GeneralPrimitive

1. summary General features of all graphics primitives
2. labels Reference,Version1

_(This page applies only to the 1.x branch of SVGFig.)_

All graphics primitives have the following features:

1. [#SVG_method SVG method]
2. [#Path_method Path method]
3. [#Member_data Member data]
4. [#Defaults Defaults]

SVG method

All graphics primitives have a *SVG* method to convert to [ClassSVG SVG].

• SVG(trans)*

trans

_default_=None

a coordinate transformation function (to override the default)

Path method

_Some_ graphics primitives also have a *Path* method to convert to [ClassPath Path].

• Path(trans, local)*

	trans		_default_=None		a coordinate transformation function (to override the default)
	local		_default_=False		express the path in local coordinates

Be careful to transform coordinates only once: the following are equivalent

• `something.Path(transformation, local=False).SVG()`
• `something.Path(transformation, local=True).SVG(transformation)`
• `something.Path(None, local=True).SVG(transformation)`
• `something.Path(None, local=False).SVG(transformation)` though the actual output may differ due to the adaptive sampling algorithm. (Straight segments might look curved under a transformation, and the sampling algorithm will want to give these segments more points if it knows about the transformation.)

Generally, you want

• `something.Path(transformation, local=False)`

Member data

Every option in a primitive's constructor may be accessed later as member data. For example,

>>> line = Line(x1=0, y1=0, x2=1, y2=1)
>>> line.x1
0
>>> line.y1 = 4

Some primitives define additional data members when they are drawn with *SVG*. For example, you can give [ClassXAxis XAxis] a vague `ticks` specification and obtain the list of ticks actually created through `last_ticks`.

>>> axis = XAxis(0, 100, 0, ticks=-10)
>>> axis.SVG()
<g (9 sub) />
>>> axis.last_ticks
{0.0: u'0', 100.0: u'100', 40.0: u'40', 80.0: u'80', 20.0: u'20', 60.0: u'60'}

Defaults

All primitives have default SVG attributes which can be changed at the class level or the instance level.

>>> LineAxis.defaults
{'stroke-width': '0.25pt'}
>>> lineaxis = LineAxis(0,0,1,1)
>>> lineaxis.attr
{'stroke-width': '0.25pt'}

Change the "stroke-width" for `lineaxis`.

>>> lineaxis.attr["stroke-width"] = "0.5pt"
>>> lineaxis.attr
{'stroke-width': '0.5pt'}

Make a new LineAxis; it has the old "stroke-width".

>>> lineaxis2 = LineAxis(0,0,1,1)
>>> lineaxis2.attr
{'stroke-width': '0.25pt'}

Change the "stroke-width" for all subsequent LineAxis instances.

>>> LineAxis.defaults["stroke-width"] = "0.5pt"
>>> lineaxis3 = LineAxis(0,0,1,1)
>>> lineaxis3.attr
{'stroke-width': '0.5pt'}

(But that didn't change the already-instantiated `lineaxis2`.

>>> lineaxis2.attr
{'stroke-width': '0.25pt'}

Some primitives have default options which are not SVG attributes. They work the same way.