movePage(id: String, newIndex: Int) {
+        imageRepository.movePage(id, newIndex)
+        _pageIds.value = imageRepository.imageIds()
+    }
+
    fun afterCaptureError() {
        _captureState.value = CaptureState.Idle
    }
@@ -238,7 +244,7 @@ class MainViewModel(
    }

    fun startNewDocument() {
-        _pageIds.value = listOf()
+        _pageIds.value = persistentListOf()
        viewModelScope.launch {
            imageRepository.clear()
        }
--- a/app/src/main/java/org/fairscan/app/data/DocumentMetadata.kt
+++ b/app/src/main/java/org/fairscan/app/data/DocumentMetadata.kt
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2025 Pierre-Yves Nicolas
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.fairscan.app.data
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class DocumentMetadata(
+    val version: Int = 1,
+    val pages: List<Page>
+)
+
+@Serializable
+data class Page(
+    val file: String,
+)
--- a/app/src/main/java/org/fairscan/app/view/CameraScreen.kt
+++ b/app/src/main/java/org/fairscan/app/view/CameraScreen.kt
@@ -76,6 +76,7 @@ import androidx.compose.ui.tooling.preview.Preview
 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.delay
 import org.fairscan.app.CameraPermissionState
 import org.fairscan.app.LiveAnalysisState
@@ -157,6 +158,7 @@ fun CameraScreen(
            CommonPageListState(
                document = document,
                onPageClick = { index -> viewModel.navigateTo(Screen.Main.Document(index)) },
+                onPageReorder = { id, index -> viewModel.movePage(id, index) },
                listState = listState,
                onLastItemPosition = { offset -> thumbnailCoords.value = offset },
            ),
@@ -468,9 +470,12 @@ private fun ScreenPreview(captureState: CaptureState, rotationDegrees: Float = 0
            pageListState =
                CommonPageListState(
                    document = fakeDocument(
-                        listOf(1, 2, 2, 2).map { "gallica.bnf.fr-bpt6k5530456s-$it.jpg" },
+                        listOf(1, 2)
+                            .map { "gallica.bnf.fr-bpt6k5530456s-$it.jpg" }
+                            .toImmutableList(),
                        LocalContext.current),
                    onPageClick = {},
+                    onPageReorder = { _,_ -> },
                    listState = LazyListState(),
                ),
            cameraUiState = CameraUiState(pageCount = 4, LiveAnalysisState(), captureState,
--- a/app/src/main/java/org/fairscan/app/view/DocumentScreen.kt
+++ b/app/src/main/java/org/fairscan/app/view/DocumentScreen.kt
@@ -52,6 +52,7 @@ import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
+import kotlinx.collections.immutable.toImmutableList
 import net.engawapg.lib.zoomable.ZoomState
 import net.engawapg.lib.zoomable.zoomable
 import org.fairscan.app.Navigation
@@ -66,6 +67,7 @@ fun DocumentScreen(
    navigation: Navigation,
    onDeleteImage: (String) -> Unit,
    onRotateImage: (String, Boolean) -> Unit,
+    onPageReorder: (String, Int) -> Unit,
 ) {
    // TODO Check how often images are loaded
    val showDeletePageDialog = rememberSaveable { mutableStateOf(false) }
@@ -81,7 +83,7 @@ fun DocumentScreen(

    val listState = rememberLazyListState()
    LaunchedEffect(currentPageIndex.intValue) {
-        listState.animateScrollToItem(currentPageIndex.intValue)
+        listState.scrollToItem(currentPageIndex.intValue)
    }

    MyScaffold(
@@ -89,6 +91,7 @@ fun DocumentScreen(
        pageListState = CommonPageListState(
            document,
            onPageClick = { index -> currentPageIndex.intValue = index },
+            onPageReorder = onPageReorder,
            currentPageIndex = currentPageIndex.intValue,
            listState = listState,
        ),
@@ -226,12 +229,13 @@ fun DocumentScreenPreview() {
    FairScanTheme {
        DocumentScreen(
            fakeDocument(
-                listOf(1, 2, 2, 2).map { "gallica.bnf.fr-bpt6k5530456s-$it.jpg" },
+                listOf(1, 2).map { "gallica.bnf.fr-bpt6k5530456s-$it.jpg" }.toImmutableList(),
                LocalContext.current),
            initialPage = 1,
            navigation = dummyNavigation(),
            onDeleteImage = { _ -> },
            onRotateImage = { _,_ -> },
+            onPageReorder = { _,_ -> },
        )
    }
 }
--- a/app/src/main/java/org/fairscan/app/view/DocumentUiModel.kt
+++ b/app/src/main/java/org/fairscan/app/view/DocumentUiModel.kt
@@ -15,9 +15,10 @@
 package org.fairscan.app.view

 import android.graphics.Bitmap
+import kotlinx.collections.immutable.ImmutableList

 data class DocumentUiModel(
-    private val pageIds: List<String>,
+    val pageIds: ImmutableList<String>,
    private val imageLoader: (String) -> Bitmap?
 ) {
    fun pageCount(): Int {
--- a/app/src/main/java/org/fairscan/app/view/HomeScreen.kt
+++ b/app/src/main/java/org/fairscan/app/view/HomeScreen.kt
@@ -54,6 +54,7 @@ import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
+import kotlinx.collections.immutable.persistentListOf
 import org.fairscan.app.CameraPermissionState
 import org.fairscan.app.Navigation
 import org.fairscan.app.R
@@ -284,7 +285,7 @@ fun HomeScreenPreviewWithCurrentDocument() {
        HomeScreen(
            cameraPermission = rememberCameraPermissionState(),
            currentDocument = fakeDocument(
-                listOf("gallica.bnf.fr-bpt6k5530456s-1.jpg"),
+                persistentListOf("gallica.bnf.fr-bpt6k5530456s-1.jpg"),
                LocalContext.current),
            navigation = dummyNavigation(),
            onClearScan = {},
--- a/app/src/main/java/org/fairscan/app/view/PageList.kt
+++ b/app/src/main/java/org/fairscan/app/view/PageList.kt
@@ -14,6 +14,7 @@
 */
 package org.fairscan.app.view

+import android.annotation.SuppressLint
 import android.content.res.Configuration
 import android.graphics.Bitmap
 import androidx.compose.foundation.Image
@@ -31,6 +32,7 @@ import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.LazyListScope
 import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.LazyRow
+import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
@@ -47,12 +49,15 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import sh.calvin.reorderable.ReorderableItem
+import sh.calvin.reorderable.rememberReorderableLazyListState

 const val PAGE_LIST_ELEMENT_SIZE_DP = 120

 data class CommonPageListState(
    val document: DocumentUiModel,
    val onPageClick: (Int) -> Unit,
+    val onPageReorder: (String, Int) -> Unit,
    val listState: LazyListState,
    val currentPageIndex: Int? = null,
    val onLastItemPosition: ((Offset) -> Unit)? = null,
@@ -64,12 +69,18 @@ fun CommonPageList(
    modifier: Modifier = Modifier,
 ) {
    val isLandscape = LocalConfiguration.current.orientation == Configuration.ORIENTATION_LANDSCAPE
+
+    val reorderableLazyListState = rememberReorderableLazyListState(state.listState) { from, to ->
+        state.onPageReorder(from.key as String, to.index)
+    }
    val content: LazyListScope.() -> Unit = {
-        items(state.document.pageCount()) { index ->
-            // TODO Use small images rather than big ones
-            val image = state.document.load(index)
-            if (image != null) {
-                PageThumbnail(image, index, state)
+        itemsIndexed(state.document.pageIds, key = { _, item -> item}) { index, item ->
+            ReorderableItem(reorderableLazyListState, key = item) { _ ->
+                // TODO Use small images rather than big ones
+                val image = state.document.load(index)
+                if (image != null) {
+                    PageThumbnail(image, index, state, Modifier.draggableHandle())
+                }
            }
        }
    }
@@ -103,33 +114,34 @@ private fun PageThumbnail(
    image: Bitmap,
    index: Int,
    state: CommonPageListState,
+    @SuppressLint("ModifierParameter") draggableModifier: Modifier,
 ) {
    val bitmap = image.asImageBitmap()
    val isSelected = index == state.currentPageIndex
    val borderColor =
        if (isSelected) MaterialTheme.colorScheme.secondary else Color.Transparent
    val maxImageSize = PAGE_LIST_ELEMENT_SIZE_DP.dp
-    var modifier =
+    var imageModifier =
        if (bitmap.height > bitmap.width)
            Modifier.height(maxImageSize)
        else
            Modifier.width(maxImageSize)
    if (index == state.document.lastIndex()) {
        val density = LocalDensity.current
-        modifier = modifier.addPositionCallback(state.onLastItemPosition, density, 1.0f)
+        imageModifier = imageModifier.addPositionCallback(state.onLastItemPosition, density, 1.0f)
    }
    Box (modifier = Modifier.height(PAGE_LIST_ELEMENT_SIZE_DP.dp)) {
        Image(
            bitmap = bitmap,
            contentDescription = null,
-            modifier = modifier
+            modifier = imageModifier
                .align(Alignment.Center)
                .padding(4.dp)
                .border(2.dp, borderColor)
                .clickable { state.onPageClick(index) }
        )
        Box(
-            modifier = Modifier
+            modifier = draggableModifier
                .padding(8.dp)
                .align(Alignment.BottomCenter)
                .background(Color.Black.copy(alpha = 0.5f), shape = RoundedCornerShape(4.dp))
--- a/app/src/main/java/org/fairscan/app/view/PreviewUtils.kt
+++ b/app/src/main/java/org/fairscan/app/view/PreviewUtils.kt
@@ -16,6 +16,8 @@ package org.fairscan.app.view

 import android.content.Context
 import android.graphics.BitmapFactory
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.persistentListOf
 import org.fairscan.app.Navigation

 fun dummyNavigation(): Navigation {
@@ -23,10 +25,10 @@ fun dummyNavigation(): Navigation {
 }

 fun fakeDocument(): DocumentUiModel {
-    return DocumentUiModel(listOf()) { _ -> null }
+    return DocumentUiModel(persistentListOf()) { _ -> null }
 }

-fun fakeDocument(pageIds: List<String>, context: Context): DocumentUiModel {
+fun fakeDocument(pageIds: ImmutableList<String>, context: Context): DocumentUiModel {
    return DocumentUiModel(pageIds) { id ->
        context.assets.open(id).use { input ->
            BitmapFactory.decodeStream(input)