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/image/image_skia.h"
19#include "ui/gfx/skbitmap_operations.h"
20
21namespace drag_utils {
22
23static void SetDragImageOnDataObject(HBITMAP hbitmap,
24                                     const gfx::Size& size,
25                                     const gfx::Vector2d& cursor_offset,
26                                     IDataObject* data_object) {
27  base::win::ScopedComPtr<IDragSourceHelper> helper;
28  HRESULT rv = CoCreateInstance(CLSID_DragDropHelper, 0, CLSCTX_INPROC_SERVER,
29                                IID_IDragSourceHelper, helper.ReceiveVoid());
30  if (SUCCEEDED(rv)) {
31    SHDRAGIMAGE sdi;
32    sdi.sizeDragImage = size.ToSIZE();
33    sdi.crColorKey = 0xFFFFFFFF;
34    sdi.hbmpDragImage = hbitmap;
35    sdi.ptOffset = gfx::PointAtOffsetFromOrigin(cursor_offset).ToPOINT();
36    helper->InitializeFromBitmap(&sdi, data_object);
37  }
38}
39
40// Blit the contents of the canvas to a new HBITMAP. It is the caller's
41// responsibility to release the |bits| buffer.
42static HBITMAP CreateHBITMAPFromSkBitmap(const SkBitmap& sk_bitmap) {
43  base::win::ScopedGetDC screen_dc(NULL);
44  BITMAPINFOHEADER header;
45  gfx::CreateBitmapHeader(sk_bitmap.width(), sk_bitmap.height(), &header);
46  void* bits;
47  HBITMAP bitmap =
48      CreateDIBSection(screen_dc, reinterpret_cast<BITMAPINFO*>(&header),
49                       DIB_RGB_COLORS, &bits, NULL, 0);
50  if (!bitmap || !bits)
51    return NULL;
52  DCHECK_EQ(sk_bitmap.rowBytes(), static_cast<size_t>(sk_bitmap.width() * 4));
53  SkAutoLockPixels lock(sk_bitmap);
54  memcpy(
55      bits, sk_bitmap.getPixels(), sk_bitmap.height() * sk_bitmap.rowBytes());
56  return bitmap;
57}
58
59void SetDragImageOnDataObject(const gfx::ImageSkia& image_skia,
60                              const gfx::Size& size,
61                              const gfx::Vector2d& cursor_offset,
62                              ui::OSExchangeData* data_object) {
63  DCHECK(data_object && !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(bitmap, size, cursor_offset,
72        ui::OSExchangeDataProviderWin::GetIDataObject(*data_object));
73  }
74
75#if defined(USE_AURA)
76  // TODO: the above code is used in non-Ash, while below is used in Ash. If we
77  // could figure this context out then we wouldn't do unnecessary work. However
78  // as it stands getting this information in ui/base would be a layering
79  // violation.
80  data_object->provider().SetDragImage(image_skia, cursor_offset);
81#endif
82}
83
84}  // namespace drag_utils
85