ui/base/dragdrop/drop_target_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 "ui/base/dragdrop/drop_target_win.h"
   6
   7 #include <shlobj.h>
   8
   9 #include "base/logging.h"
  10
  11 namespace ui {
  12
  13 IDropTargetHelper* DropTargetWin::cached_drop_target_helper_ = NULL;
  14
  15 DropTargetWin::DropTargetWin(HWND hwnd)
  16     : hwnd_(hwnd),
  17       ref_count_(0) {
  18   DCHECK(hwnd);
  19   HRESULT result = RegisterDragDrop(hwnd, this);
  20   DCHECK(SUCCEEDED(result));
  21 }
  22
  23 DropTargetWin::~DropTargetWin() {
  24 }
  25
  26 // static
  27 IDropTargetHelper* DropTargetWin::DropHelper() {
  28   if (!cached_drop_target_helper_) {
  29     CoCreateInstance(CLSID_DragDropHelper, 0, CLSCTX_INPROC_SERVER,
  30                      IID_IDropTargetHelper,
  31                      reinterpret_cast<void**>(&cached_drop_target_helper_));
  32   }
  33   return cached_drop_target_helper_;
  34 }
  35
  36 ///////////////////////////////////////////////////////////////////////////////
  37 // DropTargetWin, IDropTarget implementation:
  38
  39 HRESULT DropTargetWin::DragEnter(IDataObject* data_object,
  40                                  DWORD key_state,
  41                                  POINTL cursor_position,
  42                                  DWORD* effect) {
  43   // Tell the helper that we entered so it can update the drag image.
  44   IDropTargetHelper* drop_helper = DropHelper();
  45   if (drop_helper) {
  46     drop_helper->DragEnter(GetHWND(), data_object,
  47                            reinterpret_cast<POINT*>(&cursor_position), *effect);
  48   }
  49
  50   current_data_object_ = data_object;
  51   POINT screen_pt = { cursor_position.x, cursor_position.y };
  52   *effect =
  53       OnDragEnter(current_data_object_.get(), key_state, screen_pt, *effect);
  54   return S_OK;
  55 }
  56
  57 HRESULT DropTargetWin::DragOver(DWORD key_state,
  58                                 POINTL cursor_position,
  59                                 DWORD* effect) {
  60   // Tell the helper that we moved over it so it can update the drag image.
  61   IDropTargetHelper* drop_helper = DropHelper();
  62   if (drop_helper)
  63     drop_helper->DragOver(reinterpret_cast<POINT*>(&cursor_position), *effect);
  64
  65   POINT screen_pt = { cursor_position.x, cursor_position.y };
  66   *effect =
  67       OnDragOver(current_data_object_.get(), key_state, screen_pt, *effect);
  68   return S_OK;
  69 }
  70
  71 HRESULT DropTargetWin::DragLeave() {
  72   // Tell the helper that we moved out of it so it can update the drag image.
  73   IDropTargetHelper* drop_helper = DropHelper();
  74   if (drop_helper)
  75     drop_helper->DragLeave();
  76
  77   OnDragLeave(current_data_object_.get());
  78
  79   current_data_object_ = NULL;
  80   return S_OK;
  81 }
  82
  83 HRESULT DropTargetWin::Drop(IDataObject* data_object,
  84                             DWORD key_state,
  85                             POINTL cursor_position,
  86                             DWORD* effect) {
  87   // Tell the helper that we dropped onto it so it can update the drag image.
  88   IDropTargetHelper* drop_helper = DropHelper();
  89   if (drop_helper) {
  90     drop_helper->Drop(current_data_object_.get(),
  91                       reinterpret_cast<POINT*>(&cursor_position), *effect);
  92   }
  93
  94   POINT screen_pt = { cursor_position.x, cursor_position.y };
  95   *effect = OnDrop(current_data_object_.get(), key_state, screen_pt, *effect);
  96   return S_OK;
  97 }
  98
  99 ///////////////////////////////////////////////////////////////////////////////
 100 // DropTargetWin, IUnknown implementation:
 101
 102 HRESULT DropTargetWin::QueryInterface(const IID& iid, void** object) {
 103   *object = NULL;
 104   if (IsEqualIID(iid, IID_IUnknown) || IsEqualIID(iid, IID_IDropTarget)) {
 105     *object = this;
 106   } else {
 107     return E_NOINTERFACE;
 108   }
 109   AddRef();
 110   return S_OK;
 111 }
 112
 113 ULONG DropTargetWin::AddRef() {
 114   return ++ref_count_;
 115 }
 116
 117 ULONG DropTargetWin::Release() {
 118   if (--ref_count_ == 0) {
 119     delete this;
 120     return 0U;
 121   }
 122   return ref_count_;
 123 }
 124
 125 DWORD DropTargetWin::OnDragEnter(IDataObject* data_object,
 126                                  DWORD key_state,
 127                                  POINT cursor_position,
 128                                  DWORD effect) {
 129   return DROPEFFECT_NONE;
 130 }
 131
 132 DWORD DropTargetWin::OnDragOver(IDataObject* data_object,
 133                                 DWORD key_state,
 134                                 POINT cursor_position,
 135                                 DWORD effect) {
 136   return DROPEFFECT_NONE;
 137 }
 138
 139 void DropTargetWin::OnDragLeave(IDataObject* data_object) {
 140 }
 141
 142 DWORD DropTargetWin::OnDrop(IDataObject* data_object,
 143                             DWORD key_state,
 144                             POINT cursor_position,
 145                             DWORD effect) {
 146   return DROPEFFECT_NONE;
 147 }
 148
 149 }  // namespace ui