Merge "Add ImageLoader with improved caching and cancelling" into main

4 files changed, 219 insertions, 78 deletions

diff --git a/java/src/com/android/intentresolver/contentpreview/CachingImagePreviewImageLoader.kt b/java/src/com/android/intentresolver/contentpreview/CachingImagePreviewImageLoader.kt
new file mode 100644
index 00000000..ce064cdf
--- /dev/null
+++ b/java/src/com/android/intentresolver/contentpreview/CachingImagePreviewImageLoader.kt
@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.intentresolver.contentpreview
+
+import android.graphics.Bitmap
+import android.net.Uri
+import android.util.Log
+import androidx.core.util.lruCache
+import com.android.intentresolver.inject.Background
+import com.android.intentresolver.inject.ViewModelOwned
+import java.util.function.Consumer
+import javax.inject.Inject
+import javax.inject.Qualifier
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Deferred
+import kotlinx.coroutines.async
+import kotlinx.coroutines.ensureActive
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.sync.Semaphore
+import kotlinx.coroutines.sync.withPermit
+import kotlinx.coroutines.withContext
+
+@Qualifier
+@MustBeDocumented
+@Retention(AnnotationRetention.BINARY)
+annotation class PreviewMaxConcurrency
+
+/**
+ * Implementation of [ImageLoader].
+ *
+ * Allows for cached or uncached loading of images and limits the number of concurrent requests.
+ * Requests are automatically cancelled when they are evicted from the cache. If image loading fails
+ * or the request is cancelled (e.g. by eviction), the returned [Bitmap] will be null.
+ */
+class CachingImagePreviewImageLoader
+@Inject
+constructor(
+    @ViewModelOwned private val scope: CoroutineScope,
+    @Background private val bgDispatcher: CoroutineDispatcher,
+    private val thumbnailLoader: ThumbnailLoader,
+    @PreviewCacheSize cacheSize: Int,
+    @PreviewMaxConcurrency maxConcurrency: Int,
+) : ImageLoader {
+
+    private val semaphore = Semaphore(maxConcurrency)
+
+    private val cache =
+        lruCache(
+            maxSize = cacheSize,
+            create = { uri: Uri -> scope.async { loadUncachedImage(uri) } },
+            onEntryRemoved = { evicted: Boolean, _, oldValue: Deferred<Bitmap?>, _ ->
+                // If removed due to eviction, cancel the coroutine, otherwise it is the
+                // responsibility
+                // of the caller of [cache.remove] to cancel the removed entry when done with it.
+                if (evicted) {
+                    oldValue.cancel()
+                }
+            }
+        )
+
+    override fun loadImage(callerScope: CoroutineScope, uri: Uri, callback: Consumer<Bitmap?>) {
+        callerScope.launch { callback.accept(loadCachedImage(uri)) }
+    }
+
+    override fun prePopulate(uris: List<Uri>) {
+        uris.take(cache.maxSize()).map { cache[it] }
+    }
+
+    override suspend fun invoke(uri: Uri, caching: Boolean): Bitmap? {
+        return if (caching) {
+            loadCachedImage(uri)
+        } else {
+            loadUncachedImage(uri)
+        }
+    }
+
+    private suspend fun loadUncachedImage(uri: Uri): Bitmap? =
+        withContext(bgDispatcher) {
+            runCatching { semaphore.withPermit { thumbnailLoader.invoke(uri) } }
+                .onFailure {
+                    ensureActive()
+                    Log.d(TAG, "Failed to load preview for $uri", it)
+                }
+                .getOrNull()
+        }
+
+    private suspend fun loadCachedImage(uri: Uri): Bitmap? =
+        // [Deferred#await] is called in a [runCatching] block to catch
+        // [CancellationExceptions]s so that they don't cancel the calling coroutine/scope.
+        runCatching { cache[uri].await() }.getOrNull()
+
+    companion object {
+        private const val TAG = "CachingImgPrevLoader"
+    }
+}
diff --git a/java/src/com/android/intentresolver/contentpreview/ImageLoaderModule.kt b/java/src/com/android/intentresolver/contentpreview/ImageLoaderModule.kt
index b861a24a..7035f765 100644
--- a/java/src/com/android/intentresolver/contentpreview/ImageLoaderModule.kt
+++ b/java/src/com/android/intentresolver/contentpreview/ImageLoaderModule.kt
@@ -33,6 +33,10 @@ interface ImageLoaderModule {
     @ActivityRetainedScoped
     fun imageLoader(previewImageLoader: ImagePreviewImageLoader): ImageLoader
 
+    @Binds
+    @ActivityRetainedScoped
+    fun thumbnailLoader(thumbnailLoader: ThumbnailLoaderImpl): ThumbnailLoader
+
     companion object {
         @Provides
         @ThumbnailSize
@@ -40,5 +44,7 @@ interface ImageLoaderModule {
             resources.getDimensionPixelSize(R.dimen.chooser_preview_image_max_dimen)
 
         @Provides @PreviewCacheSize fun cacheSize() = 16
+
+        @Provides @PreviewMaxConcurrency fun maxConcurrency() = 4
     }
 }
diff --git a/java/src/com/android/intentresolver/contentpreview/ThumbnailLoader.kt b/java/src/com/android/intentresolver/contentpreview/ThumbnailLoader.kt
new file mode 100644
index 00000000..9f1d50da
--- /dev/null
+++ b/java/src/com/android/intentresolver/contentpreview/ThumbnailLoader.kt
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.intentresolver.contentpreview
+
+import android.content.ContentResolver
+import android.graphics.Bitmap
+import android.net.Uri
+import android.util.Size
+import javax.inject.Inject
+
+/** Interface for objects that can attempt load a [Bitmap] from a [Uri]. */
+interface ThumbnailLoader : suspend (Uri) -> Bitmap?
+
+/** Default implementation of [ThumbnailLoader]. */
+class ThumbnailLoaderImpl
+@Inject
+constructor(
+    private val contentResolver: ContentResolver,
+    @ThumbnailSize thumbnailSize: Int,
+) : ThumbnailLoader {
+
+    private val size = Size(thumbnailSize, thumbnailSize)
+
+    override suspend fun invoke(uri: Uri): Bitmap =
+        contentResolver.loadThumbnail(uri, size, /* signal = */ null)
+}
diff --git a/java/src/com/android/intentresolver/contentpreview/payloadtoggle/ui/viewmodel/ShareouselViewModel.kt b/java/src/com/android/intentresolver/contentpreview/payloadtoggle/ui/viewmodel/ShareouselViewModel.kt
index 8b2dd818..1b9c231b 100644
--- a/java/src/com/android/intentresolver/contentpreview/payloadtoggle/ui/viewmodel/ShareouselViewModel.kt
+++ b/java/src/com/android/intentresolver/contentpreview/payloadtoggle/ui/viewmodel/ShareouselViewModel.kt
@@ -15,11 +15,9 @@
  */
 package com.android.intentresolver.contentpreview.payloadtoggle.ui.viewmodel
 
-import android.content.Context
-import com.android.intentresolver.R
+import com.android.intentresolver.contentpreview.CachingImagePreviewImageLoader
 import com.android.intentresolver.contentpreview.HeadlineGenerator
 import com.android.intentresolver.contentpreview.ImageLoader
-import com.android.intentresolver.contentpreview.ImagePreviewImageLoader
 import com.android.intentresolver.contentpreview.payloadtoggle.domain.cursor.PayloadToggle
 import com.android.intentresolver.contentpreview.payloadtoggle.domain.interactor.ChooserRequestInteractor
 import com.android.intentresolver.contentpreview.payloadtoggle.domain.interactor.CustomActionsInteractor
@@ -27,14 +25,12 @@ import com.android.intentresolver.contentpreview.payloadtoggle.domain.interactor
 import com.android.intentresolver.contentpreview.payloadtoggle.domain.interactor.SelectionInteractor
 import com.android.intentresolver.contentpreview.payloadtoggle.shared.model.PreviewModel
 import com.android.intentresolver.contentpreview.payloadtoggle.shared.model.PreviewsModel
-import com.android.intentresolver.inject.Background
 import com.android.intentresolver.inject.ViewModelOwned
+import dagger.Binds
 import dagger.Module
 import dagger.Provides
 import dagger.hilt.InstallIn
 import dagger.hilt.android.components.ViewModelComponent
-import dagger.hilt.android.qualifiers.ApplicationContext
-import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
@@ -42,7 +38,6 @@ import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
-import kotlinx.coroutines.plus
 
 /** A dynamic carousel of selectable previews within share sheet. */
 data class ShareouselViewModel(
@@ -63,80 +58,70 @@ data class ShareouselViewModel(
 
 @Module
 @InstallIn(ViewModelComponent::class)
-object ShareouselViewModelModule {
-    @Provides
-    fun create(
-        interactor: SelectablePreviewsInteractor,
-        @PayloadToggle imageLoader: ImageLoader,
-        actionsInteractor: CustomActionsInteractor,
-        headlineGenerator: HeadlineGenerator,
-        selectionInteractor: SelectionInteractor,
-        chooserRequestInteractor: ChooserRequestInteractor,
-        // TODO: remove if possible
-        @ViewModelOwned scope: CoroutineScope,
-    ): ShareouselViewModel {
-        val keySet =
-            interactor.previews.stateIn(
-                scope,
-                SharingStarted.Eagerly,
-                initialValue = null,
-            )
-        return ShareouselViewModel(
-            headline =
-                selectionInteractor.amountSelected.map { numItems ->
-                    val contentType = ContentType.Image // TODO: convert from metadata
-                    when (contentType) {
-                        ContentType.Other -> headlineGenerator.getFilesHeadline(numItems)
-                        ContentType.Image -> headlineGenerator.getImagesHeadline(numItems)
-                        ContentType.Video -> headlineGenerator.getVideosHeadline(numItems)
-                    }
-                },
-            metadataText = chooserRequestInteractor.metadataText,
-            previews = keySet,
-            actions =
-                actionsInteractor.customActions.map { actions ->
-                    actions.mapIndexedNotNull { i, model ->
-                        val icon = model.icon
-                        val label = model.label
-                        if (icon == null && label.isBlank()) {
-                            null
-                        } else {
-                            ActionChipViewModel(
-                                label = label.toString(),
-                                icon = model.icon,
-                                onClicked = { model.performAction(i) },
-                            )
+interface ShareouselViewModelModule {
+
+    @Binds @PayloadToggle fun imageLoader(imageLoader: CachingImagePreviewImageLoader): ImageLoader
+
+    companion object {
+        @Provides
+        fun create(
+            interactor: SelectablePreviewsInteractor,
+            @PayloadToggle imageLoader: ImageLoader,
+            actionsInteractor: CustomActionsInteractor,
+            headlineGenerator: HeadlineGenerator,
+            selectionInteractor: SelectionInteractor,
+            chooserRequestInteractor: ChooserRequestInteractor,
+            // TODO: remove if possible
+            @ViewModelOwned scope: CoroutineScope,
+        ): ShareouselViewModel {
+            val keySet =
+                interactor.previews.stateIn(
+                    scope,
+                    SharingStarted.Eagerly,
+                    initialValue = null,
+                )
+            return ShareouselViewModel(
+                headline =
+                    selectionInteractor.amountSelected.map { numItems ->
+                        val contentType = ContentType.Image // TODO: convert from metadata
+                        when (contentType) {
+                            ContentType.Other -> headlineGenerator.getFilesHeadline(numItems)
+                            ContentType.Image -> headlineGenerator.getImagesHeadline(numItems)
+                            ContentType.Video -> headlineGenerator.getVideosHeadline(numItems)
                         }
-                    }
+                    },
+                metadataText = chooserRequestInteractor.metadataText,
+                previews = keySet,
+                actions =
+                    actionsInteractor.customActions.map { actions ->
+                        actions.mapIndexedNotNull { i, model ->
+                            val icon = model.icon
+                            val label = model.label
+                            if (icon == null && label.isBlank()) {
+                                null
+                            } else {
+                                ActionChipViewModel(
+                                    label = label.toString(),
+                                    icon = model.icon,
+                                    onClicked = { model.performAction(i) },
+                                )
+                            }
+                        }
+                    },
+                preview = { key ->
+                    keySet.value?.maybeLoad(key)
+                    val previewInteractor = interactor.preview(key)
+                    ShareouselPreviewViewModel(
+                        bitmap = flow { emit(key.previewUri?.let { imageLoader(it) }) },
+                        contentType = flowOf(ContentType.Image), // TODO: convert from metadata
+                        isSelected = previewInteractor.isSelected,
+                        setSelected = previewInteractor::setSelected,
+                        aspectRatio = key.aspectRatio,
+                    )
                 },
-            preview = { key ->
-                keySet.value?.maybeLoad(key)
-                val previewInteractor = interactor.preview(key)
-                ShareouselPreviewViewModel(
-                    bitmap = flow { emit(key.previewUri?.let { imageLoader(it) }) },
-                    contentType = flowOf(ContentType.Image), // TODO: convert from metadata
-                    isSelected = previewInteractor.isSelected,
-                    setSelected = previewInteractor::setSelected,
-                    aspectRatio = key.aspectRatio,
-                )
-            },
-        )
+            )
+        }
     }
-
-    @Provides
-    @PayloadToggle
-    fun imageLoader(
-        @ViewModelOwned viewModelScope: CoroutineScope,
-        @Background coroutineDispatcher: CoroutineDispatcher,
-        @ApplicationContext context: Context,
-    ): ImageLoader =
-        ImagePreviewImageLoader(
-            viewModelScope + coroutineDispatcher,
-            thumbnailSize =
-                context.resources.getDimensionPixelSize(R.dimen.chooser_preview_image_max_dimen),
-            context.contentResolver,
-            cacheSize = 16,
-        )
 }
 
 private fun PreviewsModel.maybeLoad(key: PreviewModel) {