path: root/src/api/glx/mod.rs

#![cfg(all(target_os = "linux", feature = "window"))]

use BuilderAttribs;
use ContextError;
use CreationError;
use GlContext;
use GlProfile;
use GlRequest;
use Api;
use PixelFormat;
use Robustness;

use libc;
use std::ffi::{CStr, CString};
use std::{mem, ptr};

use api::x11::ffi;

use platform::Window as PlatformWindow;

pub struct Context {
    glx: ffi::glx::Glx,
    display: *mut ffi::Display,
    window: ffi::Window,
    context: ffi::GLXContext,
    pixel_format: PixelFormat,
}

// TODO: remove me
fn with_c_str<F, T>(s: &str, f: F) -> T where F: FnOnce(*const libc::c_char) -> T {
    use std::ffi::CString;
    let c_str = CString::new(s.as_bytes().to_vec()).unwrap();
    f(c_str.as_ptr())
}

impl Context {
    pub fn new<'a>(glx: ffi::glx::Glx, xlib: &ffi::Xlib, builder: &'a BuilderAttribs<'a>,
                   display: *mut ffi::Display)
                   -> Result<ContextPrototype<'a>, CreationError>
    {
        // finding the pixel format we want
        // TODO: enumerate them instead
        let fb_config = unsafe {
            let mut visual_attributes = vec![
                ffi::glx::X_RENDERABLE as libc::c_int,  1,
                ffi::glx::DRAWABLE_TYPE as libc::c_int, ffi::glx::WINDOW_BIT as libc::c_int,
                ffi::glx::RENDER_TYPE as libc::c_int,   ffi::glx::RGBA_BIT as libc::c_int,
                ffi::glx::X_VISUAL_TYPE as libc::c_int, ffi::glx::TRUE_COLOR as libc::c_int,
                ffi::glx::RED_SIZE as libc::c_int,      8,
                ffi::glx::GREEN_SIZE as libc::c_int,    8,
                ffi::glx::BLUE_SIZE as libc::c_int,     8,
                ffi::glx::ALPHA_SIZE as libc::c_int,    8,
                ffi::glx::DEPTH_SIZE as libc::c_int,    24,
                ffi::glx::STENCIL_SIZE as libc::c_int,  8,
                ffi::glx::DOUBLEBUFFER as libc::c_int,  1,
            ];

            if let Some(val) = builder.multisampling {
                visual_attributes.push(ffi::glx::SAMPLE_BUFFERS as libc::c_int);
                visual_attributes.push(1);
                visual_attributes.push(ffi::glx::SAMPLES as libc::c_int);
                visual_attributes.push(val as libc::c_int);
            }

            if let Some(val) = builder.srgb {
                visual_attributes.push(ffi::glx_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB as libc::c_int);
                visual_attributes.push(if val {1} else {0});
            }

            visual_attributes.push(0);

            let mut num_fb: libc::c_int = mem::uninitialized();

            let fb = glx.ChooseFBConfig(display as *mut _, (xlib.XDefaultScreen)(display),
                visual_attributes.as_ptr(), &mut num_fb);
            if fb.is_null() {
                return Err(CreationError::OsError(format!("glxChooseFBConfig failed")));
            }

            let preferred_fb = if builder.transparent {
                let mut best_fbi_for_transparent = 0isize;

                for i in 0isize..num_fb as isize {
                    let vi = glx.GetVisualFromFBConfig(display as *mut _, *fb.offset(i));
                    if (*vi).depth == 32 {
                        best_fbi_for_transparent = i;
                        break;
                    }
                }

                *fb.offset(best_fbi_for_transparent)
            } else {
                *fb // TODO: choose more wisely
            };

            (xlib.XFree)(fb as *mut _);
            preferred_fb
        };

        // getting the visual infos
        let visual_infos: ffi::glx::types::XVisualInfo = unsafe {
            let vi = glx.GetVisualFromFBConfig(display as *mut _, fb_config);
            if vi.is_null() {
                return Err(CreationError::OsError(format!("glxGetVisualFromFBConfig failed")));
            }
            let vi_copy = ptr::read(vi as *const _);
            (xlib.XFree)(vi as *mut _);
            vi_copy
        };

        Ok(ContextPrototype {
            glx: glx,
            builder: builder,
            display: display,
            fb_config: fb_config,
            visual_infos: unsafe { mem::transmute(visual_infos) },
        })
    }
}

impl GlContext for Context {
    unsafe fn make_current(&self) -> Result<(), ContextError> {
        // TODO: glutin needs some internal changes for proper error recovery
        let res = self.glx.MakeCurrent(self.display as *mut _, self.window, self.context);
        if res == 0 {
            panic!("glx::MakeCurrent failed");
        }
        Ok(())
    }

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

    fn get_proc_address(&self, addr: &str) -> *const libc::c_void {
        let addr = CString::new(addr.as_bytes()).unwrap();
        let addr = addr.as_ptr();
        unsafe {
            self.glx.GetProcAddress(addr as *const _) as *const _
        }
    }

    fn swap_buffers(&self) -> Result<(), ContextError> {
        // TODO: glutin needs some internal changes for proper error recovery
        unsafe { self.glx.SwapBuffers(self.display as *mut _, self.window); }
        Ok(())
    }

    fn get_api(&self) -> ::Api {
        ::Api::OpenGl
    }

    fn get_pixel_format(&self) -> PixelFormat {
        self.pixel_format.clone()
    }
}

unsafe impl Send for Context {}
unsafe impl Sync for Context {}

impl Drop for Context {
    fn drop(&mut self) {
        unsafe {
            if self.is_current() {
                self.glx.MakeCurrent(self.display as *mut _, 0, ptr::null_mut());
            }

            self.glx.DestroyContext(self.display as *mut _, self.context);
        }
    }
}

pub struct ContextPrototype<'a> {
    glx: ffi::glx::Glx,
    builder: &'a BuilderAttribs<'a>,
    display: *mut ffi::Display,
    fb_config: ffi::glx::types::GLXFBConfig,
    visual_infos: ffi::XVisualInfo,
}

impl<'a> ContextPrototype<'a> {
    pub fn get_visual_infos(&self) -> &ffi::XVisualInfo {
        &self.visual_infos
    }

    pub fn finish(self, window: ffi::Window) -> Result<Context, CreationError> {
        let share = if let Some(win) = self.builder.sharing {
            match win {
                &PlatformWindow::X(ref win) => match win.x.context {
                    ::api::x11::Context::Glx(ref c) => c.context,
                    _ => panic!("Cannot share contexts between different APIs")
                },
                _ => panic!("Cannot use glx on a non-X11 window.")
            }
        } else {
            ptr::null()
        };

        // loading the list of extensions
        let extensions = unsafe {
            let extensions = self.glx.QueryExtensionsString(self.display as *mut _, 0);     // FIXME: screen number
            let extensions = CStr::from_ptr(extensions).to_bytes().to_vec();
            String::from_utf8(extensions).unwrap()
        };

        // loading the extra GLX functions
        let extra_functions = ffi::glx_extra::Glx::load_with(|addr| {
            with_c_str(addr, |s| {
                unsafe { self.glx.GetProcAddress(s as *const u8) as *const _ }
            })
        });

        // creating GL context
        let context = match self.builder.gl_version {
            GlRequest::Latest => {
                if let Ok(ctxt) = create_context(&self.glx, &extra_functions, &extensions, (3, 2),
                                                 self.builder.gl_profile, self.builder.gl_debug,
                                                 self.builder.gl_robustness, share,
                                                 self.display, self.fb_config, &self.visual_infos)
                {
                    ctxt
                } else if let Ok(ctxt) = create_context(&self.glx, &extra_functions, &extensions,
                                                        (3, 1), self.builder.gl_profile,
                                                        self.builder.gl_debug,
                                                        self.builder.gl_robustness, share, self.display,
                                                        self.fb_config, &self.visual_infos)
                {
                    ctxt

                } else {
                    try!(create_context(&self.glx, &extra_functions, &extensions, (1, 0),
                                        self.builder.gl_profile, self.builder.gl_debug,
                                        self.builder.gl_robustness,
                                        share, self.display, self.fb_config, &self.visual_infos))
                }
            },
            GlRequest::Specific(Api::OpenGl, (major, minor)) => {
                try!(create_context(&self.glx, &extra_functions, &extensions, (major, minor),
                                    self.builder.gl_profile, self.builder.gl_debug,
                                    self.builder.gl_robustness, share, self.display, self.fb_config,
                                    &self.visual_infos))
            },
            GlRequest::Specific(_, _) => panic!("Only OpenGL is supported"),
            GlRequest::GlThenGles { opengl_version: (major, minor), .. } => {
                try!(create_context(&self.glx, &extra_functions, &extensions, (major, minor),
                                    self.builder.gl_profile, self.builder.gl_debug,
                                    self.builder.gl_robustness, share, self.display, self.fb_config,
                                    &self.visual_infos))
            },
        };

        // vsync
        if self.builder.vsync {
            unsafe { self.glx.MakeCurrent(self.display as *mut _, window, context) };

            if extra_functions.SwapIntervalEXT.is_loaded() {
                // this should be the most common extension
                unsafe {
                    extra_functions.SwapIntervalEXT(self.display as *mut _, window, 1);
                }

                // checking that it worked
                if self.builder.strict {
                    let mut swap = unsafe { mem::uninitialized() };
                    unsafe {
                        self.glx.QueryDrawable(self.display as *mut _, window,
                                               ffi::glx_extra::SWAP_INTERVAL_EXT as i32,
                                               &mut swap);
                    }

                    if swap != 1 {
                        return Err(CreationError::OsError(format!("Couldn't setup vsync: expected \
                                                    interval `1` but got `{}`", swap)));
                    }
                }

            // GLX_MESA_swap_control is not official
            /*} else if extra_functions.SwapIntervalMESA.is_loaded() {
                unsafe {
                    extra_functions.SwapIntervalMESA(1);
                }*/

            } else if extra_functions.SwapIntervalSGI.is_loaded() {
                unsafe {
                    extra_functions.SwapIntervalSGI(1);
                }

            } else if self.builder.strict {
                return Err(CreationError::OsError(format!("Couldn't find any available vsync extension")));
            }

            unsafe { self.glx.MakeCurrent(self.display as *mut _, 0, ptr::null()) };
        }

        let pixel_format = unsafe { get_pixel_format(&self.glx, self.display, self.fb_config) };

        Ok(Context {
            glx: self.glx,
            display: self.display,
            window: window,
            context: context,
            pixel_format: pixel_format,
        })
    }
}

fn create_context(glx: &ffi::glx::Glx, extra_functions: &ffi::glx_extra::Glx, extensions: &str,
                  version: (u8, u8), profile: Option<GlProfile>, debug: bool,
                  robustness: Robustness, share: ffi::GLXContext, display: *mut ffi::Display,
                  fb_config: ffi::glx::types::GLXFBConfig,
                  visual_infos: &ffi::XVisualInfo)
                  -> Result<ffi::GLXContext, CreationError>
{
    unsafe {
        let context = if extra_functions.CreateContextAttribsARB.is_loaded() {
            let mut attributes = Vec::with_capacity(9);

            attributes.push(ffi::glx_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
            attributes.push(version.0 as libc::c_int);
            attributes.push(ffi::glx_extra::CONTEXT_MINOR_VERSION_ARB as libc::c_int);
            attributes.push(version.1 as libc::c_int);

            if let Some(profile) = profile {
                let flag = match profile {
                    GlProfile::Compatibility =>
                        ffi::glx_extra::CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
                    GlProfile::Core =>
                        ffi::glx_extra::CONTEXT_CORE_PROFILE_BIT_ARB,
                };

                attributes.push(ffi::glx_extra::CONTEXT_PROFILE_MASK_ARB as libc::c_int);
                attributes.push(flag as libc::c_int);
            }

            let flags = {
                let mut flags = 0;

                // robustness
                if extensions.split(' ').find(|&i| i == "GLX_ARB_create_context_robustness").is_some() {
                    match robustness {
                        Robustness::RobustNoResetNotification | Robustness::TryRobustNoResetNotification => {
                            attributes.push(ffi::glx_extra::CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB as libc::c_int);
                            attributes.push(ffi::glx_extra::NO_RESET_NOTIFICATION_ARB as libc::c_int);
                            flags = flags | ffi::glx_extra::CONTEXT_ROBUST_ACCESS_BIT_ARB as libc::c_int;
                        },
                        Robustness::RobustLoseContextOnReset | Robustness::TryRobustLoseContextOnReset => {
                            attributes.push(ffi::glx_extra::CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB as libc::c_int);
                            attributes.push(ffi::glx_extra::LOSE_CONTEXT_ON_RESET_ARB as libc::c_int);
                            flags = flags | ffi::glx_extra::CONTEXT_ROBUST_ACCESS_BIT_ARB as libc::c_int;
                        },
                        Robustness::NotRobust => (),
                        Robustness::NoError => (),
                    }
                } else {
                    match robustness {
                        Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
                            return Err(CreationError::NotSupported);
                        },
                        _ => ()
                    }
                }

                if debug {
                    flags = flags | ffi::glx_extra::CONTEXT_DEBUG_BIT_ARB as libc::c_int;
                }

                flags
            };

            attributes.push(ffi::glx_extra::CONTEXT_FLAGS_ARB as libc::c_int);
            attributes.push(flags);

            attributes.push(0);

            extra_functions.CreateContextAttribsARB(display as *mut _, fb_config, share, 1,
                                                    attributes.as_ptr())

        } else {
            let visual_infos: *const ffi::XVisualInfo = visual_infos;
            glx.CreateContext(display as *mut _, visual_infos as *mut _, share, 1)
        };

        if context.is_null() {
            return Err(CreationError::OsError(format!("GL context creation failed")));
        }

        Ok(context)
    }
}

unsafe fn get_pixel_format(glx: &ffi::glx::Glx, display: *mut ffi::Display,
                           fb_config: ffi::glx::types::GLXFBConfig) -> PixelFormat
{
    let get_attrib = |attrib: libc::c_int| -> i32 {
        let mut value = 0;
        glx.GetFBConfigAttrib(display as *mut _, fb_config, attrib, &mut value);
        // TODO: check return value
        value
    };

    // TODO: make sure everything is supported
    PixelFormat {
        hardware_accelerated: true,
        color_bits: get_attrib(ffi::glx::RED_SIZE as libc::c_int) as u8 +
                    get_attrib(ffi::glx::GREEN_SIZE as libc::c_int) as u8 +
                    get_attrib(ffi::glx::BLUE_SIZE as libc::c_int) as u8,
        alpha_bits: get_attrib(ffi::glx::ALPHA_SIZE as libc::c_int) as u8,
        depth_bits: get_attrib(ffi::glx::DEPTH_SIZE as libc::c_int) as u8,
        stencil_bits: get_attrib(ffi::glx::STENCIL_SIZE as libc::c_int) as u8,
        stereoscopy: get_attrib(ffi::glx::STEREO as libc::c_int) != 0,
        double_buffer: get_attrib(ffi::glx::DOUBLEBUFFER as libc::c_int) != 0,
        multisampling: if get_attrib(ffi::glx::SAMPLE_BUFFERS as libc::c_int) != 0 {
            Some(get_attrib(ffi::glx::SAMPLES as libc::c_int) as u16)
        } else {
            None
        },
        srgb: get_attrib(ffi::glx_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB as libc::c_int) != 0,
    }
}