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Merged
sagudev merged 2 commits into from
Sep 28, 2026
Merged

Convert Context into an enum #399

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f17a1d0
Convert `Context` into an enum
mrobinson Sep 27, 2026
f129f12
Respond to review comments
mrobinson Sep 27, 2026
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21 changes: 3 additions & 18 deletions src/angle/context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,31 +10,16 @@ use crate::surface::Framebuffer;
use crate::Gl;
use std::thread;

/// Represents an OpenGL rendering context.
///
/// A context allows you to issue rendering commands to a surface. When initially created, a
/// context has no attached surface, so rendering commands will fail or be ignored. Typically, you
/// attach a surface to the context before rendering.
///
/// Contexts take ownership of the surfaces attached to them. In order to mutate a surface in any
/// way other than rendering to it (e.g. presenting it to a window, which causes a buffer swap), it
/// must first be detached from its context. Each surface is associated with a single context upon
/// creation and may not be rendered to from any other context. However, you can wrap a surface in
/// a surface texture, which allows the surface to be read from another context.
///
/// OpenGL objects may not be shared across contexts directly, but surface textures effectively
/// allow for sharing of texture data. Contexts are local to a single thread and device.
///
/// A context must be explicitly destroyed with `destroy_context()`, or a panic will occur.
pub struct Context {
/// An implementation of [`crate::Context`] for ANGLE on Windows.
pub struct AngleContext {
pub(crate) egl_context: EGLContext,
pub(crate) id: ContextID,
pub(crate) framebuffer: Framebuffer<Surface, ExternalEGLSurfaces>,
pub(crate) context_is_owned: bool,
pub(crate) gl: Gl,
}

impl Drop for Context {
impl Drop for AngleContext {
#[inline]
fn drop(&mut self) {
if self.egl_context != egl::NO_CONTEXT && !thread::panicking() {
Expand Down
97 changes: 63 additions & 34 deletions src/angle/device.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@

use super::adapter::AngleAdapter;
use crate::angle::connection::Connection;
use crate::angle::context::{Context, NativeContext};
use crate::angle::context::{AngleContext, NativeContext};
use crate::angle::surface::{
Surface, SurfaceDataGuard, SurfaceTexture, Synchronization, Win32Objects,
};
Expand All @@ -20,10 +20,9 @@ use crate::egl::types::{
EGLAttrib, EGLConfig, EGLDeviceEXT, EGLDisplay, EGLNativeWindowType, EGLSurface, EGLint,
};
use crate::surface::Framebuffer;
use crate::EglContextDescriptor;
use crate::{
egl, gl, Adapter, ContextAttributes, ContextDescriptor, Error, GLApi, Gl, SurfaceAccess,
SurfaceInfo, SurfaceType,
egl, gl, Adapter, Context, ContextAttributes, ContextDescriptor, EglContextDescriptor, Error,
GLApi, Gl, SurfaceAccess, SurfaceInfo, SurfaceType,
};
use euclid::default::Size2D;
use glow::HasContext;
Expand Down Expand Up @@ -271,6 +270,7 @@ impl Device {
descriptor: &ContextDescriptor,
share_with: Option<&Context>,
) -> Result<Context, Error> {
let share_with = share_with.map(Context::angle).transpose()?;
let (egl_context, id) = {
let mut next_context_id_lock = CREATE_CONTEXT_MUTEX.lock().unwrap();
let egl_context = unsafe {
Expand Down Expand Up @@ -302,14 +302,14 @@ impl Device {
})?;
}

let context = Context {
Ok(AngleContext {
egl_context,
id,
framebuffer: Framebuffer::None,
context_is_owned: true,
gl: unsafe { Gl::from_loader_function(context::get_proc_address) },
};
Ok(context)
}
.into())
}

/// Wraps a native `EGLContext` in a context object.
Expand All @@ -324,7 +324,7 @@ impl Device {
let mut next_context_id = CREATE_CONTEXT_MUTEX.lock().unwrap();

// Create the context.
let context = Context {
let context = AngleContext {
egl_context: native_context.egl_context,
id: *next_context_id,
framebuffer: Framebuffer::External(ExternalEGLSurfaces {
Expand All @@ -336,21 +336,22 @@ impl Device {
};
next_context_id.0 += 1;

Ok(context)
Ok(context.into())
}

/// Destroys a context.
///
/// The context must have been created on this device.
pub fn destroy_context(&self, context: &mut Context) -> Result<(), Error> {
if context.egl_context == egl::NO_CONTEXT {
if context.angle()?.egl_context == egl::NO_CONTEXT {
return Ok(());
}

if let Ok(Some(mut surface)) = self.unbind_surface_from_context(context) {
self.destroy_surface(context, &mut surface)?;
}

let context: &mut AngleContext = context.try_into()?;
EGL_FUNCTIONS.with(|egl| unsafe {
egl.MakeCurrent(
self.egl_display,
Expand All @@ -372,6 +373,7 @@ impl Device {

/// Returns the descriptor that this context was created with.
pub fn context_descriptor(&self, context: &Context) -> ContextDescriptor {
let context = context.angle().expect("Passed incorrect context type");
unsafe {
EglContextDescriptor::from_egl_context(
&context.gl,
Expand All @@ -382,31 +384,35 @@ impl Device {
}
}

/// Makes the context the current OpenGL context for this thread.
///
/// After calling this function, it is valid to use OpenGL rendering commands.
pub fn make_context_current(&self, context: &Context) -> Result<(), Error> {
unsafe {
let (egl_draw_surface, egl_read_surface) = match context.framebuffer {
Framebuffer::Surface(ref surface) => (surface.egl_surface, surface.egl_surface),
Framebuffer::None => (egl::NO_SURFACE, egl::NO_SURFACE),
Framebuffer::External(ref surfaces) => (surfaces.draw, surfaces.read),
};
fn make_context_current_inner(&self, context: &AngleContext) -> Result<(), Error> {
let (egl_draw_surface, egl_read_surface) = match context.framebuffer {
Framebuffer::Surface(ref surface) => (surface.egl_surface, surface.egl_surface),
Framebuffer::None => (egl::NO_SURFACE, egl::NO_SURFACE),
Framebuffer::External(ref surfaces) => (surfaces.draw, surfaces.read),
};

EGL_FUNCTIONS.with(|egl| {
let result = egl.MakeCurrent(
EGL_FUNCTIONS.with(|egl| {
let result = unsafe {
egl.MakeCurrent(
self.egl_display,
egl_draw_surface,
egl_read_surface,
context.egl_context,
);
if result == egl::FALSE {
let err = egl.GetError().to_windowing_api_error();
return Err(Error::MakeCurrentFailed(err));
}
Ok(())
})
}
)
};
if result == egl::FALSE {
let err = unsafe { egl.GetError() }.to_windowing_api_error();
return Err(Error::MakeCurrentFailed(err));
}
Ok(())
})
}

/// Makes the context the current OpenGL context for this thread.
///
/// After calling this function, it is valid to use OpenGL rendering commands.
pub fn make_context_current(&self, context: &Context) -> Result<(), Error> {
self.make_context_current_inner(context.angle()?)
}

/// Removes the current OpenGL context from this thread.
Expand All @@ -419,14 +425,14 @@ impl Device {

pub(crate) fn temporarily_make_context_current(
&self,
context: &Context,
context: &AngleContext,
) -> Result<CurrentContextGuard, Error> {
let guard = CurrentContextGuard::new();
self.make_context_current(context)?;
self.make_context_current_inner(context)?;
Ok(guard)
}

pub(crate) fn context_is_current(&self, context: &Context) -> bool {
pub(crate) fn context_is_current(&self, context: &AngleContext) -> bool {
EGL_FUNCTIONS.with(|egl| unsafe { egl.GetCurrentContext() == context.egl_context })
}

Expand Down Expand Up @@ -477,6 +483,10 @@ impl Device {
context: &mut Context,
surface: Surface,
) -> Result<(), (Error, Surface)> {
let context: &mut AngleContext = match context.try_into() {
Ok(context) => context,
Err(error) => return Err((error, surface)),
};
if context.id != surface.context_id {
return Err((Error::IncompatibleSurface, surface));
}
Expand Down Expand Up @@ -514,7 +524,7 @@ impl Device {

if is_current {
// We need to make ourselves current again, because the surface changed.
drop(self.make_context_current(context));
drop(self.make_context_current_inner(context));
}

Ok(())
Expand All @@ -528,6 +538,7 @@ impl Device {
&self,
context: &mut Context,
) -> Result<Option<Surface>, Error> {
let context: &mut AngleContext = context.try_into()?;
match context.framebuffer {
Framebuffer::None => return Ok(None),
Framebuffer::External(_) => return Err(Error::ExternalRenderTarget),
Expand Down Expand Up @@ -559,6 +570,7 @@ impl Device {
/// Widget surfaces are internally double-buffered, so changes to them don't
/// show up in their associated widgets until this method is called.
pub fn present_bound_surface(&self, context: &mut Context) -> Result<(), Error> {
let context: &mut AngleContext = context.try_into()?;
match &context.framebuffer {
Framebuffer::Surface(surface) => surface.present(self),
_ => Ok(()),
Expand All @@ -571,6 +583,7 @@ impl Device {
context: &mut Context,
size: Size2D<i32>,
) -> Result<(), Error> {
let context: &mut AngleContext = context.try_into()?;
if let Framebuffer::Surface(surface) = &mut context.framebuffer {
surface.resize(size);
}
Expand All @@ -583,13 +596,15 @@ impl Device {
/// a new one, the new context might have the same ID as the destroyed one.
#[inline]
pub fn context_id(&self, context: &Context) -> ContextID {
let context = context.angle().expect("Passed incorrect context type");
context.id
}

/// Returns various information about the surface attached to a context.
///
/// This includes, most notably, the OpenGL framebuffer object needed to render to the surface.
pub fn context_surface_info(&self, context: &Context) -> Result<Option<SurfaceInfo>, Error> {
let context = context.angle()?;
match context.framebuffer {
Framebuffer::None => Ok(None),
Framebuffer::External(_) => Err(Error::ExternalRenderTarget),
Expand All @@ -599,6 +614,7 @@ impl Device {

/// Given a context, returns its underlying EGL context and attached surfaces.
pub fn native_context(&self, context: &Context) -> NativeContext {
let context = context.angle().expect("Passed incorrect context type");
let (egl_draw_surface, egl_read_surface) = match context.framebuffer {
Framebuffer::Surface(Surface { egl_surface, .. }) => (egl_surface, egl_surface),
Framebuffer::External(ExternalEGLSurfaces { draw, read }) => (draw, read),
Expand Down Expand Up @@ -643,6 +659,7 @@ impl Device {
let context_descriptor = self.context_descriptor(context);
let context_descriptor = context_descriptor.egl()?.clone();
let egl_config = self.context_descriptor_to_egl_config(&context_descriptor);
let context = context.angle()?;

unsafe {
let attributes = [
Expand Down Expand Up @@ -746,6 +763,7 @@ impl Device {
) -> Result<Surface, Error> {
let context_descriptor = self.context_descriptor(context).egl()?.clone();
let egl_config = self.context_descriptor_to_egl_config(&context_descriptor);
let context = context.angle()?;

unsafe {
EGL_FUNCTIONS.with(|egl| {
Expand Down Expand Up @@ -875,6 +893,11 @@ impl Device {
local_egl_surface: EGLSurface,
local_keyed_mutex: Option<ComPtr<IDXGIKeyedMutex>>,
) -> Result<SurfaceTexture, (Error, Surface)> {
let context = match context.angle() {
Ok(context) => context,
Err(error) => return Err((error, surface)),
};

EGL_FUNCTIONS.with(|egl| {
unsafe {
let _guard = self.temporarily_make_context_current(context);
Expand Down Expand Up @@ -944,6 +967,7 @@ impl Device {
context: &mut Context,
surface: &mut Surface,
) -> Result<(), Error> {
let context = context.angle()?;
if context.id != surface.context_id {
return Err(Error::IncompatibleSurface);
}
Expand Down Expand Up @@ -982,6 +1006,11 @@ impl Device {
context: &mut Context,
mut surface_texture: SurfaceTexture,
) -> Result<Surface, (Error, SurfaceTexture)> {
let context = match context.angle() {
Ok(context) => context,
Err(error) => return Err((error, surface_texture)),
};

unsafe {
if let Some(texture) = surface_texture.gl_texture.take() {
context.gl.delete_texture(texture);
Expand Down
21 changes: 3 additions & 18 deletions src/cgl/context.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -13,23 +13,8 @@ use std::ptr;
use std::rc::Rc;
use std::thread;

/// Represents an OpenGL rendering context.
///
/// A context allows you to issue rendering commands to a surface. When initially created, a
/// context has no attached surface, so rendering commands will fail or be ignored. Typically, you
/// attach a surface to the context before rendering.
///
/// Contexts take ownership of the surfaces attached to them. In order to mutate a surface in any
/// way other than rendering to it (e.g. presenting it to a window, which causes a buffer swap), it
/// must first be detached from its context. Each surface is associated with a single context upon
/// creation and may not be rendered to from any other context. However, you can wrap a surface in
/// a surface texture, which allows the surface to be read from another context.
///
/// OpenGL objects may not be shared across contexts directly, but surface textures effectively
/// allow for sharing of texture data. Contexts are local to a single thread and device.
///
/// A context must be explicitly destroyed with `destroy_context()`, or a panic will occur.
pub struct Context {
/// An implementation of [`crate::Context`] for CGL.
pub struct CglContext {
pub(crate) cgl_context: CGLContextObj,
pub(crate) id: ContextID,
pub(crate) framebuffer: Framebuffer<Surface, ()>,
Expand All @@ -39,7 +24,7 @@ pub struct Context {
/// Wraps a native CGL context object.
pub struct NativeContext(pub CGLContextObj);

impl Drop for Context {
impl Drop for CglContext {
#[inline]
fn drop(&mut self) {
if !self.cgl_context.is_null() && !thread::panicking() {
Expand Down
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