Aura: Adds custom cursors for drag and drop.

ui/aura/root_window_host_linux.cc

Index: ui/aura/root_window_host_linux.cc
diff --git a/ui/aura/root_window_host_linux.cc b/ui/aura/root_window_host_linux.cc
index 51d1013ef804b651b7b96a4c66895179dec4171b..9bde56290b6889903b06db37bfe58062f87e10b7 100644
--- a/ui/aura/root_window_host_linux.cc
+++ b/ui/aura/root_window_host_linux.cc
@@ -5,6 +5,7 @@
 #include "ui/aura/root_window_host_linux.h"
 
 #include <X11/Xatom.h>
+#include <X11/Xcursor/Xcursor.h>
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/extensions/Xfixes.h>
@@ -14,6 +15,8 @@
 #include "base/message_pump_x.h"
 #include "base/stl_util.h"
 #include "base/stringprintf.h"
+#include "grit/ui_resources_standard.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/aura/client/user_gesture_client.h"
 #include "ui/aura/dispatcher_linux.h"
 #include "ui/aura/env.h"
@@ -21,10 +24,12 @@
 #include "ui/aura/root_window.h"
 #include "ui/base/cursor/cursor.h"
 #include "ui/base/keycodes/keyboard_codes.h"
+#include "ui/base/resource/resource_bundle.h"
 #include "ui/base/touch/touch_factory.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/base/view_prop.h"
 #include "ui/gfx/compositor/layer.h"
+#include "ui/gfx/image/image.h"
 
 using std::max;
 using std::min;
@@ -292,6 +297,54 @@ const char* kAtomList[] = {
 
 }  // namespace
 
+// A utility class that provides X Cursor for NativeCursors for which we have
+// image resources.
+class RootWindowHostLinux::ImageCursors {
+ public:
+  ImageCursors() {
+    LoadImageCursor(ui::kCursorNoDrop, IDR_AURA_CURSOR_NO_DROP);
+    LoadImageCursor(ui::kCursorCopy, IDR_AURA_CURSOR_COPY);
+    // TODO (varunjain): add more cursors once we have assets.
+  }
+
+  ~ImageCursors() {
+    std::map<int, Cursor>::const_iterator it;
+    for (it = cursors_.begin(); it != cursors_.end(); ++it)
+      ui::UnrefCustomXCursor(it->second);

[sail, 2012/05/03 20:00:47]

I was thinking that you could just use XCustomCursor directly instead of
manually keeping track of ::Cursor references.
That said this seems ok to me.

+  }
+
+  // Returns true if we have an image resource loaded for the |native_cursor|.
+  bool IsImageCursor(gfx::NativeCursor native_cursor) {
+    return cursors_.find(native_cursor.native_type()) != cursors_.end();
+  }
+
+  // Gets the X Cursor corresponding to the |native_cursor|.
+  ::Cursor ImageCursorFromNative(gfx::NativeCursor native_cursor) {
+    DCHECK(cursors_.find(native_cursor.native_type()) != cursors_.end());
+    return cursors_[native_cursor.native_type()];
+  }
+
+ private:
+  // Creates an X Cursor from an image resource and puts it in the cursor map.
+  void LoadImageCursor(int id, int resource_id) {
+    const SkBitmap* bitmap =
+        ui::ResourceBundle::GetSharedInstance().GetImageNamed(
+            resource_id).ToSkBitmap();
+
+    XcursorImage* image = ui::SkBitmapToXcursorImage(bitmap, gfx::Point(0, 0));
+    cursors_[id] = ui::CreateReffedCustomXCursor(image);
+    // |bitmap| is owned by the resource bundle. So we do not need to free it.
+  }
+
+  // A map to hold all image cursors. It maps the cursor ID to the cursor
+  // object, where, the cursor object consists of the actual X Cursor and the
+  // XcursorImage. We need to keep the images as well to be able to free them
+  // on destruction.
+  std::map<int, Cursor> cursors_;
+
+  DISALLOW_COPY_AND_ASSIGN(ImageCursors);
+};
+
 RootWindowHostLinux::RootWindowHostLinux(const gfx::Rect& bounds)
     : root_window_(NULL),
       xdisplay_(base::MessagePumpX::GetDefaultXDisplay()),
@@ -301,7 +354,8 @@ RootWindowHostLinux::RootWindowHostLinux(const gfx::Rect& bounds)
       cursor_shown_(true),
       bounds_(bounds),
       focus_when_shown_(false),
-      pointer_barriers_(NULL) {
+      pointer_barriers_(NULL),
+      image_cursors_(new ImageCursors) {
   XSetWindowAttributes swa;
   memset(&swa, 0, sizeof(swa));
   swa.background_pixmap = None;
@@ -795,6 +849,8 @@ bool RootWindowHostLinux::IsWindowManagerPresent() {
 
 void RootWindowHostLinux::SetCursorInternal(gfx::NativeCursor cursor) {
   ::Cursor xcursor =
+      image_cursors_->IsImageCursor(cursor) ?
+      image_cursors_->ImageCursorFromNative(cursor) :
       cursor == ui::kCursorNone ?
       invisible_cursor_ :
       cursor == ui::kCursorCustom ?