Re: Gets vertical skylines from grob stencils (issue 5626052)

[David Kastrup]

David Kastrup <address@hidden> writes:

> "address@hidden" <address@hidden> writes:
>
>> On Feb 13, 2012, at 12:28 AM, address@hidden wrote:
>>
>>> On Feb 12, 2012, at 3:40 PM, David Kastrup wrote:
>>> 
>>>> 
>>>> What's with the translate_scale_rotate stuff?  .
>>>> 
>>>> That looks fishy.  What are you trying to do here?
>>> 
>>> Account for line thickness.  I actually have no clue how thickness
>>> works.  Is thickness in PS and SVG always added perpendicularly on
>>> either side (meaning thick/2 on both sides) of the line that is the
>>> slope of a curve at a given point?
>>> 
>>
>> Re-asking this question.  In PS and SVG, will the thickness of a curve
>> always be added perpendicularly in both directions to the line tangent
>> to the curve at a given point?  Also, with rounded caps, does the
>> radius of this cap sweep 180 degrees starting and ending at the
>> perpendicular axis to the curve while being anchored at the beginning
>> and end point?  If so, I can get rid of Translate_scale_rotate.
>
> I can't speak for SVG, but PostScript questions should be answered in
> the PostScript Language Reference Manual.  I recommend storing it in a
> reasonably accessible place on your disk.
>
> <URL:http://www.adobe.com/products/postscript/pdfs/PLRM.pdf>

To quote:


num setlinewidth –

sets the line width parameter in the graphics state to num. This
parameter controls the thickness of lines to be drawn by subsequent
invocations of stroke and related operators, such as rectstroke and
ustroke. When stroking a path, stroke paints all points whose
perpendicular distance from the path in user space is less than or equal
to half the absolute value of num. The effect produced in device space
depends on the current transformation matrix (CTM) in effect at the time
the path is stroked. If the CTM specifies scaling by different factors
in the x and y dimensions, the thickness of stroked lines in device
space will vary according to their orientation.

-- 
David Kastrup