[mapserver-dev] Canvas support for MapServer

[Brent Fraser]

Jan,

  My interest is in building a (or re-purposing an existing) tool for Cartographic Layout, for printing or rendering a graphics format for easy viewing (e.g. PDF).  Steve's comments were about using existing Web formats and syntax to describe the layout, and existing(?) web editors to do the placement/moving of the layout components.

  My (very limited) understanding of the <canvas> HTML tag is that it's a "container" recognized by the browser, and vector (and raster) graphics are rendered into it using client-side JavaScript.  Sort of the JavaScript equivalent of the SVG format.

  It would be possible to add another output format to Mapserver to generate JavaScript code of canvas rendering methods, but a more elegant approach might be to write a small(?) JavaScript module to ingest Mapserver's SVG and render the objects to the canvas.

  Are there some specific features of the direct-canvas-output approach not available in SVG that you need?

Brent Fraser


Jan Hartmann wrote:
> Hi folks,
> 
> A few weeks ago I suggested in a thread about PDF support that Mapserver 
> could perhaps be made to support the new "Canvas" tag. There were no 
> reactions to this, so I don't know if this suggestion is 
> viable/advisable/practicable, or just downright stupid. Can anyone 
> comment?  
> 
> (from 
> http://lists.osgeo.org/pipermail/mapserver-dev/2009-January/008055.html)
> 
>> I am wondering if MapServer support for the "Canvas" tag could do what 
>> Steve suggests in a more simple way. Originally, only Safari, Opera 
>> and Firefox supported this tag to allow (simple) 2D drawing, but 
>> recently a surprisingly simple Javascript interface for IE has become 
>> available, translating Canvas command to native IE VRML commands. It 
>> requires just one single script tag in the web page.
>>
>> See the tutorial at the Mozilla site at: 
>> https://developer.mozilla.org/en/Canvas_tutorial
>> and the IE interface (from the Google stables) at: 
>> http://excanvas.sourceforge.net/
>>
>> This is something I have long been looking for. The graphics are very 
>> simple, so the functionality is nothing like PDF or SVG, but I could 
>> imagine that a driver for MapServer could fulfill many needs. I can 
>> use it already by letting Mapserver generate raw coordinates and 
>> catching them with some sort of Ajax, but a separate driver would be 
>> very neat of course.
>>
>> How about it?
>>
>> Jan
>>
>>
> 
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