mirror of https://github.com/emilk/egui.git
Emil Ernerfeldt
3 years ago
6 changed files with 164 additions and 87 deletions
@ -0,0 +1,82 @@ |
|||
#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")] // hide console window on Windows in release
|
|||
|
|||
use eframe::{egui, epi}; |
|||
use poll_promise::Promise; |
|||
|
|||
fn main() { |
|||
let options = eframe::NativeOptions::default(); |
|||
eframe::run_native(Box::new(MyApp::default()), options); |
|||
} |
|||
|
|||
#[derive(Default)] |
|||
struct MyApp { |
|||
/// `None` when download hasn't started yet.
|
|||
promise: Option<Promise<ehttp::Result<egui::TextureHandle>>>, |
|||
} |
|||
|
|||
impl epi::App for MyApp { |
|||
fn name(&self) -> &str { |
|||
"Download and show an image with eframe/egui" |
|||
} |
|||
|
|||
fn update(&mut self, ctx: &egui::Context, frame: &epi::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 frame = frame.clone(); |
|||
let (sender, promise) = Promise::new(); |
|||
let request = ehttp::Request::get("https://picsum.photos/seed/1.759706314/1024"); |
|||
ehttp::fetch(request, move |response| { |
|||
frame.request_repaint(); // wake up UI thread
|
|||
let texture = response.and_then(|response| parse_response(&ctx, response)); |
|||
sender.send(texture); // send the results back to the 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(texture)) => { |
|||
let mut size = texture.size_vec2(); |
|||
size *= (ui.available_width() / size.x).min(1.0); |
|||
size *= (ui.available_height() / size.y).min(1.0); |
|||
ui.image(texture, size); |
|||
} |
|||
}); |
|||
} |
|||
} |
|||
|
|||
fn parse_response( |
|||
ctx: &egui::Context, |
|||
response: ehttp::Response, |
|||
) -> Result<egui::TextureHandle, String> { |
|||
let content_type = response.content_type().unwrap_or_default(); |
|||
if content_type.starts_with("image/") { |
|||
let image = load_image(&response.bytes).map_err(|err| err.to_string())?; |
|||
Ok(ctx.load_texture("my-image", image)) |
|||
} else { |
|||
Err(format!( |
|||
"Expected image, found content-type {:?}", |
|||
content_type |
|||
)) |
|||
} |
|||
} |
|||
|
|||
fn load_image(image_data: &[u8]) -> Result<egui::ColorImage, image::ImageError> { |
|||
use image::GenericImageView as _; |
|||
let image = image::load_from_memory(image_data)?; |
|||
let size = [image.width() as _, image.height() as _]; |
|||
let image_buffer = image.to_rgba8(); |
|||
let pixels = image_buffer.as_flat_samples(); |
|||
Ok(egui::ColorImage::from_rgba_unmultiplied( |
|||
size, |
|||
pixels.as_slice(), |
|||
)) |
|||
} |
|||
Loading…
Reference in new issue