scalacv
0.0.0-1-14e890
API
Generated with
scalacv/scalacv/Animation

Animation

scalacv.Animation
object Animation

Animation — a drawing that is a function of the frame number, rendered to a video.

The natural extension of a composable Picture: describe frame i as frame(i), and record draws every frame onto a fresh canvas and writes them out through a Recorder. Creative coding, a rendered data animation, a synthetic test clip — all fall out of the same graphics vocabulary.

// `.avi`, not `.mp4`: the default codec is MJPG, which opens only in an AVI container — see [[Codec.Mjpg]].
Animation.record("spin.avi", frames = 60, width = 320, height = 240) { i =>
 Picture.regularPolygon(Point(160, 120), sides = 5, radius = 80, rotation = i * 6)
   .strokeColor(Color.hsl(i * 6, 0.8, 0.6)).strokeWidth(3)
}

Attributes

Source
Animation.scala
Graph
Supertypes
class Object
trait Matchable
class Any
Self type
Animation.type

Members list

Value members

Concrete methods

def foreach(count: Int, width: Int, height: Int, background: Color = ...)(frame: Int => Picture)(f: Image => Unit): Unit

Renders count frames one at a time and hands each to f as an owned Image that is closed for you when f returns — on success, on failure, and on exception.

Renders count frames one at a time and hands each to f as an owned Image that is closed for you when f returns — on success, on failure, and on exception.

This is the streaming form to reach for, and the one to use for anything long: exactly one canvas is live at a time, so the peak native cost is a single frame however large count is. frames is the counterpart for when the frames must outlive a scope, at count canvases held at once.

Animation.foreach(900, 1920, 1080)(myPicture) { canvas =>
 recorder.write(canvas).fold(e => throw e, _ => ())
}

Attributes

Source
Animation.scala
def frames(count: Int, width: Int, height: Int, background: Color = ...)(frame: Int => Picture): Seq[Image]

Renders count frames as owned Images (each frame(i) on a fresh width×height background canvas) — for feeding elsewhere than a file. Each image is yours to close.

Renders count frames as owned Images (each frame(i) on a fresh width×height background canvas) — for feeding elsewhere than a file. Each image is yours to close.

These are live resources in a bare collection, which the type cannot warn you about: prefer foreach, which closes each canvas for you, unless you specifically need to hold the frames past a scope. All count canvases are alive at once here, so the peak native cost is count × width × height × 3 bytes — about 6 MB per frame at 1080p.

Strict, and deliberately not a LazyList: a lazy sequence memoises, so every canvas it has ever yielded stays reachable behind ~16 bytes of JVM heap — no GC pressure at all against a multi-megabyte native buffer — and a second traversal after the caller has closed them, which is the whole reason to reach for a re-traversable lazy type, hands back spent handles that throw. Video spells the argument out.

If frame throws partway through, the canvases already rendered are closed before the exception propagates: the Seq that would have carried them never reaches the caller, so nobody else can.

Attributes

Source
Animation.scala
def gif(path: String, frames: Int, width: Int, height: Int, fps: Double = ..., background: Color = ..., loop: Boolean = ...)(frame: Int => Picture): Either[CvError, Long]

Renders frames frames and writes them to path as an animated GIF at fps — the shareable format for a short loop (a demo, a rendered chart animation). loop true repeats forever. Returns the number of frames written, or a Left if encoding fails.

Renders frames frames and writes them to path as an animated GIF at fps — the shareable format for a short loop (a demo, a rendered chart animation). loop true repeats forever. Returns the number of frames written, or a Left if encoding fails.

GIF is 256 colours per frame; OpenCV dithers to fit. For full-colour or long clips, use record to a video instead.

Attributes

Source
Animation.scala
def record(path: String, frames: Int, width: Int, height: Int, fps: Double = ..., background: Color = ..., codec: Codec = ...)(frame: Int => Picture): Either[CvError, Long]

Renders frames frames — each the picture frame(i) drawn on a width×height background canvas — and writes them to path as a video at fps. Returns the number of frames written, or a Left if the recorder cannot open or a frame fails to encode.

Renders frames frames — each the picture frame(i) drawn on a width×height background canvas — and writes them to path as a video at fps. Returns the number of frames written, or a Left if the recorder cannot open or a frame fails to encode.

Value parameters

codec

defaults to Codec.Mjpg, the one codec videoio can always write, because it is served by the built-in MJPEG writer rather than by an FFmpeg plugin the natives may not ship. That makes path's extension part of the contract: MJPG opens only in an .avi, so a .mp4 fails to open even though the codec itself is present. Pass Codec.Mp4v with an .mp4 only on a build you know has FFmpeg.

Attributes

Source
Animation.scala
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