AW: [udig-devel] How do I mark certain places on a map?

Thu, 26 Oct 2006 09:40:20 -0700

Jesse,
thank you very much for the hints. Shapefile (together with the SLD) seems to be the solution as I want the pin to stay the same size (instead of growing when zooming in).
I created the shapefile and the index file from a program and took an existing dbf file (originally belonging to another shapefile with the same number of features, as the ESRI specs don't have details about it). It looks fine.
 
  Michael
 
Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Jesse Eichar
Gesendet: Mittwoch, 25. Oktober 2006 17:31
An: User-friendly Desktop Internet GIS
Betreff: Re: [udig-devel] How do I mark certain places on a map?

One pretty good way (but not the only way) is to make a shapefile layer.  Just a normal point layer.  And you can add points to that layer.  To have the little pins show up you can create a SLD that uses your gif to represent the points.  This will allow all the pins to be persistent and you can have thousands.  Problems are that the image will stay the same size always,  or so I think.  I seem to remember a patch that allows the image to be scaleable but I don't remember if it is used by default of a hint of some sort needs to be added.  Benefits are that you have features to play with so can add a lot of information to the layer.

Another option is to use a MapGraphic.  A Map graphic is a very light weight layer such as scalebar.  It is quite easy to program as well.  A single draw(graphics2d) method that 

For more information on any of these points just give me a shout,

Jesse

PS and example of the SLD style you would need for the point layer is:

<?xml version="1.0" encoding="UTF-8"?>
<sld:StyledLayerDescriptor xmlns:sld="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:gml="http://www.opengis.net/gml" version="1.0.0">
    <sld:UserLayer>
        <sld:LayerFeatureConstraints>
            <sld:FeatureTypeConstraint/>
        </sld:LayerFeatureConstraints>
        <sld:UserStyle>
            <sld:Name>Hospitals by Continent</sld:Name>
            <sld:Title>Default Styler</sld:Title>
            <sld:Abstract></sld:Abstract>
            <sld:FeatureTypeStyle>
                <sld:Name>name</sld:Name>
                <sld:Title>title</sld:Title>
                <sld:Abstract>abstract</sld:Abstract>
                <sld:FeatureTypeName>bc_hospitals</sld:FeatureTypeName>
                <sld:SemanticTypeIdentifier>generic:geometry</sld:SemanticTypeIdentifier>
                <sld:Rule>
                    <sld:Name>name</sld:Name>
                    <sld:Title>title</sld:Title>
                    <sld:Abstract>Abstract</sld:Abstract>
                    <sld:PointSymbolizer>
                        <sld:Graphic>
                            <sld:ExternalGraphic>
                                <sld:OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href=""file:/C">file:/C:/house2.PNG"/>
                                <sld:Format>image/png</sld:Format>
                            </sld:ExternalGraphic>
                            <sld:Opacity>
                                <ogc:Literal>1.0</ogc:Literal>
                            </sld:Opacity>
                            <sld:Size>
                                <ogc:Literal>32</ogc:Literal>
                            </sld:Size>
                            <sld:Rotation>
                                <ogc:Literal>0.0</ogc:Literal>
                            </sld:Rotation>
                        </sld:Graphic>
                    </sld:PointSymbolizer>
                </sld:Rule>
            </sld:FeatureTypeStyle>
        </sld:UserStyle>
    </sld:UserLayer>
</sld:StyledLayerDescriptor>



On 25-Oct-06, at 2:12 AM, Schneider, Michael wrote:


Hello!

Using uDIG 1.1 RC4 I want to mark certain places on a map with a symbol, e.g. a pin. How can I do that (programmatically)?

To do so I currently use gif files (small ones showing a pin) and corresponding world files. Depending on the bounding box I calculate the size of the pin (the gif) and specify the values in the world file.

This works fine as long as no changes in the scale are done. Zooming in causes the pins to grow, zooming out the pins shrink. (While this is fine when marking areas this is not nice when you just want to mark a certain place).

Isn't there a better way to mark one or more places on a map?

Another problem occurred when I used my solution for more than about 40 pins on one map (each pin gif has a size of less than 1 KB): I get a Java Heap Space error!

This happens when I do it from my program (plugin) and it also happens when I use uDIG SDK in Eclipse 3.2.1 without any changes and import the pins using the catalog.

This also happens with less than the 40 pins mentioned above when I add let's say 20 pins, remove them from the project, and add them once again. This results in the same heap space error (indicated in the progress monitor).

I detected that behaviour when I tried to repaint the pins with new values in the worldfile after zooming in; but this error occures also when just adding, removing, and adding again the pins from the catalog with no additional plugins.

Any hints or help welcome. Thank you.

  Michael

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