206543c7be
With 16k column support in Calc enabled by default in commit4c5f8ccf0a
Date: Tue Mar 8 12:44:49 2022 +0100 change default Calc number of columns to 16384 (tdf#50916) , the number of Calc cells in a spreadsheet is larger than SAL_MAX_INT32, meaning that a 32-bit a11y child index is no more enough and using it resulted in integer overflows in methods handling corresponding Calc cells in the a11y layer. This e.g. had the effect of the Orca and NVDA screen readers not announcing focused or selected cells properly when their a11y child index was out of the 32-bit integer range. Switch the internal a11y child indices to 64 bit to be able to handle this properly internally. Since the platform APIs (at least AT-SPI on Linux and IAccessible2 on Windows; from what I can see LO's macOS a11y bridge doesn't directly expose the child index) are still restricted to 32 bit, larger child indices still cannot be exposed via the platform APIs. As a consequence, use of the the IAccessible2 and AT-SPI methods that use the child index remains problematic in those cases where the child index is larger. However, as an alternative to using the AT-SPI Table interface and the IAccessibleTable/ IAccessibleTable2 interfaces with the child index to retrieve information about a specific cell, both AT-SPI and IAccessible2 also provide interfaces to retrieve that information directly from the cell object (TableCell interface for AT-SPI, IAccessibleTableCell for IAccessible2). Those interfaces are already implemented/exposed for winaccessibility (s. `CAccTable`) and the qt5/qt6/kf5 VCL plugins (s. the `QAccessibleTableCellInterface` methods implemented in `QtAccessibleInterface`). With the switch to 64-bit internal a11y child indices, these now behave correctly for cells with a child index that doesn't fit into 32 bit as well. NVDA on Windows already uses the IAccessibleTableCell interface and thus announcing focused cells works fine with this change in place. Orca on Linux currently doesn't make use of the AT-SPI TableCell interface yet, but with a suggested change to do so [1], announcement of selected cells works with the qt6 VCL plugin with a current qtbase dev branch as well - when combined with the suggested changes to implement support for the AT-SPI TableCell interface in Qt [2] [3] and the LO change based on that [4] and a fix for a nullptr dereference [5]. The gtk3 VCL plugin doesn't expose the AT-SPI TableCell interface yet, but once it does so (via `AtkTableCell`), it also works with the suggested Orca change [1] in place. (Adding that is planned for an upcoming change, works with a local WIP patch.) For handling return values that are larger than what platform APIs support, the following approach has been chosen for now: 1) When the return value is for the count of (selected) children, the maximum value N supported by the platform API is returned. (This is what `ScAccessibleTableBase::getAccessibleChildCount` did previously.) The first N elements can be accessed by their actual (selection) indices. 2) When the return value is the child/cell index, -2 is returned for objects whose index is greater than the maximum value supported by the platform API. Using a non-negative value would mean that the index would refer to *another* actually existing child. A child index of -1 on the other hand tends to be interpreted as "child is invalid" or "object isn't actually a child of its (previous) parent any more)". For the Orca case, this would result in objects with a child index of -1 not being announced, as they are considered "zombies" [6]. What's still somewhat problematic is the case where more than 2^31 children are *selected*, since access to those children still happens by the index into the selection in the platform APIs, and not all selected items are accessible this way. (Screen readers usually just retrieve the first and last element from the selection and announce those.) Orca already seems to apply different handling for the case for fully selected rows and columns, so "All cells selected" or "Columns ... to ... selected" is announced just fine even if more than 2^31 cells are selected. (Side note: While Microsoft User Interface Automation - UIA - also uses 32-bit indices, it also has specific methods in the ISelectionProvider2 interface that allow to explicitly retrieve the first and last selected item, `ISelectionProvider2::get_FirstSelectedItem` and `ISelectionProvider2::get_LastSelectedItem`, but we currently don't support UIA on Windows.) Bound checks at the beginning of the methods from the `XAccessibleContext`, `XAccessibleSelection` and `XAccessibleTable` interfaces that take a child index (or in helper methods called by those) should generally already prevent too large indices from being passed to the methods in the lower layer code that take smaller integer types. Such bound checking has been been added in various places where it wasn't present yet. If there any remaining issues of this kind that show after this commit, they can probably be solved in a similar way (s.e.g. the change to `AccessibleBrowseBox::getAccessibleChild` in this commit). A few asserts were also added at places where my understanding is that values shouldn't be larger than what is supported by a called method anyway. A test case will be added in a following change. [1] https://gitlab.gnome.org/GNOME/orca/-/merge_requests/131 [2] https://codereview.qt-project.org/c/qt/qtbase/+/428566 [3] https://codereview.qt-project.org/c/qt/qtbase/+/428567 [4] https://gerrit.libreoffice.org/c/core/+/138750 [5] https://codereview.qt-project.org/c/qt/qtbase/+/430157 [6]82c8542002/src/orca/script_utilities.py (L5155)
Change-Id: I3af590c988b0e6754fc72545918412f39e8fea07 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/139258 Tested-by: Jenkins Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
207 lines
8.9 KiB
C++
207 lines
8.9 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* This file incorporates work covered by the following license notice:
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.apache.org/licenses/LICENSE-2.0 .
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*/
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#ifndef INCLUDED_SVX_ACCESSIBLECONTROLSHAPE_HXX
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#define INCLUDED_SVX_ACCESSIBLECONTROLSHAPE_HXX
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#include <com/sun/star/beans/XPropertyChangeListener.hpp>
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#include <com/sun/star/container/XContainerListener.hpp>
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#include <com/sun/star/lang/EventObject.hpp>
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#include <com/sun/star/uno/Reference.hxx>
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#include <com/sun/star/util/XModeChangeListener.hpp>
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#include <comphelper/uno3.hxx>
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#include <cppuhelper/implbase4.hxx>
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#include <cppuhelper/weakref.hxx>
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#include <rtl/ref.hxx>
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#include <rtl/ustring.hxx>
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#include <sal/types.h>
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#include <svx/AccessibleShape.hxx>
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namespace com::sun::star {
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namespace accessibility { class XAccessible; }
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namespace accessibility { class XAccessibleContext; }
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namespace accessibility { struct AccessibleEventObject; }
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namespace accessibility { class XAccessibleRelationSet; }
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namespace awt { class XControl; }
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namespace beans { class XPropertySet; }
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namespace beans { class XPropertySetInfo; }
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namespace beans { struct PropertyChangeEvent; }
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namespace container { struct ContainerEvent; }
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namespace lang { class XComponent; }
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namespace lang { class XTypeProvider; }
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namespace uno { class XAggregation; }
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namespace util { struct ModeChangeEvent; }
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}
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namespace comphelper
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{
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class OWrappedAccessibleChildrenManager;
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}
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namespace accessibility {
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class AccessibleShapeInfo;
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class AccessibleShapeTreeInfo;
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typedef ::cppu::ImplHelper4 < css::beans::XPropertyChangeListener
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, css::util::XModeChangeListener
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, css::container::XContainerListener
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, css::accessibility::XAccessibleEventListener
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> AccessibleControlShape_Base;
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/** @descr
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*/
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class SAL_DLLPUBLIC_RTTI AccessibleControlShape final
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:public AccessibleShape
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,public AccessibleControlShape_Base
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{
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public:
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//===== internal ========================================================
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AccessibleControlShape(
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const AccessibleShapeInfo& rShapeInfo,
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const AccessibleShapeTreeInfo& rShapeTreeInfo);
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virtual ~AccessibleControlShape( ) override;
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const css::uno::Reference< css::beans::XPropertySet >& GetControlModel( ) const { return m_xControlModel;}
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AccessibleControlShape* GetLabeledByControlShape();
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private:
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//--- XAccessibleComponent -------------------------------
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/// forward the focus to the contained control(in alive mode)
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virtual void SAL_CALL grabFocus( ) override;
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//--- XAccessibleContext ---------------------------------
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virtual sal_Int64 SAL_CALL getAccessibleChildCount( ) override;
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virtual css::uno::Reference< css::accessibility::XAccessible > SAL_CALL getAccessibleChild( sal_Int64 i ) override;
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virtual css::uno::Reference< css::accessibility::XAccessibleRelationSet > SAL_CALL getAccessibleRelationSet( ) override;
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//--- XServiceInfo ---------------------------------------
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virtual OUString SAL_CALL getImplementationName( ) override;
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//--- XInterface -----------------------------------------
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DECLARE_XINTERFACE( )
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//--- XTypeProvider --------------------------------------
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DECLARE_XTYPEPROVIDER( )
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//--- XPropertyChangeListener ----------------------------
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virtual void SAL_CALL propertyChange( const css::beans::PropertyChangeEvent& _rEvent ) override;
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//--- XComponent -----------------------------------------
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virtual void SAL_CALL disposing( ) override;
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//--- XEventListener -------------------------------------
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virtual void SAL_CALL disposing(const css::lang::EventObject& Source) override;
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//--- XModeChangeListener --------------------------------
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virtual void SAL_CALL modeChanged( const css::util::ModeChangeEvent& _rSource ) override;
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//--- XAccessibleEventListener ----------------------------
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virtual void SAL_CALL notifyEvent( const css::accessibility::AccessibleEventObject& aEvent ) override;
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// XVclContainerListener
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virtual void SAL_CALL elementInserted( const css::container::ContainerEvent& Event ) override;
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virtual void SAL_CALL elementRemoved( const css::container::ContainerEvent& Event ) override;
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virtual void SAL_CALL elementReplaced( const css::container::ContainerEvent& Event ) override;
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/** Initialize a new shape. See the documentation of the base' constructor
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for the reason of this method's existence.
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*/
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virtual void Init( ) override;
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/// Create a name string that contains the accessible name.
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virtual OUString
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CreateAccessibleBaseName( ) override;
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/** Create a unique name string that contains the accessible name. The
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name consists of the base name and the index.
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*/
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virtual OUString
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CreateAccessibleName( ) override;
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/// Create a description string that contains the accessible description.
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OUString CreateAccessibleDescription();
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#ifdef DBG_UTIL
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/// Set the specified state
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virtual bool SetState( sal_Int64 _nState ) override;
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#endif // DBG_UTIL
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/// (safely) reads the given property from the model of the UNO control
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OUString getControlModelStringProperty( const OUString& _rPropertyName ) const;
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/// ensure that our control model exists(will be retrieved upon need only)
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bool ensureControlModelAccess( );
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/// ensures that we're listening for the given property if(and only if!) necessary
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bool ensureListeningState( const bool _bCurrentlyListening, const bool _bNeedNewListening,
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const OUString& _rPropertyName );
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/// starts multiplexing the state changes of our aggregate context
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void startStateMultiplexing( );
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/// stops multiplexing the state changes of our aggregate context
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void stopStateMultiplexing( );
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/** adjusts our AccessibleRole, depending on the control type we're working for
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<p>Only to be called during initialization</p>
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*/
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void adjustAccessibleRole( );
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/** initializes composed states of the context
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<p>Some of the states of our inner context need to be propagated to the "composed context", too
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(such as "checked" for check boxes). At lifetime, this is done by multiplexing state changes,
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at initialization time, this method is used.</p>
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*/
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void initializeComposedState( );
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AccessibleControlShape(const AccessibleControlShape&) = delete;
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AccessibleControlShape& operator= (const AccessibleControlShape&) = delete;
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css::uno::Reference< css::beans::XPropertySet >
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m_xControlModel;
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css::uno::Reference< css::beans::XPropertySetInfo >
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m_xModelPropsMeta; // cache this for performance reasons
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css::uno::Reference< css::awt::XControl >
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m_xUnoControl; // our UNO control
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css::uno::WeakReference< css::accessibility::XAccessibleContext >
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m_aControlContext; // the AccessibleContext of the control
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css::uno::Reference< css::uno::XAggregation >
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m_xControlContextProxy; // the proxy for "aggregating" the AccessibleContext of the control
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css::uno::Reference< css::lang::XTypeProvider >
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m_xControlContextTypeAccess; // cached interface of our aggregate
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css::uno::Reference< css::lang::XComponent >
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m_xControlContextComponent; // cached interface of our aggregate
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rtl::Reference<::comphelper::OWrappedAccessibleChildrenManager>
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m_pChildManager;
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bool m_bListeningForName : 1; // are we currently listening for changes of the "Name" property?
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bool m_bListeningForDesc : 1; // are we currently listening for changes of the "HelpText" property?
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bool m_bMultiplexingStates : 1; // are we currently multiplexing state changes of the native context?
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bool m_bDisposeNativeContext : 1; // do we need to dispose mxNativeContextComponent?
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bool m_bWaitingForControl : 1; // if we are created before our control exists, we need to wait for it to appear ...
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};
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} // end of namespace accessibility
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#endif
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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