Make ScreenInfoUiaProvider::GetSelection() Return One Selection

[carlos-zamora]

Summary of the Pull Request

We used to return multiple text ranges to represent one selection. We only support one selection at a time, so we should only return one range.

Additionally, I moved all TriggerSelection() calls to the renderer from Terminal to TermControl for consistency. This ensures we only call it once when we make a change to our selection state.

References

#2447 - helps polish Signaling for Selection
#4465 - This is more apparent as the problem holding back Signaling for Selection

PR Checklist

• Closes ScreenInfoUiaProvider::GetSelection() returns an improper result #4452

Tested using Accessibility Insights.

[DHowett-MSFT]

What does the renderer do if its only job, to signal, has been murdered?

[carlos-zamora]

What does the renderer do if its only job, to signal, has been murdered?

Ah. That's not the case. Selection is the easiest to explain so I'll do that route.

When we get a change in selection and we're rendering the new selection, UiaRenderer identifies that we need to fire an event. And it does so.

In the case of selection, the UIA Client (i.e.: Narrator) then calls GetSelection(). And that's how it knows what exactly is selected at this time.

So UiaRenderer still has an important job. And what makes other UIA Events harder is that the event doesn't map directly to an API call ☹

[ghost]

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