views/drag_utils_win.cc

   1 // Copyright (c) 2011 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 "views/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 "ui/base/dragdrop/os_exchange_data.h"
  13 #include "third_party/skia/include/core/SkBitmap.h"
  14 #include "ui/base/dragdrop/os_exchange_data_provider_win.h"
  15 #include "ui/gfx/canvas_skia.h"
  16 #include "ui/gfx/gdi_util.h"
  17 #include "ui/gfx/skbitmap_operations.h"
  18
  19 using ui::OSExchangeData;
  20 using ui::OSExchangeDataProviderWin;
  21
  22 namespace drag_utils {
  23
  24 static void SetDragImageOnDataObject(HBITMAP hbitmap,
  25                                      const gfx::Size& size,
  26                                      const gfx::Point& 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.ToSIZE();
  34     sdi.crColorKey = 0xFFFFFFFF;
  35     sdi.hbmpDragImage = hbitmap;
  36     sdi.ptOffset = 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   HDC screen_dc = GetDC(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   DCHECK(sk_bitmap.rowBytes() == sk_bitmap.width() * 4);
  52   SkAutoLockPixels lock(sk_bitmap);
  53   memcpy(
  54       bits, sk_bitmap.getPixels(), sk_bitmap.height() * sk_bitmap.rowBytes());
  55   ReleaseDC(NULL, screen_dc);
  56   return bitmap;
  57 }
  58
  59 void SetDragImageOnDataObject(const SkBitmap& sk_bitmap,
  60                               const gfx::Size& size,
  61                               const gfx::Point& cursor_offset,
  62                               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(sk_bitmap));
  69
  70   // Attach 'bitmap' to the data_object.
  71   SetDragImageOnDataObject(bitmap, size, cursor_offset,
  72       OSExchangeDataProviderWin::GetIDataObject(*data_object));
  73 }
  74
  75 } // namespace drag_utils