зеркало из https://github.com/mozilla/gecko-dev.git
81 строка
3.1 KiB
ReStructuredText
81 строка
3.1 KiB
ReStructuredText
***************
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AccessibleCaret
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***************
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AccessibleCaret is a pair of raindrop shape handles at both ends of selection
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highlight, or it is a single handle at the blinking caret in a text area. It
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assists the user to change the range of the selection highlight or the position
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of the blinking caret on platforms with touch-event support.
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Meta Bug
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========
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`Bug 1124074 <https://bugzilla.mozilla.org/show_bug.cgi?id=1124074>`__ tracks all the open issues.
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Gecko implementation details
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============================
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Preferences
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-----------
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* ``layout.accessiblecaret.enabled_on_touch`` (Enabled on Firefox with touch-event support since 51.)
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* ``layout.accessiblecaret.enabled`` (Defaults off, but it can be turn on to force enable AccessibleCaret.)
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* ``layout.accessiblecaret.hide_carets_for_mouse_input`` (Defaults on. Turn
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this on to debug AccessibleCaret on desktop browser with mouse events.)
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AccessibleCaretEventHub State Transition Diagram
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------------------------------------------------
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This diagram depicts the state transition of the state machine in
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AccessibleCaretEventHub, which handles external events and callbacks.
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Note that the diagram omits some callbacks which do not cause a state transition
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such as ``NotifySelectionChanged`` or ``Reflow``.
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This table is a mapping of the real events and callback to the actions described
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on the edge of the diagram:
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+---------------------------------------------------+--------------+
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| Real events or callbacks | Actions |
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+===================================================+==============+
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| ``eMouseDown`` or ``eTouchStart`` | Press |
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+---------------------------------------------------+--------------+
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| ``eMouseMove`` or ``eTouchMove`` | Move |
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+---------------------------------------------------+--------------+
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| ``eMouseUp`` or ``eTouchEnd`` or ``eTouchCancel`` | Release |
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+---------------------------------------------------+--------------+
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| ``eMouseLongTap`` | Long tap |
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+---------------------------------------------------+--------------+
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| ``AsyncPanZoomStarted()`` | Scroll start |
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+---------------------------------------------------+--------------+
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| ``AsyncPanZoomStopped()`` | Scroll end |
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+---------------------------------------------------+--------------+
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| ``NotifyBlur()`` | Blur |
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+---------------------------------------------------+--------------+
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.. image:: AccessibleCaretEventHubStates.png
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Debug Tips
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----------
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* Dump AccessibleCaret log from command line: run ``MOZ_LOG=AccessibleCaret:5 ./mach run``.
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* Dump AccessibleCaret log by using a preference: Open ``about:config`` and add a pref ``logging.AccessibleCaret`` with value ``debug`` or ``verbose`` (case matters).
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* ``AC_LOG()`` is useful to add new logs.
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Developers
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==========
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Current maintainer
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------------------
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* Ting-Yu Lin <aethanyc@gmail.com>
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Developers Emeritus
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-------------------
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* Morris Tseng <mtseng@mozilla.com>
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* Jeremy Chen <jeremychen@mozilla.com>
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* Boris Chiou <boris@mozilla.com>*
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