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

Concepts

Linking / Exporting

.sif files aren't always self-contained. They can link to parts of other .sif files, which creates a dependency of one on the other. This may seem strange to animators who use Flash because, in Flash, animation files are usually self-contained.

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

Recursion

Recursion of .sif files is prohibited.

Compression

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.

Synfig recognizes the ".sfg" file format as an archival file format. A .sfg is a ZIP archive that bundles a .sif and its resources together. In Synfig Studio, images and sounds can be packed using Import Image Layer or Sound Layer.

<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	What it is
version	no default, this attribute is required	0.1, always
width	480	the width of the canvas in pixels
height	270	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
focus	0 0	the anchor point for changing the view-box

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

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

<name>

The short name of the canvas.

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

<meta>

Metadata for the Synfig Studio editor. These can be safely ignored by other implementations.

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

Synfig Studio recognizes these <meta> names (source):

• grid_size
• grid_color
• grid_snap
• grid_show
• onion_skin
• onion_skin_past
• onion_skin_future
• guide_color
• guide_snap
• guide_show
• guide_x
• guide_y
• sketch
• solid_lines
• background_size
• background_first_color
• background_second_color

<author>

The name of the canvas'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>

<layer>

Overview

Layers describe the shapes and effects on a canvas.

<canvas version="0.1">
    ...
    <layer type="solid_color" version="0.1"
    ...
</canvas>

Attribute	Default	What it is
type	no default	see the list of types
version	no default	depends on the layer type
group		the name of the group that this layer belongs to
desc		a human-readable description
active	true	whether the layer is selected (?)
exclude_from_rendering	false	whether it should be rendered

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