gecko-dev/accessible/base/SelectionManager.h
James Teh 38e692da86 Bug 1905211 part 7: Notify accessibility about ranges that are added or removed from selections. r=smaug,morgan
nsISelectionListener isn't sufficient because it only notifies that the selection has changed.
A11y needs to know specifically which ranges were added or removed.
Previously, we handled this specifically for spelling errors in mozInlineSpellChecker.
That code has been removed and replaced with a more general approach.

Since we now have these notifications, rather than using nsISelectionListener just to fire events, we now use these notifications for that as well.
This avoids the need to add additional nsISelectionListeners, which would get messy particularly for custom highlights where there can be an arbitrary number of selections at any given time.

Differential Revision: https://phabricator.services.mozilla.com/D217068
2024-08-05 02:54:37 +00:00

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
#ifndef mozilla_a11y_SelectionManager_h__
#define mozilla_a11y_SelectionManager_h__
#include "nsISelectionController.h"
#include "nsISelectionListener.h"
#include "mozilla/WeakPtr.h"
namespace mozilla {
class PresShell;
namespace dom {
class AbstractRange;
class Element;
class Selection;
} // namespace dom
namespace a11y {
class AccEvent;
class HyperTextAccessible;
/**
* This special accessibility class is for the caret and selection management.
* There is only 1 visible caret per top level window. However, there may be
* several visible selections.
*
* The important selections are the one owned by each document, and the one in
* the currently focused control.
*
* On Windows this class is used to move an invisible system caret that
* shadows the Mozilla caret. Windows will also automatically map this to
* the MSAA caret accessible object (via OBJID_CARET) (as opposed to the root
* accessible tree for a window which is retrieved with OBJID_CLIENT).
*
* For ATK and IAccessible2, this class is used to fire caret move and
* selection change events.
*/
struct SelData;
class SelectionManager : public nsISelectionListener {
public:
// nsISupports
// implemented by derived nsAccessibilityService
// nsISelectionListener
NS_DECL_NSISELECTIONLISTENER
// SelectionManager
void Shutdown() { ClearControlSelectionListener(); }
/**
* Listen to selection events on the focused control.
*
* Note: only one control's selection events are listened to at a time. This
* will remove the previous control's selection listener.
*/
void SetControlSelectionListener(dom::Element* aFocusedElm);
/**
* Stop listening to selection events on the control.
*/
void ClearControlSelectionListener();
/**
* Listen to selection events on the document.
*/
void AddDocSelectionListener(PresShell* aPresShell);
/**
* Stop listening to selection events for a given document
*/
void RemoveDocSelectionListener(PresShell* aPresShell);
/**
* Process delayed event, results in caret move and text selection change
* events.
*/
void ProcessTextSelChangeEvent(AccEvent* aEvent);
/**
* Gets the current caret offset/hypertext accessible pair. If there is no
* current pair, then returns -1 for the offset and a nullptr for the
* accessible.
*/
inline HyperTextAccessible* AccessibleWithCaret(int32_t* aCaret) {
if (aCaret) *aCaret = mCaretOffset;
return mAccWithCaret;
}
/**
* Update caret offset when it doesn't go through a caret move event.
*/
inline void UpdateCaretOffset(HyperTextAccessible* aItem, int32_t aOffset) {
mAccWithCaret = aItem;
mCaretOffset = aOffset;
}
inline void ResetCaretOffset() {
mCaretOffset = -1;
mAccWithCaret = nullptr;
}
/**
* Called by DOM when a selection range is added/removed.
* We need this because nsISelectionListener isn't sufficient for spelling
* errors, etc., since it only tells us that there was a change, not which
* range changed. We don't want to unnecessarily push a cache update for all
* Accessibles in the entire selection.
* Returns false if these notifications aren't required for this selection
* type at this time.
*/
static bool SelectionRangeChanged(SelectionType aType,
const dom::AbstractRange& aRange);
~SelectionManager();
protected:
SelectionManager();
/**
* Process DOM selection change. Fire selection and caret move events.
*/
void ProcessSelectionChanged(SelData* aSelData);
private:
// Currently focused control.
int32_t mCaretOffset;
HyperTextAccessible* mAccWithCaret;
WeakPtr<dom::Selection> mCurrCtrlNormalSel;
};
} // namespace a11y
} // namespace mozilla
#endif