WebContent: Allow the WebContent process to trigger repaints

After layout, we may want to repaint the page, so we now listen for the
PageClient::page_did_invalidate() notification and use it to drive a
client-side repaint.

Note that an invalidation request from LibWeb makes a full roundtrip
to the WebContent client and back since the client drives painting.

Demos/WebView/WebContentClient.cpp

@@ -51,3 +51,11 @@ void WebContentClient::handle(const Messages::WebContentClient::DidFinishLoad& m
 {
     dbg() << "handle: WebContentClient::DidFinishLoad! url=" << message.url();
 }
+
+void WebContentClient::handle(const Messages::WebContentClient::DidInvalidateContentRect& message)
+{
+    dbg() << "handle: WebContentClient::DidInvalidateContentRect! content_rect=" << message.content_rect();
+
+    // FIXME: Figure out a way to coalesce these messages to reduce unnecessary painting
+    m_view.notify_server_did_invalidate_content_rect({}, message.content_rect());
+}

Demos/WebView/WebContentClient.h

@@ -46,6 +46,7 @@ private:
 
     virtual void handle(const Messages::WebContentClient::DidPaint&) override;
     virtual void handle(const Messages::WebContentClient::DidFinishLoad&) override;
+    virtual void handle(const Messages::WebContentClient::DidInvalidateContentRect&) override;
 
     WebContentView& m_view;
 };

Demos/WebView/WebContentView.cpp

@@ -69,6 +69,12 @@ void WebContentView::notify_server_did_paint(Badge<WebContentClient>, i32 shbuf_
         update();
 }
 
+void WebContentView::notify_server_did_invalidate_content_rect(Badge<WebContentClient>, const Gfx::IntRect& content_rect)
+{
+    dbg() << "server did invalidate content_rect: " << content_rect << ", current shbuf_id=" << m_bitmap->shbuf_id();
+    client().post_message(Messages::WebContentServer::Paint(m_bitmap->rect(), m_bitmap->shbuf_id()));
+}
+
 WebContentClient& WebContentView::client()
 {
     return *m_client;

Demos/WebView/WebContentView.h

@@ -39,6 +39,7 @@ public:
     void load(const URL&);
 
     void notify_server_did_paint(Badge<WebContentClient>, i32 shbuf_id);
+    void notify_server_did_invalidate_content_rect(Badge<WebContentClient>, const Gfx::IntRect&);
 
 private:
     WebContentView();

Services/WebContent/ClientConnection.cpp

@@ -38,7 +38,7 @@ static HashMap<int, RefPtr<ClientConnection>> s_connections;
 
 ClientConnection::ClientConnection(Core::LocalSocket& socket, int client_id)
     : IPC::ClientConnection<WebContentServerEndpoint>(*this, socket, client_id)
-    , m_page_host(PageHost::create())
+    , m_page_host(PageHost::create(*this))
 {
     s_connections.set(client_id, *this);
 }

Services/WebContent/PageHost.cpp

@@ -25,16 +25,19 @@
  */
 
 #include "PageHost.h"
+#include "ClientConnection.h"
 #include <AK/SharedBuffer.h>
 #include <LibGfx/Painter.h>
 #include <LibGfx/SystemTheme.h>
 #include <LibWeb/Frame/Frame.h>
 #include <LibWeb/Layout/LayoutDocument.h>
+#include <WebContent/WebContentClientEndpoint.h>
 
 namespace WebContent {
 
-PageHost::PageHost()
-    : m_page(make<Web::Page>(*this))
+PageHost::PageHost(ClientConnection& client)
+    : m_client(client)
+    , m_page(make<Web::Page>(*this))
 {
     setup_palette();
 }
@@ -96,4 +99,9 @@ void PageHost::set_viewport_rect(const Gfx::IntRect& rect)
     page().main_frame().set_viewport_rect(rect);
 }
 
+void PageHost::page_did_invalidate(const Gfx::IntRect& content_rect)
+{
+    m_client.post_message(Messages::WebContentClient::DidInvalidateContentRect(content_rect));
+}
+
 }

Services/WebContent/PageHost.h

@@ -30,12 +30,14 @@
 
 namespace WebContent {
 
+class ClientConnection;
+
 class PageHost : public Web::PageClient {
     AK_MAKE_NONCOPYABLE(PageHost);
     AK_MAKE_NONMOVABLE(PageHost);
 
 public:
-    static NonnullOwnPtr<PageHost> create() { return adopt_own(*new PageHost); }
+    static NonnullOwnPtr<PageHost> create(ClientConnection& client) { return adopt_own(*new PageHost(client)); }
     virtual ~PageHost();
 
     Web::Page& page() { return *m_page; }
@@ -47,11 +49,15 @@ public:
     void set_viewport_rect(const Gfx::IntRect&);
 
 private:
-    PageHost();
+    // ^PageHost
+    virtual void page_did_invalidate(const Gfx::IntRect&) override;
+
+    explicit PageHost(ClientConnection&);
 
     Gfx::Palette palette() const;
     void setup_palette();
 
+    ClientConnection& m_client;
     NonnullOwnPtr<Web::Page> m_page;
     RefPtr<Gfx::PaletteImpl> m_palette_impl;
 };

Services/WebContent/WebContentClient.ipc

@@ -1,6 +1,6 @@
 endpoint WebContentClient = 90
 {
     DidFinishLoad(URL url) =|
-
     DidPaint(Gfx::IntRect content_rect, i32 shbuf_id) =|
+    DidInvalidateContentRect(Gfx::IntRect content_rect) =|
 }