Merges context creation code. #1029

goddessfreya · 2018-06-13T08:08:05Z

Signed-off-by: Hal Gentz [email protected]

Does #1028

Currently only 4 platforms need testing and one platform needs to get working.

Compiles with the following backends:

Has been tested with the following backends:

keringar · 2018-06-13T19:35:52Z

I have a windows desktop and android device so I can help. My finals are almost over so I'll be able to help soon.

kvark · 2018-07-06T19:46:25Z

@zegentzy your PR is not configured for me to edit, so here is the iOS fix - kvark@5eb2598
Not tested, just built.

goddessfreya · 2018-07-06T21:15:30Z

Thank you @kvark!

@francesca64 Unless someone wants to volunteer for testing these changes on the remaining platforms, I think this is as complete as it can get. Can you review/merge it?

francesca64 · 2018-07-06T21:54:17Z

I can test on macOS, iOS, and Android (though that's part of review anyway). I'll start working my way through this tomorrow.

francesca64 · 2018-07-08T17:26:47Z

CHANGELOG.md

@@ -1,4 +1,6 @@
 # Unreleased
+- ***BREAKING*** Headless contexts have been removed. Please instead use 


There should be a newline between the header and the entry list

This BREAKING doesn't conform to the style precedent set by winit's CHANGELOG, which is Breaking:

This sounds a bit misleading, as in, it makes it sound like the functionality has been removed, rather than that the separate API has been removed

Adding an example program makes API migrations nicer for everyone

(whoops, I was supposed to "Start a review" instead of commenting... well, enjoy this early preview)

francesca64

Alright, spending 3 hours reviewing this should be enough for one day...

So far I've only tested on X11 and Android. X11 is broken, but Android appears fine. However, I didn't test any headless stuff.

I can't test things definitively until you've created a suitable example program.

francesca64 · 2018-07-08T17:39:04Z

src/lib.rs

 //!
 //!  - `window` allows you to create regular windows and enables the `WindowBuilder` object.
-//!  - `headless` allows you to do headless rendering, and enables
-//!     the `HeadlessRendererBuilder` object.
 //!
 //! By default only `window` is enabled.


The use of the word "only" no longer makes sense.

francesca64 · 2018-07-08T18:08:33Z

src/platform/linux/x11.rs

+        unsafe {
+            match self.context {
+                GlContext::Egl(_) | GlContext::Glx(_) => {
+                    assert_eq!((self.display.xlib.XResizeWindow)(


This assertion fails when running the window example! I can tell you neither researched nor tested this, since Xlib functions return 1 upon success: https://github.com/mirror/libX11/blob/78851f6a03130e3c720b60c3cbf96f8eb216d741/src/ChWindow.c#L53

Anyway, why are you resizing the window? resize is supposed to be called to resize the context after the window itself has been resized by other means.

Also, please include trailing commas after all match arms. It's also preferable for unsafe blocks to be tighter, since this encloses more than it needs to.

This was "tested" by seeing if this panics: gfx-rs/gfx@5399982 . I've now discovered that it incorrectly doesn't call the resize function. This was "researched" by referring to http://xfree86.org/current/XResizeWindow.3.html, which doesn't make it clear that it will return a 1 upon success. I assumed 0 upon success because, well, isn't that the standard?

I was under the impression that resize is what you call to resize the window.

Edit: Anyways, with this info I know that X11 doesn't need a resize function.

Sorry if I was mean about this. I tend to take mistakes in PRs personally.

francesca64 · 2018-07-08T18:13:50Z

src/platform/linux/mod.rs

        match *self {
-            Context::X(ref _ctxt) => (),
+            Context::X11(ref ctxt) => ctxt.resize(window.get_xlib_window().unwrap(), width, height),


Why is a no-op no longer adequate?

I (incorrectly) added resizing support. Not actually necessary to be part of this PR.

francesca64 · 2018-07-08T18:14:34Z

src/platform/linux/mod.rs

-            Context::Wayland(ref ctxt) => ctxt.get_pixel_format()
+            Context::X11(ref ctxt) | Context::X11Context(_, ref ctxt) => ctxt.get_pixel_format(),
+            Context::Wayland(ref ctxt) | Context::WaylandContext(_, ref ctxt) => ctxt.get_pixel_format(),
+            Context::OsMesa(ref _ctxt) => panic!(),


What is the purpose of this panic?

OSMesa doesn't expose a swap_buffers. OSMesa's get_pixel_format panics. OSMesa has no resize function. I just realized the headless ones should be panicking the same.

francesca64 · 2018-07-08T18:18:11Z

src/platform/macos/mod.rs

    pixel_format: PixelFormat,
 }

+pub struct HeadlessContext {
+    context: id,


This context appears to never be release'd (meaning, it leaks). Using IdRef instead would fix that.

Neither was the old one. I guess the headless one received less scrutiny. Will fix.

francesca64 · 2018-07-08T20:04:03Z

src/lib.rs

+    /// surface is resized.
+    ///
+    /// The easiest way of doing this is to call this method for each `Resized` window event that
+    /// is received with the width and height given by the event.


This is also a good opportunity to update this line, since these days you take the LogicalSize from Resized, convert it into a PhysicalSize, and pass that.

francesca64 · 2018-07-08T20:07:26Z

src/lib.rs

+        let gl_attr = gl_attr.map_sharing(|ctxt| &ctxt.context);
+        platform::Context::new_context(el, &pf_reqs, &gl_attr, shareable_with_windowed_contexts)
+            .map(|context| Context {
+                context: context,


I'd prefer Context { context } for maximum cleanliness.

francesca64 · 2018-07-08T20:12:39Z

src/lib.rs

-    /// out of memory, etc.
+    /// The generated gl context is of course shareable with other contexts
+    /// made from this function. It is possible to also share it with a headless
+    /// context made with the shareable_with_windowed_contexts flag set to true.


I'd prefer "gl" be changed to "OpenGL", and both shareable_with_windowed_contexts and true should be in backticks.

I'm not sure how appropriate "of course" is here, since it seems to take the feature for granted. Considering that context sharing is never explained, the implication that this functionality is inherently expected could seem odd to readers.

francesca64 · 2018-07-08T20:19:45Z

src/lib.rs

-pub trait GlContext {
+pub trait GlContext
+where
+    Self: Sized,


This added constraint is a breaking change, so must be mentioned in the CHANGELOG.

francesca64 · 2018-07-08T20:23:39Z

src/lib.rs

 //! # Features
 //!
-//! This crate has two Cargo features: `window` and `headless`.
+//! This crate has one Cargo feature: `window`.


The removal of a feature can cause build failures, so it must be mentioned in the CHANGELOG.

goddessfreya · 2018-07-09T00:32:39Z

swap_buffers, get_pixel_format and resize, under my understanding, should be panicking for headless contexts. It's nonsensical to, for example, call eglSwapBuffers when there is no visible native window to swap with, even if valid.

(In egl's case, if surface isn't a native window, the function silently does nothing.)

kvark · 2018-07-09T14:18:41Z

@francesca64

Alright, spending 3 hours reviewing this should be enough for one day...

Thank you for such a detailed and thoughtful review, as well as testing. Hope you aren't getting burned by this, and it the issues are to be resolved nicely.

francesca64 · 2018-07-09T16:33:25Z

@zegentzy I get what you're saying about the panics, but at bare minimum these panics would have to print explanations and have accompanying documentation notes. Though, what this tells me is that this API design is fairly problematic. I don't think it's reasonable for the API to misrepresent the context's capabilities.

@kvark I won't deny that I'm pushing myself harder than I should, but no one will want to contribute to glutin if PRs don't get reviewed. Just make sure I don't try to become the maintainer of any more of tomaka's repos!

goddessfreya · 2018-07-09T23:00:49Z

I'd like to note that users can only call those three functions from GlWindow, which they won't have if they used a headless context. Anyways, I'll add messages and notes to the documentation.

francesca64 · 2018-07-10T00:26:01Z

Alright, that sounds reasonable then. If it's outright impossible for a GlWindow to be constructed with a headless context, then you don't even need to mention it in the docs, and it could be unreachable.

goddessfreya · 2018-07-10T01:30:59Z

@francesca64 Ok, I've replaced the panics with unreachable and haven't touched the docs.

goddessfreya · 2018-07-23T05:34:01Z

I just noticed you added iOS support to the CI, @francesca64. Thank you! I'll be sure to fix the compile failure.

goddessfreya · 2018-07-24T08:10:54Z

@francesca64 I'm like 98% certain the x11-dl build failure isn't caused by me. Can you check it out?

francesca64 · 2018-07-25T16:11:14Z

Yup: AltF02/x11-rs#88

Is this PR considered complete now? I would still like to see an example program added.

felixrabe · 2018-08-05T08:21:28Z

README-SHARING.md

+>  different device context than the one referenced by , or if the contexts are
+>  otherwise incompatible (for example, one context being associated with a
+>  hardware device driver and the other with a software renderer), then
+>  ERROR_INVALID_OPERATION is generated.


Missing some stuff due to <...> getting removed. Original sections:

* If <hShareContext> is neither zero nor a valid context handle, then ERROR_INVALID_OPERATION is generated. ... * If the OpenGL server context state for <hShareContext> exists in an address space that cannot be shared with the newly created context, if <shareContext> was created on a different device context than the one referenced by <hDC>, or if the contexts are otherwise incompatible (for example, one context being associated with a hardware device driver and the other with a software renderer), then ERROR_INVALID_OPERATION is generated.

Nice catch, my bad.

Signed-off-by: Hal Gentz <[email protected]>

francesca64 · 2018-08-05T17:41:57Z

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Unreleased

+- ***Breaking*** The entire api for Headless contexts have been removed. Please instead use `Context::new()` when trying to make a context without a visible window. Also removed `headless` feature.


"api" should be capitalized, "Headless" should be lowercase.

... contexts [have -> has] been removed ...

francesca64 · 2018-08-05T17:47:06Z

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Unreleased

+- ***Breaking*** The entire api for Headless contexts have been removed. Please instead use `Context::new()` when trying to make a context without a visible window. Also removed `headless` feature.
+- ***Breaking*** Structs implementing the `GlContext` trait must now be sized.


Structs aren't the only thing that can implement traits, so "Types" is probably better. Changing "sized" to Sized could also be clearer.

francesca64 · 2018-08-05T17:48:59Z

src/lib.rs

+    ) -> Result<Self, CreationError>
+    {
+        let ContextBuilder { pf_reqs, gl_attr } = context_builder;
+        let gl_attr = gl_attr.map_sharing(|ctxt| panic!());


Shouldn't this panic! have a nice little message? Ideally referring the user to the docs.

Also, ctxt is an unused var. You should go with _ctxt so everyone doesn't see a warning.

francesca64 · 2018-08-05T17:57:21Z

examples/sharing.rs

+
+fn main() {
+    let mut events_loop = glutin::EventsLoop::new();
+    let mut size = glutin::dpi::PhysicalSize {


Is there a reason you chose this over PhysicalSize::new?

No, I didn't check if a PhysicalSize::new function exists. Updated.

francesca64 · 2018-08-05T18:23:55Z

src/lib.rs

    pub fn new(
        window_builder: WindowBuilder,
        context_builder: ContextBuilder,
        events_loop: &EventsLoop,
    ) -> Result<Self, CreationError>
+    {
+        let ContextBuilder { pf_reqs, gl_attr } = context_builder;
+        let gl_attr = gl_attr.map_sharing(|ctxt| panic!());


ctxt is unused and generates a warning.

francesca64 · 2018-08-05T18:24:41Z

src/lib.rs

+        unsafe {
+            platform::Context::new(window_builder, events_loop, &pf_reqs, &gl_attr)
+                .map(|(window, context)| GlWindow {
+                    window: window,


window: window -> window (the same goes for the context: context below)

francesca64 · 2018-08-05T18:30:17Z

src/platform/windows/mod.rs

@@ -10,13 +10,12 @@ use winit;
 use Api;


Api, ContextError, and PixelFormat are all unused.

francesca64 · 2018-08-05T20:18:50Z

I'm starting to go through and give this a final round of testing on all platforms. So far this looks pretty much ready, though it seems like the EGL module has several unused items now.

Signed-off-by: Hal Gentz <[email protected]>

goddessfreya · 2018-08-16T04:25:24Z

src/lib.rs

-                    context: Context { context },
-                })
-        }
+        platform::Context::new(window_builder, events_loop, &pf_reqs, &gl_attr)


@francesca64 Not all the platforms are safe. Some platforms have unsafe "new" functions (the platforms which support context sharing). Now it won't compile.

goddessfreya · 2018-08-16T04:26:27Z

@francesca64 The platforms which currently support context sharing had their "new" functions marked unsafe. Your latest commit stops this PR from compiling.

francesca64 · 2018-08-16T22:47:15Z

Oh, I see. Having that be inconsistent seems rather surprising; is there a better way you can handle that?

goddessfreya · 2018-08-17T00:09:20Z

@francesca64 We can mark them all unsafe or we could disable the warning. The second is probably better.

francesca64 · 2018-08-17T20:31:19Z

I'm in favor of disabling the warning (assuming I'm correct in understanding that this doesn't affect the public API) with the proviso that a comment also be added explaining why the warning was disabled.

Signed-off-by: Hal Gentz <[email protected]>

goddessfreya · 2018-08-26T22:29:29Z

@francesca64 Done.

goddessfreya · 2018-09-09T02:06:46Z

@francesca64 What's the progress on getting this merged?

francesca64 · 2018-09-11T19:51:35Z

Super sorry for the repeated delays! I was going through a tough time emotionally for a while, and I've only just recently returned to being active on glutin and winit. I think we're ready to merge now; thanks so much for all the hard work!

goddessfreya changed the title ~~Merges context creation code.~~ [WIP] [Help Requested] Merges context creation code. Jun 13, 2018

goddessfreya force-pushed the merge-contexes branch from 2f70648 to 99b10a0 Compare June 13, 2018 08:18

goddessfreya force-pushed the merge-contexes branch from 99b10a0 to e0b3d6d Compare June 17, 2018 04:23

goddessfreya mentioned this pull request Jun 18, 2018

Adds context sharing support for the X11 & Wayland backends #1031

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goddessfreya force-pushed the merge-contexes branch 2 times, most recently from 2b5ba81 to 76754c8 Compare July 4, 2018 10:48

goddessfreya mentioned this pull request Jul 5, 2018

[Do Not Merge] Use EGL for Linux headless contexts #1020

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francesca64 reviewed Jul 8, 2018

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francesca64 suggested changes Jul 8, 2018

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goddessfreya force-pushed the merge-contexes branch from 223b282 to 58b9296 Compare July 9, 2018 00:26

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This was referenced Jul 10, 2018

Adds context sharing support for the X11 & Wayland backends #1045

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Make API fully backend-agnostic gfx-rs/gfx#1619

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goddessfreya force-pushed the merge-contexes branch 2 times, most recently from 3b115ad to 880bca2 Compare July 24, 2018 07:51

goddessfreya changed the title ~~[WIP] [Help Requested] Merges context creation code.~~ [Help Requested] Merges context creation code. Jul 26, 2018

felixrabe reviewed Aug 5, 2018

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Adds README-SHARING.md, adds safe api

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Signed-off-by: Hal Gentz <[email protected]>

goddessfreya force-pushed the merge-contexes branch from fba1575 to a2626df Compare August 5, 2018 09:25

francesca64 reviewed Aug 5, 2018

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Doc grammar/spelling changes + decreased warnings.

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Signed-off-by: Hal Gentz <[email protected]>

francesca64 mentioned this pull request Aug 11, 2018

Sync version with Glutin? rust-windowing/winit#626

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Spelling check

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goddessfreya mentioned this pull request Aug 15, 2018

Gentz' Misc Changes #1058

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goddessfreya commented Aug 16, 2018

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goddessfreya mentioned this pull request Aug 26, 2018

[NOMERGE] Merge window creation, attempt 2 gfx-rs/gfx#2347

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francesca64 and others added 2 commits August 26, 2018 16:14

iOS: Fix warnings

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Fix warning

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Signed-off-by: Hal Gentz <[email protected]>

goddessfreya force-pushed the merge-contexes branch from e197feb to fcc75e8 Compare August 26, 2018 22:28

francesca64 approved these changes Sep 11, 2018

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francesca64 merged commit 209ab92 into rust-windowing:master Sep 11, 2018

Osspial mentioned this pull request Dec 6, 2018

Headless Context cannot be created without EventsLoop #1090

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		@@ -1,4 +1,6 @@
		# Unreleased
		- *BREAKING* Headless contexts have been removed. Please instead use

		@@ -1,5 +1,9 @@
		# Unreleased

		- *Breaking* The entire api for Headless contexts have been removed. Please instead use `Context::new()` when trying to make a context without a visible window. Also removed `headless` feature.

Merges context creation code. #1029

Merges context creation code. #1029

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