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 = OnDragEnter(current_data_object_, key_state, screen_pt, *effect);
  53   return S_OK;
  54 }
  55
  56 HRESULT DropTargetWin::DragOver(DWORD key_state,
  57                                 POINTL cursor_position,
  58                                 DWORD* effect) {
  59   // Tell the helper that we moved over it so it can update the drag image.
  60   IDropTargetHelper* drop_helper = DropHelper();
  61   if (drop_helper)
  62     drop_helper->DragOver(reinterpret_cast<POINT*>(&cursor_position), *effect);
  63
  64   POINT screen_pt = { cursor_position.x, cursor_position.y };
  65   *effect = OnDragOver(current_data_object_, key_state, screen_pt, *effect);
  66   return S_OK;
  67 }
  68
  69 HRESULT DropTargetWin::DragLeave() {
  70   // Tell the helper that we moved out of it so it can update the drag image.
  71   IDropTargetHelper* drop_helper = DropHelper();
  72   if (drop_helper)
  73     drop_helper->DragLeave();
  74
  75   OnDragLeave(current_data_object_);
  76
  77   current_data_object_ = NULL;
  78   return S_OK;
  79 }
  80
  81 HRESULT DropTargetWin::Drop(IDataObject* data_object,
  82                             DWORD key_state,
  83                             POINTL cursor_position,
  84                             DWORD* effect) {
  85   // Tell the helper that we dropped onto it so it can update the drag image.
  86   IDropTargetHelper* drop_helper = DropHelper();
  87   if (drop_helper) {
  88     drop_helper->Drop(current_data_object_,
  89                       reinterpret_cast<POINT*>(&cursor_position), *effect);
  90   }
  91
  92   POINT screen_pt = { cursor_position.x, cursor_position.y };
  93   *effect = OnDrop(current_data_object_, key_state, screen_pt, *effect);
  94   return S_OK;
  95 }
  96
  97 ///////////////////////////////////////////////////////////////////////////////
  98 // DropTargetWin, IUnknown implementation:
  99
 100 HRESULT DropTargetWin::QueryInterface(const IID& iid, void** object) {
 101   *object = NULL;
 102   if (IsEqualIID(iid, IID_IUnknown) || IsEqualIID(iid, IID_IDropTarget)) {
 103     *object = this;
 104   } else {
 105     return E_NOINTERFACE;
 106   }
 107   AddRef();
 108   return S_OK;
 109 }
 110
 111 ULONG DropTargetWin::AddRef() {
 112   return ++ref_count_;
 113 }
 114
 115 ULONG DropTargetWin::Release() {
 116   if (--ref_count_ == 0) {
 117     delete this;
 118     return 0U;
 119   }
 120   return ref_count_;
 121 }
 122
 123 DWORD DropTargetWin::OnDragEnter(IDataObject* data_object,
 124                                  DWORD key_state,
 125                                  POINT cursor_position,
 126                                  DWORD effect) {
 127   return DROPEFFECT_NONE;
 128 }
 129
 130 DWORD DropTargetWin::OnDragOver(IDataObject* data_object,
 131                                 DWORD key_state,
 132                                 POINT cursor_position,
 133                                 DWORD effect) {
 134   return DROPEFFECT_NONE;
 135 }
 136
 137 void DropTargetWin::OnDragLeave(IDataObject* data_object) {
 138 }
 139
 140 DWORD DropTargetWin::OnDrop(IDataObject* data_object,
 141                             DWORD key_state,
 142                             POINT cursor_position,
 143                             DWORD effect) {
 144   return DROPEFFECT_NONE;
 145 }
 146
 147 }  // namespace ui