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August 2005

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2005.08.03 09:27 "Overlay Hyperlinks On TIFF", by Chux Amobi
2005.08.03 15:27 "Re: Overlay Hyperlinks On TIFF", by Bob Friesenhahn
2005.08.08 11:02 "Re: Overlay Hyperlinks On TIFF", by Rob Tillaart
2005.08.08 11:32 "Re: Overlay Hyperlinks On TIFF", by Joris Van Damme
2005.08.08 13:55 "Re: Overlay Hyperlinks On TIFF", by Rob Tillaart
2005.08.08 15:01 "Re: Overlay Hyperlinks On TIFF", by Joris Van Damme
2005.08.08 15:18 "Re: Overlay Hyperlinks On TIFF", by Joris Van Damme
2005.08.09 06:33 "Re: Overlay Hyperlinks On TIFF", by Rob Tillaart
2005.08.09 08:45 "Re: Overlay Hyperlinks On TIFF", by Joris Van Damme
2005.08.09 10:16 "Re: Overlay Hyperlinks On TIFF", by Rob Tillaart
2005.08.09 10:29 "Re: Overlay Hyperlinks On TIFF", by Joris Van Damme
2005.08.09 15:20 "Re: Overlay Hyperlinks On TIFF", by Bob Friesenhahn
2005.08.09 15:36 "Re: Overlay Hyperlinks On TIFF", by Joris Van Damme
2005.08.08 11:43 "Re: Overlay Hyperlinks On TIFF", by Joris Van Damme

2005.08.09 06:33 "Re: Overlay Hyperlinks On TIFF", by Rob Tillaart

Joris wrote:
> The region type value can be either of
> 0: the width and height values are meaningfull, the clickable area is a
> rectangle
> 1-65534: the width and height values are to be ignored. Instead, this value
> describes are radius, and x and y describe the center point of a circular
> region. This type of region should not be included if XResolution and
> YResolution tags are in the IFD and have different values, since pixels in that
> case are not rectangular and a radius in pixels does not make sense.
> 65535: the widht and height values are to be ignored. Instead, after all regular
> rectangular regions (region type = 0) and circular regions (region type 1 to
> 65534) have been checked, and no region is found to comply, the x and y of this
> type of region that is nearest is said to be clicked. Again this type of region
> should not be included if XResolution is different from YResolution.

some refactoring :)

regiontype:	name        description
--------------------------------------
0000:         [rectangle] the width and height values are just that
0001:         [ellipse]   the width and heigth values are the lengths 
                          of the axis of the ellipse.
                          For circles they are identical
                          Note that if the X-Y res differs one still can 
                          define perfect circles 
FFFF:         [nearest]   see above 65535

This scheme include ellipses and leaves room for 60000+ other shapes and/or 
attributes. The [not] and [doubleclick] are region attributes: E.g. the
[not rectangle] is the complement area of [rectangle]. all area outside the 
rectangle.

> It can happend that multiple regions apply (either rectangular or circular, it
> cannot happen that more regions of type 65535 apply, except if these regions
> have identical x and y values). This case is undefined, and application code can
> de whatever it wants with this. Writers should avoid writing clickable area data
> with overlapping regions because the behavious in such case is not defined.

What to think about a 'nearest point with attracting factor' region type? 
define a number of points with a different charge. Gravity. Automatically 
creates area's. The ultimate region type is the polygon I guess.

> Just for the fun of it, though... ;-)

fun is the grandmother of creativity !



regards,
rob