Simple scrollable image preview view

A simple scrollale image preview view is created but not yet used.

Bug: 262280076
Test: Add a debug code that replaces legacy image preview view with the
new implementation. Verify basic functionality: small and large image
count, screenshot transition animation.

Change-Id: I5d8f00b8617abae66f76931b21872154f4726851

4 files changed, 238 insertions, 15 deletions

diff --git a/java/res/layout/image_preview_image_item.xml b/java/res/layout/image_preview_image_item.xml
new file mode 100644
index 00000000..3895b6b4
--- /dev/null
+++ b/java/res/layout/image_preview_image_item.xml
@@ -0,0 +1,24 @@
+<!--
+  ~ Copyright (C) 2023 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.
+  -->
+
+<com.android.intentresolver.widget.RoundedRectImageView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/image"
+    android:layout_width="120dp"
+    android:layout_height="104dp"
+    android:layout_alignParentTop="true"
+    android:adjustViewBounds="false"
+    android:scaleType="centerCrop"/>
diff --git a/java/src/com/android/intentresolver/widget/RecyclerViewExtensions.kt b/java/src/com/android/intentresolver/widget/RecyclerViewExtensions.kt
new file mode 100644
index 00000000..a7906001
--- /dev/null
+++ b/java/src/com/android/intentresolver/widget/RecyclerViewExtensions.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2023 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.widget
+
+import android.view.View
+import androidx.recyclerview.widget.RecyclerView
+
+internal val RecyclerView.areAllChildrenVisible: Boolean
+    get() {
+        val count = getChildCount()
+        if (count == 0) return true
+        val first = getChildAt(0)
+        val last = getChildAt(count - 1)
+        val itemCount = adapter?.itemCount ?: 0
+        return getChildAdapterPosition(first) == 0
+                && getChildAdapterPosition(last) == itemCount - 1
+                && isFullyVisible(first)
+                && isFullyVisible(last)
+    }
+
+private fun RecyclerView.isFullyVisible(view: View): Boolean =
+    view.left >= paddingLeft && view.right <= width - paddingRight
diff --git a/java/src/com/android/intentresolver/widget/ScrollableActionRow.kt b/java/src/com/android/intentresolver/widget/ScrollableActionRow.kt
index a941b97a..81630545 100644
--- a/java/src/com/android/intentresolver/widget/ScrollableActionRow.kt
+++ b/java/src/com/android/intentresolver/widget/ScrollableActionRow.kt
@@ -50,21 +50,6 @@ class ScrollableActionRow : RecyclerView, ActionRow {
         )
     }
 
-    private val areAllChildrenVisible: Boolean
-        get() {
-            val count = getChildCount()
-            if (count == 0) return true
-            val first = getChildAt(0)
-            val last = getChildAt(count - 1)
-            return getChildAdapterPosition(first) == 0
-                && getChildAdapterPosition(last) == actionsAdapter.itemCount - 1
-                && isFullyVisible(first)
-                && isFullyVisible(last)
-        }
-
-    private fun isFullyVisible(view: View): Boolean =
-        view.left >= paddingLeft && view.right <= width - paddingRight
-
     private class Adapter(private val context: Context) : RecyclerView.Adapter<ViewHolder>() {
         private val iconSize: Int =
             context.resources.getDimensionPixelSize(R.dimen.chooser_action_view_icon_size)
diff --git a/java/src/com/android/intentresolver/widget/ScrollableImagePreviewView.kt b/java/src/com/android/intentresolver/widget/ScrollableImagePreviewView.kt
new file mode 100644
index 00000000..467c404a
--- /dev/null
+++ b/java/src/com/android/intentresolver/widget/ScrollableImagePreviewView.kt
@@ -0,0 +1,178 @@
+/*
+ * Copyright (C) 2023 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.widget
+
+import android.content.Context
+import android.graphics.Rect
+import android.net.Uri
+import android.util.AttributeSet
+import android.util.TypedValue
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.ImageView
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import com.android.intentresolver.R
+import com.android.intentresolver.widget.ImagePreviewView.TransitionElementStatusCallback
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.plus
+
+private const val TRANSITION_NAME = "screenshot_preview_image"
+
+class ScrollableImagePreviewView : RecyclerView, ImagePreviewView {
+    constructor(context: Context) : this(context, null)
+    constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)
+    constructor(
+        context: Context, attrs: AttributeSet?, defStyleAttr: Int
+    ) : super(context, attrs, defStyleAttr) {
+        layoutManager = LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false)
+        adapter = Adapter(context)
+        val spacing = TypedValue.applyDimension(
+            TypedValue.COMPLEX_UNIT_DIP, 5f, context.resources.displayMetrics
+        ).toInt()
+        addItemDecoration(SpacingDecoration(spacing))
+    }
+
+    private val previewAdapter get() = adapter as Adapter
+
+    override fun onLayout(changed: Boolean, l: Int, t: Int, r: Int, b: Int) {
+        super.onLayout(changed, l, t, r, b)
+        setOverScrollMode(
+            if (areAllChildrenVisible) View.OVER_SCROLL_NEVER else View.OVER_SCROLL_ALWAYS
+        )
+    }
+
+    override fun setTransitionElementStatusCallback(callback: TransitionElementStatusCallback?) {
+        previewAdapter.transitionStatusElementCallback = callback
+    }
+
+    override fun setImages(uris: List<Uri>, imageLoader: ImageLoader) {
+        previewAdapter.setImages(uris, imageLoader)
+    }
+
+    private class Adapter(private val context: Context) : RecyclerView.Adapter<ViewHolder>() {
+        private val uris = ArrayList<Uri>()
+        private var imageLoader: ImageLoader? = null
+        var transitionStatusElementCallback: TransitionElementStatusCallback? = null
+
+        fun setImages(uris: List<Uri>, imageLoader: ImageLoader) {
+            this.uris.clear()
+            this.uris.addAll(uris)
+            this.imageLoader = imageLoader
+            notifyDataSetChanged()
+        }
+
+        override fun onCreateViewHolder(parent: ViewGroup, itemType: Int): ViewHolder {
+            return ViewHolder(
+                LayoutInflater.from(context)
+                    .inflate(R.layout.image_preview_image_item, parent, false)
+            )
+        }
+
+        override fun getItemCount(): Int = uris.size
+
+        override fun onBindViewHolder(vh: ViewHolder, position: Int) {
+            vh.bind(
+                uris[position],
+                imageLoader ?: error("ImageLoader is missing"),
+                if (position == 0 && transitionStatusElementCallback != null) {
+                    this::onTransitionElementReady
+                } else {
+                    null
+                }
+            )
+        }
+
+        override fun onViewRecycled(vh: ViewHolder) {
+            vh.unbind()
+        }
+
+        override fun onFailedToRecycleView(vh: ViewHolder): Boolean {
+            vh.unbind()
+            return super.onFailedToRecycleView(vh)
+        }
+
+        private fun onTransitionElementReady(name: String) {
+            transitionStatusElementCallback?.apply {
+                onTransitionElementReady(name)
+                onAllTransitionElementsReady()
+            }
+            transitionStatusElementCallback = null
+        }
+    }
+
+    private class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
+        private val image = view.requireViewById<ImageView>(R.id.image)
+        private var scope: CoroutineScope? = null
+
+        fun bind(
+            uri: Uri,
+            imageLoader: ImageLoader,
+            previewReadyCallback: ((String) -> Unit)?
+        ) {
+            image.setImageDrawable(null)
+            image.transitionName = if (previewReadyCallback != null) {
+                TRANSITION_NAME
+            } else {
+                null
+            }
+            resetScope().launch {
+                loadImage(uri, imageLoader, previewReadyCallback)
+            }
+        }
+
+        private suspend fun loadImage(
+            uri: Uri,
+            imageLoader: ImageLoader,
+            previewReadyCallback: ((String) -> Unit)?
+        ) {
+            val bitmap = runCatching {
+                // it's expected for all loading/caching optimizations to be implemented by the
+                // loader
+                imageLoader(uri)
+            }.getOrNull()
+            image.setImageBitmap(bitmap)
+            previewReadyCallback?.let { callback ->
+                image.waitForPreDraw()
+                callback(TRANSITION_NAME)
+            }
+        }
+
+        private fun resetScope(): CoroutineScope =
+            (MainScope() + Dispatchers.Main.immediate).also {
+                scope?.cancel()
+                scope = it
+            }
+
+        fun unbind() {
+            scope?.cancel()
+            scope = null
+        }
+    }
+
+    private class SpacingDecoration(private val margin: Int) : RecyclerView.ItemDecoration() {
+        override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: State) {
+            outRect.set(margin, 0, margin, 0)
+        }
+    }
+}