Make dependency on AndroidX appcompat optional for dialog builder.

The dependency is only used to create a dialog in
TrackSelectionDialogBuilder that is compatible with newer styling
options.

This dependendy adds over 500Kb to the apk (even if unused) and we
shoudn't force this on an app. Instead make the dependency optional by
automatically falling back to the platform version if the AndroidX one
doesn't exist.

Issue: #7357
PiperOrigin-RevId: 322143005

library/ui/build.gradle

@@ -19,7 +19,6 @@ dependencies {
     implementation project(modulePrefix + 'library-core')
     api 'androidx.media:media:' + androidxMediaVersion
     implementation 'androidx.annotation:annotation:' + androidxAnnotationVersion
-    implementation 'androidx.appcompat:appcompat:' + androidxAppCompatVersion
     implementation 'androidx.recyclerview:recyclerview:' + androidxRecyclerViewVersion
     implementation 'com.google.guava:guava:' + guavaVersion
     compileOnly 'org.checkerframework:checker-qual:' + checkerframeworkVersion

library/ui/proguard-rules.txt

@@ -0,0 +1,18 @@
+# Proguard rules specific to the UI module.
+
+# Constructor method accessed via reflection in TrackSelectionDialogBuilder
+-dontnote androidx.appcompat.app.AlertDialog.Builder
+-keepclassmembers class androidx.appcompat.app.AlertDialog$Builder {
+  <init>(android.content.Context);
+  public android.content.Context getContext();
+  public androidx.appcompat.app.AlertDialog$Builder setTitle(java.lang.CharSequence);
+  public androidx.appcompat.app.AlertDialog$Builder setView(android.view.View);
+  public androidx.appcompat.app.AlertDialog$Builder setPositiveButton(int, android.content.DialogInterface$OnClickListener);
+  public androidx.appcompat.app.AlertDialog$Builder setNegativeButton(int, android.content.DialogInterface$OnClickListener);
+  public androidx.appcompat.app.AlertDialog create();
+}
+
+# Don't warn about checkerframework and Kotlin annotations
+-dontwarn org.checkerframework.**
+-dontwarn kotlin.annotations.jvm.**
+-dontwarn javax.annotation.**

library/ui/src/main/java/com/google/android/exoplayer2/ui/TrackSelectionDialogBuilder.java

@@ -15,18 +15,21 @@
  */
 package com.google.android.exoplayer2.ui;
 
+import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+
+import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.Context;
+import android.content.DialogInterface;
 import android.view.LayoutInflater;
 import android.view.View;
 import androidx.annotation.Nullable;
-import androidx.appcompat.app.AlertDialog;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector.SelectionOverride;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector.MappedTrackInfo;
 import com.google.android.exoplayer2.trackselection.TrackSelectionUtil;
-import com.google.android.exoplayer2.util.Assertions;
+import java.lang.reflect.Constructor;
 import java.util.Collections;
 import java.util.List;
 
@@ -97,7 +100,7 @@ public final class TrackSelectionDialogBuilder {
       Context context, CharSequence title, DefaultTrackSelector trackSelector, int rendererIndex) {
     this.context = context;
     this.title = title;
-    this.mappedTrackInfo = Assertions.checkNotNull(trackSelector.getCurrentMappedTrackInfo());
+    this.mappedTrackInfo = checkNotNull(trackSelector.getCurrentMappedTrackInfo());
     this.rendererIndex = rendererIndex;
 
     TrackGroupArray rendererTrackGroups = mappedTrackInfo.getTrackGroups(rendererIndex);
@@ -205,24 +208,18 @@ public final class TrackSelectionDialogBuilder {
   }
 
   /** Builds the dialog. */
-  public AlertDialog build() {
+  public Dialog build() {
+    @Nullable Dialog dialog = buildForAndroidX();
+    return dialog == null ? buildForPlatform() : dialog;
+  }
+
+  private Dialog buildForPlatform() {
     AlertDialog.Builder builder = new AlertDialog.Builder(context);
 
     // Inflate with the builder's context to ensure the correct style is used.
     LayoutInflater dialogInflater = LayoutInflater.from(builder.getContext());
     View dialogView = dialogInflater.inflate(R.layout.exo_track_selection_dialog, /* root= */ null);
-
-    TrackSelectionView selectionView = dialogView.findViewById(R.id.exo_track_selection_view);
-    selectionView.setAllowMultipleOverrides(allowMultipleOverrides);
-    selectionView.setAllowAdaptiveSelections(allowAdaptiveSelections);
-    selectionView.setShowDisableOption(showDisableOption);
-    if (trackNameProvider != null) {
-      selectionView.setTrackNameProvider(trackNameProvider);
-    }
-    selectionView.init(mappedTrackInfo, rendererIndex, isDisabled, overrides, /* listener= */ null);
-    Dialog.OnClickListener okClickListener =
-        (dialog, which) ->
-            callback.onTracksSelected(selectionView.getIsDisabled(), selectionView.getOverrides());
+    Dialog.OnClickListener okClickListener = setUpDialogView(dialogView);
 
     return builder
         .setTitle(title)
@@ -231,4 +228,54 @@ public final class TrackSelectionDialogBuilder {
         .setNegativeButton(android.R.string.cancel, null)
         .create();
   }
+
+  // Reflection calls can't verify null safety of return values or parameters.
+  @SuppressWarnings("nullness:argument.type.incompatible")
+  @Nullable
+  private Dialog buildForAndroidX() {
+    try {
+      // This method uses reflection to avoid a dependency on AndroidX appcompat that adds 800KB to
+      // the APK size even with shrinking. See https://issuetracker.google.com/161514204.
+      // LINT.IfChange
+      Class<?> builderClazz = Class.forName("androidx.appcompat.app.AlertDialog$Builder");
+      Constructor<?> builderConstructor = builderClazz.getConstructor(Context.class);
+      Object builder = builderConstructor.newInstance(context);
+
+      // Inflate with the builder's context to ensure the correct style is used.
+      Context builderContext = (Context) builderClazz.getMethod("getContext").invoke(builder);
+      LayoutInflater dialogInflater = LayoutInflater.from(builderContext);
+      View dialogView =
+          dialogInflater.inflate(R.layout.exo_track_selection_dialog, /* root= */ null);
+      Dialog.OnClickListener okClickListener = setUpDialogView(dialogView);
+
+      builderClazz.getMethod("setTitle", CharSequence.class).invoke(builder, title);
+      builderClazz.getMethod("setView", View.class).invoke(builder, dialogView);
+      builderClazz
+          .getMethod("setPositiveButton", int.class, DialogInterface.OnClickListener.class)
+          .invoke(builder, android.R.string.ok, okClickListener);
+      builderClazz
+          .getMethod("setNegativeButton", int.class, DialogInterface.OnClickListener.class)
+          .invoke(builder, android.R.string.cancel, null);
+      return (Dialog) builderClazz.getMethod("create").invoke(builder);
+      // LINT.ThenChange(../../../../../../../../proguard-rules.txt)
+    } catch (ClassNotFoundException e) {
+      // Expected if the AndroidX compat library is not available.
+      return null;
+    } catch (Exception e) {
+      throw new IllegalStateException(e);
+    }
+  }
+
+  private Dialog.OnClickListener setUpDialogView(View dialogView) {
+    TrackSelectionView selectionView = dialogView.findViewById(R.id.exo_track_selection_view);
+    selectionView.setAllowMultipleOverrides(allowMultipleOverrides);
+    selectionView.setAllowAdaptiveSelections(allowAdaptiveSelections);
+    selectionView.setShowDisableOption(showDisableOption);
+    if (trackNameProvider != null) {
+      selectionView.setTrackNameProvider(trackNameProvider);
+    }
+    selectionView.init(mappedTrackInfo, rendererIndex, isDisabled, overrides, /* listener= */ null);
+    return (dialog, which) ->
+        callback.onTracksSelected(selectionView.getIsDisabled(), selectionView.getOverrides());
+  }
 }

library/ui/src/main/proguard-rules.txt

@@ -0,0 +1 @@
+../../proguard-rules.txt