**The Basics of Accessibility**
- [What is a User Interaction Automation (UIA) Tree?](https://docs.microsoft.com/en-us/dotnet/framework/ui-automation/ui-automation-tree-overview)
- Other projects (i.e.: Narrator) can take advantage of this UIA tree and are used to present information within it.
- Some things like XAML already have a UIA Tree. So some UIA tree navigation and features are already there. It's just a matter of getting them hooked up and looking right.
**Accessibility in our Project**
There's a few important classes...
regarding Accessibility...
- **WindowUiaProvider**: This sets up the UIA tree for a window. So this is the top-level for the UIA tree.
- **ScreenInfoUiaProvider**: This sets up the UIA tree for a terminal buffer.
- **UiaTextRange**: This is essential to interacting with the UIA tree for the terminal buffer. Actually gets portions of the buffer and presents them.
regarding the Windows Terminal window...
- **BaseWindow**: The foundation to a window. Deals with HWNDs and that kind of stuff.
- **IslandWindow**: This extends `BaseWindow` and is actually what holds our Windows Terminal
- **NonClientIslandWindow**: An extension of the `IslandWindow`
regarding ConHost...
- **IConsoleWindow**: This is an interface for the console window.
- **Window**: This is the actual window for ConHost. Extends `IConsoleWindow`
- `IConsoleWindow` changes:
- move into `Microsoft::Console::Types` (a shared space)
- Have `IslandWindow` extend it
- `WindowUiaProvider` changes:
- move into `Microsoft::Console::Types` (a shared space)
- Hook up `WindowUiaProvider` to IslandWindow (yay! we now have a tree)
### Changes to the WindowUiaProvider
As mentioned earlier, the WindowUiaProvider is the top-level UIA provider for our projects. To reuse as much code as possible, I created `Microsoft::Console::Types::WindowUiaProviderBase`. Any existing functions that reference a `ScreenInfoUiaProvider` were virtual-ized.
In each project, a `WindowUiaProvider : WindowUiaProviderBase` was created to define those virtual functions. Note that that will be the main difference between ConHost and Windows Terminal moving forward: how many TextBuffers are on the screen.
So, ConHost should be the same as before, with only one `ScreenInfoUiaProvider`, whereas Windows Terminal needs to (1) update which one is on the screen and (2) may have multiple on the screen.
🚨 Windows Terminal doesn't have the `ScreenInfoUiaProvider` hooked up yet. We'll have all the XAML elements in the UIA tree. But, since `TermControl` is a custom XAML Control, I need to hook up the `ScreenInfoUiaProvider` to it. This work will be done in a new PR and resolve GitHub Issue #1352.
### Moved to `Microsoft::Console::Types`
These files got moved to a shared area so that they can be used by both ConHost and Windows Terminal.
This means that any references to the `ServiceLocator` had to be removed.
- `IConsoleWindow`
- Windows Terminal: `IslandWindow : IConsoleWindow`
- `ScreenInfoUiaProvider`
- all references to `ServiceLocator` and `SCREEN_INFORMATION` were removed. `IRenderData` was used to accomplish this. Refer to next section for more details.
- `UiaTextRange`
- all references to `ServiceLocator` and `SCREEN_INFORMATION` were removed. `IRenderData` was used to accomplish this. Refer to next section for more details.
- since most of the functions were `static`, that means that an `IRenderData` had to be added into most of them.
### Changes to IRenderData
Since `IRenderData` is now being used to abstract out `ServiceLocator` and `SCREEN_INFORMATION`, I had to add a few functions here:
- `bool IsAreaSelected()`
- `void ClearSelection()`
- `void SelectNewRegion(...)`
- `HRESULT SearchForText(...)`
`SearchForText()` is a problem here. The overall new design is great! But Windows Terminal doesn't have a way to search for text in the buffer yet, whereas ConHost does. So I'm punting on this issue for now. It looks nasty, but just look at all the other pretty things here. :)
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