feat: add option to enable zoom with ctrl + scroll (#19127)

This PR adds a new global setting `scrollToZoom` that allows users to
enable font zooming with scrolling. When disabled, **this setting
prevents accidental font size changes** that can occur when users scroll
while holding the Ctrl key.

Note: after disabling this setting, users may still change font size
using `Ctrl+` and `Ctrl-` keyboard shortcuts. Other Ctrl+Scroll
functionality (like transparency adjustments) remains unaffected.

## Validation Steps Performed

- Verified the setting can be toggled in the Settings UI (Interaction
tab)
- Confirmed that when disabled, holding Ctrl and scrolling no longer
changes font size
- Validated that the setting persists across terminal restarts

---

Note: I used the existing `FocusFollowMouse` setting as a reference for
implementing this.

Closes #11710
Closes #3793
Closes #11906
Closes #3990

doc/cascadia/profiles.schema.json

@@ -2376,6 +2376,11 @@
           "description": "When set to true, the terminal will focus the pane on mouse hover.",
           "type": "boolean"
         },
+        "experimental.scrollToZoom": {
+          "default": true,
+          "description": "When set to true, holding the Ctrl key while scrolling will increase or decrease the terminal font size.",
+          "type": "boolean"
+        },
         "compatibility.allowHeadless": {
           "default": false,
           "description": "When set to true, Windows Terminal will run in the background. This allows globalSummon and quakeMode actions to work even when no windows are open.",

src/cascadia/TerminalControl/ControlInteractivity.cpp

@@ -519,7 +519,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         {
             _mouseTransparencyHandler(delta);
         }
-        else if (ctrlPressed)
+        else if (ctrlPressed && _core->Settings().ScrollToZoom())
         {
             _mouseZoomHandler(delta);
         }

src/cascadia/TerminalControl/IControlSettings.idl

@@ -60,6 +60,7 @@ namespace Microsoft.Terminal.Control
         Boolean CopyOnSelect { get; };
         Microsoft.Terminal.Control.CopyFormat CopyFormatting { get; };
         Boolean FocusFollowMouse { get; };
+        Boolean ScrollToZoom { get; };
 
         String Commandline { get; };
         String StartingDirectory { get; };

src/cascadia/TerminalSettingsEditor/Interaction.xaml

@@ -83,6 +83,12 @@
                               Style="{StaticResource ToggleSwitchInExpanderStyle}" />
             </local:SettingContainer>
 
+            <!--  Enable Font Size Changes with Scrolling  -->
+            <local:SettingContainer x:Uid="Globals_ScrollToZoom">
+                <ToggleSwitch IsOn="{x:Bind ViewModel.ScrollToZoom, Mode=TwoWay}"
+                              Style="{StaticResource ToggleSwitchInExpanderStyle}" />
+            </local:SettingContainer>
+
             <!--  Detect URLs  -->
             <local:SettingContainer x:Uid="Globals_DetectURLs">
                 <ToggleSwitch IsOn="{x:Bind ViewModel.DetectURLs, Mode=TwoWay}"

src/cascadia/TerminalSettingsEditor/InteractionViewModel.h

@@ -25,6 +25,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(_GlobalSettings, TrimPaste);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(_GlobalSettings, SnapToGridOnResize);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(_GlobalSettings, FocusFollowMouse);
+        PERMANENT_OBSERVABLE_PROJECTED_SETTING(_GlobalSettings, ScrollToZoom);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(_GlobalSettings, DetectURLs);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(_GlobalSettings, SearchWebDefaultQueryUrl);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(_GlobalSettings, WordDelimiters);

src/cascadia/TerminalSettingsEditor/InteractionViewModel.idl

@@ -22,6 +22,7 @@ namespace Microsoft.Terminal.Settings.Editor
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(Boolean, TrimPaste);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(Boolean, SnapToGridOnResize);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(Boolean, FocusFollowMouse);
+        PERMANENT_OBSERVABLE_PROJECTED_SETTING(Boolean, ScrollToZoom);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(Boolean, DetectURLs);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(String, SearchWebDefaultQueryUrl);
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(String, WordDelimiters);

src/cascadia/TerminalSettingsEditor/Resources/en-US/Resources.resw

@@ -1736,6 +1736,10 @@
     <value>Automatically focus pane on mouse hover</value>
     <comment>Header for a control to toggle the "focus follow mouse" setting. When enabled, hovering over a pane puts it in focus.</comment>
   </data>
+  <data name="Globals_ScrollToZoom.Header" xml:space="preserve">
+    <value>Adjust terminal font size by scrolling while holding the Ctrl key</value>
+    <comment>Header for a control to toggle font size changes with scrolling. When enabled, holding the Ctrl key while scrolling will increase or decrease the terminal font size.</comment>
+  </data>
   <data name="Globals_DisableAnimationsReversed.Header" xml:space="preserve">
     <value>Pane animations</value>
     <comment>Header for a control to toggle animations on panes. "Enabled" value enables the animations.</comment>

src/cascadia/TerminalSettingsModel/GlobalAppSettings.idl

@@ -90,6 +90,7 @@ namespace Microsoft.Terminal.Settings.Model
         INHERITABLE_SETTING(Boolean, DisableAnimations);
         INHERITABLE_SETTING(String, StartupActions);
         INHERITABLE_SETTING(Boolean, FocusFollowMouse);
+        INHERITABLE_SETTING(Boolean, ScrollToZoom);
         INHERITABLE_SETTING(WindowingMode, WindowingBehavior);
         INHERITABLE_SETTING(Boolean, TrimBlockSelection);
         INHERITABLE_SETTING(Boolean, DetectURLs);

src/cascadia/TerminalSettingsModel/MTSMSettings.h

@@ -24,6 +24,7 @@ Author(s):
     X(hstring, WordDelimiters, "wordDelimiters", DEFAULT_WORD_DELIMITERS)                                                                                                                             \
     X(bool, CopyOnSelect, "copyOnSelect", false)                                                                                                                                                      \
     X(bool, FocusFollowMouse, "focusFollowMouse", false)                                                                                                                                              \
+    X(bool, ScrollToZoom, "experimental.scrollToZoom", true)                                                                                                                                          \
     X(winrt::Microsoft::Terminal::Control::GraphicsAPI, GraphicsAPI, "rendering.graphicsAPI")                                                                                                         \
     X(bool, DisablePartialInvalidation, "rendering.disablePartialInvalidation", false)                                                                                                                \
     X(bool, SoftwareRendering, "rendering.software", false)                                                                                                                                           \

src/cascadia/TerminalSettingsModel/TerminalSettings.cpp

@@ -367,6 +367,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         _CopyOnSelect = globalSettings.CopyOnSelect();
         _CopyFormatting = globalSettings.CopyFormatting();
         _FocusFollowMouse = globalSettings.FocusFollowMouse();
+        _ScrollToZoom = globalSettings.ScrollToZoom();
         _GraphicsAPI = globalSettings.GraphicsAPI();
         _DisablePartialInvalidation = globalSettings.DisablePartialInvalidation();
         _SoftwareRendering = globalSettings.SoftwareRendering();

src/cascadia/TerminalSettingsModel/TerminalSettings.h

@@ -94,6 +94,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         INHERITABLE_SETTING(Model::TerminalSettings, bool, CopyOnSelect, false);
         INHERITABLE_SETTING(Model::TerminalSettings, Microsoft::Terminal::Control::CopyFormat, CopyFormatting, 0);
         INHERITABLE_SETTING(Model::TerminalSettings, bool, FocusFollowMouse, false);
+        INHERITABLE_SETTING(Model::TerminalSettings, bool, ScrollToZoom, true);
         INHERITABLE_SETTING(Model::TerminalSettings, bool, AllowVtChecksumReport, false);
         INHERITABLE_SETTING(Model::TerminalSettings, bool, TrimBlockSelection, true);
         INHERITABLE_SETTING(Model::TerminalSettings, bool, DetectURLs, true);

src/cascadia/inc/ControlProperties.h

@@ -42,6 +42,7 @@
     X(winrt::hstring, WordDelimiters, DEFAULT_WORD_DELIMITERS)                                                    \
     X(bool, CopyOnSelect, false)                                                                                  \
     X(bool, FocusFollowMouse, false)                                                                              \
+    X(bool, ScrollToZoom, true)                                                                                   \
     X(winrt::Windows::Foundation::IReference<winrt::Microsoft::Terminal::Core::Color>, TabColor, nullptr)         \
     X(winrt::Windows::Foundation::IReference<winrt::Microsoft::Terminal::Core::Color>, StartingTabColor, nullptr) \
     X(bool, TrimBlockSelection, true)                                                                             \