WindowServer: Support PNG wallpapers.

Fix up /bin/pape so it tells the WindowServer which wallpaper file to use.

LibGUI/GDesktop.cpp

@@ -0,0 +1,34 @@
+#include <LibGUI/GDesktop.h>
+#include <LibGUI/GEventLoop.h>
+#include <string.h>
+
+GDesktop& GDesktop::the()
+{
+    static GDesktop* s_the;
+    if (!s_the)
+        s_the = new GDesktop;
+    return *s_the;
+}
+
+GDesktop::GDesktop()
+{
+}
+
+bool GDesktop::set_wallpaper(const String& path)
+{
+    WSAPI_ClientMessage message;
+    message.type = WSAPI_ClientMessage::Type::SetWallpaper;
+    ASSERT(path.length() < (int)sizeof(message.text));
+    strncpy(message.text, path.characters(), path.length());
+    message.text_length = path.length();
+    auto response = GEventLoop::current().sync_request(message, WSAPI_ServerMessage::Type::DidSetWallpaper);
+    return response.value;
+}
+
+String GDesktop::wallpaper() const
+{
+    WSAPI_ClientMessage message;
+    message.type = WSAPI_ClientMessage::Type::GetWallpaper;
+    auto response = GEventLoop::current().sync_request(message, WSAPI_ServerMessage::Type::DidGetWallpaper);
+    return String(response.text, response.text_length);
+}

LibGUI/GDesktop.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <AK/AKString.h>
+#include <SharedGraphics/Rect.h>
+
+class GDesktop {
+public:
+    static GDesktop& the();
+
+    String wallpaper() const;
+    bool set_wallpaper(const String& path);
+
+private:
+    GDesktop();
+
+    Rect m_rect;
+};

LibGUI/GEventLoop.h

@@ -35,7 +35,7 @@ public:
 
     void quit(int);
 
-    bool post_message_to_server(const WSAPI_ClientMessage&);
+    static bool post_message_to_server(const WSAPI_ClientMessage&);
     bool wait_for_specific_event(WSAPI_ServerMessage::Type, WSAPI_ServerMessage&);
 
     WSAPI_ServerMessage sync_request(const WSAPI_ClientMessage& request, WSAPI_ServerMessage::Type response_type);

LibGUI/Makefile

@@ -46,6 +46,7 @@ LIBGUI_OBJS = \
     GMessageBox.o \
     GInputBox.o \
     GDialog.o \
+    GDesktop.o \
     GWindow.o
 
 OBJS = $(SHAREDGRAPHICS_OBJS) $(LIBGUI_OBJS)