LibGUI: Allow scrolling through a ComboBox with the mouse wheel

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/e064999e0d9

Libraries/LibGUI/ComboBox.cpp

@@ -35,9 +35,28 @@
 
 namespace GUI {
 
+class ComboBoxEditor final : public TextEditor {
+    C_OBJECT(ComboBoxEditor);
+
+public:
+    Function<void(int delta)> on_mousewheel;
+
+private:
+    ComboBoxEditor()
+        : TextEditor(TextEditor::SingleLine)
+    {
+    }
+
+    virtual void mousewheel_event(MouseEvent& event) override
+    {
+        if (on_mousewheel)
+            on_mousewheel(event.wheel_delta());
+    }
+};
+
 ComboBox::ComboBox()
 {
-    m_editor = add<TextBox>();
+    m_editor = add<ComboBoxEditor>();
     m_editor->on_change = [this] {
         if (on_change)
             on_change(m_editor->text(), m_list_view->selection().first());
@@ -74,6 +93,10 @@ ComboBox::ComboBox()
                 on_change(m_editor->text(), index);
         });
     };
+
+    m_editor->on_mousewheel = [this](int delta) {
+        m_list_view->move_selection(delta);
+    };
 }
 
 ComboBox::~ComboBox()

Libraries/LibGUI/ComboBox.h

@@ -30,6 +30,8 @@
 
 namespace GUI {
 
+class ComboBoxEditor;
+
 class ComboBox : public Widget {
     C_OBJECT(ComboBox)
 public:
@@ -62,7 +64,7 @@ protected:
     virtual void resize_event(ResizeEvent&) override;
 
 private:
-    RefPtr<TextBox> m_editor;
+    RefPtr<ComboBoxEditor> m_editor;
     RefPtr<Button> m_open_button;
     RefPtr<Window> m_list_window;
     RefPtr<ListView> m_list_view;

Libraries/LibGUI/ListView.cpp

@@ -182,6 +182,25 @@ int ListView::item_count() const
     return model()->row_count();
 }
 
+void ListView::move_selection(int steps)
+{
+    if (!model())
+        return;
+    auto& model = *this->model();
+    ModelIndex new_index;
+    if (!selection().is_empty()) {
+        auto old_index = selection().first();
+        new_index = model.index(old_index.row() + steps, old_index.column());
+    } else {
+        new_index = model.index(0, 0);
+    }
+    if (model.is_valid(new_index)) {
+        selection().set(new_index);
+        scroll_into_view(new_index, Orientation::Vertical);
+        update();
+    }
+}
+
 void ListView::keydown_event(KeyEvent& event)
 {
     if (!model())
@@ -192,33 +211,11 @@ void ListView::keydown_event(KeyEvent& event)
         return;
     }
     if (event.key() == KeyCode::Key_Up) {
-        ModelIndex new_index;
-        if (!selection().is_empty()) {
-            auto old_index = selection().first();
-            new_index = model.index(old_index.row() - 1, old_index.column());
-        } else {
-            new_index = model.index(0, 0);
-        }
-        if (model.is_valid(new_index)) {
-            selection().set(new_index);
-            scroll_into_view(new_index, Orientation::Vertical);
-            update();
-        }
+        move_selection(-1);
         return;
     }
     if (event.key() == KeyCode::Key_Down) {
-        ModelIndex new_index;
-        if (!selection().is_empty()) {
-            auto old_index = selection().first();
-            new_index = model.index(old_index.row() + 1, old_index.column());
-        } else {
-            new_index = model.index(0, 0);
-        }
-        if (model.is_valid(new_index)) {
-            selection().set(new_index);
-            scroll_into_view(new_index, Orientation::Vertical);
-            update();
-        }
+        move_selection(1);
         return;
     }
     if (event.key() == KeyCode::Key_PageUp) {

Libraries/LibGUI/ListView.h

@@ -53,6 +53,9 @@ public:
     void set_model_column(int column) { m_model_column = column; }
 
     virtual void select_all() override;
+
+    void move_selection(int steps);
+
 private:
     ListView();