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 <algorithm>
   8
   9 CEnumFormatEtc::CEnumFormatEtc() : mRefCnt(0), mCurrentIdx(0) {}
  10
  11 // Constructor used by Clone()
  12 CEnumFormatEtc::CEnumFormatEtc(nsTArray<FormatEtc>& aArray)
  13     : mRefCnt(0), mCurrentIdx(0) {
  14   // a deep copy, calls FormatEtc's copy constructor on each
  15   mFormatList.AppendElements(aArray);
  16 }
  17
  18 CEnumFormatEtc::~CEnumFormatEtc() {}
  19
  20 /* IUnknown impl. */
  21
  22 STDMETHODIMP
  23 CEnumFormatEtc::QueryInterface(REFIID riid, LPVOID* ppv) {
  24   *ppv = nullptr;
  25
  26   if (IsEqualIID(riid, IID_IUnknown) || IsEqualIID(riid, IID_IEnumFORMATETC))
  27     *ppv = (LPVOID)this;
  28
  29   if (*ppv == nullptr) return E_NOINTERFACE;
  30
  31   // AddRef any interface we'll return.
  32   ((LPUNKNOWN)*ppv)->AddRef();
  33   return S_OK;
  34 }
  35
  36 STDMETHODIMP_(ULONG)
  37 CEnumFormatEtc::AddRef() {
  38   ++mRefCnt;
  39   NS_LOG_ADDREF(this, mRefCnt, "CEnumFormatEtc", sizeof(*this));
  40   return mRefCnt;
  41 }
  42
  43 STDMETHODIMP_(ULONG)
  44 CEnumFormatEtc::Release() {
  45   uint32_t refReturn;
  46
  47   refReturn = --mRefCnt;
  48   NS_LOG_RELEASE(this, mRefCnt, "CEnumFormatEtc");
  49
  50   if (mRefCnt == 0) delete this;
  51
  52   return refReturn;
  53 }
  54
  55 /* IEnumFORMATETC impl. */
  56
  57 STDMETHODIMP
  58 CEnumFormatEtc::Next(ULONG aMaxToFetch, FORMATETC* aResult,
  59                      ULONG* aNumFetched) {
  60   // If the method retrieves the number of items requested, the return
  61   // value is S_OK. Otherwise, it is S_FALSE.
  62
  63   if (aNumFetched) *aNumFetched = 0;
  64
  65   // aNumFetched can be null if aMaxToFetch is 1
  66   if (!aNumFetched && aMaxToFetch > 1) return S_FALSE;
  67
  68   if (!aResult) return S_FALSE;
  69
  70   // We're done walking the list
  71   if (mCurrentIdx >= mFormatList.Length()) return S_FALSE;
  72
  73   uint32_t left = mFormatList.Length() - mCurrentIdx;
  74
  75   if (!aMaxToFetch) return S_FALSE;
  76
  77   uint32_t count = std::min(static_cast<uint32_t>(aMaxToFetch), left);
  78
  79   uint32_t idx = 0;
  80   while (count > 0) {
  81     // Copy out to aResult
  82     mFormatList[mCurrentIdx++].CopyOut(&aResult[idx++]);
  83     count--;
  84   }
  85
  86   if (aNumFetched) *aNumFetched = idx;
  87
  88   return S_OK;
  89 }
  90
  91 STDMETHODIMP
  92 CEnumFormatEtc::Skip(ULONG aSkipNum) {
  93   // If the method skips the number of items requested, the return value is
  94   // S_OK. Otherwise, it is S_FALSE.
  95
  96   if ((mCurrentIdx + aSkipNum) >= mFormatList.Length()) return S_FALSE;
  97
  98   mCurrentIdx += aSkipNum;
  99
 100   return S_OK;
 101 }
 102
 103 STDMETHODIMP
 104 CEnumFormatEtc::Reset(void) {
 105   mCurrentIdx = 0;
 106   return S_OK;
 107 }
 108
 109 STDMETHODIMP
 110 CEnumFormatEtc::Clone(LPENUMFORMATETC* aResult) {
 111   // Must return a new IEnumFORMATETC interface with the same iterative state.
 112
 113   if (!aResult) return E_INVALIDARG;
 114
 115   CEnumFormatEtc* pEnumObj = new CEnumFormatEtc(mFormatList);
 116
 117   if (!pEnumObj) return E_OUTOFMEMORY;
 118
 119   pEnumObj->AddRef();
 120   pEnumObj->SetIndex(mCurrentIdx);
 121
 122   *aResult = pEnumObj;
 123
 124   return S_OK;
 125 }
 126
 127 /* utils */
 128
 129 void CEnumFormatEtc::AddFormatEtc(LPFORMATETC aFormat) {
 130   if (!aFormat) return;
 131   FormatEtc* etc = mFormatList.AppendElement();
 132   // Make a copy of aFormat
 133   if (etc) etc->CopyIn(aFormat);
 134 }
 135
 136 /* private */
 137
 138 void CEnumFormatEtc::SetIndex(uint32_t aIdx) { mCurrentIdx = aIdx; }