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Re: Fix: NSBezierPath, appendBezierPathWithArcWithCenter (2)

From: Georg Fleischmann
Subject: Re: Fix: NSBezierPath, appendBezierPathWithArcWithCenter (2)
Date: Wed, 7 Mar 2001 04:56:28 +0100

Hi Nicola,

> Does this patch look right to you ?

Absolutely, and it works for all I've tested.

> ...but I
> think the macos-x doc for NSBezierPath says that we should not draw the
> line in NSBezierPath.  I need to look at it - but if the backend is using
> NSBezierPath to draw the arc, then what we need to do is adding the line
> in the backend before it draws the arc using NSBezierPath.

The macos-x doc doesn't say too much, but as far as I interpret the design of  
NSBezierPath it was designed with the PostScript architecture in mind (eg the  
arc command has the same weird parameters as PostScript has for arcs).
Without the line segment, the parameters would be extremely overdetermined (eg  
center and angle would be enough).

> To add to the confusion, the macos-x doc for NSBezier path says that the
> `clockwise' argument determines whether angles are measured clockwise or
> counterclockwise, while postscript operators and common sense push us to

I have interpreted 'angle' as the angle between the start angle and the end  
angle, so I have never seen any conflicts in the descriptions :-)

> I won't bother you with the explanation of why I don't like this
> prescription at all (but eg :-), try drawing an arc between angles 0 and
> -{a little number} (such as -0.1) using arc - the result will be either a
> full circle or nothing depending on how little the number is - on my
> system -0.001 generates a full circle, while -0.0001 generates nothing -
> it is the hardware which determines whether your arc command draws a full
> circle or nothing...)

On OpenStep this created a circle, even with -0.00000000000000001.
With ghostscript I have the same results as you have.


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