c69834e65a
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* Fix [the Samsung Keyboard Korean Cheonjiin layout
bug](https://github.com/emilk/egui/pull/7967#issuecomment-4098503570)
* Partially fix (does not close) #8046
* Supersedes #7914
* Supersedes #8047
* Related: #8068
* Related: #7983
* Related: #8078
* [x] I have followed the instructions in the PR template
This PR reworks the text input handling logic in eframe's web
integration, primarily in `text_agent.rs`.
It also adds a new `ImeEvent::DeleteSurrounding` variant, along with the
corresponding handling logic in `egui` to support the changes.
## Fix: Samsung Keyboard Cheonjiin issue
This PR fixes a bug reported by @rustbasic when using Samsung Keyboard's
Cheonjiin Korean layout.
Since Samsung Keyboard is only available on Samsung devices, I wasn't
able to verify it myself. The fix is based on @rustbasic's testing and
confirmation.
The root cause is that the layout relies on the preceding text to
correctly handle batchim composition. Previously, the text agent eagerly
cleared the text input after every IME composition, removing the context
too early. This PR makes that cleanup more conservative, preserving the
text when it may still be needed.
My understanding is that this is a quirk specific to Samsung Keyboard:
The IME reports that composition has finished even though it is
effectively still active and the composed text may continue to change.
## Fix: Keystrokes resetting keyboard layout (numpad/symbols/etc.)
Partially fixes #8046.
Previously, keystrokes would cause the on-screen keyboard to switch back
to its primary layout.
One remaining issue is that tapping within the active `TextEdit` to
reposition the cursor still resets the keyboard to its primary layout.
## About text suggestions
I originally planned to include text suggestion support in this PR
because #8068 implemented it.
However, adding text suggestion support would broaden the scope of this
PR, so I think it is better addressed in a separate PR.
For reference, [the reverted
implementation](8a4f70859c)
works fine on Android (Gboard), but not on iOS (iPadOS 17 + SwiftKey).
eframe: the egui framework
eframe is the official framework library for writing apps using egui. The app can be compiled both to run natively (for Linux, Mac, Windows, and Android) or as a web app (using Wasm).
To get started, see the examples.
To learn how to set up eframe for web and native, go to https://github.com/emilk/eframe_template/ and follow the instructions there!
There is also a tutorial video at https://www.youtube.com/watch?v=NtUkr_z7l84.
For how to use egui, see the egui docs.
eframe defaults to using wgpu for rendering (with an option to change to glow), and on native it uses egui-winit.
To use on Linux, first run:
sudo apt-get install libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev libxkbcommon-dev libssl-dev
You need to either use edition = "2024", or set resolver = "2" in the [workspace] section of your to-level Cargo.toml. See this link for more info.
You can opt-in to the using egui_glow for rendering by enabling the glow feature and setting NativeOptions::renderer to Renderer::Glow.
Alternatives
eframe is not the only way to write an app using egui! You can also try egui-miniquad, bevy_egui, egui_sdl2_gl, and others.
You can also use egui_glow and winit to build your own app as demonstrated in https://github.com/emilk/egui/blob/main/crates/egui_glow/examples/pure_glow.rs.
Limitations when running egui on the web
eframe and egui compiles to Wasm using either WebGPU (when available) or WebGL2 for rendering, and almost nothing else from the web tech stack. This has some benefits, but also produces some challenges and serious downsides.
- Rendering: Getting pixel-perfect rendering right on the web is very difficult.
- Search: you cannot search an egui web page like you would a normal web page.
- Bringing up an on-screen keyboard on mobile: there is no JS function to do this, so
eframefakes it by adding some invisible DOM elements. It doesn't always work. - Mobile text editing is not as good as for a normal web app.
- No integration with browser settings for colors and fonts.
- Accessibility: There is an experimental screen reader for
eframe, but it has to be enabled explicitly. There is no JS function to ask "Does the user want a screen reader?" (and there should probably not be such a function, due to user tracking/integrity concerns).eguisupports AccessKit, but as of early 2024, AccessKit lacks a Web backend.
In many ways, eframe is trying to make the browser do something it wasn't designed to do (though there are many things browser vendors could do to improve how well libraries like egui work).
The suggested use for eframe are for web apps where performance and responsiveness are more important than accessibility and mobile text editing.
Companion crates
Not all rust crates work when compiled to Wasm, but here are some useful crates have been designed to work well both natively and as Wasm:
Name
The frame in eframe stands both for the frame in which your egui app resides and also for "framework" (eframe is a framework, egui is a library).