[plt-scheme] image.ss: (line ...) only draws to the SouthEast

From: Robby Findler (robby at cs.uchicago.edu)
Date: Sun Feb 19 11:05:50 EST 2006

That was an oversight. I've added the ability to make lines going in
all four directions (in svn).


At Sat, 18 Feb 2006 20:12:27 -0500, Felix Klock's PLT scheme proxy wrote:
> While playing around with images today, I realized that the given  
> implementation of the LINE function in image.ss calls error when  
> given negative values for the x or y parameters.
> This implies that you can only pass non-negative values for x and y,  
> which in turn implies that the LINE function can't draw lines that go  
> "SouthWest."  You can manipulate the pinholes to get lines that go  
> NorthWest, but SouthWest and NorthEast are impossible with LINE.
> ADD-LINE is capable of drawing lines in any direction, but wouldn't  
> it be good to fix LINE so that it does handle negative x or y (and  
> keeps the pinhole at the origin)?  Or is there some reason for  
> requiring non-negative values that I'm not seeing?
> -Felix
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