[mapserver-users] GEOMTRANSFORM LABELPNT example
Brent Fraser
bfraser at geoanalytic.com
Sun Dec 11 19:10:52 EST 2011
Ian,
Using the "standard" capabilities of a POINT layer wouldn't work?
Best Regards,
Brent Fraser
On 12/11/2011 3:06 PM, Ian Walberg wrote:
>
> Brent,
>
> Ok, we had been using an earlier version of the mapserver
> documentation we had downloaded which had the text below.
>
> The latest version now describes the discussed functionally more closely.
>
> We had been looking at using the previous functionally to draw and
> rotate a symbol around the label text. Not what we are thinking but
> this could be used for something like displaying the wind speed and
> symbol rotated for the wind direction using a symbol around the outside.
>
> To do this it sounds like a new GEOMTRANSFORM type.
>
> Thanks
>
> Ian
>
> STYLE The start of a STYLE object.
>
> Label specific mechanisms of the STYLE object are the GEOMTRANSFORM
> options:
>
> GEOMTRANSFORM [labelpnt|labelpoly] Creates geometries that can be used
> for styling the label.
>
> . labelpnt generates a point with its center at the middle of the
> bounding rectangle of the text.
>
> . labelpoly generates the bounding rectangle for the text, with 1
> pixel of padding added in all directions.
>
> The resulting geometries can be styled using the mechanisms available
> in the STYLE object.
>
> New in version 6.0.
>
> *From:*Brent Fraser [mailto:bfraser at geoanalytic.com]
> *Sent:* Sunday, December 11, 2011 1:52 PM
> *To:* Ian Walberg
> *Cc:* mapserver-users at lists.osgeo.org
> *Subject:* Re: [mapserver-users] GEOMTRANSFORM LABELPNT example
>
> Ian,
>
> No, there is no ability to do that, unless you use POSITION CC.
> There had been some discussion several months ago to add functions to
> the GEOMTRANSFORM resulting in RFC 72
> (http://www.mapserver.org/development/rfc/ms-rfc-72.html)
>
> I think something like
>
> GEOMTRANSFORM (getCentroid(labelpoly))
>
> would be a good addition, but I don't have a specific use-case. What
> were you planning to do the center of the label polygon?
>
> Best Regards,
> Brent Fraser
>
>
> On 12/11/2011 2:18 PM, Ian Walberg wrote:
>
> So is it expected that labelpnt generates a point with its center at the middle of the bounding rectangle of the text?
>
> Thanks
>
> Ian
>
>
> -----Original Message-----
> From:mapserver-users-bounces at lists.osgeo.org <mailto:mapserver-users-bounces at lists.osgeo.org> [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Brent Fraser
> Sent: Sunday, December 11, 2011 1:02 PM
> To: thomas bonfort
> Cc:mapserver-users at lists.osgeo.org <mailto:mapserver-users at lists.osgeo.org>
> Subject: Re: [mapserver-users] GEOMTRANSFORM LABELPNT example
>
> Thomas,
>
> I tracked it down to the LABELCACHE setting.
>
> LABELCACHE ON gives the expected results LABELCACHE OFF gives my old blue-dot-on-the-left results.
>
> See attached PDFs.
>
> Best Regards,
> Brent Fraser
>
>
> On 12/11/2011 1:05 PM, thomas bonfort wrote:
>
> There might have been a bug in the initial implementation. trying it
>
> out with current trunk gives me the expected result, unless I'm
>
> missing something.
>
>
>
>
>
> On Sun, Dec 11, 2011 at 20:44, Brent Fraser<bfraser at geoanalytic.com> <mailto:bfraser at geoanalytic.com> wrote:
>
> Thomas,
>
> See comments below.
>
>
>
> Best Regards,
>
> Brent Fraser
>
>
>
>
>
>
>
> On 12/11/2011 12:26 PM, thomas bonfort wrote:
>
> I think this is all expected behavior, although the documentation
>
> may be incorrect.
>
>
>
> LABELPNT draws a marker on the geographic position the label is
>
> attached to. This corresponds to the center of the label text only
>
> if the label is in position CC.
>
> I think that is what is intended but my original test case (using CC
>
> ) resulted in the LABELPNT rendered on the left side of the
>
> labelpoly, seehttp://lists.osgeo.org/pipermail/mapserver-dev/attachments/20110526/47c9bc8c/labelpnt-0001.png.
>
> I had expected it to be coincident with the yellow circle and green cross.
>
>
>
>
>
> To draw a label at the center of the label text, another
>
> geomtransform would have to be implemented, named e.g. LABELBBOXCENTROID.
>
> or maybe
>
>
>
> GEOMTRANSFORM (centroid([LABELPOLY]))
>
>
>
>
>
> regards,
>
> thomas
>
>
>
> On Sun, Dec 11, 2011 at 19:34, Brent Fraser<bfraser at geoanalytic.com> <mailto:bfraser at geoanalytic.com>
>
> wrote:
>
> Hey Jeff,
>
>
>
> I've been looking into this too (not finished yet). I'm using
>
> v6.0.1 and can reproduce my original results (blue dot to the left)
>
> AND Ian's (grey dot coincident with white dot). Very strange. My
>
> shapefile dataset gets reprojected from geographic to UTM, so that
>
> may be causing the difference.
>
> I need to look into that...
>
>
>
> Best Regards,
>
> Brent Fraser
>
>
>
>
>
>
>
> On 12/11/2011 10:57 AM, Jeff McKenna wrote:
>
> On 11-12-11 11:20 AM, Ian Walberg wrote:
>
> Here is the map file we are using ms4w 3.0.3.
>
>
>
> We thought the larger grey circle should be drawn in the center
>
> of the label text.
>
>
>
> What have we done wrong?
>
>
>
>
>
> I have done some testing on this on Windows, with MapServer trunk
>
> (6.1-dev), here are my findings:
>
>
>
> - I used Brent's original example styles (from
>
>
>
> http://osgeo-org.1803224.n2.nabble.com/GEOMTRANSFORM-labelpnt-location-td6408065.html)
>
> with Ian's FEATURE layer --> Brent's "Blue Dot" LABELPNT with POSITION
>
> CC is
>
> now correctly placed in the center of the label text (so it seems
>
> this has been fixed in the code, but I can't find the ticket that
>
> says that)
>
> - If I change to POSITION LR (as in Ian's example layer) then I
>
> get Ian's issue (LABELPNT is placed at the geometry location, not
>
> in the center of the label text
>
> - but this is now an issue of understanding the developer's logic
>
> (from that thread SteveL says "Let me ponder this and get back to
>
> you. I think it makes sense to use the label point geotransform
>
> only with position CC so that it matches actual shape location.")
>
>
>
> That's all I know at this point (ha pun).
>
>
>
> -jeff
>
>
>
>
>
>
>
>
>
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