Correctly handle eglGetDisplay

1 files changed, 88 insertions, 14 deletions

diff --git a/src/api/egl/mod.rs b/src/api/egl/mod.rs
index 83cd009..f6757ac 100644
--- a/src/api/egl/mod.rs
+++ b/src/api/egl/mod.rs
@@ -16,6 +16,22 @@ use std::{mem, ptr};
 
 pub mod ffi;
 
+/// Specifies the type of display passed as `native_display`.
+pub enum NativeDisplay {
+    /// `None` means `EGL_DEFAULT_DISPLAY`.
+    X11(Option<ffi::EGLNativeDisplayType>),
+    /// `None` means `EGL_DEFAULT_DISPLAY`.
+    Gbm(Option<ffi::EGLNativeDisplayType>),
+    /// `None` means `EGL_DEFAULT_DISPLAY`.
+    Wayland(Option<ffi::EGLNativeDisplayType>),
+    /// `EGL_DEFAULT_DISPLAY` is mandatory for Android.
+    Android,
+    // TODO: should be `EGLDeviceEXT`
+    Device(ffi::EGLNativeDisplayType),
+    /// Don't specify any display type. Useful on windows. `None` means `EGL_DEFAULT_DISPLAY`.
+    Other(Option<ffi::EGLNativeDisplayType>),
+}
+
 pub struct Context {
     egl: ffi::egl::Egl,
     display: ffi::egl::types::EGLDisplay,
@@ -32,7 +48,7 @@ impl Context {
     ///
     /// To finish the process, you must call `.finish(window)` on the `ContextPrototype`.
     pub fn new<'a>(egl: ffi::egl::Egl, builder: &'a BuilderAttribs<'a>,
-                   native_display: Option<ffi::EGLNativeDisplayType>)
+                   native_display: NativeDisplay)
                    -> Result<ContextPrototype<'a>, CreationError>
     {
         if builder.sharing.is_some() {
@@ -40,28 +56,88 @@ impl Context {
         }
 
         // the first step is to query the list of extensions without any display, if supported
-        let extensions = unsafe {
+        let dp_extensions = unsafe {
             let p = egl.QueryString(ffi::egl::NO_DISPLAY, ffi::egl::EXTENSIONS as i32);
 
             // this possibility is available only with EGL 1.5 or EGL_EXT_platform_base, otherwise
             // `eglQueryString` returns an error
             if p.is_null() {
-                None
+                vec![]
             } else {
                 let p = CStr::from_ptr(p);
                 let list = String::from_utf8(p.to_bytes().to_vec()).unwrap_or_else(|_| format!(""));
-                Some(list.split(' ').map(|e| e.to_string()).collect::<Vec<_>>())
+                list.split(' ').map(|e| e.to_string()).collect::<Vec<_>>()
             }
         };
 
-        let display = unsafe {
-            let display = egl.GetDisplay(native_display.unwrap_or(mem::transmute(ffi::egl::DEFAULT_DISPLAY)));
-            if display.is_null() {
-                return Err(CreationError::OsError("No EGL display connection available".to_string()));
+        let has_dp_extension = |e: &str| dp_extensions.iter().find(|s| s == &e).is_some();
+
+        // calling `eglGetDisplay` or equivalent
+        let display = match native_display {
+            NativeDisplay::X11(display) if has_dp_extension("EGL_KHR_platform_x11") => {
+                let d = display.unwrap_or(ffi::egl::DEFAULT_DISPLAY as *const _);
+                // TODO: `PLATFORM_X11_SCREEN_KHR`
+                unsafe { egl.GetPlatformDisplay(ffi::egl::PLATFORM_X11_KHR, d as *mut _,
+                                                ptr::null()) }
+            },
+
+            NativeDisplay::X11(display) if has_dp_extension("EGL_EXT_platform_x11") => {
+                let d = display.unwrap_or(ffi::egl::DEFAULT_DISPLAY as *const _);
+                // TODO: `PLATFORM_X11_SCREEN_EXT`
+                unsafe { egl.GetPlatformDisplayEXT(ffi::egl::PLATFORM_X11_EXT, d as *mut _,
+                                                   ptr::null()) }
+            },
+
+            NativeDisplay::Gbm(display) if has_dp_extension("EGL_KHR_platform_gbm") => {
+                let d = display.unwrap_or(ffi::egl::DEFAULT_DISPLAY as *const _);
+                unsafe { egl.GetPlatformDisplay(ffi::egl::PLATFORM_GBM_KHR, d as *mut _,
+                                                ptr::null()) }
+            },
+
+            NativeDisplay::Gbm(display) if has_dp_extension("EGL_MESA_platform_gbm") => {
+                let d = display.unwrap_or(ffi::egl::DEFAULT_DISPLAY as *const _);
+                unsafe { egl.GetPlatformDisplayEXT(ffi::egl::PLATFORM_GBM_KHR, d as *mut _,
+                                                   ptr::null()) }
+            },
+
+            NativeDisplay::Wayland(display) if has_dp_extension("EGL_KHR_platform_wayland") => {
+                let d = display.unwrap_or(ffi::egl::DEFAULT_DISPLAY as *const _);
+                unsafe { egl.GetPlatformDisplay(ffi::egl::PLATFORM_WAYLAND_KHR, d as *mut _,
+                                                ptr::null()) }
+            },
+
+            NativeDisplay::Wayland(display) if has_dp_extension("EGL_EXT_platform_wayland") => {
+                let d = display.unwrap_or(ffi::egl::DEFAULT_DISPLAY as *const _);
+                unsafe { egl.GetPlatformDisplayEXT(ffi::egl::PLATFORM_WAYLAND_EXT, d as *mut _,
+                                                   ptr::null()) }
+            },
+
+            NativeDisplay::Android if has_dp_extension("EGL_KHR_platform_android") => {
+                unsafe { egl.GetPlatformDisplay(ffi::egl::PLATFORM_ANDROID_KHR,
+                                                ffi::egl::DEFAULT_DISPLAY as *mut _, ptr::null()) }
+            },
+
+            NativeDisplay::Device(display) if has_dp_extension("EGL_EXT_platform_device") => {
+                unsafe { egl.GetPlatformDisplay(ffi::egl::PLATFORM_DEVICE_EXT, display as *mut _,
+                                                ptr::null()) }
+            },
+
+            NativeDisplay::X11(Some(display)) | NativeDisplay::Gbm(Some(display)) |
+            NativeDisplay::Wayland(Some(display)) | NativeDisplay::Device(display) |
+            NativeDisplay::Other(Some(display)) => {
+                unsafe { egl.GetDisplay(display as *mut _) }
             }
-            display
+
+            NativeDisplay::X11(None) | NativeDisplay::Gbm(None) | NativeDisplay::Wayland(None) |
+            NativeDisplay::Android | NativeDisplay::Other(None) => {
+                unsafe { egl.GetDisplay(ffi::egl::DEFAULT_DISPLAY as *mut _) }
+            },
         };
 
+        if display.is_null() {
+            return Err(CreationError::OsError("Could not create EGL display object".to_string()));
+        }
+
         let egl_version = unsafe {
             let mut major: ffi::egl::types::EGLint = mem::uninitialized();
             let mut minor: ffi::egl::types::EGLint = mem::uninitialized();
@@ -73,11 +149,9 @@ impl Context {
             (major, minor)
         };
 
-        // getting the list of extensions for real
-        let extensions = if let Some(extensions) = extensions {
-            extensions
-
-        } else if egl_version >= (1, 2) {
+        // the list of extensions supported by the client once initialized is different from the
+        // list of extensions obtained earlier
+        let extensions = if egl_version >= (1, 2) {
             let p = unsafe { CStr::from_ptr(egl.QueryString(display, ffi::egl::EXTENSIONS as i32)) };
             let list = String::from_utf8(p.to_bytes().to_vec()).unwrap_or_else(|_| format!(""));
             list.split(' ').map(|e| e.to_string()).collect::<Vec<_>>()