tutorials: Set up a runloop on macOS

Fixes https://github.com/sdroege/gstreamer-rs/pull/62
Fixes https://github.com/sdroege/gstreamer-rs/issues/58

tutorials/src/bin/basic-tutorial-1.rs

@@ -1,7 +1,10 @@
 extern crate gstreamer as gst;
 use gst::prelude::*;
 
-fn main() {
+#[path = "../tutorials-common.rs"]
+mod tutorials_common;
+
+fn tutorial_main() {
     // Initialize GStreamer
     gst::init().unwrap();
 
@@ -38,3 +41,9 @@ fn main() {
     let ret = pipeline.set_state(gst::State::Null);
     assert_ne!(ret, gst::StateChangeReturn::Failure);
 }
+
+fn main() {
+    // tutorials_common::run is only required to set up the application environment on macOS
+    // (but not necessary in normal Cocoa applications where this is set up automatically)
+    tutorials_common::run(tutorial_main);
+}

tutorials/src/bin/basic-tutorial-2.rs

@@ -1,8 +1,10 @@
 extern crate gstreamer as gst;
-
 use gst::prelude::*;
 
-fn main() {
+#[path = "../tutorials-common.rs"]
+mod tutorials_common;
+
+fn tutorial_main() {
     // Initialize GStreamer
     gst::init().unwrap();
 
@@ -56,3 +58,10 @@ fn main() {
         "Unable to set the pipeline to the Null state."
     );
 }
+
+
+fn main() {
+    // tutorials_common::run is only required to set up the application environment on macOS
+    // (but not necessary in normal Cocoa applications where this is set up automatically)
+    tutorials_common::run(tutorial_main);
+}

tutorials/src/bin/basic-tutorial-3.rs

@@ -1,8 +1,10 @@
 extern crate gstreamer as gst;
-
 use gst::prelude::*;
 
-fn main() {
+#[path = "../tutorials-common.rs"]
+mod tutorials_common;
+
+fn tutorial_main() {
     // Initialize GStreamer
     gst::init().unwrap();
 
@@ -116,3 +118,9 @@ fn main() {
         "Unable to set the pipeline to the Null state."
     );
 }
+
+fn main() {
+    // tutorials_common::run is only required to set up the application environment on macOS
+    // (but not necessary in normal Cocoa applications where this is set up automatically)
+    tutorials_common::run(tutorial_main);
+}

tutorials/src/bin/basic-tutorial-4.rs

@@ -4,6 +4,9 @@ use std::io::Write;
 use gst::prelude::*;
 use gst::MessageView;
 
+#[path = "../tutorials-common.rs"]
+mod tutorials_common;
+
 struct CustomData {
     playbin: gst::Element,    // Our one and only element
     playing: bool,            // Are we in the PLAYING state?
@@ -13,7 +16,7 @@ struct CustomData {
     duration: gst::ClockTime, // How long does this media last, in nanoseconds
 }
 
-fn main() {
+fn tutorial_main() {
     // Initialize GStreamer
     gst::init().unwrap();
 
@@ -147,3 +150,9 @@ fn handle_message(custom_data: &mut CustomData, msg: &gst::GstRc<gst::MessageRef
         _ => (),
     }
 }
+
+fn main() {
+    // tutorials_common::run is only required to set up the application environment on macOS
+    // (but not necessary in normal Cocoa applications where this is set up automatically)
+    tutorials_common::run(tutorial_main);
+}

tutorials/src/bin/basic-tutorial-6.rs

@@ -2,6 +2,8 @@ extern crate gstreamer as gst;
 use gst::prelude::*;
 use gst::MessageView;
 
+#[path = "../tutorials-common.rs"]
+mod tutorials_common;
 
 fn print_caps(caps: &gst::Caps, prefix: &str) {
     if caps.is_any() {
@@ -76,7 +78,7 @@ fn print_pad_capabilities(element: &gst::Element, pad_name: &str) {
     }
 }
 
-fn main() {
+fn tutorial_main() {
     // Initialize GStreamer
     gst::init().unwrap();
 
@@ -155,3 +157,9 @@ fn main() {
     let ret = pipeline.set_state(gst::State::Null);
     assert_ne!(ret, gst::StateChangeReturn::Failure);
 }
+
+fn main() {
+    // tutorials_common::run is only required to set up the application environment on macOS
+    // (but not necessary in normal Cocoa applications where this is set up automatically)
+    tutorials_common::run(tutorial_main);
+}

tutorials/src/bin/basic-tutorial-7.rs

@@ -1,7 +1,10 @@
 extern crate gstreamer as gst;
 use gst::prelude::*;
 
-fn main() {
+#[path = "../tutorials-common.rs"]
+mod tutorials_common;
+
+fn tutorial_main() {
     // Initialize GStreamer
     if let Err(err) = gst::init() {
         eprintln!("Failed to initialize Gst: {}", err);
@@ -92,3 +95,9 @@ fn main() {
         .into_result()
         .expect("Unable to set the pipeline to the Null state.");
 }
+
+fn main() {
+    // tutorials_common::run is only required to set up the application environment on macOS
+    // (but not necessary in normal Cocoa applications where this is set up automatically)
+    tutorials_common::run(tutorial_main);
+}

tutorials/src/tutorials-common.rs

@@ -0,0 +1,23 @@
+/// macOS has a specific requirement that there must be a run loop running
+/// on the main thread in order to open windows and use OpenGL.
+
+#[cfg(target_os = "macos")]
+#[link(name = "foundation", kind = "framework")]
+extern "C" {
+    fn CFRunLoopRun();
+}
+
+/// On macOS this launches the callback function on a thread.
+/// On other platforms it's just executed immediately.
+#[cfg(not(target_os = "macos"))]
+pub fn run<F: FnOnce() + Send + 'static>(main: F) {
+    main();
+}
+
+#[cfg(target_os = "macos")]
+pub fn run<F: FnOnce() + Send + 'static>(main: F) {
+    ::std::thread::spawn(main);
+    unsafe {
+        CFRunLoopRun();
+    }
+}