Context menu

CMakeLists.txt

@@ -325,6 +325,7 @@ add_library(nanogui-obj OBJECT
   include/nanogui/stackedwidget.h src/stackedwidget.cpp
   include/nanogui/tabheader.h src/tabheader.cpp
   include/nanogui/tabwidget.h src/tabwidget.cpp
+  include/nanogui/contextmenu.h src/contextmenu.cpp
   include/nanogui/glcanvas.h src/glcanvas.cpp
   include/nanogui/formhelper.h
   include/nanogui/toolbutton.h

include/nanogui/contextmenu.h

@@ -0,0 +1,141 @@
+/*
+    nanogui/contextmenu.h -- Standard context menu with support for submenus
+
+    NanoGUI was developed by Wenzel Jakob <[email protected]>.
+    The widget drawing code is based on the NanoVG demo application
+    by Mikko Mononen.
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE.txt file.
+*/
+/** \file */
+
+#pragma once
+
+#include <nanogui/widget.h>
+#include <unordered_map>
+
+NAMESPACE_BEGIN(nanogui)
+
+/**
+ * \class ContextMenu contextmenu.h nanogui/contextmenu.h
+ *
+ * \brief Nestable context menu.
+ *
+ * A context menu may be used in either 'disposable' or 'non-disposable' mode.
+ * In disposable mode, it may be created and activated on-the-fly in an event
+ * handler, and the menu will automatically delete itself after use.
+ * In non-disposable mode, it may be created and stored before it is actually
+ * needed, and then activated inside an event handler. In this mode the menu
+ * instance is reusable as long as its parent is alive.
+ *
+ * \rst
+ * .. code-block:: cpp
+ *
+ *    auto menu = new ContextMenu(this, true);
+ *    menu->addItem("Item 1", [](){
+ *      std::cout << "Item 1 clicked!" << std::endl;
+ *    });
+ *    auto submenu = menu->addSubMenu("Submenu 1");
+ *    submenu->addItem("Subitem 1", [](){
+ *      std::cout << "Subitem 1 clicked!"
+ *    });
+ *    menu->activate();
+ *
+ * \endrst
+ */
+class NANOGUI_EXPORT ContextMenu : public Widget {
+public:
+    /**
+     * \brief Construct a new ContextMenu.
+     * \param parent Parent widget.
+     * \param disposable When true, the context menu and all submenus will be
+     *                   destroyed upon deactivation.
+     */
+    ContextMenu(Widget* parent, bool disposable);
+
+    /**
+     * \brief Activate the context menu at the given position.
+     *
+     * Make the context menu visible. When an item is clicked, the context menu
+     * will be deactivated.
+     *
+     * \param pos The desired position of the top left corner of the context
+     *            menu, relative to the parent.
+     */
+    void activate(const Vector2i& pos);
+
+    /**
+     * \brief Deactivate the context menu.
+     *
+     * This method is called automatically after an item is clicked. If the
+     * context menu is disposable, it will be removed from its parent and
+     * destroyed.
+     */
+    void deactivate();
+
+    /**
+     * \brief Add an item to the menu. The callback is called when the item is clicked.
+     * \param name Name of the item. The name is displayed in the context menu.
+     * \param cb Callback to be executed when the item is clicked.
+     * \param icon Optional icon to display to the left of the label.
+     */
+    void addItem(const std::string& name, const std::function<void()>& cb, int icon=0);
+
+    /**
+     * Add a submenu to the menu.
+     *
+     * \param name The display text of the item.
+     * \returns nullptr if a submenu or item already exists under the given name.
+     * \param icon Optional icon to display to the left of the label.
+     */
+    ContextMenu* addSubMenu(const std::string& name, int icon = 0);
+
+    Vector2i preferredSize(NVGcontext* ctx) const override;
+    bool mouseEnterEvent(const Vector2i& p, bool enter) override;
+    bool mouseMotionEvent(const Vector2i& p, const Vector2i& rel, int button, int modifiers) override;
+    bool mouseButtonEvent(const Vector2i& p, int button, bool down, int modifiers) override;
+    void draw(NVGcontext* ctx) override;
+    bool focusEvent(bool focused) override;
+
+protected:
+    /**
+     * \brief Determine if an item opens a new context menu.
+     * \param name Name of the item.
+     */
+    bool isSubMenu_(const std::string& name);
+
+    /**
+     * \brief Determine if a row contains the point `p`.
+     * \param name Name of the item that is on the desired row.
+     * \param p Point relative to self.
+     */
+    bool isRowSelected_(const std::string& name, const Vector2i& p) const;
+
+private:
+    /// Activate a submenu.
+    void activateSubmenu(const std::string& name);
+    /// Deactivate the currently active submenu if there is one.
+    void deactivateSubmenu();
+    /// Remove the context menu and all submenus from their parent widget.
+    void dispose();
+    /// Calculate a submenus position.
+    Vector2i submenuPosition(const std::string& name) const;
+
+private:
+    Widget *mItemContainer;
+    AdvancedGridLayout *mItemLayout;
+    std::unordered_map<std::string, std::function<void()>> mItems;
+    std::unordered_map<std::string, ContextMenu*> mSubmenus;
+    std::unordered_map<std::string, Label*> mLabels;
+    Label *mHighlightedItem;
+    ContextMenu *mActiveSubmenu;
+    ContextMenu *mRootMenu;
+    bool mDisposable;
+    bool mActivated;
+    bool mUpdateLayout;
+
+    Color mBackgroundColor, mMarginColor, mHighlightColor;
+};
+
+NAMESPACE_END(nanogui)

include/nanogui/nanogui.h

@@ -23,6 +23,7 @@
 #include <nanogui/toolbutton.h>
 #include <nanogui/popup.h>
 #include <nanogui/popupbutton.h>
+#include <nanogui/contextmenu.h>
 #include <nanogui/combobox.h>
 #include <nanogui/progressbar.h>
 #include <nanogui/entypo.h>