Add support for CapsFeatures

Fixes https://github.com/sdroege/gstreamer-rs/issues/13

gstreamer/src/caps.rs

@@ -6,8 +6,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use caps_features::*;
 use miniobject::*;
 use std::fmt;
+use std::ptr;
 use std::str;
 use structure::*;
 
@@ -68,12 +70,27 @@ impl GstRc<CapsRef> {
         unsafe { from_glib_full(ffi::gst_caps_merge(caps.into_ptr(), other.into_ptr())) }
     }
 
-    pub fn merge_structure(caps: Self, other: Structure) -> Self {
+    pub fn merge_structure(caps: Self, structure: Structure) -> Self {
         skip_assert_initialized!();
         unsafe {
             from_glib_full(ffi::gst_caps_merge_structure(
                 caps.into_ptr(),
-                other.into_ptr(),
+                structure.into_ptr(),
+            ))
+        }
+    }
+
+    pub fn merge_structure_full(
+        caps: Self,
+        structure: Structure,
+        features: Option<CapsFeatures>,
+    ) -> Self {
+        skip_assert_initialized!();
+        unsafe {
+            from_glib_full(ffi::gst_caps_merge_structure_full(
+                caps.into_ptr(),
+                structure.into_ptr(),
+                features.map(|f| f.into_ptr()).unwrap_or(ptr::null_mut()),
             ))
         }
     }
@@ -133,9 +150,7 @@ impl CapsRef {
                 return None;
             }
 
-            Some(StructureRef::from_glib_borrow(
-                structure as *const ffi::GstStructure,
-            ))
+            Some(StructureRef::from_glib_borrow(structure))
         }
     }
 
@@ -150,9 +165,41 @@ impl CapsRef {
                 return None;
             }
 
-            Some(StructureRef::from_glib_borrow_mut(
-                structure as *mut ffi::GstStructure,
-            ))
+            Some(StructureRef::from_glib_borrow_mut(structure))
+        }
+    }
+
+    pub fn get_features(&self, idx: u32) -> Option<&CapsFeaturesRef> {
+        if idx >= self.get_size() {
+            return None;
+        }
+
+        unsafe {
+            let features = ffi::gst_caps_get_features(self.as_ptr(), idx);
+            Some(CapsFeaturesRef::from_glib_borrow(features))
+        }
+    }
+
+    pub fn get_mut_features(&mut self, idx: u32) -> Option<&mut CapsFeaturesRef> {
+        if idx >= self.get_size() {
+            return None;
+        }
+
+        unsafe {
+            let features = ffi::gst_caps_get_features(self.as_ptr(), idx);
+            Some(CapsFeaturesRef::from_glib_borrow_mut(features))
+        }
+    }
+
+    pub fn set_features(&mut self, idx: u32, features: Option<CapsFeatures>) {
+        assert!(idx < self.get_size());
+
+        unsafe {
+            ffi::gst_caps_set_features(
+                self.as_mut_ptr(),
+                idx,
+                features.map(|f| f.into_ptr()).unwrap_or(ptr::null_mut()),
+            )
         }
     }
 
@@ -168,10 +215,28 @@ impl CapsRef {
         IterMut::new(self)
     }
 
+    pub fn iter_with_features(&self) -> IterFeatures {
+        IterFeatures::new(self)
+    }
+
+    pub fn iter_with_features_mut(&mut self) -> IterFeaturesMut {
+        IterFeaturesMut::new(self)
+    }
+
     pub fn append_structure(&mut self, structure: Structure) {
         unsafe { ffi::gst_caps_append_structure(self.as_mut_ptr(), structure.into_ptr()) }
     }
 
+    pub fn append_structure_full(&mut self, structure: Structure, features: Option<CapsFeatures>) {
+        unsafe {
+            ffi::gst_caps_append_structure_full(
+                self.as_mut_ptr(),
+                structure.into_ptr(),
+                features.map(|f| f.into_ptr()).unwrap_or(ptr::null_mut()),
+            )
+        }
+    }
+
     pub fn remove_structure(&mut self, idx: u32) {
         unsafe { ffi::gst_caps_remove_structure(self.as_mut_ptr(), idx) }
     }
@@ -250,6 +315,20 @@ impl CapsRef {
         }
     }
 
+    pub fn is_subset_structure_full(
+        &self,
+        structure: &StructureRef,
+        features: Option<&CapsFeaturesRef>,
+    ) -> bool {
+        unsafe {
+            from_glib(ffi::gst_caps_is_subset_structure_full(
+                self.as_ptr(),
+                structure.as_ptr(),
+                features.map(|f| f.as_ptr()).unwrap_or(ptr::null()),
+            ))
+        }
+    }
+
     pub fn subtract(&self, other: &Self) -> Caps {
         skip_assert_initialized!();
         unsafe {
@@ -268,7 +347,7 @@ impl glib::types::StaticType for CapsRef {
 }
 
 macro_rules! define_iter(
-    ($name:ident, $typ:ty, $styp:ty) => {
+    ($name:ident, $typ:ty, $styp:ty, $get_item:expr) => {
     pub struct $name<'a> {
         caps: $typ,
         idx: u32,
@@ -297,15 +376,13 @@ macro_rules! define_iter(
             }
 
             unsafe {
-                let structure = ffi::gst_caps_get_structure(self.caps.as_ptr(), self.idx);
-                if structure.is_null() {
+                let item = $get_item(self.caps, self.idx);
+                if item.is_none() {
                     return None;
                 }
 
                 self.idx += 1;
-                Some(StructureRef::from_glib_borrow_mut(
-                    structure as *mut ffi::GstStructure,
-                ))
+                item
             }
         }
 
@@ -329,14 +406,7 @@ macro_rules! define_iter(
             self.n_structures -= 1;
 
             unsafe {
-                let structure = ffi::gst_caps_get_structure(self.caps.as_ptr(), self.n_structures);
-                if structure.is_null() {
-                    return None;
-                }
-
-                Some(StructureRef::from_glib_borrow_mut(
-                    structure as *mut ffi::GstStructure,
-                ))
+                $get_item(self.caps, self.n_structures)
             }
         }
     }
@@ -345,8 +415,70 @@ macro_rules! define_iter(
     }
 );
 
-define_iter!(Iter, &'a CapsRef, &'a StructureRef);
-define_iter!(IterMut, &'a mut CapsRef, &'a mut StructureRef);
+define_iter!(
+    Iter,
+    &'a CapsRef,
+    &'a StructureRef,
+    |caps: &CapsRef, idx| {
+        let ptr = ffi::gst_caps_get_structure(caps.as_ptr(), idx);
+        if ptr.is_null() {
+            None
+        } else {
+            Some(StructureRef::from_glib_borrow(
+                ptr as *const ffi::GstStructure,
+            ))
+        }
+    }
+);
+define_iter!(
+    IterMut,
+    &'a mut CapsRef,
+    &'a mut StructureRef,
+    |caps: &CapsRef, idx| {
+        let ptr = ffi::gst_caps_get_structure(caps.as_ptr(), idx);
+        if ptr.is_null() {
+            None
+        } else {
+            Some(StructureRef::from_glib_borrow_mut(
+                ptr as *mut ffi::GstStructure,
+            ))
+        }
+    }
+);
+define_iter!(
+    IterFeatures,
+    &'a CapsRef,
+    (&'a StructureRef, &'a CapsFeaturesRef),
+    |caps: &CapsRef, idx| {
+        let ptr1 = ffi::gst_caps_get_structure(caps.as_ptr(), idx);
+        let ptr2 = ffi::gst_caps_get_features(caps.as_ptr(), idx);
+        if ptr1.is_null() || ptr2.is_null() {
+            None
+        } else {
+            Some((
+                StructureRef::from_glib_borrow(ptr1 as *const ffi::GstStructure),
+                CapsFeaturesRef::from_glib_borrow(ptr2 as *const ffi::GstCapsFeatures),
+            ))
+        }
+    }
+);
+define_iter!(
+    IterFeaturesMut,
+    &'a mut CapsRef,
+    (&'a mut StructureRef, &'a mut CapsFeaturesRef),
+    |caps: &CapsRef, idx| {
+        let ptr1 = ffi::gst_caps_get_structure(caps.as_ptr(), idx);
+        let ptr2 = ffi::gst_caps_get_features(caps.as_ptr(), idx);
+        if ptr1.is_null() || ptr2.is_null() {
+            None
+        } else {
+            Some((
+                StructureRef::from_glib_borrow_mut(ptr1 as *mut ffi::GstStructure),
+                CapsFeaturesRef::from_glib_borrow_mut(ptr2 as *mut ffi::GstCapsFeatures),
+            ))
+        }
+    }
+);
 
 impl fmt::Debug for CapsRef {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
@@ -379,25 +511,47 @@ impl ToOwned for CapsRef {
 unsafe impl Sync for CapsRef {}
 unsafe impl Send for CapsRef {}
 
-pub struct Builder {
+pub struct Builder<'a> {
     s: ::Structure,
+    features: Option<&'a [&'a str]>,
+    any_features: bool,
 }
 
-impl Builder {
-    fn new(name: &str) -> Self {
+impl<'a> Builder<'a> {
+    fn new<'b>(name: &'b str) -> Builder<'a> {
         Builder {
             s: ::Structure::new_empty(name),
+            features: None,
+            any_features: false,
         }
     }
 
-    pub fn field<V: ToSendValue>(mut self, name: &str, value: &V) -> Self {
+    pub fn field<'b, V: ToSendValue>(mut self, name: &'b str, value: &'b V) -> Self {
         self.s.set(name, value);
         self
     }
 
+    pub fn features(mut self, features: &'a [&'a str]) -> Self {
+        self.features = Some(features);
+        self
+    }
+
+    pub fn any_features(mut self) -> Self {
+        self.any_features = true;
+        self
+    }
+
     pub fn build(self) -> Caps {
         let mut caps = Caps::new_empty();
-        caps.get_mut().unwrap().append_structure(self.s);
+        let features = if self.any_features {
+            Some(CapsFeatures::new_any())
+        } else {
+            self.features.map(|f| CapsFeatures::new(f))
+        };
+
+        caps.get_mut()
+            .unwrap()
+            .append_structure_full(self.s, features);
         caps
     }
 }
@@ -412,7 +566,7 @@ mod tests {
     fn test_simple() {
         ::init().unwrap();
 
-        let caps = Caps::new_simple(
+        let mut caps = Caps::new_simple(
             "foo/bar",
             &[
                 ("int", &12),
@@ -427,19 +581,36 @@ mod tests {
             "foo/bar, int=(int)12, bool=(boolean)true, string=(string)bla, fraction=(fraction)1/2, array=(int)< 1, 2 >"
         );
 
-        let s = caps.get_structure(0).unwrap();
-        assert_eq!(
-            s,
-            Structure::new(
-                "foo/bar",
-                &[
-                    ("int", &12),
-                    ("bool", &true),
-                    ("string", &"bla"),
-                    ("fraction", &Fraction::new(1, 2)),
-                    ("array", &Array::new(&[&1, &2])),
-                ],
-            ).as_ref()
+        {
+            let s = caps.get_structure(0).unwrap();
+            assert_eq!(
+                s,
+                Structure::new(
+                    "foo/bar",
+                    &[
+                        ("int", &12),
+                        ("bool", &true),
+                        ("string", &"bla"),
+                        ("fraction", &Fraction::new(1, 2)),
+                        ("array", &Array::new(&[&1, &2])),
+                    ],
+                ).as_ref()
+            );
+        }
+        assert!(
+            caps.get_features(0)
+                .unwrap()
+                .is_equal(::CAPS_FEATURES_MEMORY_SYSTEM_MEMORY.as_ref())
+        );
+
+        {
+            let caps = caps.get_mut().unwrap();
+            caps.set_features(0, Some(CapsFeatures::new(&["foo:bla"])));
+        }
+        assert!(
+            caps.get_features(0)
+                .unwrap()
+                .is_equal(CapsFeatures::new(&["foo:bla"]).as_ref())
         );
     }
 
@@ -458,5 +629,17 @@ mod tests {
             caps.to_string(),
             "foo/bar, int=(int)12, bool=(boolean)true, string=(string)bla, fraction=(fraction)1/2, array=(int)< 1, 2 >"
         );
+
+        let caps = Caps::builder("foo/bar")
+            .field("int", &12)
+            .any_features()
+            .build();
+        assert_eq!(caps.to_string(), "foo/bar(ANY), int=(int)12");
+
+        let caps = Caps::builder("foo/bar")
+            .field("int", &12)
+            .features(&["foo:bla", "foo:baz"])
+            .build();
+        assert_eq!(caps.to_string(), "foo/bar(foo:bla, foo:baz), int=(int)12");
     }
 }

gstreamer/src/caps_features.rs

@@ -0,0 +1,472 @@
+// Copyright (C) 2018 Sebastian Dröge <sebastian@centricular.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::borrow::{Borrow, BorrowMut, ToOwned};
+use std::ffi::CStr;
+use std::fmt;
+use std::marker::PhantomData;
+use std::mem;
+use std::ops::{Deref, DerefMut};
+use std::ptr;
+use std::str;
+
+use ffi;
+use glib;
+use glib::translate::{
+    from_glib, from_glib_full, from_glib_none, FromGlibPtrFull, FromGlibPtrNone, GlibPtrDefault,
+    Stash, StashMut, ToGlibPtr, ToGlibPtrMut,
+};
+use glib_ffi::gpointer;
+use gobject_ffi;
+
+pub struct CapsFeatures(ptr::NonNull<CapsFeaturesRef>, PhantomData<CapsFeaturesRef>);
+unsafe impl Send for CapsFeatures {}
+unsafe impl Sync for CapsFeatures {}
+
+impl CapsFeatures {
+    pub fn new(features: &[&str]) -> Self {
+        let mut f = Self::new_empty();
+
+        for feature in features {
+            f.add(feature);
+        }
+
+        f
+    }
+
+    pub fn new_empty() -> Self {
+        assert_initialized_main_thread!();
+        unsafe {
+            CapsFeatures(
+                ptr::NonNull::new_unchecked(
+                    ffi::gst_caps_features_new_empty() as *mut CapsFeaturesRef
+                ),
+                PhantomData,
+            )
+        }
+    }
+
+    pub fn new_any() -> Self {
+        assert_initialized_main_thread!();
+        unsafe {
+            CapsFeatures(
+                ptr::NonNull::new_unchecked(
+                    ffi::gst_caps_features_new_any() as *mut CapsFeaturesRef
+                ),
+                PhantomData,
+            )
+        }
+    }
+
+    pub fn from_string(value: &str) -> Option<Self> {
+        assert_initialized_main_thread!();
+        unsafe {
+            let ptr = ffi::gst_caps_features_from_string(value.to_glib_none().0);
+            if ptr.is_null() {
+                return None;
+            }
+
+            Some(CapsFeatures(
+                ptr::NonNull::new_unchecked(ptr as *mut CapsFeaturesRef),
+                PhantomData,
+            ))
+        }
+    }
+
+    pub unsafe fn into_ptr(self) -> *mut ffi::GstCapsFeatures {
+        let ptr = self.0.as_ptr() as *mut CapsFeaturesRef as *mut ffi::GstCapsFeatures;
+        mem::forget(self);
+
+        ptr
+    }
+}
+
+impl Deref for CapsFeatures {
+    type Target = CapsFeaturesRef;
+
+    fn deref(&self) -> &CapsFeaturesRef {
+        unsafe { self.0.as_ref() }
+    }
+}
+
+impl DerefMut for CapsFeatures {
+    fn deref_mut(&mut self) -> &mut CapsFeaturesRef {
+        unsafe { self.0.as_mut() }
+    }
+}
+
+impl AsRef<CapsFeaturesRef> for CapsFeatures {
+    fn as_ref(&self) -> &CapsFeaturesRef {
+        self.deref()
+    }
+}
+
+impl AsMut<CapsFeaturesRef> for CapsFeatures {
+    fn as_mut(&mut self) -> &mut CapsFeaturesRef {
+        self.deref_mut()
+    }
+}
+
+impl Clone for CapsFeatures {
+    fn clone(&self) -> Self {
+        unsafe {
+            let ptr = ffi::gst_caps_features_copy(&self.0.as_ref().0) as *mut CapsFeaturesRef;
+            assert!(!ptr.is_null());
+            CapsFeatures(ptr::NonNull::new_unchecked(ptr), PhantomData)
+        }
+    }
+}
+
+impl Drop for CapsFeatures {
+    fn drop(&mut self) {
+        unsafe { ffi::gst_caps_features_free(&mut self.0.as_mut().0) }
+    }
+}
+
+impl fmt::Debug for CapsFeatures {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_tuple("CapsFeatures")
+            .field(&self.to_string())
+            .finish()
+    }
+}
+
+impl fmt::Display for CapsFeatures {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        // Need to make sure to not call ToString::to_string() here, which
+        // we have because of the Display impl. We need CapsFeaturesRef::to_string()
+        f.write_str(&CapsFeaturesRef::to_string(self.as_ref()))
+    }
+}
+
+impl str::FromStr for CapsFeatures {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, ()> {
+        skip_assert_initialized!();
+        CapsFeatures::from_string(s).ok_or(())
+    }
+}
+
+impl Borrow<CapsFeaturesRef> for CapsFeatures {
+    fn borrow(&self) -> &CapsFeaturesRef {
+        unsafe { self.0.as_ref() }
+    }
+}
+
+impl BorrowMut<CapsFeaturesRef> for CapsFeatures {
+    fn borrow_mut(&mut self) -> &mut CapsFeaturesRef {
+        unsafe { self.0.as_mut() }
+    }
+}
+
+impl glib::types::StaticType for CapsFeatures {
+    fn static_type() -> glib::types::Type {
+        unsafe { from_glib(ffi::gst_caps_features_get_type()) }
+    }
+}
+
+impl<'a> ToGlibPtr<'a, *const ffi::GstCapsFeatures> for CapsFeatures {
+    type Storage = &'a Self;
+
+    fn to_glib_none(&'a self) -> Stash<'a, *const ffi::GstCapsFeatures, Self> {
+        unsafe { Stash(&self.0.as_ref().0, self) }
+    }
+
+    fn to_glib_full(&self) -> *const ffi::GstCapsFeatures {
+        unsafe { ffi::gst_caps_features_copy(&self.0.as_ref().0) }
+    }
+}
+
+impl<'a> ToGlibPtr<'a, *mut ffi::GstCapsFeatures> for CapsFeatures {
+    type Storage = &'a Self;
+
+    fn to_glib_none(&'a self) -> Stash<'a, *mut ffi::GstCapsFeatures, Self> {
+        unsafe { Stash(&self.0.as_ref().0 as *const _ as *mut _, self) }
+    }
+
+    fn to_glib_full(&self) -> *mut ffi::GstCapsFeatures {
+        unsafe { ffi::gst_caps_features_copy(&self.0.as_ref().0) }
+    }
+}
+
+impl<'a> ToGlibPtrMut<'a, *mut ffi::GstCapsFeatures> for CapsFeatures {
+    type Storage = &'a mut Self;
+
+    fn to_glib_none_mut(&'a mut self) -> StashMut<*mut ffi::GstCapsFeatures, Self> {
+        unsafe { StashMut(&mut self.0.as_mut().0, self) }
+    }
+}
+
+impl FromGlibPtrNone<*const ffi::GstCapsFeatures> for CapsFeatures {
+    unsafe fn from_glib_none(ptr: *const ffi::GstCapsFeatures) -> Self {
+        assert!(!ptr.is_null());
+        let ptr = ffi::gst_caps_features_copy(ptr);
+        assert!(!ptr.is_null());
+        CapsFeatures(
+            ptr::NonNull::new_unchecked(ptr as *mut CapsFeaturesRef),
+            PhantomData,
+        )
+    }
+}
+
+impl FromGlibPtrNone<*mut ffi::GstCapsFeatures> for CapsFeatures {
+    unsafe fn from_glib_none(ptr: *mut ffi::GstCapsFeatures) -> Self {
+        assert!(!ptr.is_null());
+        let ptr = ffi::gst_caps_features_copy(ptr);
+        assert!(!ptr.is_null());
+        CapsFeatures(
+            ptr::NonNull::new_unchecked(ptr as *mut CapsFeaturesRef),
+            PhantomData,
+        )
+    }
+}
+
+impl FromGlibPtrFull<*const ffi::GstCapsFeatures> for CapsFeatures {
+    unsafe fn from_glib_full(ptr: *const ffi::GstCapsFeatures) -> Self {
+        assert!(!ptr.is_null());
+        CapsFeatures(
+            ptr::NonNull::new_unchecked(ptr as *mut CapsFeaturesRef),
+            PhantomData,
+        )
+    }
+}
+
+impl FromGlibPtrFull<*mut ffi::GstCapsFeatures> for CapsFeatures {
+    unsafe fn from_glib_full(ptr: *mut ffi::GstCapsFeatures) -> Self {
+        assert!(!ptr.is_null());
+        CapsFeatures(
+            ptr::NonNull::new_unchecked(ptr as *mut CapsFeaturesRef),
+            PhantomData,
+        )
+    }
+}
+
+impl<'a> glib::value::FromValueOptional<'a> for CapsFeatures {
+    unsafe fn from_value_optional(v: &'a glib::Value) -> Option<Self> {
+        let ptr = gobject_ffi::g_value_get_boxed(v.to_glib_none().0);
+        assert!(!ptr.is_null());
+        from_glib_none(ptr as *const ffi::GstCapsFeatures)
+    }
+}
+
+impl glib::value::SetValue for CapsFeatures {
+    unsafe fn set_value(v: &mut glib::Value, s: &Self) {
+        gobject_ffi::g_value_set_boxed(v.to_glib_none_mut().0, s.0.as_ptr() as gpointer);
+    }
+}
+
+impl glib::value::SetValueOptional for CapsFeatures {
+    unsafe fn set_value_optional(v: &mut glib::Value, s: Option<&Self>) {
+        if let Some(s) = s {
+            gobject_ffi::g_value_set_boxed(v.to_glib_none_mut().0, s.as_ptr() as gpointer);
+        } else {
+            gobject_ffi::g_value_set_boxed(v.to_glib_none_mut().0, ptr::null_mut());
+        }
+    }
+}
+
+impl GlibPtrDefault for CapsFeatures {
+    type GlibType = *mut ffi::GstCapsFeatures;
+}
+
+#[repr(C)]
+pub struct CapsFeaturesRef(ffi::GstCapsFeatures);
+
+impl CapsFeaturesRef {
+    pub unsafe fn from_glib_borrow<'a>(ptr: *const ffi::GstCapsFeatures) -> &'a CapsFeaturesRef {
+        assert!(!ptr.is_null());
+
+        &*(ptr as *mut CapsFeaturesRef)
+    }
+
+    pub unsafe fn from_glib_borrow_mut<'a>(
+        ptr: *mut ffi::GstCapsFeatures,
+    ) -> &'a mut CapsFeaturesRef {
+        assert!(!ptr.is_null());
+
+        &mut *(ptr as *mut CapsFeaturesRef)
+    }
+
+    pub unsafe fn as_ptr(&self) -> *const ffi::GstCapsFeatures {
+        self as *const Self as *const ffi::GstCapsFeatures
+    }
+
+    pub unsafe fn as_mut_ptr(&self) -> *mut ffi::GstCapsFeatures {
+        self as *const Self as *mut ffi::GstCapsFeatures
+    }
+
+    pub fn to_string(&self) -> String {
+        unsafe { from_glib_full(ffi::gst_caps_features_to_string(self.as_ptr())) }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.get_size() == 0 && !self.is_any()
+    }
+
+    pub fn is_any(&self) -> bool {
+        unsafe { from_glib(ffi::gst_caps_features_is_any(self.as_ptr())) }
+    }
+
+    pub fn contains(&self, feature: &str) -> bool {
+        unsafe {
+            from_glib(ffi::gst_caps_features_contains(
+                self.as_ptr(),
+                feature.to_glib_none().0,
+            ))
+        }
+    }
+
+    pub fn get_size(&self) -> u32 {
+        unsafe { ffi::gst_caps_features_get_size(self.as_ptr()) }
+    }
+
+    pub fn get_nth(&self, idx: u32) -> Option<&str> {
+        if idx >= self.get_size() {
+            return None;
+        }
+
+        unsafe {
+            let feature = ffi::gst_caps_features_get_nth(self.as_ptr(), idx);
+            if feature.is_null() {
+                return None;
+            }
+
+            Some(CStr::from_ptr(feature).to_str().unwrap())
+        }
+    }
+
+    pub fn add(&mut self, feature: &str) {
+        unsafe { ffi::gst_caps_features_add(self.as_mut_ptr(), feature.to_glib_none().0) }
+    }
+
+    pub fn remove(&mut self, feature: &str) {
+        unsafe { ffi::gst_caps_features_remove(self.as_mut_ptr(), feature.to_glib_none().0) }
+    }
+
+    pub fn iter(&self) -> Iter {
+        Iter::new(self)
+    }
+
+    // This is not an equivalence relation with regards to ANY. Everything is equal to ANY
+    pub fn is_equal(&self, other: &CapsFeaturesRef) -> bool {
+        unsafe {
+            from_glib(ffi::gst_caps_features_is_equal(
+                self.as_ptr(),
+                other.as_ptr(),
+            ))
+        }
+    }
+}
+
+pub struct Iter<'a> {
+    caps_features: &'a CapsFeaturesRef,
+    idx: u32,
+    n_features: u32,
+}
+
+impl<'a> Iter<'a> {
+    fn new(caps_features: &'a CapsFeaturesRef) -> Iter<'a> {
+        skip_assert_initialized!();
+        let n_features = caps_features.get_size();
+
+        Iter {
+            caps_features,
+            idx: 0,
+            n_features,
+        }
+    }
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = &'a str;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.idx >= self.n_features {
+            return None;
+        }
+
+        unsafe {
+            let feature = ffi::gst_caps_features_get_nth(self.caps_features.as_ptr(), self.idx);
+            if feature.is_null() {
+                return None;
+            }
+
+            self.idx += 1;
+
+            Some(CStr::from_ptr(feature).to_str().unwrap())
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if self.idx == self.n_features {
+            return (0, Some(0));
+        }
+
+        let remaining = (self.n_features - self.idx) as usize;
+
+        (remaining, Some(remaining))
+    }
+}
+
+impl<'a> DoubleEndedIterator for Iter<'a> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        if self.idx == self.n_features {
+            return None;
+        }
+
+        self.n_features -= 1;
+
+        unsafe {
+            let feature =
+                ffi::gst_caps_features_get_nth(self.caps_features.as_ptr(), self.n_features);
+            if feature.is_null() {
+                return None;
+            }
+
+            Some(CStr::from_ptr(feature).to_str().unwrap())
+        }
+    }
+}
+
+impl<'a> ExactSizeIterator for Iter<'a> {}
+
+impl fmt::Debug for CapsFeaturesRef {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_tuple("CapsFeatures")
+            .field(&self.to_string())
+            .finish()
+    }
+}
+
+impl fmt::Display for CapsFeaturesRef {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(&self.to_string())
+    }
+}
+
+impl ToOwned for CapsFeaturesRef {
+    type Owned = CapsFeatures;
+
+    fn to_owned(&self) -> CapsFeatures {
+        unsafe { from_glib_full(ffi::gst_caps_features_copy(self.as_ptr() as *const _) as *mut _) }
+    }
+}
+
+unsafe impl Sync for CapsFeaturesRef {}
+unsafe impl Send for CapsFeaturesRef {}
+
+lazy_static! {
+    pub static ref CAPS_FEATURE_MEMORY_SYSTEM_MEMORY: &'static str = unsafe {
+        CStr::from_ptr(ffi::GST_CAPS_FEATURE_MEMORY_SYSTEM_MEMORY)
+            .to_str()
+            .unwrap()
+    };
+    pub static ref CAPS_FEATURES_MEMORY_SYSTEM_MEMORY: CapsFeatures =
+        CapsFeatures::new(&[*CAPS_FEATURE_MEMORY_SYSTEM_MEMORY]);
+}

gstreamer/src/caps_features_serde.rs

@@ -0,0 +1,166 @@
+// Copyright (C) 2018 Sebastian Dröge <sebastian@centricular.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use serde::de;
+use serde::de::{Deserialize, Deserializer, EnumAccess, SeqAccess, VariantAccess, Visitor};
+use serde::ser::{Serialize, SerializeSeq, Serializer};
+
+use std::fmt;
+
+use CapsFeatures;
+use CapsFeaturesRef;
+
+enum CapsFeaturesVariantKinds {
+    Any,
+    Some,
+}
+
+const CAPS_FEATURES_VARIANT_ANY_ID: u32 = 0;
+const CAPS_FEATURES_VARIANT_ANY_STR: &str = "Any";
+const CAPS_FEATURES_VARIANT_SOME_ID: u32 = 1;
+const CAPS_FEATURES_VARIANT_SOME_STR: &str = "Some";
+
+const CAPS_FEATURES_VARIANT_NAMES: &[&str] = &[
+    &CAPS_FEATURES_VARIANT_ANY_STR,
+    &CAPS_FEATURES_VARIANT_SOME_STR,
+];
+
+struct CapsFeaturesForIterSe<'a>(&'a CapsFeaturesRef);
+impl<'a> Serialize for CapsFeaturesForIterSe<'a> {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        let iter = self.0.iter();
+        let size = iter.size_hint().0;
+        if size > 0 {
+            let mut seq = serializer.serialize_seq(Some(size))?;
+            for feature in iter {
+                seq.serialize_element(feature)?;
+            }
+            seq.end()
+        } else {
+            let seq = serializer.serialize_seq(None)?;
+            seq.end()
+        }
+    }
+}
+
+impl Serialize for CapsFeaturesRef {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        if self.is_any() {
+            serializer.serialize_unit_variant(
+                stringify!(CapsFeatures),
+                CAPS_FEATURES_VARIANT_ANY_ID,
+                CAPS_FEATURES_VARIANT_ANY_STR,
+            )
+        } else {
+            serializer.serialize_newtype_variant(
+                stringify!(CapsFeatures),
+                CAPS_FEATURES_VARIANT_SOME_ID,
+                CAPS_FEATURES_VARIANT_SOME_STR,
+                &CapsFeaturesForIterSe(&self),
+            )
+        }
+    }
+}
+
+impl Serialize for CapsFeatures {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        self.as_ref().serialize(serializer)
+    }
+}
+
+struct CapsFeaturesSome(CapsFeatures);
+
+struct CapsFeaturesSomeVisitor;
+impl<'de> Visitor<'de> for CapsFeaturesSomeVisitor {
+    type Value = CapsFeaturesSome;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a sequence of `&str`")
+    }
+
+    fn visit_seq<A: SeqAccess<'de>>(self, mut seq: A) -> Result<Self::Value, A::Error> {
+        let mut features = CapsFeatures::new_empty();
+        while let Some(feature) = seq.next_element::<String>()? {
+            features.add(feature.as_ref());
+        }
+        Ok(CapsFeaturesSome(features))
+    }
+}
+
+impl<'de> Deserialize<'de> for CapsFeaturesSome {
+    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<CapsFeaturesSome, D::Error> {
+        deserializer.deserialize_seq(CapsFeaturesSomeVisitor)
+    }
+}
+
+struct CapsFeaturesVariantKindsVisitor;
+impl<'de> Visitor<'de> for CapsFeaturesVariantKindsVisitor {
+    type Value = CapsFeaturesVariantKinds;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a Caps variant kind (`Any` or `Some`)")
+    }
+
+    fn visit_u32<E: de::Error>(self, value: u32) -> Result<Self::Value, E> {
+        match value {
+            CAPS_FEATURES_VARIANT_ANY_ID => Ok(CapsFeaturesVariantKinds::Any),
+            CAPS_FEATURES_VARIANT_SOME_ID => Ok(CapsFeaturesVariantKinds::Some),
+            _ => Err(de::Error::invalid_value(
+                de::Unexpected::Unsigned(value as u64),
+                &self,
+            )),
+        }
+    }
+
+    fn visit_str<E: de::Error>(self, value: &str) -> Result<Self::Value, E> {
+        match value {
+            CAPS_FEATURES_VARIANT_ANY_STR => Ok(CapsFeaturesVariantKinds::Any),
+            CAPS_FEATURES_VARIANT_SOME_STR => Ok(CapsFeaturesVariantKinds::Some),
+            _ => Err(de::Error::unknown_variant(
+                value,
+                CAPS_FEATURES_VARIANT_NAMES,
+            )),
+        }
+    }
+}
+
+impl<'de> Deserialize<'de> for CapsFeaturesVariantKinds {
+    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        deserializer.deserialize_identifier(CapsFeaturesVariantKindsVisitor)
+    }
+}
+
+struct CapsFeaturesVisitor;
+impl<'de> Visitor<'de> for CapsFeaturesVisitor {
+    type Value = CapsFeatures;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a CapsFeatures enum (`Any` or `Some()`)")
+    }
+
+    fn visit_enum<A: EnumAccess<'de>>(self, data: A) -> Result<Self::Value, A::Error> {
+        let res = match data.variant()? {
+            (CapsFeaturesVariantKinds::Any, _v) => CapsFeatures::new_any(),
+            (CapsFeaturesVariantKinds::Some, v) => v
+                .newtype_variant::<CapsFeaturesSome>()
+                .map(|caps_features_some| caps_features_some.0)?,
+        };
+
+        Ok(res)
+    }
+}
+
+impl<'de> Deserialize<'de> for CapsFeatures {
+    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        deserializer.deserialize_enum(
+            stringify!(Caps),
+            CAPS_FEATURES_VARIANT_NAMES,
+            CapsFeaturesVisitor,
+        )
+    }
+}

gstreamer/src/caps_serde.rs

@@ -13,6 +13,8 @@ use serde::ser::{Serialize, SerializeSeq, SerializeTuple, Serializer};
 use std::fmt;
 
 use Caps;
+use CapsFeatures;
+use CapsFeaturesRef;
 use CapsRef;
 use Structure;
 use StructureRef;
@@ -36,15 +38,12 @@ const CAPS_VARIANT_NAMES: &[&str] = &[
     &CAPS_VARIANT_SOME_STR,
 ];
 
-// `CapsFeature` is not available in `gstreamer-rs` yet
-struct CapsItemSe<'a>(&'a StructureRef);
+struct CapsItemSe<'a>(&'a StructureRef, Option<&'a CapsFeaturesRef>);
 impl<'a> Serialize for CapsItemSe<'a> {
     fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
         let mut tup = serializer.serialize_tuple(2)?;
         tup.serialize_element(self.0)?;
-        // `CapsFeature` is not available in `gstreamer-rs` yet
-        // Fake the type for now and use `None` as a value
-        tup.serialize_element::<Option<Structure>>(&None)?;
+        tup.serialize_element(&self.1)?;
         tup.end()
     }
 }
@@ -52,12 +51,19 @@ impl<'a> Serialize for CapsItemSe<'a> {
 struct CapsForIterSe<'a>(&'a CapsRef);
 impl<'a> Serialize for CapsForIterSe<'a> {
     fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
-        let iter = self.0.iter();
+        let iter = self.0.iter_with_features();
         let size = iter.size_hint().0;
         if size > 0 {
             let mut seq = serializer.serialize_seq(Some(size))?;
-            for structure in iter {
-                seq.serialize_element(&CapsItemSe(structure))?;
+            for (structure, features) in iter {
+                let features = if !features.is_any() && features
+                    .is_equal(::CAPS_FEATURES_MEMORY_SYSTEM_MEMORY.as_ref())
+                {
+                    None
+                } else {
+                    Some(features)
+                };
+                seq.serialize_element(&CapsItemSe(structure, features))?;
             }
             seq.end()
         } else {
@@ -98,13 +104,7 @@ impl Serialize for Caps {
     }
 }
 
-// `CapsFeature` is not available in `gstreamer-rs` yet
-struct CapsItemDe(Structure);
-impl From<CapsItemDe> for Structure {
-    fn from(caps_item: CapsItemDe) -> Structure {
-        caps_item.0
-    }
-}
+struct CapsItemDe(Structure, Option<CapsFeatures>);
 
 struct CapsItemVisitor;
 impl<'de> Visitor<'de> for CapsItemVisitor {
@@ -118,20 +118,13 @@ impl<'de> Visitor<'de> for CapsItemVisitor {
         let structure = seq
             .next_element::<Structure>()?
             .ok_or(de::Error::custom("Expected a `Structure` for `Caps` item"))?;
-        // `CapsFeature` is not available in `gstreamer-rs` yet
-        // Fake the type for now and expect `None` as a value
-        let feature_option = seq
-            .next_element::<Option<Structure>>()?
-            .ok_or(de::Error::custom(
-                "Expected an `Option<CapsFeature>` for `Caps` item",
-            ))?;
-        if feature_option.is_some() {
-            Err(de::Error::custom(
-                "Found a value for `CapsFeature`, expected `None` (not implemented yet)",
-            ))
-        } else {
-            Ok(CapsItemDe(structure))
-        }
+        let features_option =
+            seq.next_element::<Option<CapsFeatures>>()?
+                .ok_or(de::Error::custom(
+                    "Expected an `Option<CapsFeature>` for `Caps` item",
+                ))?;
+
+        Ok(CapsItemDe(structure, features_option))
     }
 }
 
@@ -156,7 +149,7 @@ impl<'de> Visitor<'de> for CapsSomeVisitor {
         {
             let caps = caps.get_mut().unwrap();
             while let Some(caps_item) = seq.next_element::<CapsItemDe>()? {
-                caps.append_structure(caps_item.into());
+                caps.append_structure_full(caps_item.0, caps_item.1);
             }
         }
         Ok(CapsSome(caps))
@@ -238,6 +231,7 @@ mod tests {
 
     use Array;
     use Caps;
+    use CapsFeatures;
     use Fraction;
 
     #[test]
@@ -274,6 +268,71 @@ mod tests {
             res,
         );
 
+        let caps = Caps::builder("foo/bar")
+            .field("int", &12)
+            .field("bool", &true)
+            .field("string", &"bla")
+            .field("fraction", &Fraction::new(1, 2))
+            .field("array", &Array::new(&[&1, &2]))
+            .features(&["foo:bar", "foo:baz"])
+            .build();
+
+        let mut pretty_config = ron::ser::PrettyConfig::default();
+        pretty_config.new_line = "".to_string();
+
+        let res = ron::ser::to_string_pretty(&caps, pretty_config.clone());
+        assert_eq!(
+            Ok(concat!(
+                "Some([",
+                "    ((\"foo/bar\", [",
+                "        (\"int\", \"i32\", 12),",
+                "        (\"bool\", \"bool\", true),",
+                "        (\"string\", \"String\", \"bla\"),",
+                "        (\"fraction\", \"Fraction\", (1, 2)),",
+                "        (\"array\", \"Array\", [",
+                "            (\"i32\", 1),",
+                "            (\"i32\", 2),",
+                "        ]),",
+                "    ]), Some(Some([",
+                "        \"foo:bar\",",
+                "        \"foo:baz\",",
+                "    ]))),",
+                "])"
+            ).to_owned()),
+            res,
+        );
+
+        let caps = Caps::builder("foo/bar")
+            .field("int", &12)
+            .field("bool", &true)
+            .field("string", &"bla")
+            .field("fraction", &Fraction::new(1, 2))
+            .field("array", &Array::new(&[&1, &2]))
+            .any_features()
+            .build();
+
+        let mut pretty_config = ron::ser::PrettyConfig::default();
+        pretty_config.new_line = "".to_string();
+
+        let res = ron::ser::to_string_pretty(&caps, pretty_config.clone());
+        assert_eq!(
+            Ok(concat!(
+                "Some([",
+                "    ((\"foo/bar\", [",
+                "        (\"int\", \"i32\", 12),",
+                "        (\"bool\", \"bool\", true),",
+                "        (\"string\", \"String\", \"bla\"),",
+                "        (\"fraction\", \"Fraction\", (1, 2)),",
+                "        (\"array\", \"Array\", [",
+                "            (\"i32\", 1),",
+                "            (\"i32\", 2),",
+                "        ]),",
+                "    ]), Some(Any)),",
+                "])"
+            ).to_owned()),
+            res,
+        );
+
         let caps_any = Caps::new_any();
         let res = ron::ser::to_string_pretty(&caps_any, pretty_config.clone());
         assert_eq!(Ok("Any".to_owned()), res);
@@ -328,6 +387,74 @@ mod tests {
                 ],
             ).as_ref()
         );
+
+        let caps_ron = r#"
+            Some([
+                (
+                    ("foo/bar", [
+                        ("int", "i32", 12),
+                        ("bool", "bool", true),
+                        ("string", "String", "bla"),
+                        ("fraction", "Fraction", (1, 2)),
+                        ("array", "Array", [
+                            ("i32", 1),
+                            ("i32", 2),
+                        ]),
+                    ]),
+                    Some(Some(["foo:bar", "foo:baz"])),
+                ),
+            ])"#;
+        let caps: Caps = ron::de::from_str(caps_ron).unwrap();
+        let s = caps.get_structure(0).unwrap();
+        assert_eq!(
+            s,
+            Structure::new(
+                "foo/bar",
+                &[
+                    ("int", &12),
+                    ("bool", &true),
+                    ("string", &"bla"),
+                    ("fraction", &Fraction::new(1, 2)),
+                    ("array", &Array::new(&[&1, &2])),
+                ],
+            ).as_ref()
+        );
+        let f = caps.get_features(0).unwrap();
+        assert!(f.is_equal(CapsFeatures::new(&["foo:bar", "foo:baz"]).as_ref()));
+
+        let caps_ron = r#"
+            Some([
+                (
+                    ("foo/bar", [
+                        ("int", "i32", 12),
+                        ("bool", "bool", true),
+                        ("string", "String", "bla"),
+                        ("fraction", "Fraction", (1, 2)),
+                        ("array", "Array", [
+                            ("i32", 1),
+                            ("i32", 2),
+                        ]),
+                    ]),
+                    Some(Any),
+                ),
+            ])"#;
+        let caps: Caps = ron::de::from_str(caps_ron).unwrap();
+        let s = caps.get_structure(0).unwrap();
+        assert_eq!(
+            s,
+            Structure::new(
+                "foo/bar",
+                &[
+                    ("int", &12),
+                    ("bool", &true),
+                    ("string", &"bla"),
+                    ("fraction", &Fraction::new(1, 2)),
+                    ("array", &Array::new(&[&1, &2])),
+                ],
+            ).as_ref()
+        );
+        let f = caps.get_features(0).unwrap();
+        assert!(f.is_any());
     }
 
     #[test]
@@ -354,5 +481,29 @@ mod tests {
         let caps_ser = ron::ser::to_string(&caps).unwrap();
         let caps_de: Caps = ron::de::from_str(caps_ser.as_str()).unwrap();
         assert!(caps_de.is_strictly_equal(&caps));
+
+        let caps = Caps::builder("foo/bar")
+            .field("int", &12)
+            .field("bool", &true)
+            .field("string", &"bla")
+            .field("fraction", &Fraction::new(1, 2))
+            .field("array", &Array::new(&[&1, &2]))
+            .features(&["foo:bar", "foo:baz"])
+            .build();
+        let caps_ser = ron::ser::to_string(&caps).unwrap();
+        let caps_de: Caps = ron::de::from_str(caps_ser.as_str()).unwrap();
+        assert!(caps_de.is_strictly_equal(&caps));
+
+        let caps = Caps::builder("foo/bar")
+            .field("int", &12)
+            .field("bool", &true)
+            .field("string", &"bla")
+            .field("fraction", &Fraction::new(1, 2))
+            .field("array", &Array::new(&[&1, &2]))
+            .any_features()
+            .build();
+        let caps_ser = ron::ser::to_string(&caps).unwrap();
+        let caps_de: Caps = ron::de::from_str(caps_ser.as_str()).unwrap();
+        assert!(caps_de.is_strictly_equal(&caps));
     }
 }

gstreamer/src/lib.rs

@@ -91,6 +91,10 @@ pub mod caps;
 pub use caps::{Caps, CapsRef};
 #[cfg(feature = "ser_de")]
 mod caps_serde;
+mod caps_features;
+pub use caps_features::{CapsFeatures, CapsFeaturesRef, CAPS_FEATURE_MEMORY_SYSTEM_MEMORY, CAPS_FEATURES_MEMORY_SYSTEM_MEMORY};
+#[cfg(feature = "ser_de")]
+mod caps_features_serde;
 
 pub mod tags;
 pub use tags::{Tag, TagList, TagListRef};