Opened 19 years ago
Closed 17 years ago
#1007 closed defect (fixed)
WMS GetLegendGraphic and out of scale layers (or empty legends)
Reported by: | dmorissette | Owned by: | mapserverbugs |
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Priority: | high | Milestone: | 5.0 release |
Component: | WMS Server | Version: | 4.3 |
Severity: | normal | Keywords: | |
Cc: | silke@…, bartvde@…, valik.solorzano.barboza@… |
Description (last modified by )
In bug 1006 and bug 809 we have run into the following situations: - In bug 1006, an exception could be returned (GD error) if the specified layer doesn't contain at least one class with a name. (Unable to create in a legend image of 0 pixels high). - In bug 809 it was reported that the GetLegendGraphic SCALE parameter should not result in an empty legend. Bart copied the following to bug 1006: > Also, here is a response from Craig Bruce from Cubewerx on the wms-dev list > (Sept 2004). What the Cubewerx server does is also an option I guess: > > "The legend/scale determination can be done by the client. It can examine > the rules to determine if a layer/rule shows anything or not. However, > if a GetLegendGraphic request is actually sent to a server for a layer > that will display nothing because of scale rules, then we can assume that > the client is not entirely smart enough to filter it out and that it is > probably expecting to receive back and display an image. The best thing > for the server to do is to return an image that somehow indicates that > you will see nothing on the map for the layer/rule. CubeWerx returns a > small image with the letters "N/A" painted into it." I'm thinking of solving both issues at once by modifying msDrawLegend() to generate a small image with the letters "N/A" in it when the legend would have been empty. This change would also impact on the CGI, but shouldn't create any bad side-effect for anyone since the current situation is a fatal error in this case.
Change History (5)
comment:2 by , 19 years ago
Cc: | added |
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comment:5 by , 17 years ago
Description: | modified (diff) |
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Resolution: | → fixed |
Status: | new → closed |
I did a few more tests with the current 5.0 code in SVN, and GetLegendGraphic requests that result in an empty legend now produce a small empty image of about 35x5 pixels. The actual size may vary depending on KEYSIZE setting in legend.
Anyway, this seems like an acceptable behavior to me. I have also verified that versions 4.8 and 4.10 also did the same (I don't have any older build to check).
Closing as fixed.
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