widget/windows/IEnumFE.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "IEnumFE.h"
   7 #include "nsAlgorithm.h"
   8 #include <algorithm>
   9
  10 CEnumFormatEtc::CEnumFormatEtc() :
  11   mRefCnt(0),
  12   mCurrentIdx(0)
  13 {
  14 }
  15
  16 // Constructor used by Clone()
  17 CEnumFormatEtc::CEnumFormatEtc(nsTArray<FormatEtc>& aArray) :
  18   mRefCnt(0),
  19   mCurrentIdx(0)
  20 {
  21   // a deep copy, calls FormatEtc's copy constructor on each
  22   mFormatList.AppendElements(aArray);
  23 }
  24
  25 CEnumFormatEtc::~CEnumFormatEtc()
  26 {
  27 }
  28
  29 /* IUnknown impl. */
  30
  31 STDMETHODIMP
  32 CEnumFormatEtc::QueryInterface(REFIID riid, LPVOID *ppv)
  33 {
  34   *ppv = NULL;
  35
  36   if (IsEqualIID(riid, IID_IUnknown) ||
  37       IsEqualIID(riid, IID_IEnumFORMATETC))
  38       *ppv = (LPVOID)this;
  39
  40   if (*ppv == NULL)
  41       return E_NOINTERFACE;
  42
  43   // AddRef any interface we'll return.
  44   ((LPUNKNOWN)*ppv)->AddRef();
  45   return S_OK;
  46 }
  47
  48 STDMETHODIMP_(ULONG)
  49 CEnumFormatEtc::AddRef()
  50 {
  51   ++mRefCnt;
  52   NS_LOG_ADDREF(this, mRefCnt, "CEnumFormatEtc",sizeof(*this));
  53   return mRefCnt;
  54 }
  55
  56 STDMETHODIMP_(ULONG)
  57 CEnumFormatEtc::Release()
  58 {
  59   uint32_t refReturn;
  60
  61   refReturn = --mRefCnt;
  62   NS_LOG_RELEASE(this, mRefCnt, "CEnumFormatEtc");
  63
  64   if (mRefCnt == 0)
  65       delete this;
  66
  67   return refReturn;
  68 }
  69
  70 /* IEnumFORMATETC impl. */
  71
  72 STDMETHODIMP
  73 CEnumFormatEtc::Next(ULONG aMaxToFetch, FORMATETC *aResult, ULONG *aNumFetched)
  74 {
  75   // If the method retrieves the number of items requested, the return
  76   // value is S_OK. Otherwise, it is S_FALSE.
  77
  78   if (aNumFetched)
  79       *aNumFetched = 0;
  80
  81   // aNumFetched can be null if aMaxToFetch is 1
  82   if (!aNumFetched && aMaxToFetch > 1)
  83       return S_FALSE;
  84
  85   if (!aResult)
  86       return S_FALSE;
  87
  88   // We're done walking the list
  89   if (mCurrentIdx >= mFormatList.Length())
  90       return S_FALSE;
  91
  92   uint32_t left = mFormatList.Length() - mCurrentIdx;
  93
  94   if (!aMaxToFetch)
  95       return S_FALSE;
  96
  97   uint32_t count = std::min(static_cast<uint32_t>(aMaxToFetch), left);
  98
  99   uint32_t idx = 0;
 100   while (count > 0) {
 101       // Copy out to aResult
 102       mFormatList[mCurrentIdx++].CopyOut(&aResult[idx++]);
 103       count--;
 104   }
 105
 106   if (aNumFetched)
 107       *aNumFetched = idx;
 108
 109   return S_OK;
 110 }
 111
 112 STDMETHODIMP
 113 CEnumFormatEtc::Skip(ULONG aSkipNum)
 114 {
 115   // If the method skips the number of items requested, the return value is S_OK.
 116   // Otherwise, it is S_FALSE.
 117
 118   if ((mCurrentIdx + aSkipNum) >= mFormatList.Length())
 119       return S_FALSE;
 120
 121   mCurrentIdx += aSkipNum;
 122
 123   return S_OK;
 124 }
 125
 126 STDMETHODIMP
 127 CEnumFormatEtc::Reset(void)
 128 {
 129   mCurrentIdx = 0;
 130   return S_OK;
 131 }
 132
 133 STDMETHODIMP
 134 CEnumFormatEtc::Clone(LPENUMFORMATETC *aResult)
 135 {
 136   // Must return a new IEnumFORMATETC interface with the same iterative state.
 137
 138   if (!aResult)
 139       return E_INVALIDARG;
 140
 141   CEnumFormatEtc * pEnumObj = new CEnumFormatEtc(mFormatList);
 142
 143   if (!pEnumObj)
 144       return E_OUTOFMEMORY;
 145
 146   pEnumObj->AddRef();
 147   pEnumObj->SetIndex(mCurrentIdx);
 148
 149   *aResult = pEnumObj;
 150
 151   return S_OK;
 152 }
 153
 154 /* utils */
 155
 156 void
 157 CEnumFormatEtc::AddFormatEtc(LPFORMATETC aFormat)
 158 {
 159   if (!aFormat)
 160       return;
 161   FormatEtc * etc = mFormatList.AppendElement();
 162   // Make a copy of aFormat
 163   if (etc)
 164       etc->CopyIn(aFormat);
 165 }
 166
 167 /* private */
 168
 169 void
 170 CEnumFormatEtc::SetIndex(uint32_t aIdx)
 171 {
 172   mCurrentIdx = aIdx;
 173 }