From cfb0fe6a17254eef20abe2584f975ab9f4dc26a4 Mon Sep 17 00:00:00 2001
From: Marijn Suijten <marijns95@gmail.com>
Date: Thu, 20 Jun 2024 10:49:14 +0200
Subject: [PATCH] examples: Add Windows support to `glupload`

WGL does not have the concept of a `Display` connection, presumably
because there's always only one compositor active.  All interop
and sharing is happening from the `Context` afterwards.

After all `glutin` doesn't have a pointer inside `RawDisplay::Wgl`,
and upstream `gstreamer` code creates a dummy display on Win32.

WINRT is not taken into account & tested yet.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1468>
---
 Cargo.lock               | 11 +++++++++++
 ci/run_windows_tests.ps1 |  2 +-
 examples/Cargo.toml      |  5 +++--
 examples/src/glupload.rs | 10 +++++++---
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 35b382a78..82b5bcabf 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -776,12 +776,14 @@ dependencies = [
  "dispatch",
  "glutin_egl_sys",
  "glutin_glx_sys",
+ "glutin_wgl_sys",
  "icrate",
  "libloading",
  "objc2",
  "once_cell",
  "raw-window-handle",
  "wayland-sys",
+ "windows-sys 0.48.0",
  "x11-dl",
 ]
 
@@ -817,6 +819,15 @@ dependencies = [
  "x11-dl",
 ]
 
+[[package]]
+name = "glutin_wgl_sys"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c8098adac955faa2d31079b65dc48841251f69efd3ac25477903fc424362ead"
+dependencies = [
+ "gl_generator",
+]
+
 [[package]]
 name = "gobject-sys"
 version = "0.20.0"
diff --git a/ci/run_windows_tests.ps1 b/ci/run_windows_tests.ps1
index f3f45fffe..faf9a1a74 100644
--- a/ci/run_windows_tests.ps1
+++ b/ci/run_windows_tests.ps1
@@ -54,7 +54,7 @@ foreach($features in $features_matrix) {
         if ($env:LocalFeatures -and ($env:LocalFeatures -ne '--no-default-features')) {
             if ($crate -eq 'examples') {
                 # FIXME: We can do --all-features for examples once we have gtk3 installed in the image
-                $env:LocalFeatures = "--features=rtsp-server,rtsp-server-record,pango-cairo,overlay-composition,gst-play,gst-player,ges,image,cairo-rs,gst-video/v1_18,windows"
+                $env:LocalFeatures = "--features=rtsp-server,rtsp-server-record,pango-cairo,overlay-composition,gst-play,gst-player,ges,image,cairo-rs,gst-video/v1_18,windows,gl"
             }
 
             if ($crate -eq 'tutorials') {
diff --git a/examples/Cargo.toml b/examples/Cargo.toml
index cb14d0230..567530603 100644
--- a/examples/Cargo.toml
+++ b/examples/Cargo.toml
@@ -30,8 +30,9 @@ byte-slice-cast = "1"
 cairo-rs = { workspace = true, features=["use_glib"], optional = true }
 derive_more = "0.99.5"
 futures = "0.3"
-glutin = { version = "0.31", optional = true, default-features = false }
-glutin-winit = { version = "0.4", optional = true, default-features = false }
+# Since there's nothing Windows-specific to enable on gstreamer-rs, unconditionally enable glutin's WGL backend
+glutin = { version = "0.31", optional = true, default-features = false, features = ["wgl"] }
+glutin-winit = { version = "0.4", optional = true, default-features = false, features = ["wgl"] }
 image = { version = "0.24", optional = true, default-features = false, features = ["png", "jpeg"] }
 memfd = { version = "0.6", optional = true }
 memmap2 = { version = "0.9", optional = true }
diff --git a/examples/src/glupload.rs b/examples/src/glupload.rs
index 730245608..9d64b3117 100644
--- a/examples/src/glupload.rs
+++ b/examples/src/glupload.rs
@@ -434,8 +434,8 @@ impl App {
 
         println!("Using raw GL context {:?}", raw_gl_context);
 
-        #[cfg(not(target_os = "linux"))]
-        compile_error!("This example only has Linux support");
+        #[cfg(not(any(target_os = "linux", windows)))]
+        compile_error!("This example only has Linux and Windows support");
 
         let api = App::map_gl_api(gl_config.api());
 
@@ -449,7 +449,6 @@ impl App {
                     unsafe { gst_gl_egl::GLDisplayEGL::with_egl_display(egl_display as usize) }
                         .context("Failed to create GLDisplayEGL from raw `EGLDisplay`")?
                         .upcast::<gst_gl::GLDisplay>();
-
                 (egl_context as usize, gl_display, gst_gl::GLPlatform::EGL)
             }
             #[cfg(feature = "gst-gl-x11")]
@@ -463,6 +462,11 @@ impl App {
                         .upcast::<gst_gl::GLDisplay>();
                 (glx_context as usize, gl_display, gst_gl::GLPlatform::GLX)
             }
+            #[cfg(windows)]
+            (glutin::display::RawDisplay::Wgl, glutin::context::RawContext::Wgl(wgl_context)) => {
+                let gl_display = gst_gl::GLDisplay::new();
+                (wgl_context as usize, gl_display, gst_gl::GLPlatform::WGL)
+            }
             #[allow(unreachable_patterns)]
             handler => anyhow::bail!("Unsupported platform: {handler:?}."),
         };