filter: add avfilter wrapper

src/filter/filter.rs

@@ -0,0 +1,107 @@
+use std::ffi::CStr;
+use std::str::from_utf8_unchecked;
+use std::marker::PhantomData;
+
+use ffi::*;
+use super::{Pad, Flags};
+
+pub struct Filter {
+	ptr: *mut AVFilter,
+}
+
+impl Filter {
+	pub unsafe fn wrap(ptr: *mut AVFilter) -> Self {
+		Filter { ptr: ptr }
+	}
+
+	pub unsafe fn as_ptr(&self) -> *const AVFilter {
+		self.ptr as *const _
+	}
+
+	pub unsafe fn as_mut_ptr(&mut self) -> *mut AVFilter {
+		self.ptr
+	}
+}
+
+impl Filter {
+	pub fn name(&self) -> &str {
+		unsafe {
+			from_utf8_unchecked(CStr::from_ptr((*self.as_ptr()).name).to_bytes())
+		}
+	}
+
+	pub fn description(&self) -> Option<&str> {
+		unsafe {
+			let ptr = (*self.as_ptr()).description;
+
+			if ptr.is_null() {
+				None
+			}
+			else {
+				Some(from_utf8_unchecked(CStr::from_ptr(ptr).to_bytes()))
+			}
+		}
+	}
+
+	pub fn inputs(&self) -> Option<PadIter> {
+		unsafe {
+			let ptr = (*self.as_ptr()).inputs;
+
+			if ptr.is_null() {
+				None
+			}
+			else {
+				Some(PadIter::new((*self.as_ptr()).inputs))
+			}
+		}
+	}
+
+	pub fn outputs(&self) -> Option<PadIter> {
+		unsafe {
+			let ptr = (*self.as_ptr()).outputs;
+
+			if ptr.is_null() {
+				None
+			}
+			else {
+				Some(PadIter::new((*self.as_ptr()).outputs))
+			}
+		}
+	}
+
+	pub fn flags(&self) -> Flags {
+		unsafe {
+			Flags::from_bits_truncate((*self.as_ptr()).flags)
+		}
+	}
+}
+
+pub struct PadIter<'a> {
+	ptr: *const AVFilterPad,
+	cur: isize,
+
+	_marker: PhantomData<&'a ()>,
+}
+
+impl<'a> PadIter<'a> {
+	pub fn new(ptr: *const AVFilterPad) -> Self {
+		PadIter { ptr: ptr, cur: 0, _marker: PhantomData }
+	}
+}
+
+impl<'a> Iterator for PadIter<'a> {
+	type Item = Pad<'a>;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		unsafe {
+			if self.cur >= avfilter_pad_count(self.ptr) as isize {
+				return None;
+			}
+
+			let pad   = Pad::wrap(self.ptr.offset(self.cur));
+			self.cur += 1;
+
+			Some(pad)
+		}
+	}
+}