LibWeb: Bring MouseEvent a bit closer to spec

Userland/Libraries/LibWeb/DOM/Document.cpp

@@ -980,7 +980,7 @@ NonnullRefPtr<Event> Document::create_event(String const& interface)
     } else if (interface_lowercase == "messageevent") {
         event = HTML::MessageEvent::create("");
     } else if (interface_lowercase.is_one_of("mouseevent", "mouseevents")) {
-        event = UIEvents::MouseEvent::create("", 0, 0, 0, 0);
+        event = UIEvents::MouseEvent::create("");
     } else if (interface_lowercase == "storageevent") {
         event = Event::create(""); // FIXME: Create StorageEvent
     } else if (interface_lowercase == "svgevents") {

Userland/Libraries/LibWeb/HTML/HTMLElement.cpp

@@ -395,7 +395,7 @@ bool HTMLElement::fire_a_synthetic_pointer_event(FlyString const& type, DOM::Ele
     // 1. Let event be the result of creating an event using PointerEvent.
     // 2. Initialize event's type attribute to e.
     // FIXME: Actually create a PointerEvent!
-    auto event = UIEvents::MouseEvent::create(type, 0.0, 0.0, 0.0, 0.0);
+    auto event = UIEvents::MouseEvent::create(type);
 
     // 3. Initialize event's bubbles and cancelable attributes to true.
     event->set_bubbles(true);

Userland/Libraries/LibWeb/Page/EventHandler.cpp

@@ -191,12 +191,12 @@ bool EventHandler::handle_mouseup(Gfx::IntPoint const& position, unsigned button
                 return false;
             }
             auto offset = compute_mouse_event_offset(position, paintable->layout_node());
-            node->dispatch_event(UIEvents::MouseEvent::create(UIEvents::EventNames::mouseup, offset.x(), offset.y(), position.x(), position.y()));
+            node->dispatch_event(UIEvents::MouseEvent::create_from_platform_event(UIEvents::EventNames::mouseup, offset.x(), offset.y(), position.x(), position.y(), button));
             handled_event = true;
 
             bool run_activation_behavior = true;
             if (node.ptr() == m_mousedown_target && button == GUI::MouseButton::Primary) {
-                run_activation_behavior = node->dispatch_event(UIEvents::MouseEvent::create(UIEvents::EventNames::click, offset.x(), offset.y(), position.x(), position.y()));
+                run_activation_behavior = node->dispatch_event(UIEvents::MouseEvent::create_from_platform_event(UIEvents::EventNames::click, offset.x(), offset.y(), position.x(), position.y(), button));
             }
 
             if (run_activation_behavior) {
@@ -308,7 +308,7 @@ bool EventHandler::handle_mousedown(Gfx::IntPoint const& position, unsigned butt
 
         m_mousedown_target = node;
         auto offset = compute_mouse_event_offset(position, paintable->layout_node());
-        node->dispatch_event(UIEvents::MouseEvent::create(UIEvents::EventNames::mousedown, offset.x(), offset.y(), position.x(), position.y()));
+        node->dispatch_event(UIEvents::MouseEvent::create_from_platform_event(UIEvents::EventNames::mousedown, offset.x(), offset.y(), position.x(), position.y(), button));
     }
 
     // NOTE: Dispatching an event may have disturbed the world.
@@ -416,7 +416,7 @@ bool EventHandler::handle_mousemove(Gfx::IntPoint const& position, unsigned butt
             }
 
             auto offset = compute_mouse_event_offset(position, paintable->layout_node());
-            node->dispatch_event(UIEvents::MouseEvent::create(UIEvents::EventNames::mousemove, offset.x(), offset.y(), position.x(), position.y()));
+            node->dispatch_event(UIEvents::MouseEvent::create_from_platform_event(UIEvents::EventNames::mousemove, offset.x(), offset.y(), position.x(), position.y()));
             // NOTE: Dispatching an event may have disturbed the world.
             if (!paint_root() || paint_root() != node->document().paint_box())
                 return true;

Userland/Libraries/LibWeb/UIEvents/MouseEvent.cpp

@@ -4,23 +4,53 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibGUI/Event.h>
 #include <LibWeb/HTML/EventNames.h>
 #include <LibWeb/UIEvents/EventNames.h>
 #include <LibWeb/UIEvents/MouseEvent.h>
 
 namespace Web::UIEvents {
 
-MouseEvent::MouseEvent(FlyString const& event_name, double offset_x, double offset_y, double client_x, double client_y)
-    : UIEvent(event_name)
-    , m_offset_x(offset_x)
-    , m_offset_y(offset_y)
-    , m_client_x(client_x)
-    , m_client_y(client_y)
+MouseEvent::MouseEvent(FlyString const& event_name, MouseEventInit const& event_init)
+    : UIEvent(event_name, event_init)
+    , m_offset_x(event_init.offset_x)
+    , m_offset_y(event_init.offset_y)
+    , m_client_x(event_init.client_x)
+    , m_client_y(event_init.client_y)
+    , m_button(event_init.button)
 {
     set_event_characteristics();
 }
 
-MouseEvent::~MouseEvent() = default;
+// https://www.w3.org/TR/uievents/#dom-mouseevent-button
+static i16 determine_button(unsigned mouse_button)
+{
+    switch (mouse_button) {
+    case GUI::MouseButton::Primary:
+        return 0;
+    case GUI::MouseButton::Middle:
+        return 1;
+    case GUI::MouseButton::Secondary:
+        return 2;
+    case GUI::MouseButton::Backward:
+        return 3;
+    case GUI::MouseButton::Forward:
+        return 4;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+NonnullRefPtr<MouseEvent> MouseEvent::create_from_platform_event(FlyString const& event_name, double offset_x, double offset_y, double client_x, double client_y, unsigned mouse_button)
+{
+    MouseEventInit event_init {};
+    event_init.offset_x = offset_x;
+    event_init.offset_y = offset_y;
+    event_init.client_x = client_x;
+    event_init.client_y = client_y;
+    event_init.button = determine_button(mouse_button);
+    return MouseEvent::create(event_name, event_init);
+}
 
 void MouseEvent::set_event_characteristics()
 {

Userland/Libraries/LibWeb/UIEvents/MouseEvent.h

@@ -12,16 +12,27 @@
 
 namespace Web::UIEvents {
 
+struct MouseEventInit : public EventModifierInit {
+    double offset_x = 0;
+    double offset_y = 0;
+    double client_x = 0;
+    double client_y = 0;
+
+    i16 button = 0;
+};
+
 class MouseEvent final : public UIEvent {
 public:
     using WrapperType = Bindings::MouseEventWrapper;
 
-    static NonnullRefPtr<MouseEvent> create(FlyString const& event_name, double offset_x, double offset_y, double client_x, double client_y)
+    static NonnullRefPtr<MouseEvent> create(FlyString const& event_name, MouseEventInit const& event_init = {})
     {
-        return adopt_ref(*new MouseEvent(event_name, offset_x, offset_y, client_x, client_y));
+        return adopt_ref(*new MouseEvent(event_name, event_init));
     }
 
-    virtual ~MouseEvent() override;
+    static NonnullRefPtr<MouseEvent> create_from_platform_event(FlyString const& event_name, double offset_x, double offset_y, double client_x, double client_y, unsigned mouse_button = 1);
+
+    virtual ~MouseEvent() override = default;
 
     double offset_x() const { return m_offset_x; }
     double offset_y() const { return m_offset_y; }
@@ -32,16 +43,18 @@ public:
     double x() const { return client_x(); }
     double y() const { return client_y(); }
 
-protected:
-    MouseEvent(FlyString const& event_name, double offset_x, double offset_y, double client_x, double client_y);
+    i16 button() const { return m_button; }
 
 private:
+    MouseEvent(FlyString const& event_name, MouseEventInit const& event_init);
+
     void set_event_characteristics();
 
     double m_offset_x { 0 };
     double m_offset_y { 0 };
     double m_client_x { 0 };
     double m_client_y { 0 };
+    i16 m_button { 0 };
 };
 
 }

Userland/Libraries/LibWeb/UIEvents/MouseEvent.idl

@@ -7,4 +7,18 @@ interface MouseEvent : UIEvent {
     readonly attribute double x;
     readonly attribute double y;
 
+    readonly attribute short button;
+
 };
+
+dictionary MouseEventInit : EventModifierInit {
+
+    // FIXME: offsetX and offsetY shouldn't be here.
+    double offsetX = 0;
+    double offsetY = 0;
+    double clientX = 0;
+    double clientY = 0;
+
+    short button = 0;
+
+};