可访问性

介绍

Accessibility in computer software is making applications usable for people with different abilities. It is important to take different people's needs into account, for example, in case of low vision, hearing, dexterity, or cognitive problems. Some examples of accessibility measures are keyboard shortcuts, a high-contrast user interface that uses specially selected colors and fonts, or support for assistive tools such as screen readers and braille displays.

任何应用程序都应瞄准的基本清单：

Usability - Usability and user centric design generally lead to more usable applications, including improvements for people with various abilities.
字体 - Font settings should follow the system/platform. This allows users to select fonts for readability and increasing the font size.
Colors - Provide enough contrast and consider the most common cases of low vision and color blindness. Make sure that the application is usable, for example, for people with red/green blindness, and don't depend on colors only.
Scalable UI - A user interface that works in various sizes and properly supports different fonts and accommodates size changes.
Sounds - Do not exclusively rely on sound notifications, provide a visual alternative when a sound signal is imperative to using the application.
Spelling - Offer spell checking wherever it makes sense, even when only a single word is expected.
Assistive Technology - Support the use of assistive tools (AT). Either use standard widgets/controls which support ATs out of the box, or make sure that your custom widgets and controls support accessibility properly. In order to learn more about this read on below.

This part of the documentation assumes that the basics for accessibility, which go hand in hand with usability, are already in good shape. The rest of this document focuses more specifically on supporting assistive technology.

Assistive Tools (or ATs) come in great variety and help users with different tasks. For this reason what individual applications offer (with the help of Qt) is a generic API that allows to inspect what is on screen in a semantic way and offers the typical interactions with the UI elements.

Applications do not usually communicate directly with the assistive tools, but through a platform specific API. Generally the communication with the ATs works though an IPC mechanism. Semantic information about user interface elements, such as buttons and scroll bars, is exposed to the assistive technologies. Qt supports Microsoft Active Accessibility (MSAA) and IAccessible2 on Windows, macOS Accessibility on macOS, and AT-SPI via DBus on Unix/X11. The platform specific technologies are abstracted by Qt, so that applications do not need any platform specific changes to work with the different native APIs. Qt tries to make adding accessibility support to your application as easy as possible, only a few changes from your side may be required to allow even more users to enjoy it.

The main reason to consult this documentation is to learn how to make custom QWidget subclasses and QQuickItem s accessible.

In this overview document, we will examine the overall Qt accessibility architecture, and how to implement accessibility for custom widgets and elements.

使应用程序可访问

这 2 页面聚焦于给出如何取得良好可达性的概述：

QWidget 应用程序的可访问性

Qt Quick 应用程序的可访问性

这些类为可访问应用程序提供支持：

QAccessible	与可访问性相关的枚举和静态函数
QAccessibleActionInterface	Implements support for invocable actions in the interface
QAccessibleEditableTextInterface	实现对具有可编辑文本的对象的支持
QAccessibleEvent	用于可访问性通知的基类
QAccessibleImageInterface	Implements support for the IAccessibleImage interface
QAccessibleInterface	定义暴露有关可访问对象的信息的接口
QAccessibleStateChangeEvent	通知可访问性框架对象的状态已改变
QAccessibleTableCellInterface	实现对 IAccessibleTable2 单元格接口的支持
QAccessibleTableInterface	Implements support for the IAccessibleTable2 interface
QAccessibleTableModelChangeEvent	表示表格、列表或树中添加或移除单元格的变化。若改变影响多行，firstColumn 和 lastColumn 将返回 -1。同样，对于列，行函数可能返回 -1
QAccessibleTextCursorEvent	光标移动的通知
QAccessibleTextInsertEvent	正在插入文本的通知
QAccessibleTextInterface	实现对文本处理的支持
QAccessibleTextRemoveEvent	正被删除文本的通知
QAccessibleTextSelectionEvent	对象文本选定改变的信号
QAccessibleTextUpdateEvent	有关文本改变的通知。这用于支持可编辑文本 (譬如：行编辑) 的可访问。例如，此事件发生，当选中文本的一部分被粘贴新文本或在编辑器覆盖模式下被替换时。
QAccessibleValueChangeEvent	描述可访问对象的值改变
QAccessibleValueInterface	实现对操纵值对象的支持
QAccessibleObject	为 QObjects 实现 QAccessibleInterface 部分
QAccessiblePlugin	为用户界面元素提供可访问性信息的插件的抽象基类
QPlatformAccessibility	The base class for integrating accessibility backends
QAccessibleWidget	为 QWidgets 实现 QAccessibleInterface
Accessible	启用 QML 项的可访问性