Improve documentation (#95)

Author: RunDevelopment

src/color/mod.rs

@@ -67,10 +67,13 @@ impl Precision {
 /// A color format with a specific number of channels and precision.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct ColorFormat {
+    /// The number and semantics of the channels.
     pub channels: Channels,
+    /// The precision/bit depth of the values in all channels.
     pub precision: Precision,
 }
 impl ColorFormat {
+    /// Creates a new `ColorFormat` with the given channels and precision.
     pub const fn new(channels: Channels, precision: Precision) -> Self {
         Self {
             channels,

src/decode/mod.rs

@@ -59,7 +59,7 @@ pub(crate) const fn get_decoders(format: Format) -> DecoderSet {
         Format::Y410 => Y410,
         Format::Y416 => Y416,
 
-        // sub-sampled formats
+        // subsampled formats
         Format::R1_UNORM => R1_UNORM,
         Format::R8G8_B8G8_UNORM => R8G8_B8G8_UNORM,
         Format::G8R8_G8B8_UNORM => G8R8_G8B8_UNORM,
@@ -223,6 +223,13 @@ pub fn decode_rect<R: Read + Seek>(
     }
 }
 
+/// Options for decoding images.
+///
+/// ## See also
+///
+/// - [`decode`]
+/// - [`decode_rect`]
+/// - [`Decoder::options`](crate::Decoder::options)
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 #[non_exhaustive]
 pub struct DecodeOptions {

src/decode/read_write.rs

@@ -1124,7 +1124,7 @@ pub(crate) fn process_bi_planar_helper<
 pub(crate) struct BiPlaneInfo {
     pub plane1_element_size: u8,
     pub plane2_element_size: u8,
-    /// The sub-sampling of plane2.
+    /// The subsampling of plane2.
     pub sub_sampling: (u8, u8),
 }
 pub(crate) fn for_each_bi_planar(

src/decoder.rs

@@ -19,6 +19,9 @@ pub struct Decoder<R> {
     layout: DataLayout,
 
     iter: SurfaceIterator,
+    /// The options used for decoding.
+    ///
+    /// Default: [`DecodeOptions::default()`]
     pub options: DecodeOptions,
 }
 impl<R> Decoder<R> {

src/detect.rs

@@ -69,7 +69,7 @@ pub(crate) const fn dxgi_format_to_supported(dxgi_format: DxgiFormat) -> Option<
         DxgiFormat::Y410 => Some(Format::Y410),
         DxgiFormat::Y416 => Some(Format::Y416),
 
-        // sub-sampled formats
+        // subsampled formats
         DxgiFormat::R8G8_B8G8_UNORM => Some(Format::R8G8_B8G8_UNORM),
         DxgiFormat::G8R8_G8B8_UNORM => Some(Format::G8R8_G8B8_UNORM),
         DxgiFormat::YUY2 => Some(Format::YUY2),

src/encode/mod.rs

@@ -61,7 +61,7 @@ pub(crate) const fn get_encoders(format: Format) -> Option<EncoderSet> {
         Format::Y410 => Y410,
         Format::Y416 => Y416,
 
-        // sub-sampled formats
+        // subsampled formats
         Format::R1_UNORM => R1_UNORM,
         Format::R8G8_B8G8_UNORM => R8G8_B8G8_UNORM,
         Format::G8R8_G8B8_UNORM => G8R8_G8B8_UNORM,
@@ -222,6 +222,12 @@ fn encode_parallel(
     progress.checked_report(1.0)
 }
 
+/// Options for encoding images.
+///
+/// ## See also
+///
+/// - [`encode`]
+/// - [`Encoder::encoding`](crate::Encoder::encoding)
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 #[non_exhaustive]
 pub struct EncodeOptions {
@@ -240,6 +246,9 @@ pub struct EncodeOptions {
     pub dithering: Dithering,
     /// The error metric for block compression formats.
     ///
+    /// This is currently only supported for BC1-3. All other formats will
+    /// ignore this option and assume [`ErrorMetric::Uniform`].
+    ///
     /// Default: [`ErrorMetric::Uniform`]
     pub error_metric: ErrorMetric,
     /// The compression quality.
@@ -276,6 +285,8 @@ impl Default for EncodeOptions {
     }
 }
 
+/// Specifies whether dithering is enabled/supported for color and/or alpha
+/// channels.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
 pub enum Dithering {
     /// Dithering is disabled for all channels.
@@ -289,6 +300,7 @@ pub enum Dithering {
     Alpha = 0b10,
 }
 impl Dithering {
+    /// Creates a new `Dithering` given the channels it is enabled for.
     pub const fn new(color: bool, alpha: bool) -> Self {
         match (color, alpha) {
             (true, true) => Dithering::ColorAndAlpha,
@@ -298,9 +310,11 @@ impl Dithering {
         }
     }
 
+    /// Whether dithering is enabled for color channels.
     pub const fn color(self) -> bool {
         matches!(self, Dithering::ColorAndAlpha | Dithering::Color)
     }
+    /// Whether dithering is enabled for the alpha channel.
     pub const fn alpha(self) -> bool {
         matches!(self, Dithering::ColorAndAlpha | Dithering::Alpha)
     }
@@ -318,10 +332,20 @@ impl Dithering {
     }
 }
 
+/// The error metric encoders use to optimize compressed formats.
+///
+/// Not all formats support all error metrics. See
+/// [`EncodeOptions::error_metric`] for more details.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
 pub enum ErrorMetric {
+    /// The error of all channels is weighted equally.
     #[default]
     Uniform,
+    /// Color is assumed to be sRGB, and the error is calculated in a
+    /// perceptually uniform color space.
+    ///
+    /// [Oklab](https://en.wikipedia.org/wiki/Oklab_color_space) is currently
+    /// used as the perceptually uniform color space.
     Perceptual,
 }
 

src/encoder.rs

@@ -21,13 +21,13 @@ pub struct Encoder<W> {
 
     /// The encoding options used to encode surfaces.
     ///
-    /// Defaults: `EncodeOptions::default()`
+    /// Default: `EncodeOptions::default()`
     pub encoding: EncodeOptions,
     /// Options regarding automatic mipmap generation.
     ///
     /// Set `self.mipmaps.generate = true` to enable automatic mipmap generation.
     ///
-    /// Defaults: `MipmapOptions::default()`
+    /// Default: `MipmapOptions::default()`
     pub mipmaps: MipmapOptions,
 
     // internal cache for resizing
@@ -283,16 +283,30 @@ impl<W> Encoder<W> {
     }
 }
 
+/// The filter to use when resizing images for mipmap generation.
+///
+/// ## See also
+///
+/// - [`MipmapOptions::resize_filter`]
 #[derive(Debug, Clone, Copy, Default)]
 pub enum ResizeFilter {
+    /// Nearest neighbor interpolation (=point filtering).
     Nearest,
+    /// Box (also called area or binning).
+    ///
+    /// This is the default filter, because it produces mipmaps that are
+    /// generally free of artifacts and sharp (without being over sharpened).
     #[default]
     Box,
+    /// Triangle filtering (=linear interpolation).
     Triangle,
+    /// Mitchell interpolation.
     Mitchell,
+    /// Lanczos interpolation with a radius of 3.
     Lanczos3,
 }
 
+/// Options for automatic mipmap generation in [`Encoder`].
 #[derive(Debug, Clone, Copy)]
 pub struct MipmapOptions {
     /// Whether to generate mipmaps for the texture.
@@ -301,23 +315,25 @@ pub struct MipmapOptions {
     /// generate all mipmaps until the next level 0 object or EOF.
     ///
     /// Note: Generating mipmaps for volume depth slices is not supported. This
-    /// will **NOT** result in an error and instead the encoder will silently
-    /// ignore the option.
+    /// will **NOT** result in an error. Instead, the encoder will silently
+    /// ignore the option and assume mipmap generation is disabled.
     ///
     /// Default: `false`
     pub generate: bool,
-    /// Whether the alpha channel (if any) is straight alpha.
+    /// Whether the alpha channel (if any) is straight alpha transparency.
     ///
     /// This is important when generating mipmaps. Resizing RGBA with straight
     /// alpha requires that the alpha channel is premultiplied into the color
-    /// channels before resizing and then unpremultiplied after resizing. This
+    /// channels before resizing and then un-premultiplied after resizing. This
     /// is necessary to avoid color bleeding.
     ///
-    /// If the alpha channel is premultiplied alpha or custom (e.g. like in
-    /// channel-packed textures), this option should be set to `false`.
+    /// If the alpha channel is premultiplied alpha transparency or custom
+    /// (e.g. like in channel-packed textures), this option should be set to
+    /// `false`.
     ///
     /// If this option is set to `false`, all channels will be resized
-    /// independently of each other.
+    /// independently of each other. If set to `true`, the alpha channel will
+    /// be interpreted as straight alpha transparency and handled accordingly.
     ///
     /// Default: `true`
     pub resize_straight_alpha: bool,

src/error.rs

@@ -272,6 +272,11 @@ pub enum EncodingError {
     /// Returned by [`Encoder`](crate::Encoder) and [`encode()`](crate::encode()) when the format
     /// does not support encoding.
     UnsupportedFormat(Format),
+    /// Returned when the format requires the image size to be a multiple of
+    /// certain dimensions, but the provided image does not satisfy this.
+    ///
+    /// The two `NonZeroU32` values specify the required width and height
+    /// multiples respectively.
     InvalidSize(NonZeroU32, NonZeroU32),
 
     /// Returned by [`Encoder`](crate::Encoder) when the user tries to write a surface

src/format.rs

@@ -49,7 +49,7 @@ pub enum Format {
     Y410,
     Y416,
 
-    // sub-sampled formats
+    // subsampled formats
     R1_UNORM,
     R8G8_B8G8_UNORM,
     G8R8_G8B8_UNORM,
@@ -147,13 +147,13 @@ impl Format {
     }
     /// Returns the format of a surface from a DXGI format.
     ///
-    /// `None` if the DXGI format is not supported for decoding.
+    /// `None` if the DXGI format is not supported for decoding/encoding.
     pub const fn from_dxgi(dxgi: DxgiFormat) -> Option<Format> {
         detect::dxgi_format_to_supported(dxgi)
     }
     /// Returns the format of a surface from a FourCC code.
     ///
-    /// `None` if the FourCC code is not supported for decoding.
+    /// `None` if the FourCC code is not supported for decoding/encoding.
     pub const fn from_four_cc(four_cc: FourCC) -> Option<Format> {
         detect::four_cc_to_supported(four_cc)
     }
@@ -240,7 +240,7 @@ impl TryFrom<Format> for DxgiFormat {
             Format::Y410 => DxgiFormat::Y410,
             Format::Y416 => DxgiFormat::Y416,
 
-            // sub-sampled
+            // subsampled
             Format::R1_UNORM => DxgiFormat::R1_UNORM,
             Format::R8G8_B8G8_UNORM => DxgiFormat::R8G8_B8G8_UNORM,
             Format::G8R8_G8B8_UNORM => DxgiFormat::G8R8_G8B8_UNORM,

src/header.rs

@@ -8,7 +8,7 @@
 //!
 //! [`RawHeader`] is a low-level representation of an unparsed DDS header. It is
 //! bit-for-bit what is on disk. You rarely need to interact with this type, but
-//! it can useful for manually detecting and parsing non-standard DDS files.
+//! it can be useful for manually detecting and parsing non-standard DDS files.
 //!
 //! # Creating a header
 //!
@@ -420,7 +420,7 @@ pub struct ParseOptions {
     /// DDS files typically start with the magic bytes `"DDS "`. By default, the
     /// decoder will check for these bytes and error if they are not present.
     ///
-    /// If this is set to `true`, the decoder assume that the magic bytes are
+    /// If this is set to `true`, the decoder assumes that the magic bytes are
     /// not present and immediately start reading the header. This can be used
     /// to read DDS files without magic bytes.
     ///
@@ -1871,7 +1871,7 @@ impl TryFrom<u32> for DxgiFormat {
     type Error = u32;
 
     fn try_from(value: u32) -> Result<Self, Self::Error> {
-        // NOTE: This implementation is NOT generated by the marco for
+        // NOTE: This implementation is NOT generated by the macro for
         // performance and code size reasons. On virtually any optimization
         // level, the below code translates to around 6 instructions, while a
         // generated match arm (0 | 1 | 2 | ... | 115 | 130 | 131 | 132 => ...)