gst/format: fix Percent Display impl

- The `GST_FORMAT_PERCENT_SCALE` was not used to compute the value
  to display.
- Added `Display` examples in the format module documentation.
- Simplified `glib_newtype_display` macro.

gstreamer/src/format/generic.rs

@@ -22,7 +22,7 @@ impl Other {
 impl_common_ops_for_newtype_uint!(Other, u64);
 impl_signed_div_mul!(Other, u64);
 option_glib_newtype_from_to!(Other, u64::MAX);
-glib_newtype_display!(Other, DisplayableOther, DisplayableOptionOther);
+glib_newtype_display!(Other, DisplayableOptionOther);
 
 impl TryFrom<u64> for Other {
     type Error = GlibNoneError;

gstreamer/src/format/macros.rs

@@ -1531,13 +1531,11 @@ macro_rules! option_glib_newtype_from_to {
     };
 }
 
-// FIXME we could automatically build `$displayable_name` and
-// `$displayable_option_name` if `concat_idents!` was stable.
+// FIXME we could automatically build `$displayable_option_name`
+// if `concat_idents!` was stable.
 // See: https://doc.rust-lang.org/std/macro.concat_idents.html
 macro_rules! glib_newtype_display {
-    ($typ:ty, $displayable_name:ident) => {
-        pub struct $displayable_name($typ);
-
+    ($typ:ty) => {
         impl std::fmt::Display for $typ {
             fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
                 std::fmt::Display::fmt(&self.0, f)
@@ -1545,16 +1543,14 @@ macro_rules! glib_newtype_display {
         }
 
         impl crate::utils::Displayable for $typ {
-            type DisplayImpl = $typ;
-            fn display(self) -> $typ {
+            type DisplayImpl = Self;
+            fn display(self) -> Self {
                 self
             }
         }
     };
 
-    ($typ:ty, $displayable_name:ident, Format::$format:ident$(,)?) => {
-        pub struct $displayable_name($typ);
-
+    ($typ:ty, Format::$format:ident) => {
         impl std::fmt::Display for $typ {
             fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
                 std::fmt::Display::fmt(&self.0, f)?;
@@ -1564,15 +1560,15 @@ macro_rules! glib_newtype_display {
         }
 
         impl crate::utils::Displayable for $typ {
-            type DisplayImpl = $typ;
-            fn display(self) -> $typ {
+            type DisplayImpl = Self;
+            fn display(self) -> Self {
                 self
             }
         }
     };
 
-    ($typ:ty, $displayable_name:ident, $displayable_option_name:ident) => {
-        glib_newtype_display!($typ, $displayable_name);
+    ($typ:ty, $displayable_option_name:ident) => {
+        glib_newtype_display!($typ);
 
         pub struct $displayable_option_name(Option<$typ>);
 
@@ -1594,8 +1590,8 @@ macro_rules! glib_newtype_display {
         }
     };
 
-    ($typ:ty, $displayable_name:ident, $displayable_option_name:ident, Format::$format:ident$(,)?) => {
-        glib_newtype_display!($typ, $displayable_name, Format::$format);
+    ($typ:ty, $displayable_option_name:ident, Format::$format:ident$(,)?) => {
+        glib_newtype_display!($typ, Format::$format);
 
         pub struct $displayable_option_name(Option<$typ>);
 
@@ -1604,8 +1600,7 @@ macro_rules! glib_newtype_display {
                 if let Some(val) = self.0.as_ref() {
                     std::fmt::Display::fmt(val, f)
                 } else {
-                    f.write_str("undef. ")?;
-                    std::fmt::Display::fmt(&Format::$format, f)
+                    write!(f, "undef. {}", Format::$format)
                 }
             }
         }

gstreamer/src/format/mod.rs

@@ -72,6 +72,10 @@
 //!
 //! assert_eq!(format!("{}", time), "12:43:54.908569837");
 //! assert_eq!(format!("{:.0}", time), "12:43:54");
+//!
+//! let percent = gst::format::Percent::try_from(0.1234).unwrap();
+//! assert_eq!(format!("{}", percent), "12.34 %");
+//! assert_eq!(format!("{:5.1}", percent), " 12.3 %");
 //! ```
 //!
 //! ## Some operations available on specific formatted values
@@ -858,13 +862,17 @@ mod tests {
         assert_eq!(&format!("{}", Some(bytes).display()), "42 bytes");
         assert_eq!(&format!("{}", Bytes::NONE.display()), "undef. bytes");
 
-        let gv_1 = GenericFormattedValue::Percent(Some(Percent(42)));
+        let gv_1 = GenericFormattedValue::Percent(Percent::try_from(0.42).ok());
         assert_eq!(&format!("{gv_1}"), "42 %");
         assert_eq!(
             &format!("{}", GenericFormattedValue::Percent(None)),
             "undef. %"
         );
 
+        let percent = Percent::try_from(0.1234).unwrap();
+        assert_eq!(&format!("{percent}"), "12.34 %");
+        assert_eq!(&format!("{percent:5.1}"), " 12.3 %");
+
         let other: Other = 42.try_into().unwrap();
         assert_eq!(&format!("{other}"), "42");
 

gstreamer/src/format/specific.rs

@@ -32,12 +32,7 @@ impl_common_ops_for_newtype_uint!(Buffers, u64);
 impl_signed_div_mul!(Buffers, u64);
 impl_format_value_traits!(Buffers, Buffers, Buffers, u64);
 option_glib_newtype_from_to!(Buffers, Buffers::OFFSET_NONE);
-glib_newtype_display!(
-    Buffers,
-    DisplayableBuffers,
-    DisplayableOptionBuffers,
-    Format::Buffers,
-);
+glib_newtype_display!(Buffers, DisplayableOptionBuffers, Format::Buffers);
 
 #[derive(PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy, Debug, Default)]
 pub struct Bytes(pub u64);
@@ -49,12 +44,7 @@ impl_common_ops_for_newtype_uint!(Bytes, u64);
 impl_signed_div_mul!(Bytes, u64);
 impl_format_value_traits!(Bytes, Bytes, Bytes, u64);
 option_glib_newtype_from_to!(Bytes, u64::MAX);
-glib_newtype_display!(
-    Bytes,
-    DisplayableBytes,
-    DisplayableOptionBytes,
-    Format::Bytes,
-);
+glib_newtype_display!(Bytes, DisplayableOptionBytes, Format::Bytes);
 
 #[derive(PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy, Debug, Default)]
 pub struct Default(pub u64);
@@ -66,12 +56,7 @@ impl_common_ops_for_newtype_uint!(Default, u64);
 impl_signed_div_mul!(Default, u64);
 impl_format_value_traits!(Default, Default, Default, u64);
 option_glib_newtype_from_to!(Default, u64::MAX);
-glib_newtype_display!(
-    Default,
-    DisplayableDefault,
-    DisplayableOptionDefault,
-    Format::Default,
-);
+glib_newtype_display!(Default, DisplayableOptionDefault, Format::Default);
 
 pub type Time = super::ClockTime;
 
@@ -86,12 +71,6 @@ impl Percent {
 
 impl_common_ops_for_newtype_uint!(Percent, u32);
 impl_signed_div_mul!(Percent, u32);
-glib_newtype_display!(
-    Percent,
-    DisplayablePercent,
-    DisplayableOptionPercent,
-    Format::Percent,
-);
 
 impl FormattedValue for Option<Percent> {
     type FullRange = Option<Percent>;
@@ -245,3 +224,36 @@ impl TryFrom<f32> for Percent {
         }
     }
 }
+
+impl std::fmt::Display for Percent {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        const ONE_PERCENT: f32 = Percent::SCALE as f32 / 100.0;
+        std::fmt::Display::fmt(&(self.0 as f32 / ONE_PERCENT), f)?;
+        f.write_str(" %")
+    }
+}
+
+impl crate::utils::Displayable for Percent {
+    type DisplayImpl = Self;
+    fn display(self) -> Self {
+        self
+    }
+}
+pub struct DisplayableOptionPercent(Option<Percent>);
+
+impl std::fmt::Display for DisplayableOptionPercent {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        if let Some(val) = self.0.as_ref() {
+            std::fmt::Display::fmt(val, f)
+        } else {
+            f.write_str("undef. %")
+        }
+    }
+}
+
+impl crate::utils::Displayable for Option<Percent> {
+    type DisplayImpl = DisplayableOptionPercent;
+    fn display(self) -> Self::DisplayImpl {
+        DisplayableOptionPercent(self)
+    }
+}

gstreamer/src/format/undefined.rs

@@ -108,4 +108,4 @@ impl From<Undefined> for Signed<u64> {
     }
 }
 
-glib_newtype_display!(Undefined, DisplayableUndefined, Format::Undefined);
+glib_newtype_display!(Undefined, Format::Undefined);