allocators: Move some methods to extension traits

So they're callable on subclasses without casting first. Also
disambiguate the `alloc()` methods with the ones from the `Allocator`
base class.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1751>

examples/src/bin/fd_allocator.rs

@@ -22,6 +22,7 @@ use std::{
 use anyhow::Error;
 use futures::StreamExt;
 use gst::{element_error, prelude::*};
+use gst_allocators::prelude::*;
 use memmap2::MmapMut;
 use uds::UnixStreamExt;
 
@@ -83,7 +84,7 @@ fn create_receiver_pipeline(
                     // will be closed when the memory is released.
                     let memory = unsafe {
                         fd_allocator
-                            .alloc(*fd, video_info.size(), gst_allocators::FdMemoryFlags::NONE)
+                            .alloc_fd(*fd, video_info.size(), gst_allocators::FdMemoryFlags::NONE)
                             .unwrap()
                     };
                     let mut buffer = gst::Buffer::new();

gstreamer-allocators/src/dma_buf_allocator.rs

@@ -42,9 +42,9 @@ impl DmaBufMemoryRef {
     }
 }
 
-impl DmaBufAllocator {
+pub trait DmaBufAllocatorExtManual: IsA<DmaBufAllocator> + 'static {
     #[doc(alias = "gst_dmabuf_allocator_alloc")]
-    pub unsafe fn alloc<A: IntoRawFd>(
+    unsafe fn alloc_dmabuf<A: IntoRawFd>(
         &self,
         fd: A,
         size: usize,
@@ -61,7 +61,7 @@ impl DmaBufAllocator {
     #[cfg(feature = "v1_16")]
     #[cfg_attr(docsrs, doc(cfg(feature = "v1_16")))]
     #[doc(alias = "gst_dmabuf_allocator_alloc_with_flags")]
-    pub unsafe fn alloc_with_flags(
+    unsafe fn alloc_dmabuf_with_flags(
         &self,
         fd: RawFd,
         size: usize,
@@ -77,3 +77,5 @@ impl DmaBufAllocator {
         .ok_or_else(|| glib::bool_error!("Failed to allocate memory"))
     }
 }
+
+impl<O: IsA<DmaBufAllocator>> DmaBufAllocatorExtManual for O {}

gstreamer-allocators/src/drm_dumb_allocator.rs

@@ -58,9 +58,11 @@ impl DRMDumbAllocator {
             .ok_or_else(|| glib::bool_error!("Failed to create allocator"))
         }
     }
+}
 
+pub trait DRMDumbAllocatorExtManual: IsA<DRMDumbAllocator> + 'static {
     #[doc(alias = "gst_drm_dumb_allocator_alloc")]
-    pub unsafe fn alloc(
+    unsafe fn alloc_drm_dumb(
         &self,
         drm_fourcc: u32,
         width: u32,
@@ -69,7 +71,7 @@ impl DRMDumbAllocator {
         skip_assert_initialized!();
         let mut out_pitch = mem::MaybeUninit::uninit();
         Option::<_>::from_glib_full(ffi::gst_drm_dumb_allocator_alloc(
-            self.to_glib_none().0,
+            self.as_ref().to_glib_none().0,
             drm_fourcc,
             width,
             height,
@@ -79,3 +81,5 @@ impl DRMDumbAllocator {
         .map(|mem| (mem, unsafe { out_pitch.assume_init() }))
     }
 }
+
+impl<O: IsA<DRMDumbAllocator>> DRMDumbAllocatorExtManual for O {}

gstreamer-allocators/src/fd_allocator.rs

@@ -44,9 +44,9 @@ impl FdMemoryRef {
     }
 }
 
-impl FdAllocator {
+pub trait FdAllocatorExtManual: IsA<FdAllocator> + 'static {
     #[doc(alias = "gst_fd_allocator_alloc")]
-    pub unsafe fn alloc(
+    unsafe fn alloc_fd(
         &self,
         fd: RawFd,
         size: usize,
@@ -65,7 +65,7 @@ impl FdAllocator {
     #[cfg(feature = "v1_28")]
     #[cfg_attr(docsrs, doc(cfg(feature = "v1_28")))]
     #[doc(alias = "gst_fd_allocator_alloc_full")]
-    pub unsafe fn alloc_full(
+    unsafe fn alloc_fd_full(
         allocator: &impl IsA<gst::Allocator>,
         fd: RawFd,
         maxsize: usize,
@@ -86,3 +86,5 @@ impl FdAllocator {
         }
     }
 }
+
+impl<O: IsA<FdAllocator>> FdAllocatorExtManual for O {}

gstreamer-allocators/src/lib.rs

@@ -59,6 +59,11 @@ pub mod prelude {
     pub use gst::prelude::*;
 
     pub use crate::auto::traits::*;
+    #[cfg(any(target_os = "linux", docsrs))]
+    pub use crate::dma_buf_allocator::DmaBufAllocatorExtManual;
+    #[cfg(any(all(feature = "v1_24", target_os = "linux"), docsrs))]
+    pub use crate::drm_dumb_allocator::DRMDumbAllocatorExtManual;
+    pub use crate::fd_allocator::FdAllocatorExtManual;
 }
 
 pub mod subclass;