New option: Pinch to Zoom Video.

app/src/main/java/ml/docilealligator/infinityforreddit/activities/ViewImageOrGifActivity.java

@@ -292,7 +292,9 @@ public class ViewImageOrGifActivity extends AppCompatActivity implements SetAsWa
         // Fixes #383
         // Not having a background will cause visual glitches on some devices.
         FrameLayout slidablePanel = findViewById(R.id.slidable_panel);
-        slidablePanel.setBackgroundColor(getResources().getColor(android.R.color.black));
+        if (slidablePanel != null) {
+            slidablePanel.setBackgroundColor(getResources().getColor(android.R.color.black));
+        }
     }
 
     private void loadImage() {

app/src/main/java/ml/docilealligator/infinityforreddit/activities/ViewVideoActivity.java

@@ -7,6 +7,7 @@ import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
 import android.content.res.Configuration;
 import android.content.res.Resources;
+import android.graphics.Matrix;
 import android.graphics.drawable.ColorDrawable;
 import android.graphics.drawable.Drawable;
 import android.media.AudioManager;
@@ -57,6 +58,7 @@ import com.google.android.exoplayer2.util.Util;
 import com.google.android.exoplayer2.video.VideoListener;
 import com.google.android.material.bottomappbar.BottomAppBar;
 import com.google.android.material.snackbar.Snackbar;
+import com.otaliastudios.zoom.ZoomEngine;
 import com.otaliastudios.zoom.ZoomSurfaceView;
 
 import org.apache.commons.io.FilenameUtils;
@@ -69,6 +71,7 @@ import javax.inject.Named;
 
 import app.futured.hauler.DragDirection;
 import app.futured.hauler.HaulerView;
+import app.futured.hauler.LockableNestedScrollView;
 import butterknife.BindView;
 import butterknife.ButterKnife;
 import ml.docilealligator.infinityforreddit.FetchGfycatOrRedgifsVideoLinks;
@@ -147,6 +150,8 @@ public class ViewVideoActivity extends AppCompatActivity {
     TextView titleTextView;
     @BindView(R.id.download_image_view_exo_playback_control_view)
     ImageView downloadImageView;
+    @BindView(R.id.lockable_nested_scroll_view_view_video_activity)
+    LockableNestedScrollView nestedScrollView;
 
     private Uri mVideoUri;
     private SimpleExoPlayer player;
@@ -371,7 +376,27 @@ public class ViewVideoActivity extends AppCompatActivity {
 
             }
         });
+        if (mSharedPreferences.getBoolean(SharedPreferencesUtils.PINCH_TO_ZOOM_VIDEO, false)) {
+            zoomSurfaceView.getEngine().addListener(new ZoomEngine.Listener() {
+                @Override
+                public void onUpdate(@NonNull ZoomEngine zoomEngine, @NonNull Matrix matrix) {
+                    if (zoomEngine.getZoom() < 1.00001) {
+                        haulerView.setDragEnabled(true);
+                        nestedScrollView.setScrollEnabled(true);
+                    } else {
+                        haulerView.setDragEnabled(false);
+                        nestedScrollView.setScrollEnabled(false);
+                    }
+                }
 
+                @Override
+                public void onIdle(@NonNull ZoomEngine zoomEngine) {
+
+                }
+            });
+        } else {
+            zoomSurfaceView.setZoomEnabled(false);
+        }
         zoomSurfaceView.setOnClickListener(view -> {
             if (playerControlView.isVisible()) {
                 playerControlView.hide();

app/src/main/java/ml/docilealligator/infinityforreddit/utils/SharedPreferencesUtils.java

@@ -194,6 +194,7 @@ public class SharedPreferencesUtils {
     public static final String LOOP_VIDEO = "loop_video";
     public static final String DEFAULT_PLAYBACK_SPEED = "default_playback_speed";
     public static final String LEGACY_AUTOPLAY_VIDEO_CONTROLLER_UI = "legacy_autoplay_video_controller_ui";
+    public static final String PINCH_TO_ZOOM_VIDEO = "pinch_to_zoom_video";
 
     public static final String DEFAULT_PREFERENCES_FILE = "ml.docilealligator.infinityforreddit_preferences";
     public static final String MAIN_PAGE_TABS_SHARED_PREFERENCES_FILE = "ml.docilealligator.infinityforreddit.main_page_tabs";

app/src/main/res/layout/activity_view_video.xml

@@ -10,7 +10,8 @@
     app:dragUpEnabled="true"
     tools:application="ml.docilealligator.infinityforreddit.activities.ViewVideoActivity">
 
-    <androidx.core.widget.NestedScrollView
+    <app.futured.hauler.LockableNestedScrollView
+        android:id="@+id/lockable_nested_scroll_view_view_video_activity"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:fillViewport="true">
@@ -45,6 +46,6 @@
 
         </androidx.coordinatorlayout.widget.CoordinatorLayout>
 
-    </androidx.core.widget.NestedScrollView>
+    </app.futured.hauler.LockableNestedScrollView>
 
 </app.futured.hauler.HaulerView>

app/src/main/res/values/strings.xml

@@ -613,6 +613,8 @@
     <string name="settings_link_handler_value_custom_tab">Custom Tab</string>
     <string name="settings_link_handler_value_internal_browser">Internal Browser</string>
     <string name="settings_legacy_autoplay_video_controller_ui_title">Legacy Video Controller UI</string>
+    <string name="settings_pinch_to_zoom_video_title">Pinch to Zoom Video</string>
+    <string name="settings_experimental_feature">Experimental feature</string>
 
     <string name="no_link_available">Cannot get the link</string>
 

app/src/main/res/xml/gestures_and_buttons_preferences.xml

@@ -54,6 +54,12 @@
         app:key="swipe_between_posts"
         app:title="@string/settings_swipe_between_posts_title" />
 
+    <SwitchPreference
+        app:defaultValue="false"
+        app:key="pinch_to_zoom_video"
+        app:title="@string/settings_pinch_to_zoom_video_title"
+        app:summary="@string/settings_experimental_feature" />
+
     <Preference
         app:title="@string/settings_swipe_action_title"
         app:fragment="ml.docilealligator.infinityforreddit.settings.SwipeActionPreferenceFragment" />