From: James Bursa <james@netsurf-browser.org>
Date: Sun, 4 May 2008 01:59:15 +0000 (-0000)
Subject: Add an overview of the library.
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=7944e8a06896097c9923c2c6659ff2ffa28c4191;p=libsvgtiny.git

Add an overview of the library.

svn path=/trunk/libsvgtiny/; revision=4122
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+Libsvgtiny
+==========
+http://www.netsurf-browser.org/projects/libsvgtiny/
+
+Libsvgtiny is a library for parsing SVG files for display.
+
+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 is Licensed under the MIT License,
+http://opensource.org/licenses/mit-license.php
+
+Written by James Bursa <james@netsurf-browser.org>.
+
+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.
+
+The style attribute is supported.
+
+Building libsvgtiny
+-------------------
+You will require the following tools:
+
+- a C compiler (some parts of C99 support are required)
+- gperf
+
+and the following libraries:
+
+- libxml2
+
+To compile libsvgtiny, use the command
+
+  make
+
+To install libsvgtiny into /usr/local, use
+
+  make install
+
+To cross-compile for RISC OS, use
+
+  make TARGET=riscos
+  make install TARGET=riscos
+
+Testing libsvgtiny
+------------------
+The svgtiny_display script uses the library to render an SVG. It requires that
+ImageMagick convert is installed.
+
+Get an SVG file, for example
+http://www.croczilla.com/svg/samples/tiger/tiger.svg
+
+Then use svgtiny_display to parse and render it:
+
+  ./svgtiny_display tiger.svg
+  ./svgtiny_display tiger.svg 2
+
+The optional 2nd argument is a scale.
+
+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 svgtiny_test.c.
+
+
+