WebContent: Basic scrolling support! :^)

The WebContentView widget now inherits from GUI::ScrollableWidget and
will pass its scroll offset over to the WebContent process as it's
changing. This is not super efficient and can get a bit laggy, but it
will do fine as an initial scrolling implementation.

Just like the single-process Web::PageView widget, WebContentView also
paints scrolled content by translating the Gfx::Painter.

4 files changed, 31 insertions, 4 deletions

diff --git a/Demos/WebView/WebContentClient.cpp b/Demos/WebView/WebContentClient.cpp
index 03a6d3497f..2083fec29c 100644
--- a/Demos/WebView/WebContentClient.cpp
+++ b/Demos/WebView/WebContentClient.cpp
@@ -74,3 +74,11 @@ void WebContentClient::handle(const Messages::WebContentClient::DidChangeSelecti
 #endif
     m_view.notify_server_did_change_selection({});
 }
+
+void WebContentClient::handle(const Messages::WebContentClient::DidLayout& message)
+{
+#ifdef DEBUG_SPAM
+    dbg() << "handle: WebContentClient::DidLayout! content_size=" << message.content_size();
+#endif
+    m_view.notify_server_did_layout({}, message.content_size());
+}
diff --git a/Demos/WebView/WebContentClient.h b/Demos/WebView/WebContentClient.h
index 2e0e6f5358..1a8f4651e8 100644
--- a/Demos/WebView/WebContentClient.h
+++ b/Demos/WebView/WebContentClient.h
@@ -48,6 +48,7 @@ private:
     virtual void handle(const Messages::WebContentClient::DidFinishLoad&) override;
     virtual void handle(const Messages::WebContentClient::DidInvalidateContentRect&) override;
     virtual void handle(const Messages::WebContentClient::DidChangeSelection&) override;
+    virtual void handle(const Messages::WebContentClient::DidLayout&) override;
 
     WebContentView& m_view;
 };
diff --git a/Demos/WebView/WebContentView.cpp b/Demos/WebView/WebContentView.cpp
index 46a5b18e16..e48bd64bc2 100644
--- a/Demos/WebView/WebContentView.cpp
+++ b/Demos/WebView/WebContentView.cpp
@@ -28,6 +28,7 @@
 #include "WebContentClient.h"
 #include <AK/SharedBuffer.h>
 #include <LibGUI/Painter.h>
+#include <LibGUI/ScrollBar.h>
 #include <LibGfx/SystemTheme.h>
 
 WebContentView::WebContentView()
@@ -59,8 +60,8 @@ void WebContentView::resize_event(GUI::ResizeEvent& event)
     auto bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGB32, event.size());
     m_bitmap = bitmap->to_bitmap_backed_by_shared_buffer();
     m_bitmap->shared_buffer()->share_with(client().server_pid());
-    client().post_message(Messages::WebContentServer::SetViewportRect(Gfx::IntRect({ 0, 0 }, event.size())));
-    client().post_message(Messages::WebContentServer::Paint(m_bitmap->rect(), m_bitmap->shbuf_id()));
+    client().post_message(Messages::WebContentServer::SetViewportRect(Gfx::IntRect({ horizontal_scrollbar().value(), vertical_scrollbar().value() }, event.size())));
+    request_repaint();
 }
 
 void WebContentView::mousedown_event(GUI::MouseEvent& event)
@@ -97,9 +98,20 @@ void WebContentView::notify_server_did_change_selection(Badge<WebContentClient>)
     request_repaint();
 }
 
+void WebContentView::notify_server_did_layout(Badge<WebContentClient>, const Gfx::IntSize& content_size)
+{
+    set_content_size(content_size);
+}
+
+void WebContentView::did_scroll()
+{
+    client().post_message(Messages::WebContentServer::SetViewportRect(Gfx::IntRect({ horizontal_scrollbar().value(), vertical_scrollbar().value() }, size())));
+    request_repaint();
+}
+
 void WebContentView::request_repaint()
 {
-    client().post_message(Messages::WebContentServer::Paint(m_bitmap->rect(), m_bitmap->shbuf_id()));
+    client().post_message(Messages::WebContentServer::Paint(m_bitmap->rect().translated(horizontal_scrollbar().value(), vertical_scrollbar().value()), m_bitmap->shbuf_id()));
 }
 
 WebContentClient& WebContentView::client()
diff --git a/Demos/WebView/WebContentView.h b/Demos/WebView/WebContentView.h
index 64734e1c4f..02be9b4017 100644
--- a/Demos/WebView/WebContentView.h
+++ b/Demos/WebView/WebContentView.h
@@ -26,11 +26,12 @@
 
 #pragma once
 
+#include <LibGUI/ScrollableWidget.h>
 #include <LibGUI/Widget.h>
 
 class WebContentClient;
 
-class WebContentView final : public GUI::Widget {
+class WebContentView final : public GUI::ScrollableWidget {
     C_OBJECT(WebContentView);
 
 public:
@@ -38,6 +39,7 @@ public:
 
     void load(const URL&);
 
+    void notify_server_did_layout(Badge<WebContentClient>, const Gfx::IntSize& content_size);
     void notify_server_did_paint(Badge<WebContentClient>, i32 shbuf_id);
     void notify_server_did_invalidate_content_rect(Badge<WebContentClient>, const Gfx::IntRect&);
     void notify_server_did_change_selection(Badge<WebContentClient>);
@@ -45,12 +47,16 @@ public:
 private:
     WebContentView();
 
+    // ^Widget
     virtual void paint_event(GUI::PaintEvent&) override;
     virtual void resize_event(GUI::ResizeEvent&) override;
     virtual void mousedown_event(GUI::MouseEvent&) override;
     virtual void mouseup_event(GUI::MouseEvent&) override;
     virtual void mousemove_event(GUI::MouseEvent&) override;
 
+    // ^ScrollableWidget
+    virtual void did_scroll() override;
+
     void request_repaint();
 
     WebContentClient& client();