Automatically generate screenshots for all examples (#2379)

Cargo.lock

@@ -1147,6 +1147,7 @@ dependencies = [
  "egui_glow",
  "glow",
  "glutin",
+ "image",
  "js-sys",
  "percent-encoding",
  "puffin",

crates/eframe/Cargo.toml

@@ -52,6 +52,10 @@ puffin = ["dep:puffin", "egui_glow?/puffin", "egui-wgpu?/puffin"]
 ## Enable screen reader support (requires `ctx.options().screen_reader = true;`)
 screen_reader = ["egui-winit/screen_reader", "tts"]
 
+## If set, eframe will look for the env-var `EFRAME_SCREENSHOT_TO` and write a screenshot to that location, and then quit.
+## This is used to generate images for the examples.
+__screenshot = ["dep:image"]
+
 ## Use [`wgpu`](https://docs.rs/wgpu) for painting (via [`egui-wgpu`](https://github.com/emilk/egui/tree/master/crates/egui-wgpu)).
 ## This overrides the `glow` feature.
 wgpu = ["dep:wgpu", "dep:egui-wgpu"]
@@ -89,6 +93,9 @@ directories-next = { version = "2", optional = true }
 egui-wgpu = { version = "0.19.0", path = "../egui-wgpu", optional = true, features = [
   "winit",
 ] }
+image = { version = "0.24", optional = true, default-features = false, features = [
+  "png",
+] }
 puffin = { version = "0.14", optional = true }
 wgpu = { version = "0.14", optional = true }
 

crates/eframe/src/lib.rs

@@ -168,6 +168,12 @@ mod native;
 pub fn run_native(app_name: &str, native_options: NativeOptions, app_creator: AppCreator) {
     let renderer = native_options.renderer;
 
+    #[cfg(not(feature = "__screenshot"))]
+    assert!(
+        std::env::var("EFRAME_SCREENSHOT_TO").is_err(),
+        "EFRAME_SCREENSHOT_TO found without compiling with the '__screenshot' feature"
+    );
+
     match renderer {
         #[cfg(feature = "glow")]
         Renderer::Glow => {

crates/eframe/src/native/run.rs

@@ -241,7 +241,7 @@ fn run_and_exit(event_loop: EventLoop<UserEvent>, mut winit_app: impl WinitApp +
     })
 }
 
-fn centere_window_pos(
+fn center_window_pos(
     monitor: Option<winit::monitor::MonitorHandle>,
     native_options: &mut epi::NativeOptions,
 ) {
@@ -308,6 +308,8 @@ mod glow_integration {
         // suspends and resumes.
         app_creator: Option<epi::AppCreator>,
         is_focused: bool,
+
+        frame_nr: u64,
     }
 
     impl GlowWinitApp {
@@ -324,6 +326,7 @@ mod glow_integration {
                 running: None,
                 app_creator: Some(app_creator),
                 is_focused: true,
+                frame_nr: 0,
             }
         }
 
@@ -517,6 +520,26 @@ mod glow_integration {
 
                 integration.post_present(window);
 
+                #[cfg(feature = "__screenshot")]
+                // give it time to settle:
+                if self.frame_nr == 2 {
+                    if let Ok(path) = std::env::var("EFRAME_SCREENSHOT_TO") {
+                        assert!(
+                            path.ends_with(".png"),
+                            "Expected EFRAME_SCREENSHOT_TO to end with '.png', got {path:?}"
+                        );
+                        let [w, h] = screen_size_in_pixels;
+                        let pixels = painter.read_screen_rgba(screen_size_in_pixels);
+                        let image = image::RgbaImage::from_vec(w, h, pixels).unwrap();
+                        let image = image::imageops::flip_vertical(&image);
+                        image.save(&path).unwrap_or_else(|err| {
+                            panic!("Failed to save screenshot to {path:?}: {err}");
+                        });
+                        eprintln!("Screenshot saved to {path:?}.");
+                        std::process::exit(0);
+                    }
+                }
+
                 let control_flow = if integration.should_close() {
                     EventResult::Exit
                 } else if repaint_after.is_zero() {
@@ -546,6 +569,8 @@ mod glow_integration {
                     std::thread::sleep(std::time::Duration::from_millis(10));
                 }
 
+                self.frame_nr += 1;
+
                 control_flow
             } else {
                 EventResult::Wait
@@ -659,7 +684,7 @@ mod glow_integration {
         if native_options.run_and_return {
             with_event_loop(native_options, |event_loop, mut native_options| {
                 if native_options.centered {
-                    centere_window_pos(event_loop.available_monitors().next(), &mut native_options);
+                    center_window_pos(event_loop.available_monitors().next(), &mut native_options);
                 }
 
                 let glow_eframe =
@@ -670,7 +695,7 @@ mod glow_integration {
             let event_loop = create_event_loop_builder(&mut native_options).build();
 
             if native_options.centered {
-                centere_window_pos(event_loop.available_monitors().next(), &mut native_options);
+                center_window_pos(event_loop.available_monitors().next(), &mut native_options);
             }
 
             let glow_eframe = GlowWinitApp::new(&event_loop, app_name, native_options, app_creator);
@@ -718,6 +743,12 @@ mod wgpu_integration {
             native_options: epi::NativeOptions,
             app_creator: epi::AppCreator,
         ) -> Self {
+            #[cfg(feature = "__screenshot")]
+            assert!(
+                std::env::var("EFRAME_SCREENSHOT_TO").is_err(),
+                "EFRAME_SCREENSHOT_TO not yet implemented for wgpu backend"
+            );
+
             Self {
                 repaint_proxy: Arc::new(std::sync::Mutex::new(event_loop.create_proxy())),
                 app_name: app_name.to_owned(),
@@ -1050,7 +1081,7 @@ mod wgpu_integration {
         if native_options.run_and_return {
             with_event_loop(native_options, |event_loop, mut native_options| {
                 if native_options.centered {
-                    centere_window_pos(event_loop.available_monitors().next(), &mut native_options);
+                    center_window_pos(event_loop.available_monitors().next(), &mut native_options);
                 }
 
                 let wgpu_eframe =
@@ -1061,7 +1092,7 @@ mod wgpu_integration {
             let event_loop = create_event_loop_builder(&mut native_options).build();
 
             if native_options.centered {
-                centere_window_pos(event_loop.available_monitors().next(), &mut native_options);
+                center_window_pos(event_loop.available_monitors().next(), &mut native_options);
             }
 
             let wgpu_eframe = WgpuWinitApp::new(&event_loop, app_name, native_options, app_creator);

crates/egui_glow/src/painter.rs

@@ -605,6 +605,38 @@ impl Painter {
         }
     }
 
+    pub fn read_screen_rgba(&self, [w, h]: [u32; 2]) -> Vec<u8> {
+        let mut pixels = vec![0_u8; (w * h * 4) as usize];
+        unsafe {
+            self.gl.read_pixels(
+                0,
+                0,
+                w as _,
+                h as _,
+                glow::RGBA,
+                glow::UNSIGNED_BYTE,
+                glow::PixelPackData::Slice(&mut pixels),
+            );
+        }
+        pixels
+    }
+
+    pub fn read_screen_rgb(&self, [w, h]: [u32; 2]) -> Vec<u8> {
+        let mut pixels = vec![0_u8; (w * h * 3) as usize];
+        unsafe {
+            self.gl.read_pixels(
+                0,
+                0,
+                w as _,
+                h as _,
+                glow::RGB,
+                glow::UNSIGNED_BYTE,
+                glow::PixelPackData::Slice(&mut pixels),
+            );
+        }
+        pixels
+    }
+
     unsafe fn destroy_gl(&self) {
         self.gl.delete_program(self.program);
         for tex in self.textures.values() {

examples/confirm_exit/Cargo.toml

@@ -9,4 +9,6 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }

examples/confirm_exit/README.md

@@ -1,3 +1,7 @@
+Example how to show a confirm dialog before exiting an application.
+
 ```sh
 cargo run -p confirm_exit
 ```
+
+![](screenshot.png)

examples/confirm_exit/src/main.rs

@@ -3,7 +3,10 @@
 use eframe::egui;
 
 fn main() {
-    let options = eframe::NativeOptions::default();
+    let options = eframe::NativeOptions {
+        initial_window_size: Some(egui::vec2(320.0, 240.0)),
+        ..Default::default()
+    };
     eframe::run_native(
         "Confirm exit",
         options,

examples/custom_3d_glow/Cargo.toml

@@ -9,6 +9,8 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe", features = ["glow"] }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 egui_glow = { path = "../../crates/egui_glow" }
 glow = "0.11"

examples/custom_3d_glow/README.md

@@ -13,3 +13,5 @@ If you are content of having egui sit on top of a 3D background, take a look at:
 ```sh
 cargo run -p custom_3d_glow
 ```
+
+![](screenshot.png)

examples/custom_3d_three-d/Cargo.toml

@@ -11,7 +11,9 @@ publish = false
 crate-type = ["cdylib", "rlib"]
 
 [dependencies]
-eframe = { path = "../../crates/eframe", features = ["glow"] }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 egui_glow = { path = "../../crates/egui_glow" }
 glow = "0.11"
 three-d = { version = "0.13", default-features = false }

examples/custom_3d_three-d/README.md

@@ -18,3 +18,5 @@ cargo run -p custom_3d_three-d
 ```
 wasm-pack build examples/custom_3d_three-d --target web
 ```
+
+![](screenshot.png)

examples/custom_font/Cargo.toml

@@ -9,4 +9,6 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }

examples/custom_font/README.md

@@ -1,3 +1,7 @@
+Example of how to use custom fonts.
+
 ```sh
 cargo run -p custom_font
 ```
+
+![](screenshot.png)

examples/custom_font/src/main.rs

@@ -3,7 +3,10 @@
 use eframe::egui;
 
 fn main() {
-    let options = eframe::NativeOptions::default();
+    let options = eframe::NativeOptions {
+        initial_window_size: Some(egui::vec2(320.0, 240.0)),
+        ..Default::default()
+    };
     eframe::run_native(
         "egui example: custom font",
         options,

examples/custom_font_style/Cargo.toml

@@ -9,4 +9,6 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }

examples/custom_font_style/README.md

@@ -1,4 +1,7 @@
+Example how to define custom test styles.
+
 ```sh
 cargo run -p custom_font_style
 ```
-![custom_font_style example](custom_font_style.png)
+
+![](screenshot.png)

examples/custom_window_frame/Cargo.toml

@@ -9,4 +9,6 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }

examples/custom_window_frame/README.md

@@ -1,3 +1,7 @@
+Example how to show a custom window frame instead of the default OS window chrome decorations.
+
 ```sh
 cargo run -p custom_window_frame
 ```
+
+![](screenshot.png)

examples/custom_window_frame/src/main.rs

@@ -11,6 +11,7 @@ fn main() {
         // To have rounded corners we need transparency:
         transparent: true,
         min_window_size: Some(egui::vec2(320.0, 100.0)),
+        initial_window_size: Some(egui::vec2(320.0, 240.0)),
         ..Default::default()
     };
     eframe::run_native(

examples/download_image/Cargo.toml

@@ -9,7 +9,9 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 egui_extras = { path = "../../crates/egui_extras", features = ["image"] }
 ehttp = "0.2"
 image = { version = "0.24", default-features = false, features = ["jpeg"] }

examples/download_image/README.md

@@ -1,3 +1,7 @@
+Example how to download and show an image with eframe/egui.
+
 ```sh
 cargo run -p download_image
 ```
+
+![](screenshot.png)

examples/file_dialog/Cargo.toml

@@ -9,5 +9,7 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 rfd = "0.10"

examples/file_dialog/README.md

@@ -3,3 +3,5 @@ How to show a file dialog using [`rfd`](https://github.com/PolyMeilex/rfd).
 ```sh
 cargo run -p file_dialog
 ```
+
+![](screenshot.png)

examples/file_dialog/src/main.rs

@@ -5,6 +5,7 @@ use eframe::egui;
 fn main() {
     let options = eframe::NativeOptions {
         drag_and_drop_support: true,
+        initial_window_size: Some(egui::vec2(320.0, 240.0)),
         ..Default::default()
     };
     eframe::run_native(

examples/hello_world/Cargo.toml

@@ -9,5 +9,7 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 tracing-subscriber = "0.3"

examples/hello_world/README.md

@@ -1,3 +1,7 @@
+Example showing some UI controls like `Label`, `TextEdit`, `Slider`, `Button`.
+
 ```sh
 cargo run -p hello_world
 ```
+
+![](screenshot.png)

examples/hello_world/src/main.rs

@@ -6,7 +6,10 @@ fn main() {
     // Log to stdout (if you run with `RUST_LOG=debug`).
     tracing_subscriber::fmt::init();
 
-    let options = eframe::NativeOptions::default();
+    let options = eframe::NativeOptions {
+        initial_window_size: Some(egui::vec2(320.0, 240.0)),
+        ..Default::default()
+    };
     eframe::run_native(
         "My egui App",
         options,

examples/keyboard_events/Cargo.toml

@@ -9,5 +9,7 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 tracing-subscriber = "0.3"

examples/keyboard_events/README.md

@@ -1,3 +1,5 @@
 ```sh
 cargo run -p hello_world
 ```
+
+![](screenshot.png)

examples/puffin_profiler/Cargo.toml

@@ -9,6 +9,8 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe", features = ["puffin"] }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 puffin = "0.14"
 puffin_http = "0.11"

examples/puffin_profiler/README.md

@@ -7,3 +7,5 @@ cargo run -p puffin_profiler &
 cargo install puffin_viewer
 puffin_viewer --url 127.0.0.1:8585
 ```
+
+![](screenshot.png)

examples/retained_image/Cargo.toml

@@ -9,6 +9,8 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 egui_extras = { path = "../../crates/egui_extras", features = ["image"] }
 image = { version = "0.24", default-features = false, features = ["png"] }

examples/retained_image/README.md

@@ -1,3 +1,7 @@
+Example how to show an image with eframe/egui.
+
 ```sh
 cargo run -p retained_image
 ```
+
+![](screenshot.png)

examples/retained_image/src/main.rs

@@ -5,7 +5,7 @@ use egui_extras::RetainedImage;
 
 fn main() {
     let options = eframe::NativeOptions {
-        initial_window_size: Some(egui::vec2(500.0, 900.0)),
+        initial_window_size: Some(egui::vec2(300.0, 900.0)),
         ..Default::default()
     };
 

examples/screenshot/Cargo.toml

@@ -9,6 +9,8 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 egui_extras = { path = "../../crates/egui_extras", features = ["image"] }
 itertools = "0.10.3"

examples/screenshot/README.md

@@ -1,3 +1,7 @@
+Example how to take screenshots and display them with eframe/egui.
+
 ```sh
 cargo run -p screenshot
 ```
+
+![](screenshot.png)

examples/screenshot/src/main.rs

@@ -74,23 +74,25 @@ impl eframe::App for MyApp {
 
         self.take_screenshot = false;
         if let Some(gl) = frame.gl() {
-            let mut buf = vec![0u8; screen_size_px[0] as usize * screen_size_px[1] as usize * 4];
+            let [w, h] = screen_size_px;
+            let mut buf = vec![0u8; w as usize * h as usize * 4];
             let pixels = glow::PixelPackData::Slice(&mut buf[..]);
             unsafe {
                 gl.read_pixels(
                     0,
                     0,
-                    screen_size_px[0] as i32,
-                    screen_size_px[1] as i32,
+                    w as i32,
+                    h as i32,
                     glow::RGBA,
                     glow::UNSIGNED_BYTE,
                     pixels,
                 );
             }
 
+            // Flip vertically:
             let mut rows: Vec<Vec<u8>> = buf
                 .into_iter()
-                .chunks(screen_size_px[0] as usize * 4)
+                .chunks(w as usize * 4)
                 .into_iter()
                 .map(|chunk| chunk.collect())
                 .collect();

examples/serial_windows/Cargo.toml

@@ -9,4 +9,6 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }

examples/serial_windows/README.md

@@ -6,3 +6,5 @@ See also <https://github.com/emilk/egui/issues/1918>.
 ```sh
 cargo run -p serial_windows
 ```
+
+![](screenshot.png)

examples/serial_windows/src/main.rs

@@ -9,6 +9,7 @@ fn main() {
 
     let options = eframe::NativeOptions {
         run_and_return: true,
+        initial_window_size: Some(egui::vec2(320.0, 240.0)),
         ..Default::default()
     };
 

examples/svg/Cargo.toml

@@ -9,5 +9,7 @@ publish = false
 
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a ascreenshot using EFRAME_SCREENSHOT_TO
+] }
 egui_extras = { path = "../../crates/egui_extras", features = ["svg"] }

examples/svg/README.md

@@ -1,6 +1,7 @@
 Example how to show an SVG image.
 
-
 ```sh
 cargo run -p svg
 ```
+
+![](screenshot.png)

sh/generate_example_screenshots.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# This script generates screenshots for all the examples in examples/
+
+set -eu
+script_path=$( cd "$(dirname "${BASH_SOURCE[0]}")" ; pwd -P )
+cd "$script_path/.."
+
+cd examples
+for VARIABLE in $(ls -1d */ | sed 's/\/$//'); do
+    EFRAME_SCREENSHOT_TO="$VARIABLE/screenshot.png" cargo run -p $VARIABLE
+done