Managed texture loading (#3297)

* add types from proposal

* add load methods on `egui::Context`

* implement loaders from proposal in `egui_extras`

* impl `From<Vec2>` for `SizeHint`

* re-export `SizeHint` from `egui` root

* rework `svg` example to use new managed `Image`

* split loaders into separate files + add logging

* add `log_trace`

* clean up `RetainedImage` from `svg` example

* refactor ehttp loader response to bytes mapping

* remove spammy trace

* load images even without extension

* fix lints

* remove unused imports

* use `Image2` in `download_image`

* use `visuals.error_fg_color` in `Image2` error state

* update lockfile

* use `Arc<ColorImage>` in `ImageData` + add `forget` API

* add `ui.image2`

* add byte size query api

* use iterators to sum loader byte sizes

* add static image loading

* use static image in `svg` example

* small refactor of `Image2::ui` texture loading code

* add `ImageFit` to size images properly

* remove println calls

* add bad image load to `download_image` example

* add loader file extension support tests

* fix lint errors in `loaders`

* remove unused `poll-promise` dependency

* add some docs to `Image2`

* add some docs to `egui_extras::loaders::install`

* explain `loaders::install` in examples

* fix lint

* upgrade `ehttp` to `0.3` for some crates

* Remove some unused dependencies

* Remove unnecessary context clone

* Turn on the `log` create feature of egui_extras in all examples

* rename `forget` and document it

* derive `Debug` on `SizeHint`

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* round when converting SizeHint from vec2

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* add `load` module docs

* docstring `add_loader` methods

* expose + document `load_include_bytes`

* cache texture handles in `DefaultTextureLoader`

* add `image2` doctest + further document `Image2`

* use `Default` for default `Image2` options

* update `image2` doc comment

* mention immediate-mode safety

* more fit calculation into inherent impl

* add hover text on spinner

* add `all-loaders` feature

* clarify `egui_extras::loaders::install` behavior

* explain how to enable image formats

* properly format `uri`

* use `thread::Builder` instead of `spawn`

* use eq op instead of `matches`

* inline `From<Arc<ColorImage>>` for `ImageData`

* allow non-`'static` bytes + `forget` in `DefaultTextureLoader`

* sort features

* change `ehttp` feature to `http`

* update `Image2` docs

* refactor loader cache type

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

examples/download_image/Cargo.toml

@@ -12,8 +12,10 @@ publish = false
 eframe = { path = "../../crates/eframe", features = [
     "__screenshot", # __screenshot is so we can dump a screenshot using EFRAME_SCREENSHOT_TO
 ] }
-egui_extras = { path = "../../crates/egui_extras", features = ["image"] }
-ehttp = "0.2"
+egui_extras = { path = "../../crates/egui_extras", features = [
+    "http",
+    "image",
+    "log",
+] }
 env_logger = "0.10"
 image = { version = "0.24", default-features = false, features = ["jpeg"] }
-poll-promise = "0.2"

examples/download_image/src/main.rs

@@ -1,8 +1,6 @@
 #![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() -> Result<(), eframe::Error> {
     env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).
@@ -10,55 +8,34 @@ fn main() -> Result<(), eframe::Error> {
     eframe::run_native(
         "Download and show an image with eframe/egui",
         options,
-        Box::new(|_cc| Box::<MyApp>::default()),
+        Box::new(|cc| {
+            // Without the following call, the `Image2` created below
+            // will simply output `not supported` error messages.
+            egui_extras::loaders::install(&cc.egui_ctx);
+            Box::new(MyApp)
+        }),
     )
 }
 
 #[derive(Default)]
-struct MyApp {
-    /// `None` when download hasn't started yet.
-    promise: Option<Promise<ehttp::Result<RetainedImage>>>,
-}
+struct MyApp;
 
 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
+        egui::CentralPanel::default().show(ctx, |ui| {
+            let width = ui.available_width();
+            let half_height = ui.available_height() / 2.0;
+
+            ui.allocate_ui(egui::Vec2::new(width, half_height), |ui| {
+                ui.add(egui::Image2::from_uri(
+                    "https://picsum.photos/seed/1.759706314/1024",
+                ))
+            });
+            ui.allocate_ui(egui::Vec2::new(width, half_height), |ui| {
+                ui.add(egui::Image2::from_uri(
+                    "https://this-is-hopefully-not-a-real-website.rs/image.png",
+                ))
             });
-            promise
-        });
-
-        egui::CentralPanel::default().show(ctx, |ui| match promise.ready() {
-            None => {
-                ui.spinner(); // still loading
-            }
-            Some(Err(err)) => {
-                ui.colored_label(ui.visuals().error_fg_color, 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:?}"
-        ))
-    }
-}

examples/retained_image/Cargo.toml

@@ -12,6 +12,6 @@ publish = false
 eframe = { path = "../../crates/eframe", features = [
     "__screenshot", # __screenshot is so we can dump a screenshot using EFRAME_SCREENSHOT_TO
 ] }
-egui_extras = { path = "../../crates/egui_extras", features = ["image"] }
+egui_extras = { path = "../../crates/egui_extras", features = ["image", "log"] }
 env_logger = "0.10"
 image = { version = "0.24", default-features = false, features = ["png"] }

examples/screenshot/Cargo.toml

@@ -17,5 +17,4 @@ eframe = { path = "../../crates/eframe", features = [
     "wgpu",
 ] }
 env_logger = "0.10"
-itertools = "0.10.3"
 image = { version = "0.24", default-features = false, features = ["png"] }

examples/svg/Cargo.toml

@@ -12,5 +12,5 @@ publish = false
 eframe = { path = "../../crates/eframe", features = [
     "__screenshot", # __screenshot is so we can dump a screenshot using EFRAME_SCREENSHOT_TO
 ] }
-egui_extras = { path = "../../crates/egui_extras", features = ["svg"] }
+egui_extras = { path = "../../crates/egui_extras", features = ["log", "svg"] }
 env_logger = "0.10"

examples/svg/src/main.rs

@@ -15,26 +15,16 @@ fn main() -> Result<(), eframe::Error> {
     eframe::run_native(
         "svg example",
         options,
-        Box::new(|_cc| Box::<MyApp>::default()),
+        Box::new(|cc| {
+            // Without the following call, the `Image2` created below
+            // will simply output a `not supported` error message.
+            egui_extras::loaders::install(&cc.egui_ctx);
+            Box::new(MyApp)
+        }),
     )
 }
 
-struct MyApp {
-    svg_image: egui_extras::RetainedImage,
-}
-
-impl Default for MyApp {
-    fn default() -> Self {
-        Self {
-            svg_image: egui_extras::RetainedImage::from_svg_bytes_with_size(
-                "rustacean-flat-happy.svg",
-                include_bytes!("rustacean-flat-happy.svg"),
-                egui_extras::image::FitTo::Original,
-            )
-            .unwrap(),
-        }
-    }
-}
+struct MyApp;
 
 impl eframe::App for MyApp {
     fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
@@ -45,7 +35,13 @@ impl eframe::App for MyApp {
             ui.separator();
 
             let max_size = ui.available_size();
-            self.svg_image.show_size(ui, max_size);
+            ui.add(
+                egui::Image2::from_static_bytes(
+                    "ferris.svg",
+                    include_bytes!("rustacean-flat-happy.svg"),
+                )
+                .size_hint(max_size),
+            );
         });
     }
 }