/src/image/src/codecs/webp/encoder.rs

Source
//! Encoding of WebP images.

use std::io::Write;

use crate::error::{EncodingError, UnsupportedError, UnsupportedErrorKind};
use crate::{DynamicImage, ExtendedColorType, ImageEncoder, ImageError, ImageFormat, ImageResult};

/// WebP Encoder.
///
/// ### Limitations
///
/// Right now only **lossless** encoding is supported.
///
/// If you need **lossy** encoding, you'll have to use `libwebp`.
/// Example code for encoding a [`DynamicImage`](crate::DynamicImage) with `libwebp`
/// via the [`webp`](https://docs.rs/webp/latest/webp/) crate can be found
/// [here](https://github.com/jaredforth/webp/blob/main/examples/convert.rs).
///
/// ### Compression ratio
///
/// This encoder reaches compression ratios higher than PNG at a fraction of the encoding time.
/// However, it does not reach the full potential of lossless WebP for reducing file size.
///
/// If you need an even higher compression ratio at the cost of much slower encoding,
/// please encode the image with `libwebp` as outlined above.
pub struct WebPEncoder<W> {
    inner: image_webp::WebPEncoder<W>,
}

impl<W: Write> WebPEncoder<W> {
    /// Create a new encoder that writes its output to `w`.
    ///
    /// Uses "VP8L" lossless encoding.
    pub fn new_lossless(w: W) -> Self {
        Self {
            inner: image_webp::WebPEncoder::new(w),
        }
    }

    /// Encode image data with the indicated color type.
    ///
    /// The encoder requires image data be Rgb8 or Rgba8.
    ///
    /// # Panics
    ///
    /// Panics if `width * height * color.bytes_per_pixel() != data.len()`.
    #[track_caller]
    pub fn encode(
        self,
        buf: &[u8],
        width: u32,
        height: u32,
        color_type: ExtendedColorType,
    ) -> ImageResult<()> {
        let expected_buffer_len = color_type.buffer_size(width, height);
        assert_eq!(
            expected_buffer_len,
            buf.len() as u64,
            "Invalid buffer length: expected {expected_buffer_len} got {} for {width}x{height} image",
            buf.len(),
        );

        let color_type = match color_type {
            ExtendedColorType::L8 => image_webp::ColorType::L8,
            ExtendedColorType::La8 => image_webp::ColorType::La8,
            ExtendedColorType::Rgb8 => image_webp::ColorType::Rgb8,
            ExtendedColorType::Rgba8 => image_webp::ColorType::Rgba8,
            _ => {
                return Err(ImageError::Unsupported(
                    UnsupportedError::from_format_and_kind(
                        ImageFormat::WebP.into(),
                        UnsupportedErrorKind::Color(color_type),
                    ),
                ))
            }
        };

        self.inner
            .encode(buf, width, height, color_type)
            .map_err(ImageError::from_webp_encode)
    }
}

impl<W: Write> ImageEncoder for WebPEncoder<W> {
    #[track_caller]
    fn write_image(
        self,
        buf: &[u8],
        width: u32,
        height: u32,
        color_type: ExtendedColorType,
    ) -> ImageResult<()> {
        self.encode(buf, width, height, color_type)
    }

    fn set_icc_profile(&mut self, icc_profile: Vec<u8>) -> Result<(), UnsupportedError> {
        self.inner.set_icc_profile(icc_profile);
        Ok(())
    }

    fn set_exif_metadata(&mut self, exif: Vec<u8>) -> Result<(), UnsupportedError> {
        self.inner.set_exif_metadata(exif);
        Ok(())
    }

    fn make_compatible_img(
        &self,
        _: crate::io::encoder::MethodSealedToImage,
        img: &DynamicImage,
    ) -> Option<DynamicImage> {
        crate::io::encoder::dynimage_conversion_8bit(img)
    }
}

impl ImageError {
    fn from_webp_encode(e: image_webp::EncodingError) -> Self {
        match e {
            image_webp::EncodingError::IoError(e) => ImageError::IoError(e),
            _ => ImageError::Encoding(EncodingError::new(ImageFormat::WebP.into(), e)),
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::{ImageEncoder, RgbaImage};

    #[test]
    fn write_webp() {
        let img = RgbaImage::from_raw(10, 6, (0..240).collect()).unwrap();

        let mut output = Vec::new();
        super::WebPEncoder::new_lossless(&mut output)
            .write_image(
                img.inner_pixels(),
                img.width(),
                img.height(),
                crate::ExtendedColorType::Rgba8,
            )
            .unwrap();

        let img2 = crate::load_from_memory_with_format(&output, crate::ImageFormat::WebP)
            .unwrap()
            .to_rgba8();

        assert_eq!(img, img2);
    }
}

Line	Count	Source
1		//! Encoding of WebP images.
2
3		use std::io::Write;
4
5		use crate::error::{EncodingError, UnsupportedError, UnsupportedErrorKind};
6		use crate::{DynamicImage, ExtendedColorType, ImageEncoder, ImageError, ImageFormat, ImageResult};
7
8		/// WebP Encoder.
9		///
10		/// ### Limitations
11		///
12		/// Right now only lossless encoding is supported.
13		///
14		/// If you need lossy encoding, you'll have to use `libwebp`.
15		/// Example code for encoding a [`DynamicImage`](crate::DynamicImage) with `libwebp`
16		/// via the [`webp`](https://docs.rs/webp/latest/webp/) crate can be found
17		/// [here](https://github.com/jaredforth/webp/blob/main/examples/convert.rs).
18		///
19		/// ### Compression ratio
20		///
21		/// This encoder reaches compression ratios higher than PNG at a fraction of the encoding time.
22		/// However, it does not reach the full potential of lossless WebP for reducing file size.
23		///
24		/// If you need an even higher compression ratio at the cost of much slower encoding,
25		/// please encode the image with `libwebp` as outlined above.
26		pub struct WebPEncoder<W> {
27		inner: image_webp::WebPEncoder<W>,
28		}
29
30		impl<W: Write> WebPEncoder<W> {
31		/// Create a new encoder that writes its output to `w`.
32		///
33		/// Uses "VP8L" lossless encoding.
34	1.87k	pub fn new_lossless(w: W) -> Self {
35	1.87k	Self {
36	1.87k	inner: image_webp::WebPEncoder::new(w),
37	1.87k	}
38	1.87k	}
39
40		/// Encode image data with the indicated color type.
41		///
42		/// The encoder requires image data be Rgb8 or Rgba8.
43		///
44		/// # Panics
45		///
46		/// Panics if `width * height * color.bytes_per_pixel() != data.len()`.
47		#[track_caller]
48	1.87k	pub fn encode(
49	1.87k	self,
50	1.87k	buf: &[u8],
51	1.87k	width: u32,
52	1.87k	height: u32,
53	1.87k	color_type: ExtendedColorType,
54	1.87k	) -> ImageResult<()> {
55	1.87k	let expected_buffer_len = color_type.buffer_size(width, height);
56	1.87k	assert_eq!(
57		expected_buffer_len,
58	1.87k	buf.len() as u64,
59	0	"Invalid buffer length: expected {expected_buffer_len} got {} for {width}x{height} image",
60	0	buf.len(),
61		);
62
63	1.87k	let color_type = match color_type {
64	0	ExtendedColorType::L8 => image_webp::ColorType::L8,
65	0	ExtendedColorType::La8 => image_webp::ColorType::La8,
66	0	ExtendedColorType::Rgb8 => image_webp::ColorType::Rgb8,
67	1.87k	ExtendedColorType::Rgba8 => image_webp::ColorType::Rgba8,
68		_ => {
69	0	return Err(ImageError::Unsupported(
70	0	UnsupportedError::from_format_and_kind(
71	0	ImageFormat::WebP.into(),
72	0	UnsupportedErrorKind::Color(color_type),
73	0	),
74	0	))
75		}
76		};
77
78	1.87k	self.inner
79	1.87k	.encode(buf, width, height, color_type)
80	1.87k	.map_err(ImageError::from_webp_encode)
81	1.87k	}
82		}
83
84		impl<W: Write> ImageEncoder for WebPEncoder<W> {
85		#[track_caller]
86	1.87k	fn write_image(
87	1.87k	self,
88	1.87k	buf: &[u8],
89	1.87k	width: u32,
90	1.87k	height: u32,
91	1.87k	color_type: ExtendedColorType,
92	1.87k	) -> ImageResult<()> {
93	1.87k	self.encode(buf, width, height, color_type)
94	1.87k	}
95
96	0	fn set_icc_profile(&mut self, icc_profile: Vec<u8>) -> Result<(), UnsupportedError> {
97	0	self.inner.set_icc_profile(icc_profile);
98	0	Ok(())
99	0	}
100
101	0	fn set_exif_metadata(&mut self, exif: Vec<u8>) -> Result<(), UnsupportedError> {
102	0	self.inner.set_exif_metadata(exif);
103	0	Ok(())
104	0	}
105
106	0	fn make_compatible_img(
107	0	&self,
108	0	_: crate::io::encoder::MethodSealedToImage,
109	0	img: &DynamicImage,
110	0	) -> Option<DynamicImage> {
111	0	crate::io::encoder::dynimage_conversion_8bit(img)
112	0	}
113		}
114
115		impl ImageError {
116	0	fn from_webp_encode(e: image_webp::EncodingError) -> Self {
117	0	match e {
118	0	image_webp::EncodingError::IoError(e) => ImageError::IoError(e),
119	0	_ => ImageError::Encoding(EncodingError::new(ImageFormat::WebP.into(), e)),
120		}
121	0	}
122		}
123
124		#[cfg(test)]
125		mod tests {
126		use crate::{ImageEncoder, RgbaImage};
127
128		#[test]
129		fn write_webp() {
130		let img = RgbaImage::from_raw(10, 6, (0..240).collect()).unwrap();
131
132		let mut output = Vec::new();
133		super::WebPEncoder::new_lossless(&mut output)
134		.write_image(
135		img.inner_pixels(),
136		img.width(),
137		img.height(),
138		crate::ExtendedColorType::Rgba8,
139		)
140		.unwrap();
141
142		let img2 = crate::load_from_memory_with_format(&output, crate::ImageFormat::WebP)
143		.unwrap()
144		.to_rgba8();
145
146		assert_eq!(img, img2);
147		}
148		}

Coverage Report

Created: 2025-10-14 06:57