Class PDF::Writer::StrokeStyle
In: lib/pdf/writer/strokestyle.rb
Parent: Object

A class that represents a style with which lines will be drawn.

Methods

new   render  

Constants

LINE_CAPS = { :butt => 0, :round => 1, :square => 2 }
LINE_JOINS = { :miter => 0, :round => 1, :bevel => 2 }
SOLID_LINE = { :pattern => [], :phase => 0 }
DEFAULT = self.new(1, :cap => :butt, :join => :miter, :dash => SOLID_LINE)

Attributes

cap  [RW]  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.
dash  [RW]  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
2, 1
represents two units on, one unit off.
      # - 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.

join  [RW]  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.
miter_limit  [RW]  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.

width  [RW]  The thickness of the line in PDF units.

Public Class methods

Public Instance methods

[Validate]