LibWeb: Handle scrolling an OutOfProcessWebView

When a mousewheel scroll event isn't handled by the web content
itself (e.g. an overflowed box or similar), the event needs to get
passed back up to the OutOfProcessWebView.

Userland/Libraries/LibWeb/OutOfProcessWebView.cpp

@@ -245,6 +245,11 @@ void OutOfProcessWebView::notify_server_did_change_title(Badge<WebContentClient>
         on_title_change(title);
 }
 
+void OutOfProcessWebView::notify_server_did_request_scroll(Badge<WebContentClient>, int wheel_delta)
+{
+    vertical_scrollbar().set_value(vertical_scrollbar().value() + wheel_delta * 20);
+}
+
 void OutOfProcessWebView::notify_server_did_request_scroll_into_view(Badge<WebContentClient>, const Gfx::IntRect& rect)
 {
     scroll_into_view(rect, true, true);

Userland/Libraries/LibWeb/OutOfProcessWebView.h

@@ -60,6 +60,7 @@ public:
     void notify_server_did_change_selection(Badge<WebContentClient>);
     void notify_server_did_request_cursor_change(Badge<WebContentClient>, Gfx::StandardCursor cursor);
     void notify_server_did_change_title(Badge<WebContentClient>, const String&);
+    void notify_server_did_request_scroll(Badge<WebContentClient>, int);
     void notify_server_did_request_scroll_into_view(Badge<WebContentClient>, const Gfx::IntRect&);
     void notify_server_did_hover_link(Badge<WebContentClient>, const URL&);
     void notify_server_did_unhover_link(Badge<WebContentClient>);

Userland/Libraries/LibWeb/Page/EventHandler.cpp

@@ -141,6 +141,10 @@ bool EventHandler::handle_mousewheel(const Gfx::IntPoint& position, unsigned int
     if (result.layout_node) {
         if (result.layout_node->handle_mousewheel({}, position, buttons, modifiers, wheel_delta))
             return true;
+    }
+
+    if (auto* page = m_frame.page()) {
+        page->client().page_did_request_scroll(wheel_delta);
         return true;
     }
 

Userland/Libraries/LibWeb/Page/Page.h

@@ -104,6 +104,7 @@ public:
     virtual void page_did_invalidate(const Gfx::IntRect&) { }
     virtual void page_did_change_favicon(const Gfx::Bitmap&) { }
     virtual void page_did_layout() { }
+    virtual void page_did_request_scroll(int) { }
     virtual void page_did_request_scroll_into_view(const Gfx::IntRect&) { }
     virtual void page_did_request_alert(const String&) { }
     virtual bool page_did_request_confirm(const String&) { return false; }

Userland/Libraries/LibWeb/WebContentClient.cpp

@@ -95,6 +95,11 @@ void WebContentClient::handle(const Messages::WebContentClient::DidChangeTitle&
     m_view.notify_server_did_change_title({}, message.title());
 }
 
+void WebContentClient::handle(const Messages::WebContentClient::DidRequestScroll& message)
+{
+    m_view.notify_server_did_request_scroll({}, message.wheel_delta());
+}
+
 void WebContentClient::handle(const Messages::WebContentClient::DidRequestScrollIntoView& message)
 {
     dbgln_if(SPAM_DEBUG, "handle: WebContentClient::DidRequestScrollIntoView! rect={}", message.rect());

Userland/Libraries/LibWeb/WebContentClient.h

@@ -57,6 +57,7 @@ private:
     virtual void handle(const Messages::WebContentClient::DidRequestCursorChange&) override;
     virtual void handle(const Messages::WebContentClient::DidLayout&) override;
     virtual void handle(const Messages::WebContentClient::DidChangeTitle&) override;
+    virtual void handle(const Messages::WebContentClient::DidRequestScroll&) override;
     virtual void handle(const Messages::WebContentClient::DidRequestScrollIntoView&) override;
     virtual void handle(const Messages::WebContentClient::DidHoverLink&) override;
     virtual void handle(const Messages::WebContentClient::DidUnhoverLink&) override;

Userland/Services/WebContent/PageHost.cpp

@@ -131,6 +131,11 @@ void PageHost::page_did_change_title(const String& title)
     m_client.post_message(Messages::WebContentClient::DidChangeTitle(title));
 }
 
+void PageHost::page_did_request_scroll(int wheel_delta)
+{
+    m_client.post_message(Messages::WebContentClient::DidRequestScroll(wheel_delta));
+}
+
 void PageHost::page_did_request_scroll_into_view(const Gfx::IntRect& rect)
 {
     m_client.post_message(Messages::WebContentClient::DidRequestScrollIntoView(rect));

Userland/Services/WebContent/PageHost.h

@@ -59,6 +59,7 @@ private:
     virtual void page_did_request_cursor_change(Gfx::StandardCursor) override;
     virtual void page_did_layout() override;
     virtual void page_did_change_title(const String&) override;
+    virtual void page_did_request_scroll(int) override;
     virtual void page_did_request_scroll_into_view(const Gfx::IntRect&) override;
     virtual void page_did_hover_link(const URL&) override;
     virtual void page_did_unhover_link() override;

Userland/Services/WebContent/WebContentClient.ipc

@@ -8,6 +8,7 @@ endpoint WebContentClient = 90
     DidRequestCursorChange(i32 cursor_type) =|
     DidLayout(Gfx::IntSize content_size) =|
     DidChangeTitle(String title) =|
+    DidRequestScroll(int wheel_delta) =|
     DidRequestScrollIntoView(Gfx::IntRect rect) =|
     DidHoverLink(URL url) =|
     DidUnhoverLink() =|