LibGUI+WindowServer: Add support for GWidget tooltips.

Any GWidget can have a tooltip and it will automatically pop up below the
center of the widget when hovered. GActions added to GToolBars will use
the action text() as their tooltip automagically. :^)

LibGUI/GApplication.cpp

@@ -2,6 +2,10 @@
 #include <LibGUI/GEventLoop.h>
 #include <LibGUI/GMenuBar.h>
 #include <LibGUI/GAction.h>
+#include <LibGUI/GWindow.h>
+#include <LibGUI/GLabel.h>
+#include <LibGUI/GPainter.h>
+#include <WindowServer/WSAPITypes.h>
 
 static GApplication* s_the;
 
@@ -65,3 +69,46 @@ GAction* GApplication::action_for_key_event(const GKeyEvent& event)
         return nullptr;
     return (*it).value;
 }
+
+class GApplication::TooltipWindow final : public GWindow {
+public:
+    TooltipWindow()
+    {
+        set_title("Tooltip");
+        set_window_type(GWindowType::Tooltip);
+        m_label = new GLabel;
+        m_label->set_background_color(Color::from_rgb(0xdac7b5));
+        m_label->set_fill_with_background_color(true);
+        m_label->set_frame_thickness(1);
+        m_label->set_frame_shape(GFrame::Shape::Container);
+        m_label->set_frame_shadow(GFrame::Shadow::Plain);
+        set_main_widget(m_label);
+    }
+
+    void set_tooltip(const String& tooltip)
+    {
+        // FIXME: Add some kind of GLabel auto-sizing feature.
+        int text_width = m_label->font().width(tooltip);
+        set_rect(100, 100, text_width + 10, m_label->font().glyph_height() + 8);
+        m_label->set_text(tooltip);
+    }
+
+    GLabel* m_label { nullptr };
+};
+
+void GApplication::show_tooltip(const String& tooltip, const Point& screen_location)
+{
+    if (!m_tooltip_window) {
+        m_tooltip_window = new TooltipWindow;
+        m_tooltip_window->set_double_buffering_enabled(false);
+    }
+    m_tooltip_window->set_tooltip(tooltip);
+    m_tooltip_window->move_to(screen_location);
+    m_tooltip_window->show();
+}
+
+void GApplication::hide_tooltip()
+{
+    if (m_tooltip_window)
+        m_tooltip_window->hide();
+}

LibGUI/GApplication.h

@@ -9,6 +9,7 @@ class GAction;
 class GKeyEvent;
 class GEventLoop;
 class GMenuBar;
+class Point;
 
 class GApplication {
 public:
@@ -25,8 +26,13 @@ public:
     void register_shortcut_action(Badge<GAction>, GAction&);
     void unregister_shortcut_action(Badge<GAction>, GAction&);
 
+    void show_tooltip(const String&, const Point& screen_location);
+    void hide_tooltip();
+
 private:
     OwnPtr<GEventLoop> m_event_loop;
     OwnPtr<GMenuBar> m_menubar;
     HashMap<GShortcut, GAction*> m_shortcut_actions;
+    class TooltipWindow;
+    TooltipWindow* m_tooltip_window { nullptr };
 };

LibGUI/GLabel.h

@@ -7,8 +7,8 @@ class GraphicsBitmap;
 
 class GLabel final : public GFrame {
 public:
-    explicit GLabel(GWidget* parent);
-    GLabel(const String& text, GWidget* parent);
+    explicit GLabel(GWidget* parent = nullptr);
+    GLabel(const String& text, GWidget* parent = nullptr);
     virtual ~GLabel() override;
 
     String text() const { return m_text; }

LibGUI/GToolBar.cpp

@@ -26,6 +26,7 @@ void GToolBar::add_action(Retained<GAction>&& action)
     item->action = move(action);
 
     auto* button = new GButton(this);
+    button->set_tooltip(item->action->text());
     if (item->action->icon())
         button->set_icon(item->action->icon());
     else

LibGUI/GWidget.cpp

@@ -6,6 +6,7 @@
 #include <AK/Assertions.h>
 #include <SharedGraphics/GraphicsBitmap.h>
 #include <LibGUI/GPainter.h>
+#include <LibGUI/GApplication.h>
 
 #include <unistd.h>
 
@@ -79,9 +80,9 @@ void GWidget::event(GEvent& event)
     case GEvent::MouseUp:
         return handle_mouseup_event(static_cast<GMouseEvent&>(event));
     case GEvent::Enter:
-        return enter_event(event);
+        return handle_enter_event(event);
     case GEvent::Leave:
-        return leave_event(event);
+        return handle_leave_event(event);
     default:
         return GObject::event(event);
     }
@@ -177,6 +178,19 @@ void GWidget::handle_mousedown_event(GMouseEvent& event)
     mousedown_event(event);
 }
 
+void GWidget::handle_enter_event(GEvent& event)
+{
+    if (has_tooltip())
+        GApplication::the().show_tooltip(m_tooltip, screen_relative_rect().center().translated(0, height() / 2));
+    enter_event(event);
+}
+
+void GWidget::handle_leave_event(GEvent& event)
+{
+    GApplication::the().hide_tooltip();
+    leave_event(event);
+}
+
 void GWidget::click_event(GMouseEvent&)
 {
 }
@@ -261,6 +275,11 @@ Rect GWidget::window_relative_rect() const
     return rect;
 }
 
+Rect GWidget::screen_relative_rect() const
+{
+    return window_relative_rect().translated(window()->position());
+}
+
 GWidget::HitTestResult GWidget::hit_test(int x, int y)
 {
     // FIXME: Care about z-order.

LibGUI/GWidget.h

@@ -34,6 +34,10 @@ public:
     Size preferred_size() const { return m_preferred_size; }
     void set_preferred_size(const Size&);
 
+    bool has_tooltip() const { return !m_tooltip.is_empty(); }
+    String tooltip() const { return m_tooltip; }
+    void set_tooltip(const String& tooltip) { m_tooltip = tooltip; }
+
     virtual void event(GEvent&) override;
     virtual void paint_event(GPaintEvent&);
     virtual void resize_event(GResizeEvent&);
@@ -56,6 +60,7 @@ public:
     Point relative_position() const { return m_relative_rect.location(); }
 
     Rect window_relative_rect() const;
+    Rect screen_relative_rect() const;
 
     int x() const { return m_relative_rect.x(); }
     int y() const { return m_relative_rect.y(); }
@@ -149,6 +154,8 @@ private:
     void handle_resize_event(GResizeEvent&);
     void handle_mousedown_event(GMouseEvent&);
     void handle_mouseup_event(GMouseEvent&);
+    void handle_enter_event(GEvent&);
+    void handle_leave_event(GEvent&);
     void do_layout();
 
     GWindow* m_window { nullptr };
@@ -158,6 +165,7 @@ private:
     Color m_background_color;
     Color m_foreground_color;
     RetainPtr<Font> m_font;
+    String m_tooltip;
 
     SizePolicy m_horizontal_size_policy { SizePolicy::Fill };
     SizePolicy m_vertical_size_policy { SizePolicy::Fill };

LibGUI/GWindow.cpp

@@ -83,7 +83,11 @@ void GWindow::hide()
     WSAPI_ClientMessage request;
     request.type = WSAPI_ClientMessage::Type::DestroyWindow;
     request.window_id = m_window_id;
-    GEventLoop::current().post_message_to_server(request);
+    GEventLoop::current().sync_request(request, WSAPI_ServerMessage::Type::DidDestroyWindow);
+    m_window_id = 0;
+    m_pending_paint_event_rects.clear();
+    m_back_bitmap = nullptr;
+    m_front_bitmap = nullptr;
 }
 
 void GWindow::set_title(const String& title)
@@ -139,6 +143,8 @@ void GWindow::set_rect(const Rect& a_rect)
     request.window_id = m_window_id;
     request.window.rect = a_rect;
     GEventLoop::current().post_message_to_server(request);
+    if (m_main_widget)
+        m_main_widget->resize(a_rect.size());
 }
 
 void GWindow::set_window_type(GWindowType window_type)
@@ -193,6 +199,8 @@ void GWindow::event(GEvent& event)
     }
 
     if (event.is_paint_event()) {
+        if (!m_window_id)
+            return;
         m_pending_paint_event_rects.clear();
         if (!m_main_widget)
             return;

LibGUI/GWindowType.h

@@ -6,4 +6,5 @@ enum class GWindowType {
     Menu,
     WindowSwitcher,
     Taskbar,
+    Tooltip,
 };