Sif Format

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A .sif file is the XML representation of a canvas. It holds the canvas's metadata, such as width and height, as well as information about its layers. Typically, a Synfig production comprises many .sif files joined in a sequence or nested within each other.

The .sif format is formidably complex and evolving. It is implementation-defined rather than spec-defined. Therefore, you should take everything on this page with a grain of salt. Indeed, the implementation can change at any point.

There are no plans to freeze the format.

Source code

The .sif format is implemented by the following file:

https://github.com/synfig/synfig/blob/master/synfig-core/src/synfig/loadcanvas.cpp

The format as of January 2016

Concepts

.sif files aren't always self-contained. They can import (read: link to) other .sif files, which creates a dependency of one on the other. This may seem strange to animators who use Flash because, in Flash, importing something causes it to be embedded in the current animation.

One drawback of Synfig's approach is that .sif dependencies can be hard to track. A tool called RenderChan solves this problem.

Recursion of .sif files is prohibited.

.sifz

Synfig recognizes .sifz as the extension of gzip-compressed .sif files. New and alternate implementations of .sif are urged to support this compression, although it is not required.

<canvas>

Overview

The top element of a .sif file is always a <canvas>.

<?xml version="1.0"?>

<canvas version="0.1" width="300" height="350" xres="2952.7559"
        yres="2952.7559" view-box="-1.5 2.5 1.5 -1" antialias="2"
        fps="12" begin-time="0f" end-time="0f" bgcolor="0.5 0.5 0.5 1">
    ...
</canvas>

Attribute	Default	Value
version	no default, this attribute is required	0.1, always
width	720	the width of the canvas in pixels
height	480	the height of the canvas in pixels
xres	2835	the width of the canvas in pixels per meter
yres	2835	the height of the canvas in pixels per meter
view-box	-4 2.25 4 -2.25	the bounding coordinates of the canvas (left top right bottom)
antialias	2	how hard Synfig should try to antialias the image
fps	24	frames per second
begin-time	0	where on the timetrack should rendering start
end-time	0	what on the timetrack should rendering end
bgcolor	0.5 0.5 0.5 1.0	the color of the background in RGBA

Inside a <canvas> you can find the following elements:

• <defs>
• <meta>
• <name>
• <desc>
• <author>
• <layer>
• <bones>
• <keyframe>

<name>

The title of the animation.

<canvas version="0.1">
    ...
    <name>Aqua Sphere</name>
    ...
</canvas>

<meta>

A miscellaneous piece of metadata.

<canvas version="0.1">
    ...
    <meta name="grid_show" content="1" />
    ...
</canvas>

<author>

The name of the .sif file's author.

<canvas version="0.1">
    ...
    <author>King Arthur</author>
    ...
</canvas>

<desc>

A human-readable description of the canvas.

<canvas version="0.1">
    ...
    <desc>This aqua-colored sphere reminds me of something from Mac OS X.</desc>
    ...
</canvas>

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