Hi André, Effectively, 600² is not too much for JS. But to get this array from JS, I have to use a XMLHTTP request to the server. The server response will be a text stream send to JS. The size of the text stream will be : - for 8bits images : 600 x 600 x (3 chars, to represent the lookup table index as text) = 1080000 bytes. So 1 MB to transfert.... - for 24bits images : 600 x 600 x 3 (for RGB values) x (3 chars for each color value) = 3240000 bytes. So 3 MB to transfert... Perhaps can I use another kind of stream ?? Nicolas
_____ De : [email protected] [mailto:[EMAIL PROTECTED] De la part de Andre M. Winter - Carto.net Envoyé : mercredi 22 juin 2005 14:22 À : [email protected] Objet : Re: [svg-developers] Re: Value of a pixel hi nicolas, you should be able to place the color value (or whatever value) info per px in a 2-dim js-array and access this on mousemove based on some returned screen coords. 600² is a lot but not too much for js. andré -- ___________________________________________________________________ andre m. winter, cartography for internet and multimedia applications schiessstand 4/1, a6091 goetzens, tyrol, austria tel.: ++43.5234.32732 email: <[EMAIL PROTECTED]> <http://www.vectoreal.com/> SVG consulting and development <http://www.carto.net/> online cartography focusing on SVG <http://www.carto.at/> print and online touristic map solutions >Hi Holger, Andreas, and all > >In fact, I allready use MapServer to produce the map which is displayed >using SVG (as background of a map with some vector layers send using XMLHTTP >and a simplified GML-like format parsed in javascript). >The raster layer is used to display thematic products and my goal is to move >a client side cursor on legend when I move the mouse over the image. For >this reason, I can't send a request to the server at each mouse move. >Images should have a size of 600x600 pixels. I can't use the method >described by Holger because of the size of data to transfert. >Another solution should be to vectorize the image before send to SVG. But >images are too complex and the XML (using GML or SVG format) of the image >may be too big to download. This solution requires also too server-side >ressources. > >So... I think there is no way using javascript... Perhaps using an ActiveX >control (I'm on IE), but I'm also in a wide Extranet and I can't force the >installation of it. > >Thanks a lot for your response. > > _____ > >De : [email protected] [mailto:[EMAIL PROTECTED] >De la part de Andreas Neumann >Envoyé : mardi 21 juin 2005 18:30 >À : [email protected] >Objet : [svg-developers] Re: Value of a pixel > > >Currently, until SVG 1.2 (or 2.0?) provides this function I would use a >webserver for that >purpose. > >For geo/carto data there is the UMN mapserver who can send back pixel >values. The >requests can be sent through a URL. (see >http://mapserver.gis.umn.edu/doc44/raster- >howto.html#query) - mapserver can also do more complex raster queries than >just simple >pixel values. > >The idea that Holger proposes might be possible, but likely to be >complicated to >implement and slow, because javascript is not very fast for things like >image-processing. > >Andreas > >--- In [email protected], "Nicolas BOUTET" <[EMAIL PROTECTED]> >wrote: > > >>Hi, >> >>does someone know if it's possible (and how), using ECMAScript, to get the >>RGB value (or LookUpTable index) of a pixel (using X,Y coordinates) of an >>image item. >> >>Thanks >> >>Nicolas >> >> >>[Non-text portions of this message have been removed] >> >> > > > > >----- >To unsubscribe send a message to: [EMAIL PROTECTED] >-or- >visit http://groups.yahoo.com/group/svg-developers and click "edit my >membership" >---- > > > > _____ > >Yahoo! Groups Links > > >* To visit your group on the web, go to: >http://groups.yahoo.com/group/svg-developers/ > > >* To unsubscribe from this group, send an email to: >[EMAIL PROTECTED] ><mailto:[EMAIL PROTECTED]> > > >* Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service ><http://docs.yahoo.com/info/terms/> . > > > > >[Non-text portions of this message have been removed] > > > >----- >To unsubscribe send a message to: [EMAIL PROTECTED] >-or- >visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" >---- >Yahoo! Groups Links > > > > > > > > ----- To unsubscribe send a message to: [EMAIL PROTECTED] -or- visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" ---- _____ Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/svg-developers/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> * Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> . [Non-text portions of this message have been removed] ----- To unsubscribe send a message to: [EMAIL PROTECTED] -or- visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" ---- Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/svg-developers/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
