Libsvgtiny
==========

Based on:
http://www.netsurf-browser.org/projects/libsvgtiny/ version 1.4

Libsvgtiny is a library for parsing SVG files into a simplified internal representation suitable for display or manipulation.

Libsvgtinywriter is a library for unparsing the internal data structures that Libsvgtiny creates, back to an SVG file.

The overall idea of the library is to take some SVG as input, and
return a list of paths and texts which can be rendered easily. The
library does not do the actual rendering.

All supported SVG objects, for example circles, lines, and gradient
filled shapes, are converted to flat-filled paths or a fragment of
text, and all coordinates are converted, transformed etc. to pixels.

Libsvgtiny and Libsvgtinywriter  is Licensed under the MIT License,
http://opensource.org/licenses/mit-license.php

Written by James Bursa <james@netsurf-browser.org>.
Modifications by David Phillip Oster


SVG support
-----------

Libsvgtiny is initially aiming to implement SVG Tiny, as defined in
http://www.w3.org/TR/SVGMobile/.

SVG Tiny elements supported: defs, g, svg, circle, line, path, polygon,
polyline, rect, text

SVG Tiny elements not yet supported: desc, metadata, title, use, a,
switch, ellipse, image, font, font-face, font-face-name, font-face-src,
glyph, hkern, missing-glyph, animate, animateColor, animateMotion,
animateTransform, mpath, set, foreignObject

Additional elements supported: linearGradient, stop

Text support is incomplete: no fonts. linearGradient support is incomplete: They parse, but the internal data structure doesn't (yet) represent the gradient.

The style attribute is supported.

Oster's Fork:
-------------

* stroke-opacity and fill-opacity are supported.

* stroke-width is a float, not an int.

* This just opens and builds using Xcode. It removes the dependency on
colors.gperf, and the dependency on the 'dom' parsing library, using the libxml2 that is
pre-installed on OS X and iOS.

Building libsvgtiny
-------------------

Oster's Fork: 
-------------

You can also just open the Xcode project and compile it - No external dependencies.

The apple_main.c is an example of parsing an SVG file as a string, unparsing it to a new string, parsing again, and unparsing it again. The two string are written to the Xcode console so you can see that it writes equivalent SVG files, and that file is equivalent to the original.


Using libsvgtiny
----------------

The interface is in the header svgtiny.h

  #include "svgtiny.h"

First create a svgtiny_diagram using svgtiny_create():

  struct svgtiny_diagram *diagram;
  diagram = svgtiny_create();

This will return a pointer to a new diagram, or NULL if there was not enough
memory.

SVGs are parsed from memory using svgtiny_parse():

  svgtiny_code code;
  code = svgtiny_parse(diagram, buffer, size, url, 1000, 1000);

The arguments are the pointer returned by svgtiny_create(), a buffer
containing the SVG data, the size of the SVG in bytes, the url that
the SVG came from, and the target viewport width and height in pixels.

The function returns svgtiny_OK if there were no problems, and diagram
is updated. The diagram can then be rendered by looping through the
array diagram->shape[0..diagram->shape_count]:

  for (unsigned int i = 0; i != diagram->shape_count; i++) {

Path shapes have a non-NULL path pointer. The path is an array of
floats of length path_length. The array contains segment type codes
followed by 0 to 3 pairs of coordinates (depending on the segment
type):

- svgtiny_PATH_MOVE x y
- svgtiny_PATH_CLOSE
- svgtiny_PATH_LINE x y
- svgtiny_PATH_BEZIER x1 y1 x2 y2 x3 y3

A path always starts with a MOVE.

The fill and stroke attributes give the colors of the path, or
svgtiny_TRANSPARENT if the path is not filled or stroked. Colors are
in 0xRRGGBB format (except when compiled for RISC OS). The macros
svgtiny_RED, svgtiny_GREEN, and svgtiny_BLUE can be used to extract
the components.

The width of the path is in stroke_width.

Text shapes have a NULL path pointer and a non-NULL text pointer. Text
is in UTF-8. The coordinates of the text are in text_x, text_y. Text
colors and stroke width are as for paths.

If memory runs out during parsing, svgtiny_parse() returns
svgtiny_OUT_OF_MEMORY, but the diagram is still valid up to the point
when memory was exhausted, and may safely be rendered.

If there is an error in the SVG (for example, an element is missing an
attribute required by the specification), svgtiny_SVG_ERROR is
returned, but the diagram is still valid up to the point of the
error. The error is recorded in diagram->error_message and the line
that caused it in diagram->error_line.

svgtiny_LIBXML_ERROR indicates that parsing the XML failed. The
returned diagram will contain no shapes. svgtiny_NOT_SVG means that
the XML did not contain a top-level <svg> element.

To free memory used by a diagram, use svgtiny_free():

  svgtiny_free(diagram);

For an example, see appl_main.c.


[1] http://upload.wikimedia.org/wikipedia/commons/f/fd/Ghostscript_Tiger.svg