b7ebe16cfb
The purpose of this is to expose `frame.storage()` and `frame.storage_mut()` so users can save/load app state from the `App::update` function, without having to add another parameter to that function. Changes: * Added `Frame::storage()` and `Frame::storage_mut()` * `App::update` now takes a `&mut Frame` rather than just `&Frame` * `Frame` is no longer `Clone` or `Sync` (doesn't have to be since https://github.com/emilk/egui/pull/1366)
64 lines
2.2 KiB
Rust
64 lines
2.2 KiB
Rust
#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")] // hide console window on Windows in release
|
|
|
|
use eframe::egui;
|
|
use egui_extras::RetainedImage;
|
|
use poll_promise::Promise;
|
|
|
|
fn main() {
|
|
let options = eframe::NativeOptions::default();
|
|
eframe::run_native(
|
|
"Download and show an image with eframe/egui",
|
|
options,
|
|
Box::new(|_cc| Box::new(MyApp::default())),
|
|
);
|
|
}
|
|
|
|
#[derive(Default)]
|
|
struct MyApp {
|
|
/// `None` when download hasn't started yet.
|
|
promise: Option<Promise<ehttp::Result<RetainedImage>>>,
|
|
}
|
|
|
|
impl eframe::App for MyApp {
|
|
fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
|
|
let promise = self.promise.get_or_insert_with(|| {
|
|
// Begin download.
|
|
// We download the image using `ehttp`, a library that works both in WASM and on native.
|
|
// We use the `poll-promise` library to communicate with the UI thread.
|
|
let ctx = ctx.clone();
|
|
let (sender, promise) = Promise::new();
|
|
let request = ehttp::Request::get("https://picsum.photos/seed/1.759706314/1024");
|
|
ehttp::fetch(request, move |response| {
|
|
let image = response.and_then(parse_response);
|
|
sender.send(image); // send the results back to the UI thread.
|
|
ctx.request_repaint(); // wake up UI thread
|
|
});
|
|
promise
|
|
});
|
|
|
|
egui::CentralPanel::default().show(ctx, |ui| match promise.ready() {
|
|
None => {
|
|
ui.add(egui::Spinner::new()); // still loading
|
|
}
|
|
Some(Err(err)) => {
|
|
ui.colored_label(egui::Color32::RED, err); // something went wrong
|
|
}
|
|
Some(Ok(image)) => {
|
|
image.show_max_size(ui, ui.available_size());
|
|
}
|
|
});
|
|
}
|
|
}
|
|
|
|
#[allow(clippy::needless_pass_by_value)]
|
|
fn parse_response(response: ehttp::Response) -> Result<RetainedImage, String> {
|
|
let content_type = response.content_type().unwrap_or_default();
|
|
if content_type.starts_with("image/") {
|
|
RetainedImage::from_image_bytes(&response.url, &response.bytes)
|
|
} else {
|
|
Err(format!(
|
|
"Expected image, found content-type {:?}",
|
|
content_type
|
|
))
|
|
}
|
|
}
|