Display raster at 'actual' size

[Martijn van Exel]

Hello, dear mappers,

I'm trying to accomplish the following:
* Have user upload a polygon as a SHP file
* Return a map with a topographic background (raster file) and the poly as a
layer on top of this.

I use ASP.NET and the C# implementation of MapScript to accomplish this in a
simple web interface.
All works well, BUT for one thing:

The output should be at a *calculated* scale, such that that the raster
background is always displayed at its 'native' size. And ideally it should
output at 300DPI to be suitable for printing.

The current method I employ is:
* Init MapObj with a mapfile that has the background raster file
* Read in SHP as a ShapeObj and add to the map.
* Get the extent of the ShapeObj
* Add a margin
* Use this extent to set the map.width and map.height
* Draw.

But I don't want to set the w/h and calculate the scale, what I want to do
is SET the scale and have the W/H calculated. Is this an option? And how
about outputting @ 300DPI? I know at least tiff supports internal
resolution.

Thanks a bundle.

Met vriendelijke groeten, 
Bridgis B.V. 
  
Martijn van Exel 
Manager Data Service Centre 
  
Sint Walburgkerkpad 3 
4001 MG  Tiel 
T (0344) 63 62 42 
M (06) 534 75 786 
   
*Kijk op onze vernieuwde website www.bridgis.nl*