Export Web Map Set Scale

Question

I've built a tool that uses the export web map gp service and I've got a text input that allows the user to set the scale of the print out e.g. the current map scale may be 1:100,000, but they can set the text to say 1:50,000 and the printout will be at that scale rather than 1:100,000.

I can't get this to work. What I thought I'd to is set the scale to whatevers in the text input then set it back after the export web map process has finished, but doesn't seem to work. I think it's because I have to wait till the scale has changed, so I'm using this:

https://developers.arcgis.com/en/javascript/jsapi/map.html#setscale

which is this for me 
map.setScale($("#mapScale").val());

How to I add a listener for when the scale has changed. Or is there a better way to do this? by just sending the scale to the export web map task or something?

Cheers 🙂

VinayBansal · Answer

You can also create your json and pass the scale in map options as shown in the specification and call rest api
http://resources.arcgis.com/en/help/main/10.1/index.html#//0154000004w8000000

Regards,
Vinay Bansal

TimCollyer · Answer

Here is some code. Testing

TimCollyer · Answer

I haven't done this, but it seems like using esri.geometry.getExtentForScale (https://developers.arcgis.com/en/javascript/jsapi/namespace_geometry.html#getextentforscale) to determine the extent, then using that extent to construct the bbox parameter for the "export" call on your map service should work?

http://services.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer/export?bbox=-43761126.8422267%2C-27462691.4120116%2C43761126.8422267%2C27462691.4120115&bboxSR=&layers=&layerdefs=&size=&imageSR=&format=png&transparent=false&dpi=&time=&layerTimeOptions=&f=image