MapServer
Undocumented WEB EXTENT keyword
Currently, there is no mention of EXTENT at https://mapserver.org/mapfile/web.html
It is read at:
https://github.com/MapServer/MapServer/blob/1dd7b072be5aa307d9dcb120dd2fa7f3f0dd041b/mapfile.c#L5746
It is written out to the Mapfile at:
https://github.com/MapServer/MapServer/blob/1dd7b072be5aa307d9dcb120dd2fa7f3f0dd041b/mapfile.c#L5678
From the MapScript docs and mapserver.h comments it is used as the clipping extent. I'm not sure what this actually means though.
Trying to see how this is used. I thought it might automatically clip data, for example hiding one of the points below.
However both are displayed when running mapserv QUERY_STRING="map=style_position.map&mode=map&layer=center" > temp.png
MAP
STATUS ON
EXTENT 0 0 400 300
SIZE 200 150
IMAGETYPE png24
symbolset "symbolset"
WEB
EXTENT 0 0 100 100
END
LAYER
NAME "center"
TYPE POINT
STATUS on
CLASS
STYLE
COLOR 0 0 255
SIZE 30
WIDTH 1
SYMBOL "circle"
END
END
FEATURE POINTS 50 50 END END
FEATURE POINTS 200 200 END END
END
END
Let me document what the code is actually doing and add it to the ticket. Originally the idea was to alter the computed extent. Not clipping so much as an offset, so if one panned too far to the west it would snap it back in bounds but he scale would be preserved. I don't recall the behavior if the requested extent contains the web extent - that might just leave it alone (that would make sense to me). A more interesting test with you example might be to set the map extent to -50 0 0 50...
--Steve
From: Seth G @.> Sent: Monday, March 8, 2021 3:56 PM To: MapServer/MapServer-documentation @.> Cc: Subscribed @.***> Subject: Re: [MapServer/MapServer-documentation] Undocumented WEB EXTENT keyword (#461)
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Trying to see how this is used. I thought it might automatically clip data, for example hiding one of the points below. However both are displayed when running mapserv QUERY_STRING="map=style_position.map&mode=map&layer=center" > temp.png
MAP
STATUS ON
EXTENT 0 0 400 300
SIZE 200 150
IMAGETYPE png24
symbolset "symbolset"
WEB
EXTENT 0 0 100 100
END
LAYER
NAME "center"
TYPE POINT
STATUS on
CLASS
STYLE
COLOR 0 0 255
SIZE 30
WIDTH 1
SYMBOL "circle"
END
END
FEATURE POINTS 50 50 END END
FEATURE POINTS 200 200 END END
END
END
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