gtk4paintablesink: Don't initialize a GL context unless a GL platform is enabled

And also don't suggest in the template caps that GL might be supported.

For clarification, the wayland feature is also renamed to waylandegl and
using wayland gives a deprecation warning.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1837>

video/gtk4/Cargo.toml

@@ -45,11 +45,13 @@ gst-plugin-version-helper.workspace = true
 [features]
 default = []
 static = []
-wayland = ["gdk-wayland", "gst-gl-wayland"]
+# Deprecated
+wayland = ["waylandegl"]
+waylandegl = ["gdk-wayland", "gst-gl-wayland"]
 x11glx = ["gdk-x11", "gst-gl-x11"]
 x11egl = ["gdk-x11", "gst-gl-egl"]
 winegl = ["gdk-win32/egl", "gst-gl-egl"]
-dmabuf = ["gst-allocators", "wayland", "gtk_v4_14", "gst-video/v1_24"]
+dmabuf = ["gst-allocators", "gtk_v4_14", "gst-video/v1_24"]
 capi = []
 doc = ["gst/v1_18"]
 gtk_v4_10 = ["gtk/v4_10"]

video/gtk4/README.md

@@ -4,7 +4,7 @@ GTK 4 provides `gtk::Video` & `gtk::Picture` for rendering media such as videos.
 offer the possibility to use a custom `gst::Pipeline`. The plugin provides a `gst_video::VideoSink` along with a `gdk::Paintable` that's capable of rendering the sink's frames.
 
 The sink can generate GL Textures if the system is capable of it, but it needs
-to be compiled with either `wayland`, `x11glx` or `x11egl` cargo features. On
+to be compiled with either `waylandegl`, `x11glx` or `x11egl` cargo features. On
 Windows and macOS this is enabled by default.
 
 Additionally, the sink can render DMABufs directly on Linux if GTK 4.14 or
@@ -52,7 +52,7 @@ To build and include the plugin in a Flatpak manifest, you can add the following
                 }
             },
             "build-commands": [
-                "cargo cinstall --offline --release --features=wayland,x11glx,x11egl,dmabuf --library-type=cdylib --prefix=/app"
+                "cargo cinstall --offline --release --features=waylandegl,x11glx,x11egl,dmabuf --library-type=cdylib --prefix=/app"
             ]
         }
     ]

video/gtk4/build.rs

@@ -1,3 +1,7 @@
 fn main() {
+    #[cfg(feature = "wayland")]
+    {
+        println!("cargo:warning=\"wayland\" feature is deprecated, use \"waylandegl\" instead");
+    }
     gst_plugin_version_helper::info()
 }

video/gtk4/src/sink/imp.rs

@@ -36,6 +36,7 @@ use crate::utils;
 enum GLContext {
     Uninitialized,
     Unsupported,
+    #[allow(unused)]
     Initialized {
         display: gst_gl::GLDisplay,
         wrapped_context: gst_gl::GLContext,
@@ -261,10 +262,24 @@ impl ElementImpl for PaintableSink {
                 }
 
                 for features in [
+                    #[cfg(any(
+                        feature = "x11egl",
+                        feature = "x11glx",
+                        feature = "waylandegl",
+                        target_os = "macos",
+                        target_os = "windows"
+                    ))]
                     Some(gst::CapsFeatures::new([
                         gst_gl::CAPS_FEATURE_MEMORY_GL_MEMORY,
                         gst_video::CAPS_FEATURE_META_GST_VIDEO_OVERLAY_COMPOSITION,
                     ])),
+                    #[cfg(any(
+                        feature = "x11egl",
+                        feature = "x11glx",
+                        feature = "waylandegl",
+                        target_os = "macos",
+                        target_os = "windows"
+                    ))]
                     Some(gst::CapsFeatures::new([
                         gst_gl::CAPS_FEATURE_MEMORY_GL_MEMORY,
                     ])),
@@ -818,9 +833,27 @@ impl PaintableSink {
     }
 
     fn create_paintable(&self, paintable_storage: &mut Option<ThreadGuard<Paintable>>) {
+        #[cfg(any(
+            feature = "x11egl",
+            feature = "x11glx",
+            feature = "waylandegl",
+            target_os = "macos",
+            target_os = "windows"
+        ))]
         {
             self.initialize_gl_context();
         }
+        #[cfg(not(any(
+            feature = "x11egl",
+            feature = "x11glx",
+            feature = "waylandegl",
+            target_os = "macos",
+            target_os = "windows"
+        )))]
+        {
+            gst::debug!(CAT, imp = self, "No GL platform enabled");
+            *GL_CONTEXT.lock().unwrap() = GLContext::Unsupported;
+        }
 
         self.configure_caps();
         self.initialize_paintable(paintable_storage);
@@ -862,6 +895,13 @@ impl PaintableSink {
         *self.sender.lock().unwrap() = Some(sender);
     }
 
+    #[cfg(any(
+        feature = "x11egl",
+        feature = "x11glx",
+        feature = "waylandegl",
+        target_os = "macos",
+        target_os = "windows"
+    ))]
     fn initialize_gl_context(&self) {
         gst::debug!(CAT, imp = self, "Realizing GDK GL Context");
 
@@ -871,6 +911,13 @@ impl PaintableSink {
         });
     }
 
+    #[cfg(any(
+        feature = "x11egl",
+        feature = "x11glx",
+        feature = "waylandegl",
+        target_os = "macos",
+        target_os = "windows"
+    ))]
     fn initialize_gl_context_main(&self) {
         gst::debug!(CAT, imp = self, "Realizing GDK GL Context from main thread");
 
@@ -965,6 +1012,13 @@ impl PaintableSink {
         };
     }
 
+    #[cfg(any(
+        feature = "x11egl",
+        feature = "x11glx",
+        feature = "waylandegl",
+        target_os = "macos",
+        target_os = "windows"
+    ))]
     fn initialize_gst_gl(
         &self,
         gdk_display: &gdk::Display,
@@ -975,7 +1029,7 @@ impl PaintableSink {
             "GdkX11GLContextEGL" => self.initialize_x11egl(gdk_display),
             #[cfg(feature = "x11glx")]
             "GdkX11GLContextGLX" => self.initialize_x11glx(gdk_display),
-            #[cfg(feature = "wayland")]
+            #[cfg(feature = "waylandegl")]
             "GdkWaylandGLContext" => self.initialize_waylandegl(gdk_display),
             #[cfg(target_os = "macos")]
             "GdkMacosGLContext" => self.initialize_macosgl(gdk_display),
@@ -1094,7 +1148,7 @@ impl PaintableSink {
         }
     }
 
-    #[cfg(feature = "wayland")]
+    #[cfg(feature = "waylandegl")]
     fn initialize_waylandegl(
         &self,
         display: &gdk::Display,