LibWeb+UI: Add an explicit IPC to handle mouse leave events

The faux position we created here is adjusted by the device pixel ratio
later on, which would invoke integer overflow on screens with a DPR
greater than 1.

Instead of creating special data for a mouse move event, let's just add
an explicit leave event handler.

Author: trflynn89

Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp

@@ -279,6 +279,8 @@ void EventLoop::process_input_events() const
                         return page.handle_mouseup(mouse_event.position, mouse_event.screen_position, mouse_event.button, mouse_event.buttons, mouse_event.modifiers);
                     case MouseEvent::Type::MouseMove:
                         return page.handle_mousemove(mouse_event.position, mouse_event.screen_position, mouse_event.buttons, mouse_event.modifiers);
+                    case MouseEvent::Type::MouseLeave:
+                        return page.handle_mouseleave();
                     case MouseEvent::Type::MouseWheel:
                         return page.handle_mousewheel(mouse_event.position, mouse_event.screen_position, mouse_event.button, mouse_event.buttons, mouse_event.modifiers, mouse_event.wheel_delta_x, mouse_event.wheel_delta_y);
                     case MouseEvent::Type::DoubleClick:

Libraries/LibWeb/Page/EventHandler.cpp

@@ -861,6 +861,44 @@ EventResult EventHandler::handle_mousemove(CSSPixelPoint viewport_position, CSSP
     return EventResult::Handled;
 }
 
+EventResult EventHandler::handle_mouseleave()
+{
+    if (should_ignore_device_input_event())
+        return EventResult::Dropped;
+
+    if (!m_navigable->active_document())
+        return EventResult::Dropped;
+    if (!m_navigable->active_document()->is_fully_active())
+        return EventResult::Dropped;
+
+    m_navigable->active_document()->update_layout(DOM::UpdateLayoutReason::EventHandlerHandleMouseMove);
+
+    if (!paint_root())
+        return EventResult::Dropped;
+
+    auto& document = *m_navigable->active_document();
+    auto& page = m_navigable->page();
+
+    if (auto* hovered_node = document.hovered_node()) {
+        if (auto* paintable = hovered_node->paintable(); paintable && paintable->wants_mouse_events())
+            paintable->handle_mouseleave({});
+
+        document.set_hovered_node(nullptr);
+    }
+
+    if (page.is_in_tooltip_area()) {
+        page.set_is_in_tooltip_area(false);
+        page.client().page_did_leave_tooltip_area();
+    }
+
+    if (page.is_hovering_link()) {
+        page.set_is_hovering_link(false);
+        page.client().page_did_unhover_link();
+    }
+
+    return EventResult::Handled;
+}
+
 EventResult EventHandler::handle_doubleclick(CSSPixelPoint viewport_position, CSSPixelPoint screen_position, u32 button, u32 buttons, u32 modifiers)
 {
     if (should_ignore_device_input_event())

Libraries/LibWeb/Page/EventHandler.h

@@ -29,6 +29,7 @@ class EventHandler {
     EventResult handle_mouseup(CSSPixelPoint, CSSPixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers);
     EventResult handle_mousedown(CSSPixelPoint, CSSPixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers);
     EventResult handle_mousemove(CSSPixelPoint, CSSPixelPoint screen_position, unsigned buttons, unsigned modifiers);
+    EventResult handle_mouseleave();
     EventResult handle_mousewheel(CSSPixelPoint, CSSPixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers, int wheel_delta_x, int wheel_delta_y);
     EventResult handle_doubleclick(CSSPixelPoint, CSSPixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers);
 

Libraries/LibWeb/Page/InputEvent.h

@@ -44,6 +44,7 @@ struct MouseEvent {
         MouseDown,
         MouseUp,
         MouseMove,
+        MouseLeave,
         MouseWheel,
         DoubleClick,
     };

Libraries/LibWeb/Page/Page.cpp

@@ -209,6 +209,11 @@ EventResult Page::handle_mousemove(DevicePixelPoint position, DevicePixelPoint s
     return top_level_traversable()->event_handler().handle_mousemove(device_to_css_point(position), device_to_css_point(screen_position), buttons, modifiers);
 }
 
+EventResult Page::handle_mouseleave()
+{
+    return top_level_traversable()->event_handler().handle_mouseleave();
+}
+
 EventResult Page::handle_mousewheel(DevicePixelPoint position, DevicePixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers, DevicePixels wheel_delta_x, DevicePixels wheel_delta_y)
 {
     return top_level_traversable()->event_handler().handle_mousewheel(device_to_css_point(position), device_to_css_point(screen_position), button, buttons, modifiers, wheel_delta_x.value(), wheel_delta_y.value());

Libraries/LibWeb/Page/Page.h

@@ -92,6 +92,7 @@ class Page final : public JS::Cell {
     EventResult handle_mouseup(DevicePixelPoint, DevicePixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers);
     EventResult handle_mousedown(DevicePixelPoint, DevicePixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers);
     EventResult handle_mousemove(DevicePixelPoint, DevicePixelPoint screen_position, unsigned buttons, unsigned modifiers);
+    EventResult handle_mouseleave();
     EventResult handle_mousewheel(DevicePixelPoint, DevicePixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers, DevicePixels wheel_delta_x, DevicePixels wheel_delta_y);
     EventResult handle_doubleclick(DevicePixelPoint, DevicePixelPoint screen_position, unsigned button, unsigned buttons, unsigned modifiers);
 

Libraries/LibWeb/Painting/Paintable.h

@@ -89,6 +89,7 @@ class Paintable
     virtual DispatchEventOfSameName handle_mousedown(Badge<EventHandler>, CSSPixelPoint, unsigned button, unsigned modifiers);
     virtual DispatchEventOfSameName handle_mouseup(Badge<EventHandler>, CSSPixelPoint, unsigned button, unsigned modifiers);
     virtual DispatchEventOfSameName handle_mousemove(Badge<EventHandler>, CSSPixelPoint, unsigned buttons, unsigned modifiers);
+    virtual void handle_mouseleave(Badge<EventHandler>) { }
 
     virtual bool handle_mousewheel(Badge<EventHandler>, CSSPixelPoint, unsigned buttons, unsigned modifiers, int wheel_delta_x, int wheel_delta_y);
 

Libraries/LibWeb/Painting/PaintableBox.cpp

@@ -979,6 +979,19 @@ Paintable::DispatchEventOfSameName PaintableBox::handle_mousemove(Badge<EventHan
     return Paintable::DispatchEventOfSameName::Yes;
 }
 
+void PaintableBox::handle_mouseleave(Badge<EventHandler>)
+{
+    auto previous_draw_enlarged_horizontal_scrollbar = m_draw_enlarged_horizontal_scrollbar;
+    m_draw_enlarged_horizontal_scrollbar = false;
+    if (previous_draw_enlarged_horizontal_scrollbar != m_draw_enlarged_horizontal_scrollbar)
+        set_needs_display();
+
+    auto previous_draw_enlarged_vertical_scrollbar = m_draw_enlarged_vertical_scrollbar;
+    m_draw_enlarged_vertical_scrollbar = false;
+    if (previous_draw_enlarged_vertical_scrollbar != m_draw_enlarged_vertical_scrollbar)
+        set_needs_display();
+}
+
 bool PaintableBox::scrollbar_contains_mouse_position(ScrollDirection direction, CSSPixelPoint position)
 {
     TemporaryChange force_enlarged_horizontal_scrollbar { m_draw_enlarged_horizontal_scrollbar, true };

Libraries/LibWeb/Painting/PaintableBox.h

@@ -301,6 +301,7 @@ class PaintableBox : public Paintable
     virtual DispatchEventOfSameName handle_mousedown(Badge<EventHandler>, CSSPixelPoint, unsigned button, unsigned modifiers) override;
     virtual DispatchEventOfSameName handle_mouseup(Badge<EventHandler>, CSSPixelPoint, unsigned button, unsigned modifiers) override;
     virtual DispatchEventOfSameName handle_mousemove(Badge<EventHandler>, CSSPixelPoint, unsigned buttons, unsigned modifiers) override;
+    virtual void handle_mouseleave(Badge<EventHandler>) override;
 
     bool scrollbar_contains_mouse_position(ScrollDirection, CSSPixelPoint);
     void scroll_to_mouse_position(CSSPixelPoint);

UI/AppKit/Interface/LadybirdWebView.mm

@@ -1576,9 +1576,7 @@ - (BOOL)isFlipped
 
 - (void)mouseExited:(NSEvent*)event
 {
-    static constexpr Web::DevicePixelPoint point { NumericLimits<Web::DevicePixels::Type>::max(), NumericLimits<Web::DevicePixels::Type>::max() };
-
-    Web::MouseEvent mouse_event { Web::MouseEvent::Type::MouseMove, point, point, Web::UIEvents::MouseButton::None, Web::UIEvents::MouseButton::None, Web::UIEvents::KeyModifier::Mod_None, 0, 0, nullptr };
+    Web::MouseEvent mouse_event { Web::MouseEvent::Type::MouseLeave, {}, {}, Web::UIEvents::MouseButton::None, Web::UIEvents::MouseButton::None, Web::UIEvents::KeyModifier::Mod_None, 0, 0, nullptr };
     m_web_view_bridge->enqueue_input_event(move(mouse_event));
 }