Struct Offscreen 

pub struct Offscreen {
    pub attribute: Attribute,
    pub parameter: Parameter,
    pub data: Option<BlockData>,
}

A decoded offscreen.

Fields

attribute: Attribute

The attribute.

parameter: Parameter

Its Parameter section.

data: Option<BlockData>

The block data, when the payload is stored.

Implementations

impl Offscreen

pub fn parse(attribute: &[u8], payload: Option<&[u8]>) -> Result<Self>

Parses an attribute and, if given, its block data payload, and checks they agree.

pub fn kind(&self) -> PixelKind

The pixel layout.

pub fn for_each_block( &self, visit: impl FnMut(usize, &[u8]) -> Result<()>, ) -> Result<()>

Visit every stored block decompressed: (block index, raw bytes).

pub fn to_rgba(&self) -> Result<RgbaImage>

Colour, gray and monochrome offscreens as RGBA (not premultiplied). Blocks that are not stored are transparent (or the init colour).

pub fn stored_boxes(&self) -> Vec<(u32, u32, u32, u32)>

Boxes (x0, y0, x1, y1) in offscreen pixels of the blocks that store data. Nothing is decompressed; edge blocks end at the offscreen’s size.

pub fn to_rgba_region(&self, region: (i64, i64, i64, i64)) -> Result<RgbaImage>

Offscreen::to_rgba of the box (x0, y0, x1, y1) in offscreen pixels, which may reach outside the offscreen (that part is transparent). Only the blocks the box overlaps are decompressed, so part of a large sheet can be read without decoding all of it.

pub fn to_rgba_halved(&self, halvings: u32) -> Result<RgbaImage>

Offscreen::to_rgba halved halvings times with RgbaImage::halve, one block at a time, so a large offscreen read at a small scale never exists at full size. Blocks are 256 pixels and aligned, so up to 8 halvings give exactly the result of halving the whole image; more are done on the reduced image.

pub fn to_mask_rgba_halved(&self, halvings: u32) -> Result<RgbaImage>

The mask plane as opaque grey pixels (v, v, v, 255), halved like Offscreen::to_rgba_halved.

pub fn to_alpha(&self) -> Result<GrayImage>

The first plane as an 8-bit image (masks: 0 = hidden, 255 = shown).

pub fn reencode_check(&self) -> Result<(usize, usize, usize)>

Re-encode the decoded pixels and compare with the stored blocks: (blocks equal byte for byte, blocks with equal pixels, stored blocks).

Trait Implementations

impl Clone for Offscreen

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Offscreen

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.