Add middle-button scrolling support

src/cascadia/TerminalControl/ControlCore.idl

@@ -136,6 +136,7 @@ namespace Microsoft.Terminal.Control
         void ToggleMarkMode();
         Boolean SwitchSelectionEndpoint();
         Boolean ExpandSelectionToWord();
+        Boolean IsVtMouseModeEnabled();
         void ClearBuffer(ClearBufferType clearType);
 
         void SetHoveredCell(Microsoft.Terminal.Core.Point terminalPosition);

src/cascadia/TerminalControl/ControlInteractivity.cpp

@@ -364,6 +364,14 @@ namespace winrt::Microsoft::Terminal::Control::implementation
                 }
             }
         }
+        else if (WI_IsFlagSet(buttonState, MouseButtonState::IsMiddleButtonDown))
+        {
+            const auto action = _core->Settings().MiddleClickAction();
+            if (action == Control::MiddleClickAction::Paste)
+            {
+                RequestPasteTextFromClipboard();
+            }
+        }
     }
 
     void ControlInteractivity::TouchPressed(const Core::Point contactPoint)

src/cascadia/TerminalControl/IControlSettings.idl

@@ -29,6 +29,13 @@ namespace Microsoft.Terminal.Control
         MinGW,
     };
 
+    enum MiddleClickAction
+    {
+        Pan = 0,
+        Paste,
+        None,
+    };
+
     // Class Description:
     // TerminalSettings encapsulates all settings that control the
     //      TermControl's behavior. In these settings there is both the entirety
@@ -77,6 +84,7 @@ namespace Microsoft.Terminal.Control
 
         PathTranslationStyle PathTranslationStyle { get; };
         String DragDropDelimiter { get; };
+        Microsoft.Terminal.Control.MiddleClickAction MiddleClickAction { get; };
 
         // NOTE! When adding something here, make sure to update ControlProperties.h too!
     };

src/cascadia/TerminalControl/TermControl.cpp

@@ -1995,6 +1995,15 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         else
         {
             const auto cursorPosition = point.Position();
+            if (point.Properties().IsMiddleButtonPressed() && !_core.IsVtMouseModeEnabled())
+            {
+                const auto action = _core.Settings().MiddleClickAction();
+                if (action == Control::MiddleClickAction::Pan)
+                {
+                    _isPanning = true;
+                    _panningAnchorPos = cursorPosition;
+                }
+            }
             _interactivity.PointerPressed(point.PointerId(),
                                           TermControl::GetPressedMouseButtons(point),
                                           TermControl::GetPointerUpdateKind(point),
@@ -2019,7 +2028,10 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             return;
         }
 
-        RestorePointerCursor.raise(*this, nullptr);
+        if (!_isPanning)
+        {
+            RestorePointerCursor.raise(*this, nullptr);
+        }
 
         const auto ptr = args.Pointer();
         const auto point = args.GetCurrentPoint(*this);
@@ -2041,11 +2053,39 @@ namespace winrt::Microsoft::Terminal::Control::implementation
                                                                        ControlKeyStates(args.KeyModifiers()),
                                                                        pixelPosition);
 
+            if (_isPanning && _panningAnchorPos)
+            {
+                const auto dy = cursorPosition.Y - _panningAnchorPos->Y;
+                constexpr auto MinPanDist = 5.0;
+
+                if (const auto window = CoreWindow::GetForCurrentThread())
+                {
+                    if (std::abs(dy) > MinPanDist)
+                    {
+                        window.PointerCursor(CoreCursor(CoreCursorType::SizeNorthSouth, 1));
+                    }
+                    else
+                    {
+                        window.PointerCursor(CoreCursor(CoreCursorType::SizeAll, 1));
+                    }
+                }
+
+                if (std::abs(dy) > MinPanDist)
+                {
+                    const auto scrollDist = dy > 0 ? (dy - MinPanDist) : (dy + MinPanDist);
+                    const auto newVelocity = _GetAutoScrollSpeed(std::abs(scrollDist)) * (dy > 0 ? 1.0 : -1.0);
+                    _TryStartAutoScroll(point, newVelocity);
+                }
+                else
+                {
+                    _TryStopAutoScroll(ptr.PointerId());
+                }
+            }
             // GH#9109 - Only start an auto-scroll when the drag actually
             // started within our bounds. Otherwise, someone could start a drag
             // outside the terminal control, drag into the padding, and trick us
             // into starting to scroll.
-            if (!suppressFurtherHandling && _focused && _pointerPressedInBounds && point.Properties().IsLeftButtonPressed())
+            else if (!suppressFurtherHandling && _focused && _pointerPressedInBounds && point.Properties().IsLeftButtonPressed())
             {
                 // We want to find the distance relative to the bounds of the
                 // SwapChainPanel, not the entire control. If they drag out of
@@ -2124,6 +2164,16 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             _interactivity.TouchReleased();
         }
 
+        if (_isPanning)
+        {
+            _isPanning = false;
+            _panningAnchorPos = std::nullopt;
+            if (const auto window = CoreWindow::GetForCurrentThread())
+            {
+                window.PointerCursor(CoreCursor(CoreCursorType::IBeam, 1));
+            }
+        }
+
         _TryStopAutoScroll(ptr.PointerId());
 
         args.Handled(true);

src/cascadia/TerminalControl/TermControl.h

@@ -308,6 +308,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         SafeDispatcherTimer _autoScrollTimer;
         std::optional<std::chrono::high_resolution_clock::time_point> _lastAutoScrollUpdateTime;
         bool _pointerPressedInBounds{ false };
+        bool _isPanning{ false };
+        std::optional<Windows::Foundation::Point> _panningAnchorPos;
 
         winrt::Windows::UI::Composition::ScalarKeyFrameAnimation _bellLightAnimation{ nullptr };
         winrt::Windows::UI::Composition::ScalarKeyFrameAnimation _bellDarkAnimation{ nullptr };

src/cascadia/TerminalSettingsModel/EnumMappings.cpp

@@ -54,6 +54,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
     DEFINE_ENUM_MAP(Microsoft::Terminal::Settings::Model::IntenseStyle, IntenseTextStyle);
     DEFINE_ENUM_MAP(Microsoft::Terminal::Core::AdjustTextMode, AdjustIndistinguishableColors);
     DEFINE_ENUM_MAP(Microsoft::Terminal::Control::PathTranslationStyle, PathTranslationStyle);
+    DEFINE_ENUM_MAP(Microsoft::Terminal::Control::MiddleClickAction, MiddleClickAction);
 
     // Actions
     DEFINE_ENUM_MAP(Microsoft::Terminal::Settings::Model::ResizeDirection, ResizeDirection);

src/cascadia/TerminalSettingsModel/EnumMappings.h

@@ -52,6 +52,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         static winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Microsoft::Terminal::Settings::Model::IntenseStyle> IntenseTextStyle();
         static winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Microsoft::Terminal::Core::AdjustTextMode> AdjustIndistinguishableColors();
         static winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Microsoft::Terminal::Control::PathTranslationStyle> PathTranslationStyle();
+        static winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Microsoft::Terminal::Control::MiddleClickAction> MiddleClickAction();
 
         // Actions
         static winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Microsoft::Terminal::Settings::Model::ResizeDirection> ResizeDirection();

src/cascadia/TerminalSettingsModel/EnumMappings.idl

@@ -34,6 +34,7 @@ namespace Microsoft.Terminal.Settings.Model
         static Windows.Foundation.Collections.IMap<String, UInt16> FontWeight { get; };
         static Windows.Foundation.Collections.IMap<String, Microsoft.Terminal.Settings.Model.IntenseStyle> IntenseTextStyle { get; };
         static Windows.Foundation.Collections.IMap<String, Microsoft.Terminal.Control.PathTranslationStyle> PathTranslationStyle { get; };
+        static Windows.Foundation.Collections.IMap<String, Microsoft.Terminal.Control.MiddleClickAction> MiddleClickAction { get; };
 
         // Actions
         static Windows.Foundation.Collections.IMap<String, Microsoft.Terminal.Settings.Model.ResizeDirection> ResizeDirection { get; };

src/cascadia/TerminalSettingsModel/MTSMSettings.h

@@ -111,7 +111,8 @@ Author(s):
     X(bool, AllowOscNotifications, "compatibility.allowOSC777", false)                                                                                         \
     X(bool, AllowKeypadMode, "compatibility.allowDECNKM", false)                                                                                               \
     X(hstring, DragDropDelimiter, "dragDropDelimiter", L" ")                                                                                                   \
-    X(Microsoft::Terminal::Control::PathTranslationStyle, PathTranslationStyle, "pathTranslationStyle", Microsoft::Terminal::Control::PathTranslationStyle::None)
+    X(Microsoft::Terminal::Control::PathTranslationStyle, PathTranslationStyle, "pathTranslationStyle", Microsoft::Terminal::Control::PathTranslationStyle::None) \
+    X(Microsoft::Terminal::Control::MiddleClickAction, MiddleClickAction, "experimental.middleClickAction", Microsoft::Terminal::Control::MiddleClickAction::Pan)
 
 // Intentionally omitted Profile settings:
 // * Name

src/cascadia/TerminalSettingsModel/Profile.idl

@@ -97,5 +97,6 @@ namespace Microsoft.Terminal.Settings.Model
 
         INHERITABLE_PROFILE_SETTING(Microsoft.Terminal.Control.PathTranslationStyle, PathTranslationStyle);
         INHERITABLE_PROFILE_SETTING(String, DragDropDelimiter);
+        INHERITABLE_PROFILE_SETTING(Microsoft.Terminal.Control.MiddleClickAction, MiddleClickAction);
     }
 }

src/cascadia/TerminalSettingsModel/TerminalSettingsSerializationHelpers.h

@@ -874,6 +874,15 @@ JSON_ENUM_MAPPER(::winrt::Microsoft::Terminal::Control::PathTranslationStyle)
     };
 };
 
+JSON_ENUM_MAPPER(::winrt::Microsoft::Terminal::Control::MiddleClickAction)
+{
+    static constexpr std::array<pair_type, 3> mappings = {
+        pair_type{ "pan", ValueType::Pan },
+        pair_type{ "paste", ValueType::Paste },
+        pair_type{ "none", ValueType::None },
+    };
+};
+
 JSON_ENUM_MAPPER(::winrt::Microsoft::Terminal::Control::WarnAboutMultiLinePaste)
 {
     JSON_MAPPINGS(3) = {

src/cascadia/UnitTests_Control/ControlInteractivityTests.cpp

@@ -42,6 +42,7 @@ namespace ControlUnitTests
 
         TEST_METHOD(GetMouseEventsInTest);
         TEST_METHOD(AltBufferClampMouse);
+        TEST_METHOD(TestMiddleClick);
 
         TEST_CLASS_SETUP(ClassSetup)
         {
@@ -1070,4 +1071,32 @@ namespace ControlUnitTests
                                       cursorPosition1.to_core_point());
         VERIFY_ARE_EQUAL(0u, expectedOutput.size(), L"Validate we drained all the expected output");
     }
+
+    void ControlInteractivityTests::TestMiddleClick()
+    {
+        WEX::TestExecution::DisableVerifyExceptions disableVerifyExceptions{};
+
+        auto [settings, conn] = _createSettingsAndConnection();
+        auto [core, interactivity] = _createCoreAndInteractivity(*settings, *conn);
+        _standardInit(core, interactivity);
+
+        const auto modifiers = ControlKeyStates();
+        const auto midMouseDown{ Control::MouseButtonState::IsMiddleButtonDown };
+
+        bool pasteRequested = false;
+        interactivity->PasteFromClipboard([&](auto&&, auto&&) {
+            pasteRequested = true;
+        });
+
+        settings->MiddleClickAction(Control::MiddleClickAction::Paste);
+
+        interactivity->PointerPressed(0,
+                                      midMouseDown,
+                                      WM_MBUTTONDOWN,
+                                      0,
+                                      modifiers,
+                                      Core::Point{ 0, 0 });
+
+        VERIFY_IS_TRUE(pasteRequested);
+    }
 }

src/cascadia/inc/ControlProperties.h

@@ -89,4 +89,5 @@
     X(winrt::Microsoft::Terminal::Control::CopyFormat, CopyFormatting, 0)                                                                                \
     X(bool, RightClickContextMenu, false)                                                                                                                \
     X(winrt::Microsoft::Terminal::Control::PathTranslationStyle, PathTranslationStyle, winrt::Microsoft::Terminal::Control::PathTranslationStyle::None)  \
-    X(winrt::hstring, DragDropDelimiter, L" ")
+    X(winrt::hstring, DragDropDelimiter, L" ")                                                                                                           \
+    X(winrt::Microsoft::Terminal::Control::MiddleClickAction, MiddleClickAction, winrt::Microsoft::Terminal::Control::MiddleClickAction::Pan)