Struct mtpng::Header

pub struct Header { /* private fields */ }

PNG header representation.

You must create one of these with image metadata when encoding, and can reuse the header for multiple encodings if desired.

Implementations

impl Header

pub fn new() -> Header

Create a new Header struct with default settings.

This will be 1x1 pixels, TruecolorAlpha 8-bit, with the standard compression, filter, and interlace methods. You can mutate the state using the set_* methods.

pub fn width(&self) -> u32

Get the pixel width of the image.

pub fn height(&self) -> u32

Get the pixel height of the image.

pub fn depth(&self) -> u8

Get the color depth of the image in bits.

pub fn color_type(&self) -> ColorType

Get the color type of the image.

pub fn compression_method(&self) -> CompressionMethod

Get the compression method defined for the image.

pub fn filter_method(&self) -> FilterMethod

Get the filter method defined for the image.

pub fn interlace_method(&self) -> InterlaceMethod

Get the interlace method defined for the image.

pub fn bytes_per_pixel(&self) -> usize

Calculate the bytes per pixel, for PNG filtering purposes.

If the bit depth is < 8, this will clamp at 1.

pub fn stride(&self) -> usize

Calculate the stride in bytes for the encoded pixel rows.

Will panic on arithmetic overflow if given pathologically long rows.

pub fn set_size(&mut self, width: u32, height: u32) -> Result<()>

Set the pixel dimensions of the image.

Returns error if width or height are 0.

Warning: it’s possible to make combinations of width and color type that cannot fit in memory on 32-bit systems. These are not detected here, but will panic when stride() is called.

pub fn set_color(&mut self, color_type: ColorType, depth: u8) -> Result<()>

Set the color type and depth of the image.

Returns error if depth is invalid for the given color type.

Warning: it’s possible to make combinations of width and color type that cannot fit in memory on 32-bit systems. These are not detected here, but will panic when stride() is called.

pub fn set_compression_method( &mut self, compression_method: CompressionMethod ) -> Result<()>

Set the compression method.

This is not very useful, as only deflate is supported.

pub fn set_filter_method(&mut self, filter_method: FilterMethod) -> Result<()>

Set the filter method.

Currently only Standard is supported.

pub fn set_interlace_method( &mut self, interlace_method: InterlaceMethod ) -> Result<()>

Set the interlace method.

Currently only Standard is supported; requesting Adam7 will return an error.

Trait Implementations

impl Clone for Header

fn clone(&self) -> Header

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for Header

fn default() -> Self

Returns the “default value” for a type.

impl Copy for Header