| Bring vidya in cfd3e36 nandi 19d ago | 1 | //! Embed a window / taskbar app icon from PNG bytes. |
| 2 | //! |
| 3 | //! Apps typically `include_bytes!` a 128–256px PNG and pass it through |
| 4 | //! [`with_app_icon`] / [`with_app_icon_id`] when building the eframe viewport: |
| 5 | //! |
| 6 | //! ```ignore |
| 7 | //! use egui::ViewportBuilder; |
| 8 | //! use vidya::with_app_icon_id; |
| 9 | //! |
| 10 | //! let viewport = with_app_icon_id( |
| 11 | //! ViewportBuilder::default().with_title("My App"), |
| 12 | //! "my-app", // Wayland app_id — match .desktop StartupWMClass / file id |
| 13 | //! include_bytes!("../assets/icon-256.png"), |
| 14 | //! ); |
| 15 | //! ``` |
| 16 | //! |
| 17 | //! On Wayland, [`with_app_icon_id`] is preferred: the compositor matches |
| 18 | //! `app_id` to a FreeDesktop entry’s `Icon=` when the `.desktop` is on |
| 19 | //! `XDG_DATA_DIRS`. The embedded icon still sets the client-side window icon |
| 20 | //! where the platform supports it (X11, Windows, …). |
| 21 | |
| 22 | use std::io::Cursor; |
| 23 | use std::sync::Arc; |
| 24 | |
| 25 | use egui::{IconData, ViewportBuilder}; |
| 26 | |
| 27 | /// Error decoding an app icon PNG. |
| 28 | #[derive(Debug, Clone)] |
| 29 | pub struct AppIconError(String); |
| 30 | |
| 31 | impl AppIconError { |
| 32 | pub fn message(&self) -> &str { |
| 33 | &self.0 |
| 34 | } |
| 35 | } |
| 36 | |
| 37 | impl std::fmt::Display for AppIconError { |
| 38 | fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| 39 | write!(f, "app icon: {}", self.0) |
| 40 | } |
| 41 | } |
| 42 | |
| 43 | impl std::error::Error for AppIconError {} |
| 44 | |
| 45 | /// Decode PNG bytes into egui [`IconData`] (RGBA8, unpremultiplied). |
| 46 | /// |
| 47 | /// Intended for `include_bytes!("…png")` assets used as the native window icon. |
| 48 | pub fn icon_data_from_png(png_bytes: &[u8]) -> Result<IconData, AppIconError> { |
| 49 | let (width, height, rgba) = decode_png_rgba(png_bytes)?; |
| 50 | Ok(IconData { |
| 51 | rgba, |
| 52 | width, |
| 53 | height, |
| 54 | }) |
| 55 | } |
| 56 | |
| 57 | /// Attach an embedded PNG as the viewport window icon. |
| 58 | /// |
| 59 | /// On decode failure the viewport is returned unchanged so a bad asset never |
| 60 | /// blocks app launch. |
| 61 | pub fn with_app_icon(viewport: ViewportBuilder, png_bytes: &[u8]) -> ViewportBuilder { |
| 62 | match icon_data_from_png(png_bytes) { |
| 63 | Ok(icon) => viewport.with_icon(Arc::new(icon)), |
| 64 | Err(_) => viewport, |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | /// Like [`with_app_icon`], and set Wayland `app_id`. |
| 69 | /// |
| 70 | /// `app_id` should match the FreeDesktop application id / `StartupWMClass` |
| 71 | /// (e.g. `"usage"` for `usage.desktop`). |
| 72 | pub fn with_app_icon_id( |
| 73 | viewport: ViewportBuilder, |
| 74 | app_id: impl Into<String>, |
| 75 | png_bytes: &[u8], |
| 76 | ) -> ViewportBuilder { |
| 77 | with_app_icon(viewport.with_app_id(app_id), png_bytes) |
| 78 | } |
| 79 | |
| 80 | /// Fallible variant of [`with_app_icon`]. |
| 81 | pub fn try_with_app_icon( |
| 82 | viewport: ViewportBuilder, |
| 83 | png_bytes: &[u8], |
| 84 | ) -> Result<ViewportBuilder, AppIconError> { |
| 85 | let icon = icon_data_from_png(png_bytes)?; |
| 86 | Ok(viewport.with_icon(Arc::new(icon))) |
| 87 | } |
| 88 | |
| 89 | /// Fallible variant of [`with_app_icon_id`]. |
| 90 | pub fn try_with_app_icon_id( |
| 91 | viewport: ViewportBuilder, |
| 92 | app_id: impl Into<String>, |
| 93 | png_bytes: &[u8], |
| 94 | ) -> Result<ViewportBuilder, AppIconError> { |
| 95 | try_with_app_icon(viewport.with_app_id(app_id), png_bytes) |
| 96 | } |
| 97 | |
| 98 | fn decode_png_rgba(bytes: &[u8]) -> Result<(u32, u32, Vec<u8>), AppIconError> { |
| 99 | let mut decoder = png::Decoder::new(Cursor::new(bytes)); |
| 100 | decoder.set_transformations(png::Transformations::EXPAND | png::Transformations::ALPHA); |
| 101 | let mut reader = decoder |
| 102 | .read_info() |
| 103 | .map_err(|e| AppIconError(format!("png header: {e}")))?; |
| 104 | let mut buf = vec![0; reader.output_buffer_size()]; |
| 105 | let info = reader |
| 106 | .next_frame(&mut buf) |
| 107 | .map_err(|e| AppIconError(format!("png frame: {e}")))?; |
| 108 | let w = info.width; |
| 109 | let h = info.height; |
| 110 | let raw = &buf[..info.buffer_size()]; |
| 111 | let rgba: Vec<u8> = match info.color_type { |
| 112 | png::ColorType::Rgba => raw.to_vec(), |
| 113 | png::ColorType::Rgb => { |
| 114 | let mut out = Vec::with_capacity((w * h * 4) as usize); |
| Clear the clippy backlog the new CI enforces 4956d1e nandi 13d ago | 115 | for chunk in raw.as_chunks::<3>().0 { |
| Bring vidya in cfd3e36 nandi 19d ago | 116 | out.extend_from_slice(&[chunk[0], chunk[1], chunk[2], 255]); |
| 117 | } |
| 118 | out |
| 119 | } |
| 120 | other => { |
| 121 | return Err(AppIconError(format!( |
| 122 | "unsupported png color type: {other:?}" |
| 123 | ))); |
| 124 | } |
| 125 | }; |
| 126 | if rgba.len() != (w * h * 4) as usize { |
| 127 | return Err(AppIconError(format!( |
| 128 | "rgba length {} != {}×{}×4", |
| 129 | rgba.len(), |
| 130 | w, |
| 131 | h |
| 132 | ))); |
| 133 | } |
| 134 | Ok((w, h, rgba)) |
| 135 | } |
| 136 | |
| 137 | #[cfg(test)] |
| 138 | mod tests { |
| 139 | use super::*; |
| 140 | |
| 141 | /// 1×1 red RGB PNG (valid CRC). |
| 142 | const TINY_PNG: &[u8] = &[ |
| 143 | 0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00, 0x0d, 0x49, 0x48, 0x44, |
| 144 | 0x52, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x08, 0x02, 0x00, 0x00, 0x00, 0x90, |
| 145 | 0x77, 0x53, 0xde, 0x00, 0x00, 0x00, 0x0c, 0x49, 0x44, 0x41, 0x54, 0x78, 0x9c, 0x63, 0xf8, |
| 146 | 0xcf, 0xc0, 0x00, 0x00, 0x03, 0x01, 0x01, 0x00, 0xc9, 0xfe, 0x92, 0xef, 0x00, 0x00, 0x00, |
| 147 | 0x00, 0x49, 0x45, 0x4e, 0x44, 0xae, 0x42, 0x60, 0x82, |
| 148 | ]; |
| 149 | |
| 150 | #[test] |
| 151 | fn icon_data_from_tiny_png() { |
| 152 | let icon = icon_data_from_png(TINY_PNG).expect("decode"); |
| 153 | assert_eq!(icon.width, 1); |
| 154 | assert_eq!(icon.height, 1); |
| 155 | assert_eq!(icon.rgba.len(), 4); |
| 156 | } |
| 157 | |
| 158 | #[test] |
| 159 | fn with_app_icon_id_sets_app_id() { |
| 160 | let vp = with_app_icon_id(ViewportBuilder::default(), "usage", TINY_PNG); |
| 161 | assert_eq!(vp.app_id.as_deref(), Some("usage")); |
| 162 | assert!(vp.icon.is_some()); |
| 163 | } |
| 164 | |
| 165 | #[test] |
| 166 | fn bad_png_leaves_viewport_unchanged() { |
| 167 | let vp = with_app_icon(ViewportBuilder::default(), b"not a png"); |
| 168 | assert!(vp.icon.is_none()); |
| 169 | assert!(icon_data_from_png(b"not a png").is_err()); |
| 170 | } |
| 171 | } |