gui2/label: Use the hyperlink mouse cursor while hovering links

This also moves gui2:🏷️:can_mouse_focus()'s declaration to a
section that makes more sense for it to be in. Thanks to jyrkive for
pointing out the existence of this method.

changelog.md

@@ -18,6 +18,7 @@
  ### Units
    * Undead variations for Falcon, Giant Rat, serpents, and Gorer/Tusklet
  ### User interface
+   * Text labels now use the hyperlink mouse cursor while hovering links.
  ### WML Engine
  ### Miscellaneous and Bug Fixes
    * Fixed several possible crashes in wmllint

src/gui/widgets/label.cpp

@@ -25,6 +25,7 @@
 #include "gui/widgets/settings.hpp"
 #include "gui/widgets/window.hpp"
 
+#include "cursor.hpp"
 #include "desktop/clipboard.hpp"
 #include "desktop/open.hpp"
 #include "gettext.hpp"
@@ -52,6 +53,8 @@ label::label(const implementation::builder_label& builder)
 {
 	connect_signal<event::LEFT_BUTTON_CLICK>(std::bind(&label::signal_handler_left_button_click, this, std::placeholders::_2, std::placeholders::_3));
 	connect_signal<event::RIGHT_BUTTON_CLICK>(std::bind(&label::signal_handler_right_button_click, this, std::placeholders::_2, std::placeholders::_3));
+	connect_signal<event::MOUSE_MOTION>(std::bind(&label::signal_handler_mouse_motion, this, std::placeholders::_2, std::placeholders::_3, std::placeholders::_5));
+	connect_signal<event::MOUSE_LEAVE>(std::bind(&label::signal_handler_mouse_leave, this, std::placeholders::_2, std::placeholders::_3));
 }
 
 bool label::can_wrap() const
@@ -205,6 +208,51 @@ void label::signal_handler_right_button_click(const event::ui_event /* event */,
 	handled = true;
 }
 
+void label::signal_handler_mouse_motion(const event::ui_event /* event */, bool& handled, const point& coordinate)
+{
+	DBG_GUI_E << "label mouse motion" << std::endl;
+
+	if(!get_link_aware()) {
+		return; // without marking event as "handled"
+	}
+
+	point mouse = coordinate;
+
+	mouse.x -= get_x();
+	mouse.y -= get_y();
+
+	update_mouse_cursor(!get_label_link(mouse).empty());
+
+	handled = true;
+}
+
+void label::signal_handler_mouse_leave(const event::ui_event /*event*/, bool& handled)
+{
+	DBG_GUI_E << "label mouse leave" << std::endl;
+
+	if(!get_link_aware()) {
+		return; // without marking event as "handled"
+	}
+
+	// We left the widget, so just unconditionally reset the cursor
+	update_mouse_cursor(false);
+
+	handled = true;
+}
+
+void label::update_mouse_cursor(bool enable)
+{
+	// Someone else may set the mouse cursor for us to something unusual (e.g.
+	// the WAIT cursor) so we ought to mess with that only if it's set to
+	// NORMAL or HYPERLINK.
+
+	if(enable && cursor::get() == cursor::NORMAL) {
+		cursor::set(cursor::HYPERLINK);
+	} else if(!enable && cursor::get() == cursor::HYPERLINK) {
+		cursor::set(cursor::NORMAL);
+	}
+}
+
 // }---------- DEFINITION ---------{
 
 label_definition::label_definition(const config& cfg)

src/gui/widgets/label.hpp

@@ -60,6 +60,12 @@ public:
 	/** See @ref widget::disable_click_dismiss. */
 	bool disable_click_dismiss() const override;
 
+	/** See @ref widget::can_mouse_focus. */
+	virtual bool can_mouse_focus() const override
+	{
+		return !tooltip().empty() || get_link_aware();
+	}
+
 	/***** ***** ***** setters / getters for members ***** ****** *****/
 
 	void set_can_wrap(const bool wrap)
@@ -73,8 +79,6 @@ public:
 
 	void set_link_color(const color_t& color);
 
-	virtual bool can_mouse_focus() const override { return !tooltip().empty(); }
-
 	void set_can_shrink(bool can_shrink)
 	{
 		can_shrink_ = can_shrink;
@@ -153,6 +157,21 @@ private:
 	 * Right click signal handler: checks if we clicked on a hyperlink, copied to clipboard
 	 */
 	void signal_handler_right_button_click(const event::ui_event event, bool & handled);
+
+	/**
+	 * Mouse motion signal handler: checks if the cursor is on a hyperlink
+	 */
+	void signal_handler_mouse_motion(const event::ui_event event, bool& handled, const point& coordinate);
+
+	/**
+	 * Mouse leave signal handler: checks if the cursor left a hyperlink
+	 */
+	void signal_handler_mouse_leave(const event::ui_event event, bool& handled);
+
+	/**
+	 * Implementation detail for (re)setting the hyperlink cursor.
+	 */
+	void update_mouse_cursor(bool enable);
 };
 
 // }---------- DEFINITION ---------{