Re: Custom text area accessibility

Subject: Re: Custom text area accessibility
From: Patti Hoa <email@hidden>
Date: Tue, 02 Aug 2016 10:17:12 -0700

Based on symptom #1, it sounds like you have an editable text area. In this case, static text protocol is probably not what you are looking for. Instead, return NSAccessibilityTextAreaRole for the accessibilityRole

For editable text, there are two important ax notifications: NSAccessibilityValueChangedNotification & NSAccessibilitySelectedTextChangedNotification.

There are two Apple provided tools to observe notifications to see if they are fired as expected.
1. Accessibility Inspector (the new developer tool introduced with Xcode 8.0). In the app, select the app you want to inspect from the target chooser. Then select Window->Show Notifications from the menubar
2. From Terminal, run /usr/local/bin/accesstool. Type the command “targetapp <your app>” to specified the app to inspect. Then type “add observer *” to observer every ax notifications that occurs in the target app. To learn more about this command line tool, type the command “help"

And to narrow down if the problem is isolated to keyboard navigation, try your steps using VoiceOver navigation (control-option-shift down arrow to start interacting with the text area, then control-option-right/left arrow to move by word (control-option-shift-right/left arrow to move by character)

Note that you can simulate how VoiceOver sees the text via the tool /usr/local/bin/accesstool. With each keyboard arrow navigation, VoiceOver expects a NSAccessibilitySelectedTextChangedNotification. Then using a combination of the various attributes, including where the insertion point is (accessibilitySelectedTextRange), it forms what to speak.

Patti Hoa

Accessibility Team, Apple

On Aug 1, 2016, at 8:30 AM, Tim Burgess <email@hidden> wrote:

Hi,

I’m trying to add accessibility to a c++ application. There are 3 windows requiring accessibility per document:

1 - a status bar;

2 - a sort of preview bar;

3 - A document text area.

I’ve successfully added accessibility to the first two windows by writing some Objective-C++ code to provide a translation layer between c++ and the NSAccessibility properties and methods.

I’m still having trouble handling text navigation within the text area, however. Other members of this list advised me to initially attempt to get navigation working using the Navigable Static Text protocol, so I implemented support for the following:

accessibilityFrameForRange
accessibilityLineForIndex
accessibilityRangeForLine
accessibilityStringForRange

I believe that these methods are the minimum requirement for the Navigable Static Text protocol.

Additionally, with a view to being able to manipulate the text once its window’s role is set to AXTextArea, I implemented:

accessibilityEnabled
accessibilityValue
accessibilityFocused
accessibilityNumberOfCharacters
accessibilityInsertionPointLineNumber
accessibilitySelectedText
accessibilitySelectedTextRange
accessibilityVisibleCharacterRange

Testing seems to indicate that these methods are all returning sane values when used as getters.

Unfortunately, my keyboard navigation has not improved one jot. The symptoms are:

1 - Starting with a blank document and VoiceOver set to echo characters and words, the initial letter typed is announced correctly. Subsequent letters in the word start to announce themselves, but get truncated by the announcement of “space”.

2 - Pressing Space at the end of a word announces the first word in the document.

3 - Pressing left arrow or Option+left arrow works fine for navigating by previous character or word.

4 - Pressing right arrow normally works for navigating forward by character, but sometimes fails to advance and announces nothing.

5 - Pressing Option+right arrow fails to advance by word and announces nothing.

Can anybody please offer any clues as to what might be going wrong?

Best wishes.

Tim Burgess

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>Custom text area accessibility (From: Tim Burgess <email@hidden>)

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