office-gobmx/winaccessibility/source/UAccCOM/EnumVariant.cxx
Michael Weghorn 00c0ee8cf0 tdf#147083 wina11y: Return a11y object instead of child ID
Quoting MSAA doc about implementing child IDs [1]:

> # How Servers Implement Child IDs
>
> Server developers can assign child IDs to both simple elements and
> accessible objects. However, the recommended approach is to support the
> standard Component Object Model (COM) interface IEnumVARIANT in every
> accessible object that has children.
>
> If you implement IEnumVARIANT, you must:
>
> * Enumerate all children, both simple elements and accessible objects.
>   Provide child IDs for all simple elements and provide the IDispatch to
>   each accessible object.
> * For accessible objects, set the vt member of the VARIANT to
>   VT_DISPATCH. The pdispVal member must contain a pointer to the IDispatch
>   interface. Note that the VARIANT is allocated and freed by the client.
> * For simple elements, the child ID is any 32-bit positive integer.
>   Note that zero and negative integers are reserved by Microsoft Active
>   Accessibility. Set the VARIANT structure vt member to VT_I4 and the lVal
>   member to the child ID.
>
> If you do not support IEnumVARIANT, you must assign child IDs and
> number the children in each object sequentially starting with one.

So far, LibreOffice was returning negative "child IDs" instead of pointers
to accessible objects, which were not conformant to the MSAA
specification and not accepted by NVDA as valid child IDs
(s.a. discussion on the first version of my related NVDA pull request
to fix the announcement of a single selected cell in Calc, [2]).

Adapt that to return pointers to accessible objects and
drop the now unused 'CMAccessible::Get_XAccChildID'.

[1] https://docs.microsoft.com/en-us/windows/win32/winauto/how-servers-implement-child-ids
[2] https://github.com/nvaccess/nvda/pull/13277

Change-Id: I52a6f637adf334dee66627e6992451e6d81a7c9a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/129201
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
2022-01-31 17:31:11 +01:00

245 lines
6.6 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
#include "stdafx.h"
#include "EnumVariant.h"
#include "MAccessible.h"
#if defined __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wnon-virtual-dtor"
#endif
#include <UAccCOM.h>
#if defined __clang__
#pragma clang diagnostic pop
#endif
#include <vcl/svapp.hxx>
using namespace com::sun::star::uno;
using namespace com::sun::star::accessibility;
// CEnumVariant
/**
* enumerate method,get next element
* @param cElements The number of elements to be returned.
* @param pvar An array of at least size celt in which the elements are to be returned.
* @param pcElementFetched Pointer to the number of elements returned in rgVar, or Null
* @return Result.
*/
HRESULT STDMETHODCALLTYPE CEnumVariant::Next(ULONG cElements,VARIANT __RPC_FAR *pvar,ULONG __RPC_FAR *pcElementFetched)
{
SolarMutexGuard g;
long l1;
ULONG l2;
if (pvar == nullptr)
return E_INVALIDARG;
if (pcElementFetched != nullptr)
*pcElementFetched = 0;
// Retrieve the next cElements.
for (l1=m_lCurrent, l2=0; l1<m_pXAccessibleSelection->getSelectedAccessibleChildCount() &&
l2<cElements; l1++, l2++)
{
Reference< XAccessible > pRXAcc = m_pXAccessibleSelection->getSelectedAccessibleChild(l1);
IAccessible* pChild = nullptr;
bool isGet = CMAccessible::get_IAccessibleFromXAccessible(pRXAcc.get(),
&pChild);
if(isGet)
{
pvar[l2].vt = VT_DISPATCH;
pvar[l2].pdispVal = pChild;
pChild->AddRef();
}
else if(pRXAcc.is())
{
if(CMAccessible::g_pAgent)
CMAccessible::g_pAgent->InsertAccObj(pRXAcc.get(),pUNOInterface);
isGet = CMAccessible::get_IAccessibleFromXAccessible(
pRXAcc.get(), &pChild);
if(isGet)
{
pvar[l2].vt = VT_DISPATCH;
pvar[l2].pdispVal = pChild;
pChild->AddRef();
}
}
}
// Set count of elements retrieved.
if (pcElementFetched != nullptr)
*pcElementFetched = l2;
m_lCurrent = l1;
return (l2 < cElements) ? S_FALSE : NOERROR;
}
/**
* skip the elements in the given range when enumerate elements
* @param cElements The number of elements to skip.
* @return Result.
*/
HRESULT STDMETHODCALLTYPE CEnumVariant::Skip(ULONG cElements)
{
SolarMutexGuard g;
m_lCurrent += cElements;
if (m_lCurrent > static_cast<long>(m_lLBound+m_pXAccessibleSelection->getSelectedAccessibleChildCount()))
{
m_lCurrent = m_lLBound+m_pXAccessibleSelection->getSelectedAccessibleChildCount();
return E_FAIL;
}
else
return NOERROR;
}
/**
* reset the enumaration position to initial value
* @param
* @return Result.
*/
HRESULT STDMETHODCALLTYPE CEnumVariant::Reset()
{
SolarMutexGuard g;
m_lCurrent = m_lLBound;
return NOERROR;
}
/**
*create a new IEnumVariant object,
*copy current enumaration container and its state to
*the new object
*AT will use the copy object to get elements
* @param ppenum On return, pointer to the location of the clone enumerator
* @return Result.
*/
HRESULT STDMETHODCALLTYPE CEnumVariant::Clone(IEnumVARIANT __RPC_FAR *__RPC_FAR *ppenum)
{
SolarMutexGuard g;
CEnumVariant * penum = nullptr;
HRESULT hr;
if (ppenum == nullptr)
return E_INVALIDARG;
*ppenum = nullptr;
hr = Create(&penum);
if( hr == S_OK )
{
penum->PutSelection(reinterpret_cast<hyper>(pUNOInterface));
*ppenum = penum;
}
else
{
if (penum)
penum->Release();
}
return hr;
}
/**
*Static public method to create a CLSID_EnumVariant com object.
* @param ppenum Pointer to accept com object.
* @return Result.
*/
HRESULT STDMETHODCALLTYPE CEnumVariant::Create(CEnumVariant __RPC_FAR *__RPC_FAR *ppenum)
{
SolarMutexGuard g;
HRESULT hr = createInstance<CEnumVariant>(IID_IEnumVariant, ppenum);
if (S_OK != hr)
{
return E_FAIL;
}
return S_OK;
}
/**
*Return count of elements in current container
* @param.
* @return count of elements in current container.
*/
long CEnumVariant::GetCountOfElements()
{
if(m_pXAccessibleSelection.is())
return m_pXAccessibleSelection->getSelectedAccessibleChildCount();
return 0;
}
/**
* Set member m_pXAccessibleSelection to NULL and m_lCurrent to m_lLBound.
* @param.
* @return Result
*/
COM_DECLSPEC_NOTHROW STDMETHODIMP CEnumVariant::ClearEnumeration()
{
// internal IEnumVariant - no mutex meeded
pUNOInterface = nullptr;
m_pXAccessibleSelection = nullptr;
m_lCurrent = m_lLBound;
return S_OK;
}
/**
*Static method to fetch XAccessibleSelection
* @param pXAcc XAccessible interface.
* @return XAccessibleSelection interface.
*/
static Reference<XAccessibleSelection> GetXAccessibleSelection(XAccessible* pXAcc)
{
if( pXAcc == nullptr)
return nullptr;
Reference< XAccessibleContext > pRContext = pXAcc->getAccessibleContext();
if( !pRContext.is() )
return nullptr;
Reference< XAccessibleSelection > pRSelection(pRContext,UNO_QUERY);
if( !pRSelection.is() )
return nullptr;
return pRSelection;
}
/**
* Put valid UNO XAccessible interface.
* @param pXSelection XAccessible interface.
* @return Result...
*/
STDMETHODIMP CEnumVariant::PutSelection(hyper pXSelection)
{
// internal IEnumVariant - no mutex meeded
pUNOInterface = reinterpret_cast<XAccessible*>(pXSelection);
m_pXAccessibleSelection = GetXAccessibleSelection(pUNOInterface);
return S_OK;
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */