From 7734725da1119658b76951b53af4699d21e6cca5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Fri, 18 May 2018 11:37:57 +0300
Subject: [PATCH] Change appsrc example to directly push data from the
 need-data callback

There's no need to start yet another thread just to push data in this
case, we can simply use the callback and store the frame counter in the
mutable environment of the closure.
---
 examples/src/bin/appsrc.rs | 85 ++++++++++++++++++++------------------
 1 file changed, 45 insertions(+), 40 deletions(-)

diff --git a/examples/src/bin/appsrc.rs b/examples/src/bin/appsrc.rs
index e36e58bab..df8326f67 100644
--- a/examples/src/bin/appsrc.rs
+++ b/examples/src/bin/appsrc.rs
@@ -5,8 +5,6 @@ extern crate gstreamer_video as gst_video;
 
 extern crate glib;
 
-use std::thread;
-
 use std::error::Error as StdError;
 
 extern crate failure;
@@ -35,7 +33,7 @@ struct ErrorMessage {
 const WIDTH: usize = 320;
 const HEIGHT: usize = 240;
 
-fn create_pipeline() -> Result<(gst::Pipeline, gst_app::AppSrc), Error> {
+fn create_pipeline() -> Result<gst::Pipeline, Error> {
     gst::init()?;
 
     let pipeline = gst::Pipeline::new(None);
@@ -59,45 +57,52 @@ fn create_pipeline() -> Result<(gst::Pipeline, gst_app::AppSrc), Error> {
 
     appsrc.set_caps(&info.to_caps().unwrap());
     appsrc.set_property_format(gst::Format::Time);
-    appsrc.set_max_bytes(1);
-    appsrc.set_property_block(true);
 
-    Ok((pipeline, appsrc))
+    // Our frame counter, that is stored in the mutable environment
+    // of the closure of the need-data callback
+    let mut i = 0;
+    appsrc.set_callbacks(
+        gst_app::AppSrcCallbacks::new()
+            .need_data(move |appsrc, _| {
+                if i == 100 {
+                    let _ = appsrc.end_of_stream();
+                    return;
+                }
+
+                println!("Producing frame {}", i);
+
+                let r = if i % 2 == 0 { 0 } else { 255 };
+                let g = if i % 3 == 0 { 0 } else { 255 };
+                let b = if i % 5 == 0 { 0 } else { 255 };
+
+                let mut buffer = gst::Buffer::with_size(WIDTH * HEIGHT * 4).unwrap();
+                {
+                    let buffer = buffer.get_mut().unwrap();
+                    buffer.set_pts(i * 500 * gst::MSECOND);
+
+                    let mut data = buffer.map_writable().unwrap();
+
+                    for p in data.as_mut_slice().chunks_mut(4) {
+                        assert_eq!(p.len(), 4);
+                        p[0] = b;
+                        p[1] = g;
+                        p[2] = r;
+                        p[3] = 0;
+                    }
+                }
+
+                i += 1;
+
+                // appsrc already handles the error here
+                let _ = appsrc.push_buffer(buffer);
+            })
+            .build(),
+    );
+
+    Ok(pipeline)
 }
 
-fn main_loop(pipeline: gst::Pipeline, appsrc: gst_app::AppSrc) -> Result<(), Error> {
-    thread::spawn(move || {
-        for i in 0..100 {
-            println!("Producing frame {}", i);
-
-            let r = if i % 2 == 0 { 0 } else { 255 };
-            let g = if i % 3 == 0 { 0 } else { 255 };
-            let b = if i % 5 == 0 { 0 } else { 255 };
-
-            let mut buffer = gst::Buffer::with_size(WIDTH * HEIGHT * 4).unwrap();
-            {
-                let buffer = buffer.get_mut().unwrap();
-                buffer.set_pts(i * 500 * gst::MSECOND);
-
-                let mut data = buffer.map_writable().unwrap();
-
-                for p in data.as_mut_slice().chunks_mut(4) {
-                    assert_eq!(p.len(), 4);
-                    p[0] = b;
-                    p[1] = g;
-                    p[2] = r;
-                    p[3] = 0;
-                }
-            }
-
-            if appsrc.push_buffer(buffer) != gst::FlowReturn::Ok {
-                break;
-            }
-        }
-
-        let _ = appsrc.end_of_stream();
-    });
-
+fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
     pipeline.set_state(gst::State::Playing).into_result()?;
 
     let bus = pipeline
@@ -130,7 +135,7 @@ fn main_loop(pipeline: gst::Pipeline, appsrc: gst_app::AppSrc) -> Result<(), Err
 }
 
 fn example_main() {
-    match create_pipeline().and_then(|(pipeline, appsrc)| main_loop(pipeline, appsrc)) {
+    match create_pipeline().and_then(main_loop) {
         Ok(r) => r,
         Err(e) => eprintln!("Error! {}", e),
     }