add option for better render resolution ( code included)

[giko45]

Hi,
To get a better resolution in renderd images I usually change in the webshot.js file (system.file("webshot.js", package="webshot"))

the follwoing line
casper.start(url).viewport(opts.vwidth, opts.vheight);
to
casper.start(url).viewport(opts.vwidth, opts.vheight).zoom(2);

Could that be added as a option instead?

[wch]

Sounds like a good idea. It would also be nice to do HiDPI (Retina-resolution) screenshots (i.e. with a window.devicePixelRatio) which could differ from a zoomed screenshot because a page may load different, higher-res images when it thinks it's rendering on a HiDPI device.

[giko45]

Hi,

I checked the code you checked and noticed that you also changed the viewport. I only did use casper.start(url).viewport(opts.vwidth, opts.vheight).zoom(2) without changeing the viewport.

Wy is the change in viewport needed. Does that not lead to changed fontsizes etc?

[wch]

Maybe we have a different understanding of what the zoom is supposed to do, but without changing the viewport, the "virtual" viewport size changes when you zoom, so the end result can have a very different layout.

For example, here's the R homepage taken with no zoom:

Here it is with zoom=2, but no changing of the viewport. The pixel dimensions are the same but the layout changes:

Here it is with zoom=2 and a doubling of the viewport (you may need to open this in a new window to see how it differs from the first image: