Basic DragImage implementation.

Only the chromium part is for review. The webkit part shows how that will look when I create the patch for webkit later. This can be landed without the change to webkit.

TODO later:
- use the image on windows, mac
- implement the other DragImageRef functions

TEST=drag an image from the render view in GTK
BUG=11457

Review URL: http://codereview.chromium.org/668125

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@41799 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 27 insertions, 3 deletions

diff --git a/chrome/browser/gtk/notifications/balloon_view_host_gtk.h b/chrome/browser/gtk/notifications/balloon_view_host_gtk.h
index 0c40864..4bcd5b4 100644
--- a/chrome/browser/gtk/notifications/balloon_view_host_gtk.h
+++ b/chrome/browser/gtk/notifications/balloon_view_host_gtk.h
@@ -79,7 +79,9 @@ class BalloonViewHost : public RenderViewHostDelegate,
                                  const gfx::Rect& initial_pos) {}
   virtual void ShowContextMenu(const ContextMenuParams& params) {}
   virtual void StartDragging(const WebDropData& drop_data,
-                             WebKit::WebDragOperationsMask allowed_ops) {}
+                             WebKit::WebDragOperationsMask allowed_ops,
+                             const SkBitmap& image,
+                             const gfx::Point& image_offset) {}
   virtual void UpdateDragCursor(WebKit::WebDragOperation operation) {}
   virtual void GotFocus() {}
   virtual void TakeFocus(bool reverse) {}
diff --git a/chrome/browser/gtk/tab_contents_drag_source.cc b/chrome/browser/gtk/tab_contents_drag_source.cc
index 85ebe0c..45f0f1f 100644
--- a/chrome/browser/gtk/tab_contents_drag_source.cc
+++ b/chrome/browser/gtk/tab_contents_drag_source.cc
@@ -6,6 +6,7 @@
 
 #include <string>
 
+#include "app/gfx/gtk_util.h"
 #include "app/gtk_dnd_util.h"
 #include "base/file_util.h"
 #include "base/mime_util.h"
@@ -69,7 +70,9 @@ TabContents* TabContentsDragSource::tab_contents() const {
 }
 
 void TabContentsDragSource::StartDragging(const WebDropData& drop_data,
-                                          GdkEventButton* last_mouse_down) {
+                                          GdkEventButton* last_mouse_down,
+                                          const SkBitmap& image,
+                                          const gfx::Point& image_offset) {
   int targets_mask = 0;
 
   if (!drop_data.plain_text.empty())
@@ -98,6 +101,8 @@ void TabContentsDragSource::StartDragging(const WebDropData& drop_data,
   }
 
   drop_data_.reset(new WebDropData(drop_data));
+  drag_image_ = image;
+  image_offset_ = image_offset;
 
   GtkTargetList* list = gtk_dnd_util::GetTargetListFromCodeMask(targets_mask);
   if (targets_mask & gtk_dnd_util::CHROME_WEBDROP_FILE_CONTENTS) {
@@ -303,6 +308,14 @@ void TabContentsDragSource::OnDragBegin(GdkDragContext* drag_context) {
                             generated_download_file_name.value().c_str()),
                         generated_download_file_name.value().length());
   }
+
+  if (!drag_image_.isNull()) {
+    GdkPixbuf* pixbuf = gfx::GdkPixbufFromSkBitmap(&drag_image_);
+    gtk_drag_set_icon_pixbuf(drag_context, pixbuf,
+                             image_offset_.x(), image_offset_.y());
+    // Let the drag take ownership.
+    g_object_unref(pixbuf);
+  }
 }
 
 void TabContentsDragSource::OnDragEnd(GdkDragContext* drag_context,
diff --git a/chrome/browser/gtk/tab_contents_drag_source.h b/chrome/browser/gtk/tab_contents_drag_source.h
index edef7ad..35693e9 100644
--- a/chrome/browser/gtk/tab_contents_drag_source.h
+++ b/chrome/browser/gtk/tab_contents_drag_source.h
@@ -10,9 +10,11 @@
 #include "app/gfx/native_widget_types.h"
 #include "base/basictypes.h"
 #include "base/file_path.h"
+#include "base/gfx/point.h"
 #include "base/message_loop.h"
 #include "base/string16.h"
 #include "googleurl/src/gurl.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebDragOperation.h"
 
 class TabContents;
@@ -31,7 +33,9 @@ class TabContentsDragSource : public MessageLoopForUI::Observer {
   // Starts a drag for the tab contents this TabContentsDragSource was
   // created for.
   void StartDragging(const WebDropData& drop_data,
-                     GdkEventButton* last_mouse_down);
+                     GdkEventButton* last_mouse_down,
+                     const SkBitmap& image,
+                     const gfx::Point& image_offset);
 
   // MessageLoop::Observer implementation:
   virtual void WillProcessEvent(GdkEvent* event);
@@ -79,6 +83,11 @@ class TabContentsDragSource : public MessageLoopForUI::Observer {
   // view). Non-NULL iff there is a current drag.
   scoped_ptr<WebDropData> drop_data_;
 
+  // The image used for depicting the drag, and the offset between the cursor
+  // and the top left pixel.
+  SkBitmap drag_image_;
+  gfx::Point image_offset_;
+
   // The mime type for the file contents of the current drag (if any).
   GdkAtom drag_file_mime_type_;