Crate alpha2_extensions 

Extension providers: frames of formats the host’s video and image decoders do not read, supplied through one contract.

A provider probes bytes (never a file name) and opens a source that answers frames by source time. The host registers the providers its build includes, in priority order, and feeds their frames to the engine like any other source’s; the engine and the renderer know nothing of them. Each format is a cargo feature: a build without one still renders everything else, and reports that format’s sources as unsupported.

Structs

AnimatedImageProvider

Reads GIF, animated WebP, and APNG. A still file of those formats is not this provider’s: the host’s image decoders read it.

ExrProvider

Reads still OpenEXR images.

LinearColor

What linear-light media’s RGB is: the primaries it is in, and where that was learned.

LottieProvider

Reads Lottie JSON and dotLottie packages.

NoResources

A resolver with nothing registered.

ProbeReport

What probing a file finds.

ProgressWatch

Ends a watch_progress watch, restoring the one before it.

Registry

The providers a host’s build includes, highest priority first.

SvgProvider

Reads static SVG documents.

VisualFrame

One frame of a source.

Enums

ColorOrigin

Where a source’s color description comes from.

Diagnostic

Something a provider did that the user should know about.

ExtensionError

Why a provider could not answer.

Format

A format a provider reads.

FramePixels

A frame’s pixels, rows packed without padding, in the precision its source has. Shared, never copied, with what the source keeps: a frame a source answers again (a still, a frame it holds) costs no copy.

Timing

When a source’s frames are shown, in source time.

Constants

DEFAULT_FRAME_BUDGET

Decoded bytes an animated source or an image sequence keeps between requests.

MAX_ANIMATION_FRAMES

Most frames an animated image may have.

MAX_ANIMATION_PIXELS

Most pixels an animated image’s frames may cover, all frames together: what one pass through it decodes and composites, whatever its canvas. About a thousand whole 1080p frames, which one pass decodes in about ten seconds natively.

MAX_CANVAS_PIXELS

Largest canvas a provider opens, in pixels: 8K UHD.

MAX_CANVAS_SIDE

Largest canvas side a provider opens, in pixels.

MAX_NORMALIZED_DELAY_MS

The longest delay not taken as meant: a frame declaring this or less (zero included) is shown for NORMALIZED_DELAY_MS and reported. A GIF counts delays in hundredths of a second, so its 0 and 1 are the delays normalized; APNG and WebP declare frame times exactly, and a longer delay (60 fps is 16 or 17 ms) plays as declared, in every format alike.

MAX_SOURCE_IMAGE_PIXELS

Most pixels the raster images inside one source may decode to, all of them together: four whole canvases of MAX_CANVAS_PIXELS. An SVG decodes every image it draws on each render (an image drawn twice, as through <use>, counts twice) and a Lottie animation decodes its image assets once, when it opens, and holds them; each image is also within check_canvas on its own. A source past it is refused.

NORMALIZED_DELAY_MS

What a delay of MAX_NORMALIZED_DELAY_MS or less becomes.

Traits

ResourceResolver

Bytes a source needs besides its own: an image sequence’s frames, and the fonts and images an SVG names. A provider never fetches anything else. It may be asked from inside a parser (usvg asks for each image it draws), which requires it to be shared across threads.

VisualProvider

Reads one family of formats.

VisualSource

A source a provider opened: asked for frames by source time.

Functions

check_canvas

Refuses a canvas larger than a provider opens.

check_document_size

Refuses a source’s file of length bytes larger than its document_limit, before it is read or parsed.

check_image_pixels

Refuses images that together decode to more than MAX_SOURCE_IMAGE_PIXELS.

document_limit

The most bytes a provider reads of a source’s own file, for the formats it reads whole: a dotLottie package (MAX_PROVIDER_DOCUMENT_BYTES), a Lottie JSON file (MAX_LOTTIE_DOCUMENT_BYTES), and an SVG document (MAX_SVG_DOCUMENT_BYTES), with what the file is called; None for the formats a provider decodes as it goes. head is the file’s start: a Lottie source’s file is a package when it starts as a ZIP file does.

open_sequence

Opens an image sequence: frames in play order (None for a gap in the numbering), at rate, their bytes from resolver as they are shown; OpenEXR frames in primaries when given. Only the first frame is read here.

premultiply

Premultiplies straight RGBA8 in place, rounding to nearest.

watch_progress

Calls progressed on this thread each time a provider call it makes gets further, until the returned watch drops.

Type Aliases

SharedResolver

A resolver a source may keep: an image sequence reads each frame from it when it shows that frame, never all of them when it opens.