Text positioning


We have been doing alot of GIS to SVG work and have been having a great deal of trouble with point symbolisation.  Due to the fact that I cannot manipulate the markers defined in the defs section via javascript we have had to find a better way to dynamically place and resize "point" symbols (eg we resize programatically when the changes the scale (eg zooms) to maintain the point symbol size, also we sometimes wish to change the colour of elements defined in the defs section, but cannot do it dynamically). To "work around" the marker issue we have defined " points" via the text element and CSS.  The major problem with the placement of text elements at a point is the difficulty in positioning the text centred on the point.  It is common to symbolise a point with a single TTF character and for the centre point of that character to be the exact location of the point.  In GIS we have the concept of a label point which can be as shown in the attached image (ie lower left, centre, upper right etc).  For example, this would give us the ability to place two pieces of text at the same point, one could be the symbol for the point with label point of "centre" and the other could be the name of the feature and have a label point of "upper left".  Currently I am having to use CSS to define a style such as: 
.BRIDGE {font-weight:bold;font-family:ftsymbols;fill:rgb(0,0,255);text-anchor:middle;baseline-shift:-0.35em;pointer-event:none;}
This does not place the text centred exactly on the point coordinate that defines it, this can cause confusion in complex maps.

We would be very grateful if this issue could be addressed either via allowing manipulation (via javascript etc) of elements defined in the <defs> section and/or by providing a text placement attribute on the text element.

Thank you.

Steve Harwin
GIS Developer
Forestry Tasmania
+61 3 62338197

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Received on Monday, 2 February 2004 17:46:19 UTC