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//! Set the native app icon at runtime.
//!
//! TODO(emilk): port this to [`winit`].
use std::sync::Arc;
use egui::IconData;
pub struct AppTitleIconSetter {
title: String,
icon_data: Option<Arc<IconData>>,
status: AppIconStatus,
}
impl AppTitleIconSetter {
pub fn new(title: String, mut icon_data: Option<Arc<IconData>>) -> Self {
if let Some(icon) = &icon_data
&& **icon == IconData::default()
{
icon_data = None;
}
Self {
title,
icon_data,
status: AppIconStatus::NotSetTryAgain,
}
}
/// Call once per frame; we will set the icon when we can.
pub fn update(&mut self) {
if self.status == AppIconStatus::NotSetTryAgain {
self.status = set_title_and_icon(&self.title, self.icon_data.as_deref());
}
}
}
/// In which state the app icon is (as far as we know).
#[derive(PartialEq, Eq)]
enum AppIconStatus {
/// We did not set it or failed to do it. In any case we won't try again.
NotSetIgnored,
/// We haven't set the icon yet, we should try again next frame.
///
/// This can happen repeatedly due to lazy window creation on some platforms.
NotSetTryAgain,
/// We successfully set the icon and it should be visible now.
#[allow(clippy::allow_attributes, dead_code)] // Not used on Linux
Set,
}
/// Sets app icon at runtime.
///
/// By setting the icon at runtime and not via resource files etc. we ensure that we'll get the chance
/// to set the same icon when the process/window is started from python (which sets its own icon ahead of us!).
///
/// Since window creation can be lazy, call this every frame until it's either successfully or gave up.
/// (See [`AppIconStatus`])
fn set_title_and_icon(_title: &str, _icon_data: Option<&IconData>) -> AppIconStatus {
profiling::function_scope!();
#[cfg(target_os = "windows")]
{
if let Some(icon_data) = _icon_data {
return set_app_icon_windows(icon_data);
}
}
#[cfg(target_os = "macos")]
return set_title_and_icon_mac(_title, _icon_data);
#[allow(clippy::allow_attributes, unreachable_code)]
AppIconStatus::NotSetIgnored
}
/// Set icon for Windows applications.
#[cfg(target_os = "windows")]
#[expect(unsafe_code)]
fn set_app_icon_windows(icon_data: &IconData) -> AppIconStatus {
use crate::icon_data::IconDataExt as _;
use windows_sys::Win32::UI::Input::KeyboardAndMouse::GetActiveWindow;
use windows_sys::Win32::UI::WindowsAndMessaging::{
CreateIconFromResourceEx, GetSystemMetrics, HICON, ICON_BIG, ICON_SMALL, LR_DEFAULTCOLOR,
SM_CXICON, SM_CXSMICON, SendMessageW, WM_SETICON,
};
// We would get fairly far already with winit's `set_window_icon` (which is exposed to eframe) actually!
// However, it only sets ICON_SMALL, i.e. doesn't allow us to set a higher resolution icon for the task bar.
// Also, there is scaling issues, detailed below.
// TODO(andreas): This does not set the task bar icon for when our application is started from python.
// Things tried so far:
// * Querying for an owning window and setting icon there (there doesn't seem to be an owning window)
// * using undocumented SetConsoleIcon method (successfully queried via GetProcAddress)
// SAFETY: WinApi function without side-effects.
let window_handle = unsafe { GetActiveWindow() };
if window_handle.is_null() {
// The Window isn't available yet. Try again later!
return AppIconStatus::NotSetTryAgain;
}
fn create_hicon_with_scale(unscaled_image: &image::RgbaImage, target_size: i32) -> HICON {
let image_scaled = image::imageops::resize(
unscaled_image,
target_size as _,
target_size as _,
image::imageops::Lanczos3,
);
// Creating transparent icons with WinApi is a huge mess.
// We'd need to go through CreateIconIndirect's ICONINFO struct which then
// takes a mask HBITMAP and a color HBITMAP and creating each of these is pain.
// Instead we workaround this by creating a png which CreateIconFromResourceEx magically understands.
// This is a pretty horrible hack as we spend a lot of time encoding, but at least the code is a lot shorter.
let mut image_scaled_bytes: Vec<u8> = Vec::new();
if image_scaled
.write_to(
&mut std::io::Cursor::new(&mut image_scaled_bytes),
image::ImageFormat::Png,
)
.is_err()
{
return std::ptr::null_mut();
}
// SAFETY: Creating an HICON which should be readonly on our data.
unsafe {
CreateIconFromResourceEx(
image_scaled_bytes.as_mut_ptr(),
image_scaled_bytes.len() as u32,
1, // Means this is an icon, not a cursor.
0x00030000, // Version number of the HICON
target_size, // Note that this method can scale, but it does so *very* poorly. So let's avoid that!
target_size,
LR_DEFAULTCOLOR,
)
}
}
let unscaled_image = match icon_data.to_image() {
Ok(unscaled_image) => unscaled_image,
Err(err) => {
log::warn!("Invalid icon: {err}");
return AppIconStatus::NotSetIgnored;
}
};
// Only setting ICON_BIG with the icon size for big icons (SM_CXICON) works fine
// but the scaling it does then for the small icon is pretty bad.
// Instead we set the correct sizes manually and take over the scaling ourselves.
// For this to work we first need to set the big icon and then the small one.
//
// Note that ICON_SMALL may be used even if we don't render a title bar as it may be used in alt+tab!
{
// SAFETY: WinAPI getter function with no known side effects.
let icon_size_big = unsafe { GetSystemMetrics(SM_CXICON) };
let icon_big = create_hicon_with_scale(&unscaled_image, icon_size_big);
if icon_big.is_null() {
log::warn!("Failed to create HICON (for big icon) from embedded png data.");
return AppIconStatus::NotSetIgnored; // We could try independently with the small icon but what's the point, it would look bad!
} else {
// SAFETY: Unsafe WinApi function, takes objects previously created with WinAPI, all checked for null prior.
unsafe {
SendMessageW(
window_handle,
WM_SETICON,
ICON_BIG as usize,
icon_big as isize,
);
}
}
}
{
// SAFETY: WinAPI getter function with no known side effects.
let icon_size_small = unsafe { GetSystemMetrics(SM_CXSMICON) };
let icon_small = create_hicon_with_scale(&unscaled_image, icon_size_small);
if icon_small.is_null() {
log::warn!("Failed to create HICON (for small icon) from embedded png data.");
return AppIconStatus::NotSetIgnored;
} else {
// SAFETY: Unsafe WinApi function, takes objects previously created with WinAPI, all checked for null prior.
unsafe {
SendMessageW(
window_handle,
WM_SETICON,
ICON_SMALL as usize,
icon_small as isize,
);
}
}
}
// It _probably_ worked out.
AppIconStatus::Set
}
/// Set icon & app title for `MacOS` applications.
#[cfg(target_os = "macos")]
#[expect(unsafe_code)]
fn set_title_and_icon_mac(title: &str, icon_data: Option<&IconData>) -> AppIconStatus {
use crate::icon_data::IconDataExt as _;
profiling::function_scope!();
use objc2::AnyThread as _;
use objc2_app_kit::{NSApplication, NSImage};
use objc2_foundation::NSString;
// Do NOT use png even though creating `NSImage` from it is much easier than from raw images data!
//
// Some MacOS versions have a bug where creating an `NSImage` from a png will cause it to load an arbitrary `libpng.dylib`.
// If this dylib isn't the right version, the application will crash with SIGBUS.
// For details see https://github.com/emilk/egui/issues/7155
let image = if let Some(icon_data) = icon_data {
match icon_data.to_image() {
Ok(image) => Some(image),
Err(err) => {
log::warn!("Failed to read icon data: {err}");
return AppIconStatus::NotSetIgnored;
}
}
} else {
None
};
// TODO(madsmtm): Move this into `objc2-app-kit`
unsafe extern "C" {
static NSApp: Option<&'static NSApplication>;
}
// SAFETY: we don't do anything dangerous here
unsafe {
let Some(app) = NSApp else {
log::debug!("NSApp is null");
return AppIconStatus::NotSetIgnored;
};
if let Some(image) = image {
use objc2_app_kit::{NSBitmapImageRep, NSDeviceRGBColorSpace};
use objc2_foundation::NSSize;
log::trace!(
"NSBitmapImageRep::initWithBitmapDataPlanes_pixelsWide_pixelsHigh_bitsPerSample_samplesPerPixel_hasAlpha_isPlanar_colorSpaceName_bytesPerRow_bitsPerPixel"
);
let Some(image_rep) = NSBitmapImageRep::initWithBitmapDataPlanes_pixelsWide_pixelsHigh_bitsPerSample_samplesPerPixel_hasAlpha_isPlanar_colorSpaceName_bytesPerRow_bitsPerPixel(
NSBitmapImageRep::alloc(),
[image.as_raw().as_ptr().cast_mut()].as_mut_ptr(),
image.width() as isize,
image.height() as isize,
8, // bits per sample
4, // samples per pixel
true, // has alpha
false, // is not planar
NSDeviceRGBColorSpace,
(image.width() * 4) as isize, // bytes per row
32 // bits per pixel
) else {
log::warn!("Failed to create NSBitmapImageRep from app icon data.");
return AppIconStatus::NotSetIgnored;
};
log::trace!("NSImage::initWithSize");
let app_icon = NSImage::initWithSize(
NSImage::alloc(),
NSSize::new(image.width() as f64, image.height() as f64),
);
log::trace!("NSImage::addRepresentation");
app_icon.addRepresentation(&image_rep);
profiling::scope!("setApplicationIconImage_");
log::trace!("setApplicationIconImage…");
app.setApplicationIconImage(Some(&app_icon));
}
// Change the title in the top bar - for python processes this would be again "python" otherwise.
if let Some(main_menu) = app.mainMenu()
&& let Some(item) = main_menu.itemAtIndex(0)
&& let Some(app_menu) = item.submenu()
{
profiling::scope!("setTitle_");
app_menu.setTitle(&NSString::from_str(title));
}
// The title in the Dock apparently can't be changed.
// At least these people didn't figure it out either:
// https://stackoverflow.com/questions/69831167/qt-change-application-title-dynamically-on-macos
// https://stackoverflow.com/questions/28808226/changing-cocoa-app-icon-title-and-menu-labels-at-runtime
}
AppIconStatus::Set
}