Bug 1458063 - Introduce a new wheel action for pinch-zooming. r=kats

MozReview-Commit-ID: 7DWNvQc2pBE

--HG--
extra : rebase_source : 02d3efe180fb1cd6d49ca9b8a49e4051e6e05cac

browser/app/profile/firefox.js

@@ -626,8 +626,9 @@ pref("browser.snapshots.limit", 0);
 // 0: Nothing happens
 // 1: Scrolling contents
 // 2: Go back or go forward, in your history
-// 3: Zoom in or out.
+// 3: Zoom in or out (reflowing zoom).
 // 4: Treat vertical wheel as horizontal scroll
+// 5: Zoom in or out (pinch zoom).
 #ifdef XP_MACOSX
 // On macOS, if the wheel has one axis only, shift+wheel comes through as a
 // horizontal scroll event. Thus, we can't assign anything other than normal

dom/events/EventStateManager.cpp

@@ -6257,6 +6257,8 @@ EventStateManager::APZWheelActionFor(const WidgetWheelEvent* aEvent)
   case WheelPrefs::ACTION_SCROLL:
   case WheelPrefs::ACTION_HORIZONTALIZED_SCROLL:
     return Some(layers::APZWheelAction::Scroll);
+  case WheelPrefs::ACTION_PINCH_ZOOM:
+    return Some(layers::APZWheelAction::PinchZoom);
   default:
     return Nothing();
   }

dom/events/EventStateManager.h

@@ -587,7 +587,8 @@ protected:
       // original values. For more details, refer to
       // mozilla::WheelDeltaAdjustmentStrategy::eHorizontalize
       ACTION_HORIZONTALIZED_SCROLL,
-      ACTION_LAST = ACTION_HORIZONTALIZED_SCROLL,
+      ACTION_PINCH_ZOOM,
+      ACTION_LAST = ACTION_PINCH_ZOOM,
       // Following actions are used only by internal processing.  So, cannot
       // specified by prefs.
       ACTION_SEND_TO_PLUGIN,

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -1268,13 +1268,26 @@ APZCTreeManager::ReceiveInputEvent(InputData& aEvent,
         return result;
       }
 
-      MOZ_ASSERT(wheelInput.mAPZAction == APZWheelAction::Scroll);
-
       RefPtr<AsyncPanZoomController> apzc = GetTargetAPZC(wheelInput.mOrigin,
                                                             &hitResult);
       if (apzc) {
         MOZ_ASSERT(hitResult != CompositorHitTestInfo::eInvisibleToHitTest);
 
+        if (wheelInput.mAPZAction == APZWheelAction::PinchZoom) {
+          // The mousewheel may have hit a subframe, but we want to send the
+          // pinch-zoom events to the root-content APZC.
+          {
+            RecursiveMutexAutoLock lock(mTreeLock);
+            apzc = FindRootContentApzcForLayersId(apzc->GetLayersId());
+          }
+          if (apzc) {
+            SynthesizePinchGestureFromMouseWheel(wheelInput, apzc);
+          }
+          return nsEventStatus_eConsumeNoDefault;
+        }
+
+        MOZ_ASSERT(wheelInput.mAPZAction == APZWheelAction::Scroll);
+
         // For wheel events, the call to ReceiveInputEvent below may result in
         // scrolling, which changes the async transform. However, the event we
         // want to pass to gecko should be the pre-scroll event coordinates,
@@ -1835,6 +1848,63 @@ APZCTreeManager::SetupScrollbarDrag(MouseInput& aMouseInput,
   }
 }
 
+void
+APZCTreeManager::SynthesizePinchGestureFromMouseWheel(
+    const ScrollWheelInput& aWheelInput,
+    const RefPtr<AsyncPanZoomController>& aTarget)
+{
+  MOZ_ASSERT(aTarget);
+
+  ScreenPoint focusPoint = aWheelInput.mOrigin;
+
+  // Compute span values based on the wheel delta.
+  // See the PinchGestureInput constructor called below for why
+  // it's OK to use ParentLayer coordinates for the span values.
+  ParentLayerCoord oldSpan = 100;
+  ParentLayerCoord newSpan = oldSpan + aWheelInput.mDeltaY;
+
+  // There's no ambiguity as to the target for pinch gesture events.
+  TargetConfirmationFlags confFlags{true};
+
+  PinchGestureInput pinchStart{
+      PinchGestureInput::PINCHGESTURE_START,
+      aWheelInput.mTime,
+      aWheelInput.mTimeStamp,
+      focusPoint,
+      oldSpan,
+      oldSpan,
+      aWheelInput.modifiers};
+  PinchGestureInput pinchScale1{
+      PinchGestureInput::PINCHGESTURE_SCALE,
+      aWheelInput.mTime,
+      aWheelInput.mTimeStamp,
+      focusPoint,
+      oldSpan,
+      oldSpan,
+      aWheelInput.modifiers};
+  PinchGestureInput pinchScale2{
+      PinchGestureInput::PINCHGESTURE_SCALE,
+      aWheelInput.mTime,
+      aWheelInput.mTimeStamp,
+      focusPoint,
+      oldSpan,
+      newSpan,
+      aWheelInput.modifiers};
+  PinchGestureInput pinchEnd{
+      PinchGestureInput::PINCHGESTURE_END,
+      aWheelInput.mTime,
+      aWheelInput.mTimeStamp,
+      PinchGestureInput::BothFingersLifted<ScreenPixel>(),
+      newSpan,
+      newSpan,
+      aWheelInput.modifiers};
+
+  mInputQueue->ReceiveInputEvent(aTarget, confFlags, pinchStart, nullptr);
+  mInputQueue->ReceiveInputEvent(aTarget, confFlags, pinchScale1, nullptr);
+  mInputQueue->ReceiveInputEvent(aTarget, confFlags, pinchScale2, nullptr);
+  mInputQueue->ReceiveInputEvent(aTarget, confFlags, pinchEnd, nullptr);
+}
+
 void
 APZCTreeManager::UpdateWheelTransaction(LayoutDeviceIntPoint aRefPoint,
                                         EventMessage aEventMessage)

gfx/layers/apz/src/APZCTreeManager.h

@@ -692,6 +692,10 @@ private:
                                                   uint64_t* aOutInputBlockId);
   void FlushRepaintsToClearScreenToGeckoTransform();
 
+  void SynthesizePinchGestureFromMouseWheel(const ScrollWheelInput& aWheelInput,
+                                            const RefPtr<AsyncPanZoomController>& aTarget);
+
+
   already_AddRefed<HitTestingTreeNode> RecycleOrCreateNode(TreeBuildingState& aState,
                                                            AsyncPanZoomController* aApzc,
                                                            LayersId aLayersId);

gfx/layers/apz/src/APZUtils.h

@@ -53,7 +53,8 @@ enum class ScrollSource {
 };
 
 MOZ_DEFINE_ENUM_CLASS_WITH_BASE(APZWheelAction, uint8_t, (
-    Scroll
+    Scroll,
+    PinchZoom
 ))
 
 // Epsilon to be used when comparing 'float' coordinate values

modules/libpref/init/all.js

@@ -2631,11 +2631,12 @@ pref("mousewheel.system_scroll_override_on_root_content.horizontal.factor", 200)
 // 0: Nothing happens
 // 1: Scrolling contents
 // 2: Go back or go forward, in your history
-// 3: Zoom in or out.
+// 3: Zoom in or out (reflowing zoom).
 // 4: Treat vertical wheel as horizontal scroll
 //      This treats vertical wheel operation (i.e., deltaY) as horizontal
 //      scroll.  deltaX and deltaZ are always ignored.  So, only
 //      "delta_multiplier_y" pref affects the scroll speed.
+// 5: Zoom in or out (pinch zoom).
 pref("mousewheel.default.action", 1);
 pref("mousewheel.with_alt.action", 2);
 pref("mousewheel.with_control.action", 3);