Enum ImageFormat 

pub enum ImageFormat {
    Png,
    Jpeg,
    Webp,
    Gif,
    Bmp,
    Tiff,
    Heif,
    Unknown,
}

An encoded image format: what BitmapInfo::format reports and EncodeSpec::format asks for. Not every backend encodes every one: ask Toolkit::encode_formats (the Cap::ImageEncode pair of Toolkit::font_families/Cap::FontList) rather than assuming.

Variants

Png

Jpeg

Webp

Gif

Bmp

Tiff

Heif

HEIF/HEIC, Apple’s camera format; decodable on the Apple backends and Android, and encodable almost nowhere.

Unknown

Decoded from bytes whose magic numbers ImageFormat::sniff does not know. A backend may still decode it: the platform decoders read more formats than Day names.

Implementations

impl ImageFormat

pub fn mime(self) -> &'static str

The IANA media type, which is also the string the ArkUI packer, GDI+ and the browser’s toBlob take. Unknown answers application/octet-stream.

pub fn dimensions(bytes: &[u8]) -> Option<(u32, u32)>

The pixel size the encoded bytes declare, read from the container’s own header (docs/images.md).

Every backend that decodes natively reports its own dimensions; this exists for the one that cannot. The XAML backend’s (windows-winui) BitmapImage learns its size asynchronously, only once the element has been shown, so a synchronous image_info there would have nothing to say. Reading the header instead gives the same answer the decoder would, before any decoding.

None when the header is absent, truncated, or a container this does not parse.

pub fn sniff(bytes: &[u8]) -> Option<ImageFormat>

The format bytes begins with, by magic number: enough to fill BitmapInfo::format on every backend, including the ones whose decoder never says what it decoded.

Hand-rolled rather than a crate: it is a dozen byte comparisons against fixed prefixes, and the alternative is an image-decoding dependency in the one crate that must stay dependency-free.

Trait Implementations

impl Clone for ImageFormat

fn clone(&self) -> ImageFormat

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ImageFormat

impl Debug for ImageFormat

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

Formats the value using the given formatter.

impl Default for ImageFormat

fn default() -> ImageFormat

Returns the “default value” for a type.

impl Eq for ImageFormat

impl Hash for ImageFormat

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ImageFormat

fn eq(&self, other: &ImageFormat) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ImageFormat