wezterm/window/src/egl.rs

use anyhow::{anyhow, bail, ensure, Error};
use std::ffi::c_void;

#[allow(non_camel_case_types, clippy::unreadable_literal)]
pub mod ffi {
    // gl_generator emits these weird cyclical and redundant type references;
    // the types appear to have to be in a module and need to reference super,
    // with some of the types specified in both scopes :-/
    pub mod generated {
        pub type khronos_utime_nanoseconds_t = super::khronos_utime_nanoseconds_t;
        pub type khronos_uint64_t = super::khronos_uint64_t;
        pub type khronos_ssize_t = super::khronos_ssize_t;
        pub type EGLNativeDisplayType = super::EGLNativeDisplayType;
        pub type EGLNativePixmapType = super::EGLNativePixmapType;
        pub type EGLNativeWindowType = super::EGLNativeWindowType;
        pub type EGLint = super::EGLint;
        pub type NativeDisplayType = super::EGLNativeDisplayType;
        pub type NativePixmapType = super::EGLNativePixmapType;
        pub type NativeWindowType = super::EGLNativeWindowType;

        include!(concat!(env!("OUT_DIR"), "/egl_bindings.rs"));
    }

    pub use generated::*;

    use std::os::raw;

    pub type EGLint = i32;
    pub type khronos_ssize_t = raw::c_long;
    pub type khronos_utime_nanoseconds_t = khronos_uint64_t;
    pub type khronos_uint64_t = u64;
    pub type EGLNativeDisplayType = *const raw::c_void;
    pub type EGLNativePixmapType = *const raw::c_void;

    #[cfg(target_os = "windows")]
    pub type EGLNativeWindowType = winapi::shared::windef::HWND;
    #[cfg(not(target_os = "windows"))]
    pub type EGLNativeWindowType = *const raw::c_void;
}

struct EglWrapper {
    _lib: libloading::Library,
    egl: ffi::Egl,
}

pub struct GlState {
    egl: EglWrapper,
    display: ffi::types::EGLDisplay,
    surface: ffi::types::EGLSurface,
    context: ffi::types::EGLContext,
}

impl Drop for GlState {
    fn drop(&mut self) {
        unsafe {
            self.egl.egl.MakeCurrent(
                self.display,
                ffi::NO_SURFACE,
                ffi::NO_SURFACE,
                ffi::NO_CONTEXT,
            );
            self.egl.egl.DestroySurface(self.display, self.surface);
            self.egl.egl.DestroyContext(self.display, self.context);
            self.egl.egl.Terminate(self.display);
        }
    }
}

type GetProcAddressFunc =
    unsafe extern "C" fn(*const std::os::raw::c_char) -> *const std::os::raw::c_void;

impl EglWrapper {
    pub fn load_egl(lib: libloading::Library) -> anyhow::Result<Self> {
        let get_proc_address: libloading::Symbol<GetProcAddressFunc> =
            unsafe { lib.get(b"eglGetProcAddress\0")? };
        let egl = ffi::Egl::load_with(|s: &'static str| {
            let sym_name = std::ffi::CString::new(s).expect("symbol to be cstring compatible");
            if let Ok(sym) = unsafe { lib.get(sym_name.as_bytes_with_nul()) } {
                return *sym;
            }
            unsafe { get_proc_address(sym_name.as_ptr()) }
        });
        Ok(Self { _lib: lib, egl })
    }

    fn get_display(
        &self,
        display: Option<ffi::EGLNativeDisplayType>,
    ) -> anyhow::Result<ffi::types::EGLDisplay> {
        let display = unsafe { self.egl.GetDisplay(display.unwrap_or(ffi::DEFAULT_DISPLAY)) };
        if display.is_null() {
            Err(self.error("egl GetDisplay"))
        } else {
            Ok(display)
        }
    }

    pub fn error(&self, context: &str) -> Error {
        let label = match unsafe { self.egl.GetError() } as u32 {
            ffi::NOT_INITIALIZED => "NOT_INITIALIZED".into(),
            ffi::BAD_ACCESS => "BAD_ACCESS".into(),
            ffi::BAD_ALLOC => "BAD_ALLOC".into(),
            ffi::BAD_ATTRIBUTE => "BAD_ATTRIBUTE".into(),
            ffi::BAD_CONTEXT => "BAD_CONTEXT".into(),
            ffi::BAD_CURRENT_SURFACE => "BAD_CURRENT_SURFACE".into(),
            ffi::BAD_DISPLAY => "BAD_DISPLAY".into(),
            ffi::BAD_SURFACE => "BAD_SURFACE".into(),
            ffi::BAD_MATCH => "BAD_MATCH".into(),
            ffi::BAD_PARAMETER => "BAD_PARAMETER".into(),
            ffi::BAD_NATIVE_PIXMAP => "BAD_NATIVE_PIXMAP".into(),
            ffi::BAD_NATIVE_WINDOW => "BAD_NATIVE_WINDOW".into(),
            ffi::CONTEXT_LOST => "CONTEXT_LOST".into(),
            ffi::SUCCESS => "Failed but with error code: SUCCESS".into(),
            err => format!("EGL Error code: {}", err),
        };
        anyhow!("{}: {}", context, label)
    }

    pub fn initialize_and_get_version(
        &self,
        display: ffi::types::EGLDisplay,
    ) -> anyhow::Result<(ffi::EGLint, ffi::EGLint)> {
        let mut major = 0;
        let mut minor = 0;
        unsafe {
            if self.egl.Initialize(display, &mut major, &mut minor) != 0 {
                Ok((major, minor))
            } else {
                Err(self.error("egl Initialize"))
            }
        }
    }

    fn config_attrib(
        &self,
        display: ffi::types::EGLDisplay,
        config: ffi::types::EGLConfig,
        attribute: u32,
    ) -> Option<ffi::EGLint> {
        let mut value = 0;
        let res = unsafe {
            self.egl
                .GetConfigAttrib(display, config, attribute as ffi::EGLint, &mut value)
        };
        if res == 1 {
            Some(value)
        } else {
            None
        }
    }

    fn log_config_info(&self, display: ffi::types::EGLDisplay, config: ffi::types::EGLConfig) {
        #[derive(Debug)]
        struct ConfigInfo {
            config: ffi::types::EGLConfig,
            alpha_size: Option<ffi::EGLint>,
            red_size: Option<ffi::EGLint>,
            green_size: Option<ffi::EGLint>,
            blue_size: Option<ffi::EGLint>,
            depth_size: Option<ffi::EGLint>,
            conformant: Option<String>,
            renderable_type: Option<String>,
            native_visual_id: Option<ffi::EGLint>,
            surface_type: Option<String>,
        }

        fn conformant_bits(bits: ffi::EGLint) -> String {
            let bits = bits as ffi::types::EGLenum;
            let mut s = String::new();
            if bits & ffi::OPENGL_BIT != 0 {
                s.push_str("OPENGL ");
            }
            if bits & ffi::OPENGL_ES2_BIT != 0 {
                s.push_str("OPENGL_ES2 ");
            }
            if bits & ffi::OPENGL_ES3_BIT != 0 {
                s.push_str("OPENGL_ES3 ");
            }
            if bits & ffi::OPENVG_BIT != 0 {
                s.push_str("OPENVG_BIT ");
            }
            s
        }

        fn surface_bits(bits: ffi::EGLint) -> String {
            let bits = bits as ffi::types::EGLenum;
            let mut s = String::new();
            if bits & ffi::PBUFFER_BIT != 0 {
                s.push_str("PBUFFER ");
            }
            if bits & ffi::PIXMAP_BIT != 0 {
                s.push_str("PIXMAP ");
            }
            if bits & ffi::WINDOW_BIT != 0 {
                s.push_str("WINDOW ");
            }
            s
        }

        let info = ConfigInfo {
            config,
            alpha_size: self.config_attrib(display, config, ffi::ALPHA_SIZE),
            red_size: self.config_attrib(display, config, ffi::RED_SIZE),
            green_size: self.config_attrib(display, config, ffi::GREEN_SIZE),
            blue_size: self.config_attrib(display, config, ffi::BLUE_SIZE),
            depth_size: self.config_attrib(display, config, ffi::DEPTH_SIZE),
            conformant: self
                .config_attrib(display, config, ffi::CONFORMANT)
                .map(conformant_bits),
            renderable_type: self
                .config_attrib(display, config, ffi::RENDERABLE_TYPE)
                .map(conformant_bits),
            native_visual_id: self.config_attrib(display, config, ffi::NATIVE_VISUAL_ID),
            surface_type: self
                .config_attrib(display, config, ffi::SURFACE_TYPE)
                .map(surface_bits),
        };

        log::info!("{:?}", info);
    }

    pub fn choose_config(
        &self,
        display: ffi::types::EGLDisplay,
        attributes: &[u32],
    ) -> anyhow::Result<Vec<ffi::types::EGLConfig>> {
        ensure!(
            !attributes.is_empty() && attributes[attributes.len() - 1] == ffi::NONE,
            "attributes list must be terminated with ffi::NONE"
        );

        let mut num_configs = 0;
        if unsafe {
            self.egl
                .GetConfigs(display, std::ptr::null_mut(), 0, &mut num_configs)
        } != 1
        {
            return Err(self.error("egl GetConfigs to count possible number of configurations"));
        }

        let mut configs = vec![std::ptr::null(); num_configs as usize];

        if unsafe {
            self.egl
                .GetConfigs(display, configs.as_mut_ptr(), num_configs, &mut num_configs)
        } != 1
        {
            return Err(self.error("egl GetConfigs to enumerate configurations"));
        }

        log::info!("Available Configuration(s):");
        for c in &configs {
            self.log_config_info(display, *c);
        }

        if unsafe {
            self.egl.ChooseConfig(
                display,
                attributes.as_ptr() as *const ffi::EGLint,
                configs.as_mut_ptr(),
                configs.len() as ffi::EGLint,
                &mut num_configs,
            )
        } != 1
        {
            return Err(self.error("egl ChooseConfig to select configurations"));
        }

        configs.resize(num_configs as usize, std::ptr::null());

        log::info!("Matching Configuration(s):");
        for c in &configs {
            self.log_config_info(display, *c);
        }

        // If we're running on a system with 30bpp color depth then ChooseConfig
        // will bias towards putting 10bpc matches first, but we want 8-bit.
        // Let's filter out matches that are too deep
        configs.retain(|config| {
            self.config_attrib(display, *config, ffi::RED_SIZE) == Some(8)
                && self.config_attrib(display, *config, ffi::GREEN_SIZE) == Some(8)
                && self.config_attrib(display, *config, ffi::BLUE_SIZE) == Some(8)
        });

        log::info!("Filtered down to these configuration(s):");
        for c in &configs {
            self.log_config_info(display, *c);
        }

        Ok(configs)
    }

    pub fn create_window_surface(
        &self,
        display: ffi::types::EGLDisplay,
        config: ffi::types::EGLConfig,
        window: ffi::EGLNativeWindowType,
    ) -> anyhow::Result<ffi::types::EGLSurface> {
        let surface = unsafe {
            self.egl
                .CreateWindowSurface(display, config, window, std::ptr::null())
        };
        if surface.is_null() {
            Err(self.error("EGL CreateWindowSurface"))
        } else {
            Ok(surface)
        }
    }

    pub fn create_context(
        &self,
        display: ffi::types::EGLDisplay,
        config: ffi::types::EGLConfig,
        share_context: ffi::types::EGLContext,
        attributes: &[u32],
    ) -> anyhow::Result<ffi::types::EGLConfig> {
        ensure!(
            !attributes.is_empty() && attributes[attributes.len() - 1] == ffi::NONE,
            "attributes list must be terminated with ffi::NONE"
        );
        let context = unsafe {
            self.egl.CreateContext(
                display,
                config,
                share_context,
                attributes.as_ptr() as *const i32,
            )
        };
        if context.is_null() {
            Err(self.error("EGL CreateContext"))
        } else {
            Ok(context)
        }
    }
}

impl GlState {
    fn with_egl_lib<F: FnMut(EglWrapper) -> anyhow::Result<Self>>(
        mut func: F,
    ) -> anyhow::Result<Self> {
        let paths = [
            // While EGL is cross platform, it isn't available on macOS nor is it
            // available on my nvidia based system
            #[cfg(target_os = "windows")]
            "libEGL.dll",
            #[cfg(target_os = "windows")]
            "atioglxx.dll",
            #[cfg(not(target_os = "windows"))]
            "libEGL.so.1",
            #[cfg(not(target_os = "windows"))]
            "libEGL.so",
        ];

        let mut errors = vec![];

        for path in &paths {
            if let Ok(lib) = libloading::Library::new(path) {
                match EglWrapper::load_egl(lib) {
                    Ok(egl) => match func(egl) {
                        Ok(result) => {
                            log::info!("initialized {}", path);
                            return Ok(result);
                        }
                        Err(e) => {
                            errors.push(format!("with_egl_lib({}) failed: {}", path, e));
                        }
                    },
                    Err(e) => {
                        errors.push(format!("load_egl {} failed: {}", path, e));
                    }
                }
            }
        }
        bail!("with_egl_lib failed: {}", errors.join(", "))
    }

    #[cfg(all(unix, feature = "wayland", not(target_os = "macos")))]
    pub fn create_wayland(
        display: Option<ffi::EGLNativeDisplayType>,
        wegl_surface: &wayland_egl::WlEglSurface,
    ) -> anyhow::Result<Self> {
        Self::create(display, wegl_surface.ptr())
    }

    pub fn create(
        display: Option<ffi::EGLNativeDisplayType>,
        window: ffi::EGLNativeWindowType,
    ) -> anyhow::Result<Self> {
        Self::with_egl_lib(|egl| {
            let egl_display = egl.get_display(display)?;

            let (major, minor) = egl.initialize_and_get_version(egl_display)?;
            log::info!("initialized EGL version {}.{}", major, minor);

            let configs = egl.choose_config(
                egl_display,
                &[
                    // We're explicitly asking for any alpha size; this is
                    // the default behavior but we're making it explicit here
                    // for the sake of documenting our intent.
                    // In general we want 32bpp with 8bpc, but for displays
                    // that are natively 10bpc we should be fine with relaxing
                    // this to 0 alpha bits, so by asking for 0 here we effectively
                    // indicate that we don't care.
                    // In our implementation of choose_config we will return
                    // only entries with 8bpc for red/green/blue so we should
                    // end up with either 24bpp/8bpc with no alpha, or 32bpp/8bpc
                    // with 8bpc alpha.
                    ffi::ALPHA_SIZE,
                    0,
                    // Request at least 8bpc, 24bpp.  The implementation may
                    // return a context capable of more than this.
                    ffi::RED_SIZE,
                    8,
                    ffi::GREEN_SIZE,
                    8,
                    ffi::BLUE_SIZE,
                    8,
                    ffi::DEPTH_SIZE,
                    24,
                    ffi::CONFORMANT,
                    ffi::OPENGL_ES3_BIT,
                    ffi::RENDERABLE_TYPE,
                    ffi::OPENGL_ES3_BIT,
                    // Wayland EGL doesn't give us a working context if we request
                    // PBUFFER|PIXMAP.  We don't appear to require these for X11,
                    // so we're just asking for a WINDOW capable context
                    ffi::SURFACE_TYPE,
                    ffi::WINDOW_BIT, //| ffi::PBUFFER_BIT | ffi::PIXMAP_BIT,
                    ffi::NONE,
                ],
            )?;

            let first_config = *configs
                .first()
                .ok_or_else(|| anyhow!("no compatible EGL configuration was found"))?;

            let surface = egl.create_window_surface(egl_display, first_config, window)?;

            let context = egl.create_context(
                egl_display,
                first_config,
                std::ptr::null(),
                &[ffi::CONTEXT_MAJOR_VERSION, 3, ffi::NONE],
            )?;

            Ok(Self {
                egl,
                display: egl_display,
                context,
                surface,
            })
        })
    }
}

unsafe impl glium::backend::Backend for GlState {
    fn swap_buffers(&self) -> Result<(), glium::SwapBuffersError> {
        let res = unsafe { self.egl.egl.SwapBuffers(self.display, self.surface) };
        if res != 1 {
            Err(glium::SwapBuffersError::AlreadySwapped)
        } else {
            Ok(())
        }
    }

    unsafe fn get_proc_address(&self, symbol: &str) -> *const c_void {
        let sym_name = std::ffi::CString::new(symbol).expect("symbol to be cstring compatible");
        self.egl.egl.GetProcAddress(sym_name.as_ptr()) as *const c_void
    }

    fn get_framebuffer_dimensions(&self) -> (u32, u32) {
        let mut width = 0;
        let mut height = 0;

        unsafe {
            self.egl
                .egl
                .QuerySurface(self.display, self.surface, ffi::WIDTH as i32, &mut width);
        }
        unsafe {
            self.egl
                .egl
                .QuerySurface(self.display, self.surface, ffi::HEIGHT as i32, &mut height);
        }
        (width as u32, height as u32)
    }

    fn is_current(&self) -> bool {
        unsafe { self.egl.egl.GetCurrentContext() == self.context }
    }

    unsafe fn make_current(&self) {
        self.egl
            .egl
            .MakeCurrent(self.display, self.surface, self.surface, self.context);
    }
}