specifying quality factor for jpg images

[fjhub]

I came across the ability to specify the jpeg quality factor when reading about PhantomJS and was wondering if node-phantom would be able to handle this capability. So I looked at the call to 'render' and noticed the only parameter to pageRender is the filename. Not knowing how much of this works, specifically to which function 'pageRender' really maps, I put in a test to see if I could add an additional argument for the quality value. Unfortunately I didn't see any variation in the resulting jpeg file. For what its worth, I'm using jsgui-node-render-svg which has the node-phantom dependency.

Is there any way of getting at the quality factor?

thanks

---

As I was cleaning up things from my test, I realized that bridge.js has the actual call to page.render() so I did another test to check for an additional argument and if present pass it along to page.render() and I got what I expected.

So I guess all this means is that it is currently not supported in this release…I can make my modifications available here if anyone so desires.

[markstos]

I'd be interested in a patch for this, thanks.

[fjhub]

There were 2 modifications I made to support a quality factor for jpeg images.

First, in node-phantom.js, I modified the render function in the case pageCreated' block from:

render:function(filename,callback){ request((socket,[id,'pageRender',filename],callbackOrDummy(callback)); },

to be:

render:function(filename,options,callback){ if(callback === undefined) { request(socket,[id,'pageRender',filename],callbackOrDummy(options)); } else { request(socket,[id,'pageRender',filename,options],callbackOrDummy(callback)); } },

Second, in bridge.js, I modified the case 'pageRender' block from:

case 'pageRender':
    page.render(request[3]);
    respond([id,cmdId,'pageRendered']);
    break;

to be:

case 'pageRender':
   if(request[4]!=undefined) {
       page.render(request[3], request[4]);
   } else {
       page.render(request[3]);
   }
   respond([id,cmdId,'pageRendered']);
   break;

and finally, in my call to page.render, I added the quality factor (which only makes sense with jpg images):

... page.render(imagePath, { quality: qualityFactor }, function (errRender) { ... });