soundboard/src/icon.rs

// https://github.com/emilk/egui/issues/920

#[cfg(not(windows))]
pub fn load_app_icon(_icon_name: &str) -> eframe::egui::IconData {
    let (icon_rgba, icon_width, icon_height) = {
        let icon = include_bytes!("../../icons/soundboard.ico");
        let image = image::load_from_memory(icon)
            .expect("Failed to open icon path")
            .into_rgba8();
        let (width, height) = image.dimensions();
        let rgba = image.into_raw();
        (rgba, width, height)
    };

    eframe::egui::IconData {
        rgba: icon_rgba,
        width: icon_width,
        height: icon_height,
    }
}

#[cfg(windows)]
pub use from_windows::load_app_icon;

#[cfg(windows)]
mod from_windows {
    use std::{ffi::OsStr, os::windows::ffi::OsStrExt};

    use eframe::egui;
    use windows::{
        core::PCWSTR,
        Win32::{
            Graphics::Gdi::{
                CreateCompatibleDC, DeleteDC, GetDIBits, GetObjectA, SelectObject, BITMAP,
                BITMAPINFO, BITMAPINFOHEADER, DIB_RGB_COLORS,
            },
            System::LibraryLoader::GetModuleHandleW,
            UI::WindowsAndMessaging::{
                GetIconInfo, LoadImageW, HICON, ICONINFO, IMAGE_ICON, LR_DEFAULTCOLOR,
            },
        },
    };

    fn to_wstring(str: &str) -> Vec<u16> {
        OsStr::new(str)
            .encode_wide()
            .chain(Some(0).into_iter())
            .collect::<Vec<_>>()
    }

    // Grab the icon from the exe and hand it over to egui
    pub fn load_app_icon(icon_name: &str) -> egui::IconData {
        let (mut buffer, width, height) = unsafe {
            let resource_name = to_wstring(icon_name);
            let h_instance = GetModuleHandleW(None).unwrap();
            let icon = LoadImageW(
                h_instance,
                PCWSTR(resource_name.as_ptr()),
                IMAGE_ICON,
                512,
                512,
                LR_DEFAULTCOLOR,
            )
            .unwrap();

            let mut icon_info = ICONINFO::default();
            GetIconInfo(HICON(icon.0), &mut icon_info as *mut _).expect("Failed to load icon info");

            let mut bitmap = BITMAP::default();
            GetObjectA(
                icon_info.hbmColor,
                std::mem::size_of::<BITMAP>() as i32,
                Some(&mut bitmap as *mut _ as *mut _),
            );

            let width = bitmap.bmWidth;
            let height = bitmap.bmHeight;

            let b_size = (width * height * 4) as usize;
            let mut buffer = Vec::<u8>::with_capacity(b_size);

            let h_dc = CreateCompatibleDC(None);
            let h_bitmap = SelectObject(h_dc, icon_info.hbmColor);

            let mut bitmap_info = BITMAPINFO::default();
            bitmap_info.bmiHeader.biSize = std::mem::size_of::<BITMAPINFOHEADER>() as u32;
            bitmap_info.bmiHeader.biWidth = width;
            bitmap_info.bmiHeader.biHeight = height;
            bitmap_info.bmiHeader.biPlanes = 1;
            bitmap_info.bmiHeader.biBitCount = 32;
            bitmap_info.bmiHeader.biCompression = 0;
            bitmap_info.bmiHeader.biSizeImage = 0;

            let res = GetDIBits(
                h_dc,
                icon_info.hbmColor,
                0,
                height as u32,
                Some(buffer.spare_capacity_mut().as_mut_ptr() as *mut _),
                &mut bitmap_info as *mut _,
                DIB_RGB_COLORS,
            );
            if res == 0 {
                panic!("Failed to get RGB DI bits");
            }

            SelectObject(h_dc, h_bitmap);
            let _ = DeleteDC(h_dc);

            assert_eq!(
                bitmap_info.bmiHeader.biSizeImage as usize, b_size,
                "returned biSizeImage must equal to b_size"
            );

            // set the new size
            buffer.set_len(bitmap_info.bmiHeader.biSizeImage as usize);

            (buffer, width as u32, height as u32)
        };

        // RGBA -> BGRA
        for pixel in buffer.as_mut_slice().chunks_mut(4) {
            pixel.swap(0, 2);
        }

        // Flip the image vertically
        let row_size = width as usize * 4; // number of pixels in each row
        let row_count = buffer.len() as usize / row_size; // number of rows in the image
        for row in 0..row_count / 2 {
            // loop through half of the rows
            let start = row * row_size; // index of the start of the current row
            let end = (row_count - row - 1) * row_size; // index of the end of the current row
            for i in 0..row_size {
                buffer.swap(start + i, end + i);
            }
        }

        egui::IconData {
            rgba: buffer,
            width,
            height,
        }
    }
}