loongoffice/include/svx/AccessibleTextHelper.hxx

/* -*- 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 .
 */

#ifndef INCLUDED_SVX_ACCESSIBLETEXTHELPER_HXX
#define INCLUDED_SVX_ACCESSIBLETEXTHELPER_HXX

#include <memory>
#include <vector>

#include <com/sun/star/uno/Reference.hxx>
#include <sal/types.h>
#include <svx/svxdllapi.h>

namespace com::sun::star
{
namespace accessibility
{
class XAccessible;
}
namespace accessibility
{
class XAccessibleEventListener;
}
namespace awt
{
struct Point;
}
}

class Point;
class SvxEditSource;

namespace accessibility
{
class AccessibleTextHelper_Impl;

/** Helper class for objects containing EditEngine/Outliner text

    This class provides the methods from the XAccessibleContext,
    XAccessibleEventBroadcaster and XAccessibleComponent
    interfaces, that are common to all accessible objects
    containing an edit engine.

    The text contained in the EditEngine/Outliner is presented as
    children of this class, namely for every text paragraph a
    AccessibleEditableTextPara child object is generated. As this
    class manages these children for itself, it has to send out
    AccessibleEventId::CHILD events on your
    behalf. Thus, you must forward every call to your
    addEventListener()/removeEventListener() methods to the
    AccessibleTextHelper (methods
    AddEventListener/RemoveEventListener), otherwise none or not
    everyone of your event listener will notice child changes.

    You have to implement the SvxEditSource, SvxTextForwarder,
    SvxViewForwarder and SvxEditViewForwarder interfaces in order
    to enable your object to cooperate with this
    class. SvxTextForwarder encapsulates the fact that text
    objects do not necessarily have an EditEngine at their
    disposal, SvxViewForwarder and SvxEditViewForwarder do the
    same for the document and the edit view. The three mentioned
    forwarder objects are not stored by the AccessibleTextHelper,
    but fetched every time from the SvxEditSource. So you are best
    off making your SvxEditSource::Get*Forwarder methods cache the
    current forwarder.

    To support changes in edit mode or conversion of fixed text
    into EditEngine text, you can change the SvxEditSource this
    class is referring to. This might render all children invalid
    and change the child count, since the AccessibleTextHelper
    reinitializes itself from scratch.

    This class registers itself at the SvxEditSource as a state
    listener and manages the state of its children (i.e. the
    paragraphs). See the method documentation of
    AccessibleTextHelper::SetEditSource for the expected
    events. Generally, be prepared that when sending any of these
    events via SvxEditSource::GetBroadcaster() broadcaster, the
    AccessibleTextHelper will call the SvxEditSource and their
    forwarder to update it's state. Avoid being inconsistent in
    the facts you tell in the events, e.g. when sending a
    SfxHintId::TextParaInserted event, the
    SvxEditSource::GetTextForwarder().GetParagraphCount() should
    already include the newly inserted paragraph.

    @attention All public methods must not be called with any
    mutex hold, except when calling from the main thread (with
    holds the solar mutex), unless stated otherwise. This is
    because they themselves might need the solar mutex in addition
    to the object mutex, and the ordering of the locking must be:
    first solar mutex, then object mutex. Furthermore, state
    change events might be fired internally.

    @derive Use this class in an aggregation and forward, or
    derive from it and overwrite.
    too.

    @see SvxEditSource
    @see SvxTextForwarder
    @see SvxViewForwarder
    @see SvxEditViewForwarder
*/
class SVX_DLLPUBLIC AccessibleTextHelper final
{
public:
    typedef ::std::vector<sal_Int16> VectorOfStates;

    /** Create accessible text object for given edit source

        @param pEditSource
        The edit source to use. Object ownership is transferred
        from the caller to the callee. The object listens on the
        SvxEditSource for object disposal, so no provisions have
        to be taken if the caller destroys the data (e.g. the
        model) contained in the given SvxEditSource.

    */
    explicit AccessibleTextHelper(::std::unique_ptr<SvxEditSource>&& pEditSource);

    ~AccessibleTextHelper();

    AccessibleTextHelper(const AccessibleTextHelper&) = delete;
    AccessibleTextHelper& operator=(const AccessibleTextHelper&) = delete;

    /** Query the current edit source

        @attention This method returns by reference, so you are
        responsible for serialization (typically, you acquired the
        solar mutex when calling this method). Thus, the method
        should only be called from the main office thread.

    */
    const SvxEditSource& GetEditSource() const;

    /** Set the current edit source

        @attention Might fire state change events, therefore,
        don't hold any mutex except solar mutex, which you are
        required to lock before. This method should only be called
        from the main office thread.

        The EditSource set here is required to broadcast out the
        following hints: SfxHintId::EditSourceParasMoved,
        SfxHintId::EditSourceSelectionChanged, SfxHintId::TextModified,
        SfxHintId::TextParaInserted, SfxHintId::TextParaRemoved,
        SfxHintId::TextHeightChanged,
        SfxHintId::TextViewScrolled. Otherwise, not all state changes
        will get noticed by the accessibility object. Further
        more, when the corresponding core object or the model is
        dying, either the edit source must be set to NULL or it
        has to broadcast a SfxHintId::Dying hint.

        If the SvxEditSource's managed text can change between
        edit/non-edit mode (i.e. there are times when
        SvxEditSource::GetEditViewForwarder(sal_False) returns
        NULL), then the two additional hints are required:
        SdrHintKind::BeginEdit and SdrHintKind::EndEdit. When the
        AccessibleTextHelper receives a SdrHintKind::BeginEdit, it expects
        the SvxEditSource already in edit mode. On a SdrHintKind::EndEdit,
        edit mode must already been left. The rationale for these
        events are the fact that focus and selection have to be
        updated in edit mode, and completely relinquished and
        reset to the parent (for the focus) in non-edit mode.

        This class does not have a dispose method, since it is not
        a UNO component. Nevertheless, it holds C++ references to
        several core objects, so you should issue a
        SetEditSource(::std::unique_ptr<SvxEditSource>()) in
        your dispose() method.

        @param pEditSource
        The new edit source to set. Object ownership is transferred
        from the caller to the callee.
    */
    void SetEditSource(::std::unique_ptr<SvxEditSource>&& pEditSource);

    /** Set the event source

        You should set the event source before registering any
        event listener and before requesting any child. Children
        of this object receive the event source as their parent
        accessible object. That is, the event source is best set
        in your object's init method.

        @attention When setting a reference here, you should call
        Dispose() when you as the owner are disposing, since until
        then this object will hold that reference

        @param rInterface
        The interface that should be set as the source for
        accessibility events sent by this object.
    */
    void SetEventSource(const css::uno::Reference<css::accessibility::XAccessible>& rInterface);

    /** Set offset of EditEngine/Outliner from parent

        If the origin of the underlying EditEngine/Outliner does
        not correspond to the upper left corner of the object
        using this class, you have to specify the offset.

        @attention Might fire state change events, therefore,
        don't hold any mutex except solar mutex, which you are
        required to lock before. This method should only be called
        from the main office thread.

        @param rPoint
        The offset in screen coordinates (i.e. pixel)
    */
    void SetOffset(const Point& rPoint);

    /** Set offset the object adds to all children's indices

        This can be used if the owner of this object has children
        handled by itself. Setting an offset different from 0
        leads to this object mimicking that all its children are
        within the range [nOffset, GetChildCount()+nOffset). That
        means, GetChild() also expects the index to be in this
        range.

        @attention Might fire state change events, therefore,
        don't hold any mutex except solar mutex, which you are
        required to lock before. This method should only be called
        from the main office thread.

        @param nOffset
        The offset to add to every children's index.
    */
    void SetStartIndex(sal_Int32 nOffset);

    /** Query offset the object adds to all children's indices

        @return the offset to add to every children's index.
    */
    sal_Int32 GetStartIndex() const;

    /** Sets a bitset of additional accessible states.

        The states are passed to every created child object
        (text paragraph). The state values are defined in
        css::accessibility::AccessibleStateType.

        This function has to be called before querying for
        any children (e.g. with GetChild()).
    */
    void SetAdditionalChildStates(sal_Int64 rChildStates);

    /** Update the visible children

        @attention Might fire state change events, therefore,
        don't hold any mutex except solar mutex, which you are
        required to lock before. This method should only be called
        from the main office thread.

        This method reevaluates the visibility of all
        children. Call this method if your visibility state has
        changed somehow, e.g. if the visible area has changed and
        the AccessibleTextHelper isn't notified internally
        (e.g. via SfxHintId::TextViewScrolled). Normally, there should
        not be a need to call this method.
    */
    void UpdateChildren();

    /** Drop all references and enter disposed state

        This method drops all references to external objects (also
        the event source reference set via SetEventSource()) and
        sets the object into the disposed state (i.e. the methods
        return default values or throw a uno::DisposedException
        exception).
    */
    void Dispose();

    /** Set the focus state of the accessibility object

        Since this class handles children which also might get the
        focus, the user of this class is encouraged to delegate
        focus handling. Whenever the focus state of the
        surrounding object changes, this method has to be called.

        The protocol of focus handling for a user of this class is
        then to call SetFocus() with the appropriate focus state,
        and HaveFocus() to determine the focus state you tell the
        outside.

        @attention Might fire state change events, therefore,
        don't hold any mutex except solar mutex, which you are
        required to lock before. This method should only be called
        from the main office thread.

        @param bHaveFocus
        Whether we got or we lost the focus. Set to true if
        focus is gotten, false otherwise.

        @see HaveFocus()
    */
    void SetFocus(bool bHaveFocus = true);

    /** Query the focus state of the surrounding object

        If focus handling is delegated to this class, determine
        focus state with this method. Be prepared that even if you
        set the focus with SetFocus(true), this method might
        return false. This is the case if one of the children
        actually got the focus.

        @return the state of the focus ownership
    */
    bool HaveFocus();

    // XAccessibleContext child handling methods

    /** Implements getAccessibleChildCount

        @attention Don't call with locked mutexes. You may hold
        the solar mutex, but this method acquires it anyway.
    */
    sal_Int64 GetChildCount() const;
    /** Implements getAccessibleChild

        @attention Don't call with locked mutexes. You may hold
        the solar mutex, but this method acquires it anyway.
    */
    css::uno::Reference<css::accessibility::XAccessible> GetChild(sal_Int64 i);

    // XAccessibleEventBroadcaster child related methods

    /** Implements addEventListener

        @attention Don't call with locked mutexes
    */
    void AddEventListener(
        const css::uno::Reference<css::accessibility::XAccessibleEventListener>& xListener);
    /** Implements removeEventListener

        @attention Don't call with locked mutexes
    */
    void RemoveEventListener(
        const css::uno::Reference<css::accessibility::XAccessibleEventListener>& xListener);

    // XAccessibleComponent child related methods

    /** Implements getAccessibleAt

        @attention Don't call with locked mutexes. You may hold
        the solar mutex, but this method acquires it anyway.
    */
    css::uno::Reference<css::accessibility::XAccessible> GetAt(const css::awt::Point& aPoint);

private:
    /// @dyn
    const std::unique_ptr<AccessibleTextHelper_Impl> mpImpl;
};

} // end of namespace accessibility

#endif // INCLUDED_SVX_ACCESSIBLETEXTHELPER_HXX

/* vim:set shiftwidth=4 softtabstop=4 expandtab: */