Add support for horizontal mouse wheel events

This adds support for horizontal mouse wheel events (WM_MOUSEHWHEEL).
With this change, applications running in the terminal can now receive
and respond to horizontal scroll inputs from the mouse/trackpad.

Fixes: #19245

Author: aymanbagabas

src/cascadia/TerminalControl/ControlInteractivity.cpp

@@ -485,6 +485,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     // - modifiers: The modifiers pressed during this event, in the form of a VirtualKeyModifiers
     // - delta: the mouse wheel delta that triggered this event.
     bool ControlInteractivity::MouseWheel(const ::Microsoft::Terminal::Core::ControlKeyStates modifiers,
+                                          const bool horizontal,
                                           const int32_t delta,
                                           const Core::Point pixelPosition,
                                           const Control::MouseButtonState buttonState)
@@ -506,7 +507,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             // PointerPoint to work with. So, we're just going to do a
             // mousewheel event manually
             return _sendMouseEventHelper(terminalPosition,
-                                         WM_MOUSEWHEEL,
+                                         horizontal ? WM_MOUSEHWHEEL : WM_MOUSEWHEEL,
                                          modifiers,
                                          ::base::saturated_cast<short>(delta),
                                          buttonState);
@@ -667,7 +668,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         {
             return false;
         }
-        return _core->ShouldSendAlternateScroll(WM_MOUSEWHEEL, delta);
+        return _core->ShouldSendAlternateScroll(WM_MOUSEWHEEL, delta) || _core->ShouldSendAlternateScroll(WM_MOUSEHWHEEL, delta);
     }
 
     // Method Description:

src/cascadia/TerminalControl/ControlInteractivity.h

@@ -74,6 +74,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         void TouchReleased();
 
         bool MouseWheel(const ::Microsoft::Terminal::Core::ControlKeyStates modifiers,
+                        const bool horizontal,
                         const int32_t delta,
                         const Core::Point pixelPosition,
                         const Control::MouseButtonState state);

src/cascadia/TerminalControl/ControlInteractivity.idl

@@ -60,6 +60,7 @@ namespace Microsoft.Terminal.Control
         void TouchReleased();
 
         Boolean MouseWheel(Microsoft.Terminal.Core.ControlKeyStates modifiers,
+                           Boolean horizontal,
                            Int32 delta,
                            Microsoft.Terminal.Core.Point pixelPosition,
                            MouseButtonState state);

src/cascadia/TerminalControl/IMouseWheelListener.idl

@@ -11,6 +11,6 @@ namespace Microsoft.Terminal.Control
     [uuid("65b8b8c5-988f-43ff-aba9-e89368da1598")]
     interface IMouseWheelListener
     {
-        Boolean OnMouseWheel(Windows.Foundation.Point coord, Int32 delta, Boolean leftButtonDown, Boolean midButtonDown, Boolean rightButtonDown);
+        Boolean OnMouseWheel(Windows.Foundation.Point coord, Boolean horizontal, Int32 delta, Boolean leftButtonDown, Boolean midButtonDown, Boolean rightButtonDown);
     }
 }

src/cascadia/TerminalControl/TermControl.cpp

@@ -2164,14 +2164,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         RestorePointerCursor.raise(*this, nullptr);
 
         const auto point = args.GetCurrentPoint(*this);
-        // GH#10329 - we don't need to handle horizontal scrolls. Only vertical ones.
-        // So filter out the horizontal ones.
-        if (point.Properties().IsHorizontalMouseWheel())
-        {
-            return;
-        }
-
         auto result = _interactivity.MouseWheel(ControlKeyStates{ args.KeyModifiers() },
+                                                point.Properties().IsHorizontalMouseWheel(),
                                                 point.Properties().MouseWheelDelta(),
                                                 _toTerminalOrigin(point.Position()),
                                                 TermControl::GetPressedMouseButtons(point));
@@ -2192,6 +2186,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     // - delta: the mouse wheel delta that triggered this event.
     // - state: the state for each of the mouse buttons individually (pressed/unpressed)
     bool TermControl::OnMouseWheel(const Windows::Foundation::Point location,
+                                   const bool horizontal,
                                    const int32_t delta,
                                    const bool leftButtonDown,
                                    const bool midButtonDown,
@@ -2204,7 +2199,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         WI_SetFlagIf(state, Control::MouseButtonState::IsMiddleButtonDown, midButtonDown);
         WI_SetFlagIf(state, Control::MouseButtonState::IsRightButtonDown, rightButtonDown);
 
-        return _interactivity.MouseWheel(modifiers, delta, _toTerminalOrigin(location), state);
+        return _interactivity.MouseWheel(modifiers, horizontal, delta, _toTerminalOrigin(location), state);
     }
 
     // Method Description:

src/cascadia/TerminalControl/TermControl.h

@@ -147,7 +147,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
         bool OnDirectKeyEvent(const uint32_t vkey, const uint8_t scanCode, const bool down);
 
-        bool OnMouseWheel(const Windows::Foundation::Point location, const int32_t delta, const bool leftButtonDown, const bool midButtonDown, const bool rightButtonDown);
+        bool OnMouseWheel(const Windows::Foundation::Point location, const bool horizontal, const int32_t delta, const bool leftButtonDown, const bool midButtonDown, const bool rightButtonDown);
 
         ~TermControl();
 

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -745,7 +745,7 @@ void AppHost::_RaiseVisualBell(const winrt::Windows::Foundation::IInspectable&,
 // - delta: the wheel delta that triggered this event.
 // Return Value:
 // - <none>
-void AppHost::_WindowMouseWheeled(const winrt::Windows::Foundation::Point coord, const int32_t delta)
+void AppHost::_WindowMouseWheeled(const winrt::Windows::Foundation::Point coord, const int32_t delta, const bool horizontal)
 {
     if (_windowLogic)
     {
@@ -772,7 +772,7 @@ void AppHost::_WindowMouseWheeled(const winrt::Windows::Foundation::Point coord,
                     const auto mButtonDown = WI_IsFlagSet(GetKeyState(VK_MBUTTON), KeyPressed);
                     const auto rButtonDown = WI_IsFlagSet(GetKeyState(VK_RBUTTON), KeyPressed);
 
-                    if (control.OnMouseWheel(offsetPoint, delta, lButtonDown, mButtonDown, rButtonDown))
+                    if (control.OnMouseWheel(offsetPoint, horizontal, delta, lButtonDown, mButtonDown, rButtonDown))
                     {
                         // If the element handled the mouse wheel event, don't
                         // continue to iterate over the remaining controls.

src/cascadia/WindowsTerminal/AppHost.h

@@ -73,7 +73,7 @@ class AppHost : public std::enable_shared_from_this<AppHost>
 
     void _RaiseVisualBell(const winrt::Windows::Foundation::IInspectable& sender,
                           const winrt::Windows::Foundation::IInspectable& arg);
-    void _WindowMouseWheeled(const winrt::Windows::Foundation::Point coord, const int32_t delta);
+    void _WindowMouseWheeled(const winrt::Windows::Foundation::Point coord, const int32_t delta, const bool horizontal);
     void _WindowActivated(bool activated);
     void _WindowMoved();
 

src/cascadia/WindowsTerminal/IslandWindow.cpp

@@ -595,6 +595,7 @@ void IslandWindow::_OnGetMinMaxInfo(const WPARAM /*wParam*/, const LPARAM lParam
         WindowCloseButtonClicked.raise();
         return 0;
     }
+    case WM_MOUSEHWHEEL:
     case WM_MOUSEWHEEL:
         try
         {
@@ -626,7 +627,7 @@ void IslandWindow::_OnGetMinMaxInfo(const WPARAM /*wParam*/, const LPARAM lParam
             const auto wheelDelta = static_cast<short>(HIWORD(wparam));
 
             // Raise an event, so any listeners can handle the mouse wheel event manually.
-            MouseScrolled.raise(real, wheelDelta);
+            MouseScrolled.raise(real, wheelDelta, message == WM_MOUSEHWHEEL);
             return 0;
         }
         CATCH_LOG();

src/cascadia/WindowsTerminal/IslandWindow.h

@@ -74,7 +74,7 @@ class IslandWindow :
 
     til::event<winrt::delegate<>> DragRegionClicked;
     til::event<winrt::delegate<>> WindowCloseButtonClicked;
-    til::event<winrt::delegate<void(winrt::Windows::Foundation::Point, int32_t)>> MouseScrolled;
+    til::event<winrt::delegate<void(winrt::Windows::Foundation::Point, int32_t, bool)>> MouseScrolled;
     til::event<winrt::delegate<void(bool)>> WindowActivated;
     til::event<winrt::delegate<void()>> NotifyNotificationIconPressed;
     til::event<winrt::delegate<void()>> NotifyWindowHidden;