Handlers for reading/writing image density info in PNG/JPEG?

Trevor DeVore lists at mangomultimedia.com
Thu Jun 12 13:16:15 EDT 2014

Hi everyone,

Now that LiveCode has high-dpi support we can create images using export
snapshot whose physical pixels dimensions are not the dimensions the image
should be displayed at. For example, on an OS X retina computer with a
screen pixel scale of 2 you could create an image that has 600x300 pixels
of data but should be displayed at 300x150.

Currently the engine does not provide a way to embed the pixel density
information in the PNG/JPEG files that it can create. In addition, the
engine cannot read pixel density information from images on the clipboard.
This means we can't determine what dimensions the clipboard image should be
displayed at.

I'm wondering if anybody has already created handlers for reading and
writing pixel density information to JPEG and PNG data that they would be
willing to share?

If not I'll take a look at the file formats and come up with something but
if someone already did this that would be great.


Trevor DeVore
Blue Mango Learning Systems
www.screensteps.com    -    www.clarify-it.com

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