//! The text agent is a hidden `` 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>,
}
impl TextAgent {
/// Attach the agent to the document.
pub fn attach(runner_ref: &WebRunner, root: Node) -> Result {
let document = web_sys::window().unwrap().document().unwrap();
// create an `` element
let input = document
.create_element("input")?
.dyn_into::()?;
input.set_autofocus(true)?;
let input = input.dyn_into::()?;
input.set_type("text");
input.set_attribute("autocapitalize", "off")?;
// append it to `` 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")?;
if root.has_type::() {
// root object is a document, append to its body
root.dyn_into::()?
.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();
// Fix android virtual keyboard Gboard
// This removes the virtual keyboard's suggestion.
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 = {
let input = input.clone();
move |_: web_sys::CompositionEvent, runner: &mut AppRunner| {
input.set_value("");
let event = egui::Event::Ime(egui::ImeEvent::Enabled);
runner.input.raw.events.push(event);
// 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,
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(()) };
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();
// This is where the IME input will point to:
style.set_property(
"left",
&format!("{}px", cursor_rect.center().x * zoom_factor),
)?;
style.set_property(
"top",
&format!("{}px", cursor_rect.center().y * zoom_factor),
)?;
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)
}