WindowServer+LibGUI: Pass drag&drop bitmaps via Gfx::ShareableBitmap

This makes them backed by anonymous files instead of shbufs and also
simplifies the code significantly on both client and server side.

Userland/Libraries/LibGUI/DragOperation.cpp

@@ -51,22 +51,17 @@ DragOperation::Outcome DragOperation::exec()
     ASSERT(!m_event_loop);
     ASSERT(m_mime_data);
 
-    int bitmap_id = -1;
-    Gfx::IntSize bitmap_size;
-    RefPtr<Gfx::Bitmap> shared_bitmap;
+    Gfx::ShareableBitmap drag_bitmap;
     if (m_mime_data->has_format("image/x-raw-bitmap")) {
         auto data = m_mime_data->data("image/x-raw-bitmap");
         auto bitmap = Gfx::Bitmap::create_from_serialized_byte_buffer(move(data));
-        shared_bitmap = bitmap->to_bitmap_backed_by_shared_buffer();
-        shared_bitmap->shared_buffer()->share_with(WindowServerConnection::the().server_pid());
-        bitmap_id = shared_bitmap->shbuf_id();
-        bitmap_size = shared_bitmap->size();
+        drag_bitmap = bitmap->to_shareable_bitmap();
     }
 
     auto response = WindowServerConnection::the().send_sync<Messages::WindowServer::StartDrag>(
         m_mime_data->text(),
         m_mime_data->all_data(),
-        bitmap_id, bitmap_size);
+        drag_bitmap);
 
     if (!response->started()) {
         m_outcome = Outcome::Cancelled;

Userland/Services/WindowServer/ClientConnection.cpp

@@ -747,18 +747,7 @@ OwnPtr<Messages::WindowServer::StartDragResponse> ClientConnection::handle(const
     if (wm.dnd_client())
         return make<Messages::WindowServer::StartDragResponse>(false);
 
-    RefPtr<Gfx::Bitmap> bitmap;
-    if (message.bitmap_id() != -1) {
-        auto shared_buffer = SharedBuffer::create_from_shbuf_id(message.bitmap_id());
-        ssize_t size_in_bytes = message.bitmap_size().area() * sizeof(Gfx::RGBA32);
-        if (size_in_bytes > shared_buffer->size()) {
-            did_misbehave("SetAppletBackingStore: Shared buffer is too small for applet size");
-            return {};
-        }
-        bitmap = Gfx::Bitmap::create_with_shared_buffer(Gfx::BitmapFormat::RGBA32, *shared_buffer, message.bitmap_size());
-    }
-
-    wm.start_dnd_drag(*this, message.text(), bitmap, Core::MimeData::construct(message.mime_data()));
+    wm.start_dnd_drag(*this, message.text(), message.drag_bitmap().bitmap(), Core::MimeData::construct(message.mime_data()));
     return make<Messages::WindowServer::StartDragResponse>(true);
 }
 

Userland/Services/WindowServer/WindowManager.cpp

@@ -1383,7 +1383,7 @@ Gfx::IntRect WindowManager::maximized_window_rect(const Window& window) const
     return rect;
 }
 
-void WindowManager::start_dnd_drag(ClientConnection& client, const String& text, Gfx::Bitmap* bitmap, const Core::MimeData& mime_data)
+void WindowManager::start_dnd_drag(ClientConnection& client, const String& text, const Gfx::Bitmap* bitmap, const Core::MimeData& mime_data)
 {
     ASSERT(!m_dnd_client);
     m_dnd_client = client;

Userland/Services/WindowServer/WindowManager.h

@@ -104,7 +104,7 @@ public:
     const Gfx::Bitmap* dnd_bitmap() const { return m_dnd_bitmap; }
     Gfx::IntRect dnd_rect() const;
 
-    void start_dnd_drag(ClientConnection&, const String& text, Gfx::Bitmap*, const Core::MimeData&);
+    void start_dnd_drag(ClientConnection&, const String& text, const Gfx::Bitmap*, const Core::MimeData&);
     void end_dnd_drag();
 
     Window* active_window() { return m_active_window.ptr(); }

Userland/Services/WindowServer/WindowServer.ipc

@@ -94,7 +94,7 @@ endpoint WindowServer = 2
     SetWindowCursor(i32 window_id, i32 cursor_type) => ()
     SetWindowCustomCursor(i32 window_id, Gfx::ShareableBitmap cursor) => ()
 
-    StartDrag([UTF8] String text, HashMap<String,ByteBuffer> mime_data, i32 bitmap_id, Gfx::IntSize bitmap_size) => (bool started)
+    StartDrag([UTF8] String text, HashMap<String,ByteBuffer> mime_data, Gfx::ShareableBitmap drag_bitmap) => (bool started)
 
     SetSystemTheme(String theme_path, [UTF8] String theme_name) => (bool success)
     GetSystemTheme() => ([UTF8] String theme_name)