206543c7be
With 16k column support in Calc enabled by default in
commit 4c5f8ccf0a
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>
233 lines
11 KiB
C++
233 lines
11 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_EDITENG_ACCESSIBLESTATICTEXTBASE_HXX
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#define INCLUDED_EDITENG_ACCESSIBLESTATICTEXTBASE_HXX
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#include <memory>
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#include <tools/gen.hxx>
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#include <cppuhelper/implbase2.hxx>
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#include <com/sun/star/uno/Reference.hxx>
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#include <com/sun/star/accessibility/AccessibleScrollType.hpp>
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#include <com/sun/star/accessibility/XAccessibleText.hpp>
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#include <com/sun/star/accessibility/XAccessibleTextAttributes.hpp>
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#include <com/sun/star/accessibility/TextSegment.hpp>
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#include <editeng/editengdllapi.h>
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namespace com::sun::star::accessibility { class XAccessible; }
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class SvxEditSource;
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namespace accessibility
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{
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class AccessibleStaticTextBase_Impl;
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typedef ::cppu::ImplHelper2<
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css::accessibility::XAccessibleText,
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css::accessibility::XAccessibleTextAttributes > AccessibleStaticTextBase_BASE;
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/** Helper class for objects containing EditEngine/Outliner text
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This class implements the XAccessibleText interface for static
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text, somewhat similar to the children of the
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AccessibleTextHelper class. Currently, there are no children,
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i.e. the whole text is presented in one big chunk. This might
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change in the future, if a need for image bullets should
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arise. These, by convention, would be represented as children
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of the text.
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You have to implement the SvxEditSource, SvxTextForwarder,
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SvxViewForwarder and SvxEditViewForwarder interfaces in order
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to enable your object to cooperate with this
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class. SvxTextForwarder encapsulates the fact that text
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objects do not necessarily have an EditEngine at their
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disposal, SvxViewForwarder and SvxEditViewForwarder do the
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same for the document and the edit view. The three mentioned
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forwarder objects are not stored by the AccessibleTextHelper,
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but fetched every time from the SvxEditSource. So you are best
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off making your SvxEditSource::Get*Forwarder methods cache the
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current forwarder.
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As this class is intended for static (i.e. non-changing) text
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only, no event broadcasting is necessary. You must handle
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visibility by yourself, the bounding boxes returned by
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getCharacterBounds() are relative to your accessibility
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object.
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@attention All public non-UNO methods (those are the uppercase
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ones) must not be called with any mutex hold, except when
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calling from the main thread (with holds the solar mutex),
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unless stated otherwise. This is because they themselves might
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need the solar mutex in addition to the object mutex, and the
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ordering of the locking must be: first solar mutex, then
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object mutex. Furthermore, state change events might be fired
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internally.
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@derive Use this class as a base for objects containing static
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edit engine text. To avoid overwriting every interface method
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to intercept derived object defunc state, just set NULL as the
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edit source. Every interface method will then properly throw
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an exception.
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*/
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class EDITENG_DLLPUBLIC AccessibleStaticTextBase : public AccessibleStaticTextBase_BASE
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{
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public:
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/** Create accessible text object for given edit source
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@param pEditSource
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The edit source to use. Object ownership is transferred
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from the caller to the callee. The object listens on the
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SvxEditSource for object disposal, so no provisions have
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to be taken if the caller destroys the data (e.g. the
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model) contained in the given SvxEditSource.
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*/
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explicit AccessibleStaticTextBase( ::std::unique_ptr< SvxEditSource > && pEditSource );
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virtual ~AccessibleStaticTextBase();
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private:
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AccessibleStaticTextBase( const AccessibleStaticTextBase& ) = delete;
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AccessibleStaticTextBase& operator= ( const AccessibleStaticTextBase& ) = delete;
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public:
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/** Set the current edit source
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@attention You are required to have the solar mutex
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locked, when calling this method. Thus, the method should
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only be called from the main office thread.
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The EditSource set here is required to broadcast out the
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following hints: SfxHintId::EditSourceParasMoved,
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SfxHintId::EditSourceSelectionChanged, SfxHintId::TextModified,
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SfxHintId::TextParaInserted, SfxHintId::TextParaRemoved,
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SfxHintId::TextHeightChanged,
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SfxHintId::TextViewScrolled. Otherwise, not all state changes
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will get noticed by the accessibility object. Further
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more, when the corresponding core object or the model is
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dying, either the edit source must be set to NULL or it
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has to broadcast a SfxHintId::Dying hint.
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This class does not have a dispose method, since it is not
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a UNO component. Nevertheless, it holds C++ references to
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several core objects, so you should issue a
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SetEditSource(::std::unique_ptr<SvxEditSource>()) in
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your dispose() method.
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@param pEditSource
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The new edit source to set. Object ownership is transferred
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from the caller to the callee.
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*/
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void SetEditSource( ::std::unique_ptr< SvxEditSource > && pEditSource );
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/** Set the event source
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@attention When setting a reference here, you should call
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Dispose() when you as the owner are disposing, since until
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then this object will hold that reference
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@param rInterface
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The interface that should be set as the source for
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accessibility events sent by this object.
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*/
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void SetEventSource( const css::uno::Reference< css::accessibility::XAccessible >& rInterface );
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/** Set offset of EditEngine from parent
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@attention You are required to have the solar mutex
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locked, when calling this method. Thus, the method should
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only be called from the main office thread.
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If the origin of the underlying EditEngine does
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not correspond to the upper left corner of the object
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using this class, you have to specify the offset.
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@param rPoint
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The offset in screen coordinates (i.e. pixel)
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*/
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void SetOffset( const Point& rPoint );
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/** Drop all references and enter disposed state
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This method drops all references to external objects (also
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the event source reference set via SetEventSource()) and
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sets the object into the disposed state (i.e. the methods
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return default values or throw a uno::DisposedException
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exception).
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*/
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void Dispose();
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// XAccessibleText interface implementation
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virtual sal_Int32 SAL_CALL getCaretPosition() override;
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virtual sal_Bool SAL_CALL setCaretPosition( sal_Int32 nIndex ) override;
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virtual sal_Unicode SAL_CALL getCharacter( sal_Int32 nIndex ) override;
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virtual css::uno::Sequence< css::beans::PropertyValue > SAL_CALL getCharacterAttributes( sal_Int32 nIndex, const css::uno::Sequence< OUString >& aRequestedAttributes ) override;
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virtual css::awt::Rectangle SAL_CALL getCharacterBounds( sal_Int32 nIndex ) override;
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virtual sal_Int32 SAL_CALL getCharacterCount() override;
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virtual sal_Int32 SAL_CALL getIndexAtPoint( const css::awt::Point& aPoint ) override;
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virtual OUString SAL_CALL getSelectedText() override;
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virtual sal_Int32 SAL_CALL getSelectionStart() override;
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virtual sal_Int32 SAL_CALL getSelectionEnd() override;
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/// This will only work with a functional SvxEditViewForwarder, i.e. an EditEngine/Outliner in edit mode
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virtual sal_Bool SAL_CALL setSelection( sal_Int32 nStartIndex, sal_Int32 nEndIndex ) override;
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virtual OUString SAL_CALL getText() override;
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virtual OUString SAL_CALL getTextRange( sal_Int32 nStartIndex, sal_Int32 nEndIndex ) override;
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/// Does not support AccessibleTextType::SENTENCE (missing feature in EditEngine)
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virtual css::accessibility::TextSegment SAL_CALL getTextAtIndex( sal_Int32 nIndex, sal_Int16 aTextType ) override;
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/// Does not support AccessibleTextType::SENTENCE (missing feature in EditEngine)
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virtual css::accessibility::TextSegment SAL_CALL getTextBeforeIndex( sal_Int32 nIndex, sal_Int16 aTextType ) override;
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/// Does not support AccessibleTextType::SENTENCE (missing feature in EditEngine)
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virtual css::accessibility::TextSegment SAL_CALL getTextBehindIndex( sal_Int32 nIndex, sal_Int16 aTextType ) override;
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/// This will only work with a functional SvxEditViewForwarder, i.e. an EditEngine/Outliner in edit mode
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virtual sal_Bool SAL_CALL copyText( sal_Int32 nStartIndex, sal_Int32 nEndIndex ) override;
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virtual sal_Bool SAL_CALL scrollSubstringTo( sal_Int32 nStartIndex, sal_Int32 nEndIndex, css::accessibility::AccessibleScrollType aScrollType) override;
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// XAccessibleTextAttributes
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virtual css::uno::Sequence< css::beans::PropertyValue > SAL_CALL getDefaultAttributes( const css::uno::Sequence< OUString >& RequestedAttributes ) override;
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virtual css::uno::Sequence< css::beans::PropertyValue > SAL_CALL getRunAttributes( sal_Int32 Index, const css::uno::Sequence< OUString >& RequestedAttributes ) override;
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// child-related methods from XAccessibleContext
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/// @throws css::uno::RuntimeException
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virtual sal_Int64 SAL_CALL getAccessibleChildCount();
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/// @throws css::lang::IndexOutOfBoundsException
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/// @throws css::uno::RuntimeException
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virtual css::uno::Reference< css::accessibility::XAccessible > SAL_CALL getAccessibleChild( sal_Int64 i );
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// child-related methods from XAccessibleComponent
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/// @throws css::uno::RuntimeException
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virtual css::uno::Reference< css::accessibility::XAccessible > SAL_CALL getAccessibleAtPoint( const css::awt::Point& aPoint );
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protected:
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tools::Rectangle GetParagraphBoundingBox() const;
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private:
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/// @dyn
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const std::unique_ptr< AccessibleStaticTextBase_Impl > mpImpl;
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};
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} // end of namespace accessibility
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#endif // INCLUDED_EDITENG_ACCESSIBLESTATICTEXTBASE_HXX
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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