Struct image::codecs::jpeg::JpegEncoder

pub struct JpegEncoder<W> {
    writer: BitWriter<W>,
    components: Vec<Component>,
    tables: Vec<[u8; 64]>,
    luma_dctable: Cow<'static, [(u8, u16); 256]>,
    luma_actable: Cow<'static, [(u8, u16); 256]>,
    chroma_dctable: Cow<'static, [(u8, u16); 256]>,
    chroma_actable: Cow<'static, [(u8, u16); 256]>,
    pixel_density: PixelDensity,
}

The representation of a JPEG encoder

Fields

writer: BitWriter<W>

components: Vec<Component>

tables: Vec<[u8; 64]>

luma_dctable: Cow<'static, [(u8, u16); 256]>

luma_actable: Cow<'static, [(u8, u16); 256]>

chroma_dctable: Cow<'static, [(u8, u16); 256]>

chroma_actable: Cow<'static, [(u8, u16); 256]>

pixel_density: PixelDensity

Implementations

impl<W: Write> JpegEncoder<W>

pub fn new(w: W) -> JpegEncoder<W>

Create a new encoder that writes its output to w

pub fn new_with_quality(w: W, quality: u8) -> JpegEncoder<W>

Create a new encoder that writes its output to w, and has the quality parameter quality with a value in the range 1-100 where 1 is the worst and 100 is the best.

pub fn set_pixel_density(&mut self, pixel_density: PixelDensity)

Set the pixel density of the images the encoder will encode. If this method is not called, then a default pixel aspect ratio of 1x1 will be applied, and no DPI information will be stored in the image.

pub fn encode( &mut self, image: &[u8], width: u32, height: u32, color_type: ColorType, ) -> ImageResult<()>

Encodes the image stored in the raw byte buffer image that has dimensions width and height and ColorType c

The Image in encoded with subsampling ratio 4:2:2

Panics

Panics if width * height * color_type.bytes_per_pixel() != image.len().

pub fn encode_image<I: GenericImageView>( &mut self, image: &I, ) -> ImageResult<()>

where I::Pixel: PixelWithColorType,

Encodes the given image.

As a special feature this does not require the whole image to be present in memory at the same time such that it may be computed on the fly, which is why this method exists on this encoder but not on others. Instead the encoder will iterate over 8-by-8 blocks of pixels at a time, inspecting each pixel exactly once. You can rely on this behaviour when calling this method.

The Image in encoded with subsampling ratio 4:2:2

fn encode_gray<I: GenericImageView>(&mut self, image: &I) -> Result<()>

fn encode_rgb<I: GenericImageView>(&mut self, image: &I) -> Result<()>

Trait Implementations

impl<W: Write> ImageEncoder for JpegEncoder<W>

fn write_image( self, buf: &[u8], width: u32, height: u32, color_type: ColorType, ) -> ImageResult<()>

Writes all the bytes in an image to the encoder.