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