| Accessibility |
| ============= |
| |
| iOS and Android accessibility APIs want to synchronously communicate |
| with the main thread, so we need to ship a description of the UI to a |
| service on the main thread, from our Dart thread. |
| |
| On the Dart side, we need a RenderAccessibleBox on the render tree, |
| which can be configured with all the various things the accessibility |
| APIs might care about (e.g. accessible name, checkedness, etc). |
| Separate from the layout and paint phases we have a phase that builds |
| an accessibility tree and sends it over to the aforementioned thread. |
| When a RenderAccessibleBox's configuration changes, it updates the |
| main thread also. |
| |
| Maybe RenderParagraph also participates in this so that all text is |
| automatically exposed. |
| |
| The main thread can send events like "activate" or "increment slider" |
| back to a RenderAccessibleBox, which should expose them somehow. |
| |
| On the Widget side we'd have an Accessible widget that is a |
| OneChildRenderNodeWrapper for RenderAccessibleBox and does what you'd |
| expect, maybe also exposing the callbacks. |
| |
| Components would wrap their interactive parts with these Accessible |
| widgets. |
| |
| Ideally we'd have a way to make the default "activate" action |
| automatically turn into a "tap" gesture. |
