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From: Willem <willem@toad.stack.nl>
Newsgroups: alt.comp.lang.borland-delphi,comp.lang.c,comp.lang.java.programmer
Subject: Re: names for parameters of ranges (was: ...)
Date: Wed, 23 May 2012 09:43:36 +0000 (UTC)
Organization: Stack Usenet News Service
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Xref: csiph.com comp.lang.c:21228 comp.lang.java.programmer:14750

Stefan Ram wrote:
)   Yes. But it is not only Java, it also is English used for
)   mnemonic identifiers. And in English, phrases like ?from
)   index? and ?to index? have a meaning.
)
)   So, if one would name a parameter ?maximum? and then specify
)   this to mean the maximum plus 1, it would be a bad name.
)
)   For example, we can read:
)
)       ?The left and right edges of the rectangle are at x and x + width.
)       The top and bottom edges are at y and y + height.?
)
) http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics.html#drawRect(int, int, int, int)
)
)   Now, let's take this ?width? to be 1, and x to be 3,
)   y = 5, height = 3, we have the following rectangle
)   drawn according to the documentation:
)
) 9
) 8  ##
) 7  ##
) 6  ##
) 5  ##
) 4
) 3
) 2
) 1
) 0123456789
)
)   When one looks at this rectangle, would one say that its
)   width was 1 and its height was 3? Yet this is the way the
)   parameters are named!

One would, if one were to define a 'line' to be centered on the pixel.
You seem to define it to be on the edge of the pixel.  Both are plausible.

Look at this, for example:
10
9 +---+---+
8 |   |   |  
7 |   |   |  
6 |   |   |  
5 +---+---+
4 |   |   |  
3 |   |   |  
2 |   |   |  
1 +---+---+
0
 0123456789

Is it four 4x4 rectangles that together form an 8x8 rectangle,
or is it four 5x5 rectangles that form a 9x9 rectangle?
The latter would be odd, given that 5+5=10 (and not 9).

And once you get into transforming coordinates, anti-aliasing
and whatnot, your definition falls flat on its face.


SaSW, Willem
-- 
Disclaimer: I am in no way responsible for any of the statements
            made in the above text. For all I know I might be
            drugged or something..
            No I'm not paranoid. You all think I'm paranoid, don't you !
#EOT