Fl_Menu_Button

The Fl_Menu_Button widget is a button that pops up a menu (or hierarchy of menus) when pushed. The menu is defined by an array of Fl_Menu_Item objects.

#include <FL/Fl_Menu_Button.H>

Inheritance

Fl_Widget → Fl_Menu_ → Fl_Menu_Button

Constructor

Fl_Menu_Button()

Creates a new menu button widget.

Fl_Menu_Button(int X, int Y, int W, int H, const char *label = 0);

int

X coordinate of the widget

int

Y coordinate of the widget

int

Width of the widget

int

Height of the widget

label

const char*

Optional label for the button

Example:

Fl_Menu_Button *menu_btn = new Fl_Menu_Button(100, 100, 120, 30, "Options");

Overview

The Fl_Menu_Button can operate in two modes:

Normal menu button: Any mouse button pops up the menu, aligned below the button
Popup menu: Only specific mouse buttons trigger the menu (configured via type())

The menu will also pop up in response to shortcuts indicated by putting a & character in the label. The type() value determines which mouse buttons trigger the menu:

enum popup_buttons

enum popup_buttons {
  POPUP1 = 1,    // Pops up with mouse button 1 (left)
  POPUP2,        // Pops up with mouse button 2 (middle)
  POPUP12,       // Pops up with mouse button 1 or 2
  POPUP3,        // Pops up with mouse button 3 (right)
  POPUP13,       // Pops up with mouse button 1 or 3
  POPUP23,       // Pops up with mouse button 2 or 3
  POPUP123       // Pops up with any mouse button
};

POPUP3 is the most commonly used type for right-click context menus.

Example:

Fl_Menu_Button *menu = new Fl_Menu_Button(10, 10, 100, 30);
menu->type(Fl_Menu_Button::POPUP3);  // Right-click only

Methods

Displays the popup menu and returns the selected item.

const Fl_Menu_Item* popup();

Returns: Pointer to the selected Fl_Menu_Item, or NULL if no selection was made. Example:

const Fl_Menu_Item *item = menu_btn->popup();
if (item) {
  printf("Selected: %s\n", item->label());
}

handle()

Handles events for the widget.

int handle(int event) override;

event

int

FLTK event type (e.g., FL_PUSH, FL_RELEASE)

Returns: Non-zero if the event was handled.

Using add()

Dynamically add menu items using pathname syntax:

Fl_Menu_Button *menu = new Fl_Menu_Button(100, 100, 120, 30, "Menu");
menu->add("File/New",   FL_CTRL+'n', new_cb);
menu->add("File/Open",  FL_CTRL+'o', open_cb);
menu->add("File/Save",  FL_CTRL+'s', save_cb, 0, FL_MENU_DIVIDER);
menu->add("File/Quit",  FL_CTRL+'q', quit_cb);
menu->add("Edit/Copy",  FL_CTRL+'c', copy_cb);
menu->add("Edit/Paste", FL_CTRL+'v', paste_cb);

Using Static Array

Define menu items as a static array:

static Fl_Menu_Item items[] = {
  {"&New",   FL_CTRL+'n', new_cb},
  {"&Open",  FL_CTRL+'o', open_cb},
  {"&Save",  FL_CTRL+'s', save_cb, 0, FL_MENU_DIVIDER},
  {"&Quit",  FL_CTRL+'q', quit_cb},
  {0}
};

Fl_Menu_Button *menu = new Fl_Menu_Button(100, 100, 120, 30, "File");
menu->copy(items);

Callbacks

When a user clicks a menu item:

value() is set to that item
If the item has a callback, it’s invoked with:
- The Fl_Menu_Button as the first argument
- The item’s user_data() as the second argument
If the item doesn’t have a callback, the Fl_Menu_Button’s callback is invoked instead

Example: Single Callback

void menu_cb(Fl_Widget *w, void*) {
  Fl_Menu_Button *menu = (Fl_Menu_Button*)w;
  const Fl_Menu_Item *item = menu->mvalue();
  
  if (item) {
    printf("Selected: %s\n", item->label());
  }
}

Fl_Menu_Button *menu = new Fl_Menu_Button(100, 100, 120, 30);
menu->callback(menu_cb);
menu->add("Option 1");
menu->add("Option 2");
menu->add("Option 3");

Example: Individual Callbacks

void opt1_cb(Fl_Widget*, void*) { printf("Option 1\n"); }
void opt2_cb(Fl_Widget*, void*) { printf("Option 2\n"); }
void opt3_cb(Fl_Widget*, void*) { printf("Option 3\n"); }

menu->add("Option 1", 0, opt1_cb);
menu->add("Option 2", 0, opt2_cb);
menu->add("Option 3", 0, opt3_cb);

Context Menus (Right-Click)

Create right-click context menus by setting the type to POPUP3:

class MyWidget : public Fl_Widget {
  Fl_Menu_Button *context_menu;
  
public:
  MyWidget(int X, int Y, int W, int H) : Fl_Widget(X, Y, W, H) {
    context_menu = new Fl_Menu_Button(0, 0, 0, 0);
    context_menu->type(Fl_Menu_Button::POPUP3);
    context_menu->add("Cut",   FL_CTRL+'x', cut_cb);
    context_menu->add("Copy",  FL_CTRL+'c', copy_cb);
    context_menu->add("Paste", FL_CTRL+'v', paste_cb);
  }
  
  int handle(int event) override {
    if (event == FL_PUSH && Fl::event_button() == FL_RIGHT_MOUSE) {
      const Fl_Menu_Item *item = context_menu->popup();
      if (item && item->callback()) {
        item->do_callback((Fl_Widget*)this);
      }
      return 1;
    }
    return Fl_Widget::handle(event);
  }
};

Dynamic Context Menus

Create menus on-the-fly for context-sensitive operations: From examples/table-with-right-click-menu.cxx:

void PostContextMenu() {
  int row = callback_row();
  int col = callback_col();
  
  char label[80];
  sprintf(label, "Cell %c%d", 'A' + col, row);
  
  // Create menu at mouse position
  Fl_Menu_Button menu(Fl::event_x(), Fl::event_y(), 80, 1);
  menu.add(label, 0, 0, 0, FL_MENU_DIVIDER | FL_MENU_INACTIVE);
  menu.add("Cut");
  menu.add("Copy");
  menu.add("Paste");
  
  const Fl_Menu_Item *item = menu.popup();
  if (item) {
    printf("You chose '%s' for %s\n", item->label(), label);
  }
}

Events

FL_BEFORE_MENU Event

FLTK triggers an FL_BEFORE_MENU event right before displaying the menu. This provides an opportunity to update menu item states:

class MyMenuButton : public Fl_Menu_Button {
public:
  MyMenuButton(int X, int Y, int W, int H) : Fl_Menu_Button(X, Y, W, H) {}
  
  int handle(int event) override {
    if (event == FL_BEFORE_MENU) {
      // Update menu states before showing
      Fl_Menu_Item *paste = (Fl_Menu_Item*)find_item("Paste");
      if (clipboard_has_data()) {
        paste->activate();
      } else {
        paste->deactivate();
      }
    }
    return Fl_Menu_Button::handle(event);
  }
};

Checkboxes

menu->add("Options/Auto Save", 0, 0, 0, FL_MENU_TOGGLE);
menu->add("Options/Verbose",   0, 0, 0, FL_MENU_TOGGLE | FL_MENU_VALUE);

Radio Buttons

menu->add("Size/Small",  0, 0, 0, FL_MENU_RADIO);
menu->add("Size/Medium", 0, 0, 0, FL_MENU_RADIO | FL_MENU_VALUE);
menu->add("Size/Large",  0, 0, 0, FL_MENU_RADIO);

Submenus

menu->add("File/Recent/Document1.txt");
menu->add("File/Recent/Document2.txt");
menu->add("File/Recent/Document3.txt");

Dividers

menu->add("Copy",  FL_CTRL+'c', copy_cb, 0, FL_MENU_DIVIDER);
menu->add("Paste", FL_CTRL+'v', paste_cb);

Inactive Items

menu->add("Paste", FL_CTRL+'v', paste_cb, 0, FL_MENU_INACTIVE);

Invisible Items

menu->add("Debug Mode", 0, debug_cb, 0, FL_MENU_INVISIBLE);
// Item is hidden but shortcut still works

Complete Example

#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Menu_Button.H>
#include <FL/Fl_Box.H>
#include <stdio.h>

void menu_callback(Fl_Widget *w, void*) {
  Fl_Menu_Button *menu = (Fl_Menu_Button*)w;
  const Fl_Menu_Item *item = menu->mvalue();
  
  if (item) {
    printf("Selected: %s\n", item->label());
    
    if (item->flags & FL_MENU_TOGGLE) {
      printf("Toggle value: %s\n", item->value() ? "on" : "off");
    }
  }
}

int main() {
  Fl_Window *win = new Fl_Window(400, 300, "Menu Button Demo");
  
  // Normal menu button
  Fl_Menu_Button *menu1 = new Fl_Menu_Button(50, 50, 120, 30, "Menu");
  menu1->callback(menu_callback);
  menu1->add("File/New",   FL_CTRL+'n');
  menu1->add("File/Open",  FL_CTRL+'o');
  menu1->add("File/Save",  FL_CTRL+'s', 0, 0, FL_MENU_DIVIDER);
  menu1->add("File/Quit",  FL_CTRL+'q');
  menu1->add("Edit/Copy",  FL_CTRL+'c');
  menu1->add("Edit/Paste", FL_CTRL+'v');
  
  // Right-click popup menu button
  Fl_Menu_Button *menu2 = new Fl_Menu_Button(50, 100, 120, 30, "Right-Click Me");
  menu2->type(Fl_Menu_Button::POPUP3);
  menu2->callback(menu_callback);
  menu2->add("Cut");
  menu2->add("Copy");
  menu2->add("Paste", 0, 0, 0, FL_MENU_DIVIDER);
  menu2->add("Select All");
  
  // Menu with checkboxes and radio buttons
  Fl_Menu_Button *menu3 = new Fl_Menu_Button(50, 150, 120, 30, "Options");
  menu3->callback(menu_callback);
  menu3->add("View/Show Toolbar",  0, 0, 0, FL_MENU_TOGGLE | FL_MENU_VALUE);
  menu3->add("View/Show Statusbar", 0, 0, 0, FL_MENU_TOGGLE);
  menu3->add("View/Zoom/50%",  0, 0, 0, FL_MENU_RADIO);
  menu3->add("View/Zoom/100%", 0, 0, 0, FL_MENU_RADIO | FL_MENU_VALUE);
  menu3->add("View/Zoom/200%", 0, 0, 0, FL_MENU_RADIO);
  
  win->end();
  win->show();
  return Fl::run();
}

Advanced Usage

Finding and Modifying Items

// Find an item
Fl_Menu_Item *item = (Fl_Menu_Item*)menu->find_item("Edit/Paste");

if (item) {
  // Enable/disable
  item->activate();
  item->deactivate();
  
  // Show/hide
  item->show();
  item->hide();
  
  // Check/uncheck
  item->set();
  item->clear();
  
  // Change label
  item->label("Paste Special");
  
  // Change shortcut
  item->shortcut(FL_CTRL+FL_SHIFT+'v');
}

Getting Item Information

const Fl_Menu_Item *item = menu->mvalue();

if (item) {
  const char *label = item->label();
  int shortcut = item->shortcut();
  int is_active = item->active();
  int is_visible = item->visible();
  int is_checked = item->value();
  int is_checkbox = item->checkbox();
  int is_radio = item->radio();
  int is_submenu = item->submenu();
}

Removing Items

// Remove by index
int index = menu->find_index("File/Save");
if (index >= 0) {
  menu->remove(index);
}

// Clear entire menu
menu->clear();

Appearance Customization

// Button appearance
menu->box(FL_FLAT_BOX);
menu->color(FL_LIGHT2);
menu->labelcolor(FL_BLACK);
menu->labelfont(FL_HELVETICA_BOLD);
menu->labelsize(14);

// Menu popup appearance
menu->textfont(FL_HELVETICA);
menu->textsize(12);
menu->textcolor(FL_BLACK);
menu->menu_box(FL_BORDER_BOX);

Common Patterns

menu->add("File/New",      FL_CTRL+'n', new_cb);
menu->add("File/Open",     FL_CTRL+'o', open_cb);
menu->add("File/Save",     FL_CTRL+'s', save_cb);
menu->add("File/Save As",  FL_CTRL+FL_SHIFT+'s', save_as_cb, 0, FL_MENU_DIVIDER);
menu->add("File/Exit",     FL_ALT+FL_F+4, exit_cb);

menu->add("Edit/Undo",  FL_CTRL+'z', undo_cb);
menu->add("Edit/Redo",  FL_CTRL+'y', redo_cb, 0, FL_MENU_DIVIDER);
menu->add("Edit/Cut",   FL_CTRL+'x', cut_cb);
menu->add("Edit/Copy",  FL_CTRL+'c', copy_cb);
menu->add("Edit/Paste", FL_CTRL+'v', paste_cb);

menu->add("Settings/Auto Save",        0, 0, 0, FL_MENU_TOGGLE);
menu->add("Settings/Show Line Numbers", 0, 0, 0, FL_MENU_TOGGLE | FL_MENU_VALUE);
menu->add("Settings/Word Wrap",        0, 0, 0, FL_MENU_TOGGLE);

Core Classes

Basic Widgets

Menu Widgets

Container Widgets

Complex Widgets

Drawing & Graphics

Documentation Index

​Fl_Menu_Button

​Header

​Inheritance

​Constructor

​Fl_Menu_Button()

​Overview

​Popup Button Types

​enum popup_buttons

​Methods

​popup()

​handle()

​Adding Menu Items

​Using add()

​Using Static Array

​Callbacks

​Example: Single Callback

​Example: Individual Callbacks

​Context Menus (Right-Click)

​Dynamic Context Menus

​Events

​FL_BEFORE_MENU Event

​Menu Item Types

​Checkboxes

​Radio Buttons

​Submenus

​Dividers

​Inactive Items

​Invisible Items

​Complete Example

​Advanced Usage

​Finding and Modifying Items

​Getting Item Information

​Removing Items

​Appearance Customization

​Common Patterns

​File Menu

​Edit Menu

​Settings Menu with Checkboxes

​See Also

Fl_Menu_Button

Header

Inheritance

Constructor

Fl_Menu_Button()

Overview

Popup Button Types

enum popup_buttons

Methods

popup()

handle()

Adding Menu Items

Using add()

Using Static Array

Callbacks

Example: Single Callback

Example: Individual Callbacks

Context Menus (Right-Click)

Dynamic Context Menus

Events

FL_BEFORE_MENU Event

Menu Item Types

Checkboxes

Radio Buttons

Submenus

Dividers

Inactive Items

Invisible Items

Complete Example

Advanced Usage

Finding and Modifying Items

Getting Item Information

Removing Items

Appearance Customization

Common Patterns

File Menu

Edit Menu

Settings Menu with Checkboxes

See Also