From 0b70e52032b6496e5578346b614294bfc9faae8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Fri, 9 Oct 2020 11:30:44 +0300
Subject: [PATCH] gstreamer/audio/video: Correctly implement ExactSizeIterator

len() is optional but size_hint() must return the correct values. Also
this shouldn't return the overall length but the remaining length.
---
 gstreamer-audio/src/audio_format.rs | 14 ++++++++++----
 gstreamer-video/src/video_format.rs | 14 ++++++++++----
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/gstreamer-audio/src/audio_format.rs b/gstreamer-audio/src/audio_format.rs
index 2d3ffa457..10db2259a 100644
--- a/gstreamer-audio/src/audio_format.rs
+++ b/gstreamer-audio/src/audio_format.rs
@@ -263,14 +263,20 @@ impl Iterator for AudioFormatIterator {
             Some(fmt)
         }
     }
-}
 
-impl ExactSizeIterator for AudioFormatIterator {
-    fn len(&self) -> usize {
-        self.len
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if self.idx == self.len {
+            return (0, Some(0));
+        }
+
+        let remaining = (self.len - self.idx) as usize;
+
+        (remaining, Some(remaining))
     }
 }
 
+impl ExactSizeIterator for AudioFormatIterator {}
+
 impl DoubleEndedIterator for AudioFormatIterator {
     fn next_back(&mut self) -> Option<Self::Item> {
         if self.idx >= self.len {
diff --git a/gstreamer-video/src/video_format.rs b/gstreamer-video/src/video_format.rs
index 6b90ace76..55aa36271 100644
--- a/gstreamer-video/src/video_format.rs
+++ b/gstreamer-video/src/video_format.rs
@@ -402,14 +402,20 @@ impl Iterator for VideoFormatIterator {
             Some(fmt)
         }
     }
-}
 
-impl ExactSizeIterator for VideoFormatIterator {
-    fn len(&self) -> usize {
-        self.len
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if self.idx == self.len {
+            return (0, Some(0));
+        }
+
+        let remaining = (self.len - self.idx) as usize;
+
+        (remaining, Some(remaining))
     }
 }
 
+impl ExactSizeIterator for VideoFormatIterator {}
+
 impl DoubleEndedIterator for VideoFormatIterator {
     fn next_back(&mut self) -> Option<Self::Item> {
         if self.idx >= self.len {