Sketcher: Add contextual input hints to edit tools (InputHints Phase 3) (#21806)

* Add input hints to fillet and chamfer tools

* Add hints to trimming tool

* Add hints to splitting tool

* Implement hints for extend tool

* Add hints to external geometry

* Add hints to Carbon Copy tool

* Hint updates to align with developer guidelines

* change "click to set" to "set" per PR comments

* Use enum (or declare one) to be type safe per PR comments

* For "trivial" one-step / one-state tools, refactor with direct hint return rather than using declarative / table pattern.

* Refactor hint tables initializers with C++20 features per PR feedback

- Use designated initializers (.state = , .hints = ) for clearer structure
- Add 'using enum Gui::InputHint::UserInput' to eliminate repetitive prefixes
- Applied to DrawSketchHandlerExtend and DrawSketchHandlerFillet

* Refactor Splitting tool hint implementation with direct return (trivial) pattern

* For fillet change "vertex" to "point" per PR feedback

* Change hint to "pick location on edge to split" per PR feedback

src/Mod/Sketcher/Gui/DrawSketchHandlerCarbonCopy.h

@@ -191,6 +191,7 @@ public:
                 return true;
             }
         }
+        updateHint();
         return false;
     }
 
@@ -218,6 +219,13 @@ private:
         Q_UNUSED(sketchgui);
         setAxisPickStyle(true);
     }
+
+public:
+    std::list<Gui::InputHint> getToolHints() const override
+    {
+        return {{QObject::tr("%1 pick sketch to copy", "Sketcher CarbonCopy: hint"),
+                 {Gui::InputHint::UserInput::MouseLeft}}};
+    }
 };
 
 }  // namespace SketcherGui

src/Mod/Sketcher/Gui/DrawSketchHandlerExtend.h

@@ -344,6 +344,8 @@ public:
             sketchgui
                 ->purgeHandler();  // no code after this line, Handler get deleted in ViewProvider
         }
+
+        updateHint();
         return true;
     }
 
@@ -371,6 +373,24 @@ protected:
     double Increment;
     std::vector<AutoConstraint> SugConstr;
 
+    // Add hint structures here
+    struct HintEntry
+    {
+        SelectMode state;
+        std::list<Gui::InputHint> hints;
+    };
+
+    using HintTable = std::vector<HintEntry>;
+
+    static HintTable getExtendHintTable();
+    static std::list<Gui::InputHint> lookupExtendHints(SelectMode state);
+
+public:
+    std::list<Gui::InputHint> getToolHints() const override
+    {
+        return lookupExtendHints(Mode);
+    }
+
 private:
     int crossProduct(Base::Vector2d& vec1, Base::Vector2d& vec2)
     {
@@ -378,8 +398,29 @@ private:
     }
 };
 
+DrawSketchHandlerExtend::HintTable DrawSketchHandlerExtend::getExtendHintTable()
+{
+    using enum Gui::InputHint::UserInput;
+
+    return {
+        {.state = STATUS_SEEK_First,
+         .hints = {{QObject::tr("%1 pick edge to extend", "Sketcher Extend: hint"), {MouseLeft}}}},
+        {.state = STATUS_SEEK_Second,
+         .hints = {
+             {QObject::tr("%1 set extension length", "Sketcher Extend: hint"), {MouseLeft}}}}};
+}
+
+std::list<Gui::InputHint> DrawSketchHandlerExtend::lookupExtendHints(SelectMode state)
+{
+    const auto extendHintTable = getExtendHintTable();
+
+    auto it = std::ranges::find_if(extendHintTable, [state](const HintEntry& entry) {
+        return entry.state == state;
+    });
+
+    return (it != extendHintTable.end()) ? it->hints : std::list<Gui::InputHint> {};
+}
 
 }  // namespace SketcherGui
 
-
 #endif  // SKETCHERGUI_DrawSketchHandlerExtend_H

src/Mod/Sketcher/Gui/DrawSketchHandlerExternal.h

@@ -208,6 +208,8 @@ public:
                 return true;
             }
         }
+        updateHint();
+
         return false;
     }
 
@@ -242,8 +244,14 @@ private:
 
     bool alwaysReference;
     bool intersection;
-};
 
+public:
+    std::list<Gui::InputHint> getToolHints() const override
+    {
+        return {{QObject::tr("%1 pick external geometry", "Sketcher External: hint"),
+                 {Gui::InputHint::UserInput::MouseLeft}}};
+    }
+};
 
 }  // namespace SketcherGui
 

src/Mod/Sketcher/Gui/DrawSketchHandlerFillet.h

@@ -402,6 +402,7 @@ private:
                 moveToNextMode();
             }
         }
+        updateHint();
     }
 
 
@@ -409,6 +410,23 @@ private:
     bool preserveCorner;
     int vtId, geoId1, geoId2;
     Base::Vector2d firstPos, secondPos;
+
+    struct HintEntry
+    {
+        SelectMode state;
+        std::list<Gui::InputHint> hints;
+    };
+
+    using HintTable = std::vector<HintEntry>;
+
+    static HintTable getFilletHintTable();
+    static std::list<Gui::InputHint> lookupFilletHints(SelectMode state);
+
+public:
+    std::list<Gui::InputHint> getToolHints() const override
+    {
+        return lookupFilletHints(state());
+    }
 };
 
 template<>
@@ -456,7 +474,33 @@ void DSHFilletController::adaptDrawingToCheckboxChange(int checkboxindex, bool v
     handler->updateCursor();
 }
 
+
+DrawSketchHandlerFillet::HintTable DrawSketchHandlerFillet::getFilletHintTable()
+{
+    using enum Gui::InputHint::UserInput;
+
+    return {{.state = SelectMode::SeekFirst,
+             .hints = {{QObject::tr("%1 pick first edge or point", "Sketcher Fillet/Chamfer: hint"),
+                        {MouseLeft}}}},
+            {.state = SelectMode::SeekSecond,
+             .hints = {{QObject::tr("%1 pick second edge", "Sketcher Fillet/Chamfer: hint"),
+                        {MouseLeft}}}},
+            {.state = SelectMode::End,
+             .hints = {
+                 {QObject::tr("%1 create fillet", "Sketcher Fillet/Chamfer: hint"), {MouseLeft}}}}};
+}
+
+std::list<Gui::InputHint> DrawSketchHandlerFillet::lookupFilletHints(SelectMode state)
+{
+    const auto filletHintTable = getFilletHintTable();
+
+    auto it = std::ranges::find_if(filletHintTable, [state](const HintEntry& entry) {
+        return entry.state == state;
+    });
+
+    return (it != filletHintTable.end()) ? it->hints : std::list<Gui::InputHint> {};
+}
+
 }  // namespace SketcherGui
 
-
 #endif  // SKETCHERGUI_DrawSketchHandlerFillet_H

src/Mod/Sketcher/Gui/DrawSketchHandlerSplitting.h

@@ -187,6 +187,22 @@ private:
     {
         return QStringLiteral("Sketcher_Pointer_Splitting");
     }
+
+    enum State
+    {
+        WaitingForEdge
+    };
+
+private:
+    std::vector<Base::Vector2d> EditMarkers;
+    bool mousePressed = false;
+
+public:
+    std::list<Gui::InputHint> getToolHints() const override
+    {
+        return {{QObject::tr("%1 pick location on edge to split", "Sketcher Splitting: hint"),
+                 {Gui::InputHint::UserInput::MouseLeft}}};
+    }
 };
 
 }  // namespace SketcherGui

src/Mod/Sketcher/Gui/DrawSketchHandlerTrimming.h

@@ -208,10 +208,15 @@ private:
 private:
     std::vector<Base::Vector2d> EditMarkers;
     bool mousePressed = false;
-};
 
+public:
+    std::list<Gui::InputHint> getToolHints() const override
+    {
+        return {{QObject::tr("%1 pick edge to trim", "Sketcher Trimming: hint"),
+                 {Gui::InputHint::UserInput::MouseLeft}}};
+    }
+};
 
 }  // namespace SketcherGui
 
-
 #endif  // SKETCHERGUI_DrawSketchHandlerTrimming_H