mirror of
https://github.com/emilk/egui.git
synced 2026-06-26 22:53:14 -04:00
f624e30786
**fix(web): prevent entire page from scrolling out of view in Chrome (WASM)** * Closes #7887 **Problem** When using `egui` on the web, the browser (especially Chrome) occasionally triggers an unwanted page-level scroll. This happens because the hidden input element (text agent) used for IME/text input is sometimes positioned outside the visible bounds of the canvas, causing the browser to "scroll it into view." **Solution** I modified the `move_to` function in the web's `text_agent` to ensure the input element's position stays within the canvas height. By clamping the `top` property between `0.0` and `canvas_height`, we prevent the browser from incorrectly scrolling the entire page when the text agent moves. - **Specific change:** Applied `clamp(0.0, canvas_height)` to the `clamped_y` value before setting the CSS `top` property.
230 lines
8.3 KiB
Rust
230 lines
8.3 KiB
Rust
//! The text agent is a hidden `<input>` element used to capture
|
|
//! IME and mobile keyboard input events.
|
|
|
|
use std::cell::Cell;
|
|
|
|
use wasm_bindgen::prelude::*;
|
|
use web_sys::{Document, Node};
|
|
|
|
use super::{AppRunner, WebRunner};
|
|
|
|
pub struct TextAgent {
|
|
input: web_sys::HtmlInputElement,
|
|
prev_ime_output: Cell<Option<egui::output::IMEOutput>>,
|
|
}
|
|
|
|
impl TextAgent {
|
|
/// Attach the agent to the document.
|
|
pub fn attach(runner_ref: &WebRunner, root: Node) -> Result<Self, JsValue> {
|
|
let document = web_sys::window().unwrap().document().unwrap();
|
|
|
|
// create an `<input>` element
|
|
let input = document
|
|
.create_element("input")?
|
|
.dyn_into::<web_sys::HtmlElement>()?;
|
|
input.set_autofocus(true)?;
|
|
let input = input.dyn_into::<web_sys::HtmlInputElement>()?;
|
|
input.set_type("text");
|
|
input.set_attribute("autocapitalize", "off")?;
|
|
|
|
// append it to `<body>` and hide it outside of the viewport
|
|
let style = input.style();
|
|
style.set_property("background-color", "transparent")?;
|
|
style.set_property("border", "none")?;
|
|
style.set_property("outline", "none")?;
|
|
style.set_property("width", "1px")?;
|
|
style.set_property("height", "1px")?;
|
|
style.set_property("caret-color", "transparent")?;
|
|
style.set_property("position", "absolute")?;
|
|
style.set_property("top", "0")?;
|
|
style.set_property("left", "0")?;
|
|
// Prevent auto-zoom on mobile browsers (requires at least 16px).
|
|
style.set_property("font-size", "16px")?;
|
|
|
|
if root.has_type::<Document>() {
|
|
// root object is a document, append to its body
|
|
root.dyn_into::<Document>()?
|
|
.body()
|
|
.unwrap()
|
|
.append_child(&input)?;
|
|
} else {
|
|
// append input into root directly
|
|
root.append_child(&input)?;
|
|
}
|
|
|
|
// attach event listeners
|
|
|
|
let on_input = {
|
|
let input = input.clone();
|
|
move |event: web_sys::InputEvent, runner: &mut AppRunner| {
|
|
let text = input.value();
|
|
// Workaround for an Android Gboard issue: after typing a word,
|
|
// the user has to delete invisible characters (whose count
|
|
// matches the length of the current suggestion) before actual
|
|
// characters are deleted, unless the focus has been reset.
|
|
//
|
|
// this issue appears to have been fixed in Gboard sometime
|
|
// between versions 14.7.09 and 17.0.12.
|
|
if !event.is_composing() {
|
|
input.blur().ok();
|
|
input.focus().ok();
|
|
}
|
|
// if `is_composing` is true, then user is using IME, for example: emoji, pinyin, kanji, hangul, etc.
|
|
// In that case, the browser emits both `input` and `compositionupdate` events,
|
|
// and we need to ignore the `input` event.
|
|
if !text.is_empty() && !event.is_composing() {
|
|
input.set_value("");
|
|
let event = egui::Event::Text(text);
|
|
runner.input.raw.events.push(event);
|
|
runner.needs_repaint.repaint_asap();
|
|
}
|
|
}
|
|
};
|
|
|
|
let on_composition_start = {
|
|
move |_: web_sys::CompositionEvent, runner: &mut AppRunner| {
|
|
// Repaint moves the text agent into place,
|
|
// see `move_to` in `AppRunner::handle_platform_output`.
|
|
runner.needs_repaint.repaint_asap();
|
|
}
|
|
};
|
|
|
|
let on_composition_update = {
|
|
move |event: web_sys::CompositionEvent, runner: &mut AppRunner| {
|
|
let Some(text) = event.data() else { return };
|
|
let event = egui::Event::Ime(egui::ImeEvent::Preedit(text));
|
|
runner.input.raw.events.push(event);
|
|
runner.needs_repaint.repaint_asap();
|
|
}
|
|
};
|
|
|
|
let on_composition_end = {
|
|
let input = input.clone();
|
|
move |event: web_sys::CompositionEvent, runner: &mut AppRunner| {
|
|
let Some(text) = event.data() else { return };
|
|
input.set_value("");
|
|
let event = egui::Event::Ime(egui::ImeEvent::Commit(text));
|
|
runner.input.raw.events.push(event);
|
|
runner.needs_repaint.repaint_asap();
|
|
}
|
|
};
|
|
|
|
runner_ref.add_event_listener(&input, "input", on_input)?;
|
|
runner_ref.add_event_listener(&input, "compositionstart", on_composition_start)?;
|
|
runner_ref.add_event_listener(&input, "compositionupdate", on_composition_update)?;
|
|
runner_ref.add_event_listener(&input, "compositionend", on_composition_end)?;
|
|
|
|
// The canvas doesn't get keydown/keyup events when the text agent is focused,
|
|
// so we need to forward them to the runner:
|
|
runner_ref.add_event_listener(&input, "keydown", super::events::on_keydown)?;
|
|
runner_ref.add_event_listener(&input, "keyup", super::events::on_keyup)?;
|
|
|
|
Ok(Self {
|
|
input,
|
|
prev_ime_output: Default::default(),
|
|
})
|
|
}
|
|
|
|
pub fn move_to(
|
|
&self,
|
|
ime: Option<egui::output::IMEOutput>,
|
|
canvas: &web_sys::HtmlCanvasElement,
|
|
zoom_factor: f32,
|
|
) -> Result<(), JsValue> {
|
|
// Don't move the text agent unless the position actually changed:
|
|
if self.prev_ime_output.get() == ime {
|
|
return Ok(());
|
|
}
|
|
self.prev_ime_output.set(ime);
|
|
|
|
let Some(ime) = ime else { return Ok(()) };
|
|
|
|
if ime.should_interrupt_composition {
|
|
// no-op for now: currently, the text agent is sizeless, so any
|
|
// click shifts focus to the canvas, which naturally interrupts the
|
|
// composition.
|
|
}
|
|
|
|
let mut canvas_rect = super::canvas_content_rect(canvas);
|
|
// Fix for safari with virtual keyboard flapping position
|
|
if is_mobile_safari() {
|
|
canvas_rect.min.y = canvas.offset_top() as f32;
|
|
}
|
|
let cursor_rect = ime.cursor_rect.translate(canvas_rect.min.to_vec2());
|
|
|
|
let style = self.input.style();
|
|
let native_ppp = super::native_pixels_per_point();
|
|
|
|
// Clamp the input position within the canvas width to prevent unwanted horizontal scrolling.
|
|
let logical_canvas_width = canvas.width() as f32 / native_ppp;
|
|
let visible_x = cursor_rect.center().x * zoom_factor;
|
|
let clamped_x = visible_x.clamp(0.0, logical_canvas_width);
|
|
|
|
// Clamp the input position within the canvas height to prevent unwanted vertical scrolling.
|
|
let logical_canvas_height = canvas.height() as f32 / native_ppp;
|
|
let visible_y = cursor_rect.center().y * zoom_factor;
|
|
let clamped_y = visible_y.clamp(0.0, logical_canvas_height);
|
|
|
|
// This is where the IME input will point to:
|
|
style.set_property("left", &format!("{clamped_x}px"))?;
|
|
style.set_property("top", &format!("{clamped_y}px"))?;
|
|
|
|
Ok(())
|
|
}
|
|
|
|
pub fn set_focus(&self, on: bool) {
|
|
if on {
|
|
self.focus();
|
|
} else {
|
|
self.blur();
|
|
}
|
|
}
|
|
|
|
pub fn has_focus(&self) -> bool {
|
|
super::has_focus(&self.input)
|
|
}
|
|
|
|
pub fn focus(&self) {
|
|
if self.has_focus() {
|
|
return;
|
|
}
|
|
|
|
log::trace!("Focusing text agent");
|
|
|
|
if let Err(err) = self.input.focus() {
|
|
log::error!("failed to set focus: {}", super::string_from_js_value(&err));
|
|
}
|
|
}
|
|
|
|
pub fn blur(&self) {
|
|
if !self.has_focus() {
|
|
return;
|
|
}
|
|
|
|
log::trace!("Blurring text agent");
|
|
|
|
if let Err(err) = self.input.blur() {
|
|
log::error!("failed to set focus: {}", super::string_from_js_value(&err));
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Drop for TextAgent {
|
|
fn drop(&mut self) {
|
|
self.input.remove();
|
|
}
|
|
}
|
|
|
|
/// Returns `true` if the app is likely running on a mobile device on navigator Safari.
|
|
fn is_mobile_safari() -> bool {
|
|
(|| {
|
|
let user_agent = web_sys::window()?.navigator().user_agent().ok()?;
|
|
let is_ios = user_agent.contains("iPhone")
|
|
|| user_agent.contains("iPad")
|
|
|| user_agent.contains("iPod");
|
|
let is_safari = user_agent.contains("Safari");
|
|
Some(is_ios && is_safari)
|
|
})()
|
|
.unwrap_or(false)
|
|
}
|