Make appsink/appsrc callbacks builder more consistent with other code

Move the constructor of the builder to the main type

examples/src/bin/appsink.rs

@@ -61,7 +61,7 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
     ));
 
     appsink.set_callbacks(
-        gst_app::AppSinkCallbacksBuilder::new()
+        gst_app::AppSinkCallbacks::new()
             .new_sample(|appsink| {
                 let sample = match appsink.pull_sample() {
                     None => return gst::FlowReturn::Eos,

gstreamer-app/src/app_sink.rs

@@ -22,14 +22,8 @@ pub struct AppSinkCallbacks {
     callbacks: ffi::GstAppSinkCallbacks,
 }
 
-pub struct AppSinkCallbacksBuilder {
-    eos: Option<Box<Fn(&AppSink) + Send + Sync + 'static>>,
-    new_preroll: Option<Box<Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>>,
-    new_sample: Option<Box<Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>>,
-}
-
-impl AppSinkCallbacksBuilder {
-    pub fn new() -> Self {
+impl AppSinkCallbacks {
+    pub fn new() -> AppSinkCallbacksBuilder {
         skip_assert_initialized!();
         AppSinkCallbacksBuilder {
             eos: None,
@@ -37,7 +31,15 @@ impl AppSinkCallbacksBuilder {
             new_sample: None,
         }
     }
+}
 
+pub struct AppSinkCallbacksBuilder {
+    eos: Option<Box<Fn(&AppSink) + Send + Sync + 'static>>,
+    new_preroll: Option<Box<Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>>,
+    new_sample: Option<Box<Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>>,
+}
+
+impl AppSinkCallbacksBuilder {
     pub fn eos<F: Fn(&AppSink) + Send + Sync + 'static>(self, eos: F) -> Self {
         Self {
             eos: Some(Box::new(eos)),

gstreamer-app/src/app_src.rs

@@ -21,6 +21,18 @@ pub struct AppSrcCallbacks {
     callbacks: ffi::GstAppSrcCallbacks,
 }
 
+impl AppSrcCallbacks {
+    pub fn new() -> AppSrcCallbacksBuilder {
+        skip_assert_initialized!();
+
+        AppSrcCallbacksBuilder {
+            need_data: None,
+            enough_data: None,
+            seek_data: None,
+        }
+    }
+}
+
 pub struct AppSrcCallbacksBuilder {
     need_data: Option<Box<Fn(&AppSrc, u32) + Send + Sync + 'static>>,
     enough_data: Option<Box<Fn(&AppSrc) + Send + Sync + 'static>>,