Let notifications use avatar fallback.

Extract code which handles Matrix image to its own api / impl / test modules.

libraries/matrixmedia/api/build.gradle.kts

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+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+plugins {
+    id("io.element.android-library")
+}
+
+android {
+    namespace = "io.element.android.libraries.matrix.ui.media.api"
+}
+
+dependencies {
+    implementation(projects.libraries.designsystem)
+    implementation(projects.libraries.matrix.api)
+    implementation(libs.coil.compose)
+}

libraries/matrixmedia/api/src/main/kotlin/io/element/android/libraries/matrix/ui/media/Avatar.kt

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+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2023-2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.ui.media
+
+/**
+ * The size in pixel of the thumbnail to generate for the avatar.
+ * This is not the size of the avatar displayed in the UI but the size to get from the servers.
+ * Servers SHOULD produce thumbnails with the following dimensions and methods:
+ *
+ * 32x32, crop
+ * 96x96, crop
+ * 320x240, scale
+ * 640x480, scale
+ * 800x600, scale
+ *
+ * Let's always use the same size so coil caching works properly.
+ */
+const val AVATAR_THUMBNAIL_SIZE_IN_PIXEL = 240L

libraries/matrixmedia/api/src/main/kotlin/io/element/android/libraries/matrix/ui/media/ImageLoaderHolder.kt

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+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.ui.media
+
+import coil3.ImageLoader
+import io.element.android.libraries.matrix.api.MatrixClient
+import io.element.android.libraries.matrix.api.core.SessionId
+
+interface ImageLoaderHolder {
+    fun get(): ImageLoader
+    fun get(client: MatrixClient): ImageLoader
+    fun remove(sessionId: SessionId)
+}

libraries/matrixmedia/api/src/main/kotlin/io/element/android/libraries/matrix/ui/media/InitialsAvatarBitmapGenerator.kt

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+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.ui.media
+
+import android.graphics.Bitmap
+import io.element.android.libraries.designsystem.components.avatar.AvatarData
+
+/**
+ * Generates a bitmap for an initials avatar based on the provided [io.element.android.libraries.designsystem.components.avatar.AvatarData].
+ */
+interface InitialsAvatarBitmapGenerator {
+    fun generateBitmap(
+        size: Int,
+        avatarData: AvatarData,
+        useDarkTheme: Boolean,
+        fontSizePercentage: Float = 0.5f,
+    ): Bitmap?
+}

libraries/matrixmedia/api/src/main/kotlin/io/element/android/libraries/matrix/ui/media/MediaRequestData.kt

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+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2023-2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.ui.media
+
+import io.element.android.libraries.matrix.api.media.MediaSource
+
+/**
+ * Can be use with [coil3.compose.AsyncImage] to load a [MediaSource].
+ * This will go internally through our CoilMediaFetcher.
+ *
+ * Example of usage:
+ *  AsyncImage(
+ *      model = MediaRequestData(mediaSource, MediaRequestData.Kind.Content),
+ *      contentScale = ContentScale.Fit,
+ *  )
+ *
+ */
+data class MediaRequestData(
+    val source: MediaSource?,
+    val kind: Kind
+) {
+    sealed interface Kind {
+        data object Content : Kind
+
+        data class File(
+            val fileName: String,
+            val mimeType: String,
+        ) : Kind
+
+        data class Thumbnail(val width: Long, val height: Long) : Kind {
+            constructor(size: Long) : this(size, size)
+        }
+    }
+}
+
+/** Max width a thumbnail can have according to [the spec](https://spec.matrix.org/v1.10/client-server-api/#thumbnails). */
+const val MAX_THUMBNAIL_WIDTH = 800L
+
+/** Max height a thumbnail can have according to [the spec](https://spec.matrix.org/v1.10/client-server-api/#thumbnails). */
+const val MAX_THUMBNAIL_HEIGHT = 600L