ui/base/dragdrop/drag_utils_win.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/base/dragdrop/drag_utils.h"
   6
   7 #include <objidl.h>
   8 #include <shlobj.h>
   9 #include <shobjidl.h>
  10
  11 #include "base/win/scoped_comptr.h"
  12 #include "base/win/scoped_hdc.h"
  13 #include "third_party/skia/include/core/SkBitmap.h"
  14 #include "ui/base/dragdrop/os_exchange_data.h"
  15 #include "ui/base/dragdrop/os_exchange_data_provider_win.h"
  16 #include "ui/gfx/canvas.h"
  17 #include "ui/gfx/gdi_util.h"
  18 #include "ui/gfx/geometry/size.h"
  19 #include "ui/gfx/image/image_skia.h"
  20 #include "ui/gfx/skbitmap_operations.h"
  21
  22 namespace drag_utils {
  23
  24 static void SetDragImageOnDataObject(HBITMAP hbitmap,
  25                                      const gfx::Size& size_in_pixels,
  26                                      const gfx::Vector2d& cursor_offset,
  27                                      IDataObject* data_object) {
  28   base::win::ScopedComPtr<IDragSourceHelper> helper;
  29   HRESULT rv = CoCreateInstance(CLSID_DragDropHelper, 0, CLSCTX_INPROC_SERVER,
  30                                 IID_IDragSourceHelper, helper.ReceiveVoid());
  31   if (SUCCEEDED(rv)) {
  32     SHDRAGIMAGE sdi;
  33     sdi.sizeDragImage = size_in_pixels.ToSIZE();
  34     sdi.crColorKey = 0xFFFFFFFF;
  35     sdi.hbmpDragImage = hbitmap;
  36     sdi.ptOffset = gfx::PointAtOffsetFromOrigin(cursor_offset).ToPOINT();
  37     helper->InitializeFromBitmap(&sdi, data_object);
  38   }
  39 }
  40
  41 // Blit the contents of the canvas to a new HBITMAP. It is the caller's
  42 // responsibility to release the |bits| buffer.
  43 static HBITMAP CreateHBITMAPFromSkBitmap(const SkBitmap& sk_bitmap) {
  44   base::win::ScopedGetDC screen_dc(NULL);
  45   BITMAPINFOHEADER header;
  46   gfx::CreateBitmapHeader(sk_bitmap.width(), sk_bitmap.height(), &header);
  47   void* bits;
  48   HBITMAP bitmap =
  49       CreateDIBSection(screen_dc, reinterpret_cast<BITMAPINFO*>(&header),
  50                        DIB_RGB_COLORS, &bits, NULL, 0);
  51   if (!bitmap || !bits)
  52     return NULL;
  53   DCHECK_EQ(sk_bitmap.rowBytes(), static_cast<size_t>(sk_bitmap.width() * 4));
  54   SkAutoLockPixels lock(sk_bitmap);
  55   memcpy(
  56       bits, sk_bitmap.getPixels(), sk_bitmap.height() * sk_bitmap.rowBytes());
  57   return bitmap;
  58 }
  59
  60 void SetDragImageOnDataObject(const gfx::ImageSkia& image_skia,
  61                               const gfx::Vector2d& cursor_offset,
  62                               ui::OSExchangeData* data_object) {
  63   DCHECK(data_object && !image_skia.size().IsEmpty());
  64   // InitializeFromBitmap() doesn't expect an alpha channel and is confused
  65   // by premultiplied colors, so unpremultiply the bitmap.
  66   // SetDragImageOnDataObject(HBITMAP) takes ownership of the bitmap.
  67   HBITMAP bitmap = CreateHBITMAPFromSkBitmap(
  68       SkBitmapOperations::UnPreMultiply(*image_skia.bitmap()));
  69   if (bitmap) {
  70     // Attach 'bitmap' to the data_object.
  71     SetDragImageOnDataObject(
  72         bitmap,
  73         gfx::Size(image_skia.bitmap()->width(), image_skia.bitmap()->height()),
  74         cursor_offset,
  75         ui::OSExchangeDataProviderWin::GetIDataObject(*data_object));
  76   }
  77
  78   // TODO: the above code is used in non-Ash, while below is used in Ash. If we
  79   // could figure this context out then we wouldn't do unnecessary work. However
  80   // as it stands getting this information in ui/base would be a layering
  81   // violation.
  82   data_object->provider().SetDragImage(image_skia, cursor_offset);
  83 }
  84
  85 }  // namespace drag_utils