A class that represents a style with which lines will be drawn.
The type of cap to put on the line.
:butt |
The stroke is squared off at the endpoint of the path. There is no projection beyond the end of the path. |
:round |
A semicircular arc with a diameter equal to the line width is drawn around the endpoint and filled in. |
:square |
The stroke continues beyond the endpoint of the path for a distance equal to half the line width and is squared off. |
nil |
Keeps the current line cap. |
Controls the pattern of dashes and gaps used to stroke paths. This value must either be nil, or a hash with the following values:
:pattern |
An array of numbers specifying the lengths (in PDF userspace units) of alternating dashes and gaps. The array is processed cyclically, so that a :pattern of [3] represents three units on, three units off, and a :pattern of
|
# - represents on, _ represents off ---___---___--- # pattern [3] --_--_--_--_--_ # pattern [2, 1]
:phase |
The offset in the :pattern where the drawing of the stroke begins. Using a :phase of 1, the :pattern [3] will start offset by one phase, for two units on, three units off, three units on. |
--___---___---_ # pattern [3], phase 1 -_--_--_--_--_- # pattern [2, 1], phase 1
The constant SOLID_LINE may be used to restore line drawing to a solid line; this corresponds to an empty pattern with zero phase ([] 0).
Dashed lines wrap around curves and corners just as solid stroked lines do, with normal cap and join handling with no consideration of the dash pattern. A path with several subpaths treats each subpath independently; the complete dash pattern is restarted at the beginning of each subpath.
How two lines join together.
:miter |
The outer edges of the strokes for the two segments are extended until they meet at an angle, as in a picture frame. If the segments meet at too sharp an angle (as defined by the miter_limit), a bevel join is used instead. |
:round |
An arc of a circle with a diameter equal to the line width is drawn around the point where the two segments meet, connecting the outer edges of the strokes for the two segments. This pie-slice shaped figure is filled in, producing a rounded corner. |
:bevel |
The two segments are finished with butt caps and the the resulting notch beyond the ends of the segments is filled with a triangle, forming a flattened edge on the join. |
nil |
Keeps the current line join. |
When two line segments meet and :miter joins have been specified, the miter may extend far beyond the thickness of the line stroking the path. miter_limit imposes a maximum ratio miter length to line width at which point the join will be converted from a miter to a bevel. Adobe points out that the ratio is directly related to the angle between the segments in user space. With [p] representing the angle at which the segments meet:
miter_length / line_width == 1 / (sin ([p] / 2))
A miter limit of 1.414 converts miters to bevels for [p] less than 90 degrees, a limit of 2.0 converts them for [p] less than 60 degrees, and a limit of 10.0 converts them for [p] less than approximately 11.5 degrees.
# File lib/pdf/writer/strokestyle.rb, line 125 def render(debug = false) s = "" s << "#{width} w" if @width > 0 s << " #{LINE_CAPS[@cap]} J" if @cap s << " #{LINE_JOINS[@join]} j" if @join s << " #{@miter_limit} M" if @miter_limit if @dash s << " [" @dash[:pattern].each { |len| s << " #{len}" } s << " ] #{@dash[:phase] or 0} d" end s end
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