Rendering Info Structure

FxFactory lets you designate one of the structure inputs of your Quartz composition to receive a Rendering Info Structure. This mapping is available under the Inputs section of the plug-in development UI.
The value fed to the selected input port is a dictionary with the following keys and values:

  • scaleX contains the current horizontal scaling factor used by the host
  • scaleY contains the current vertical scaling factor used by the host

The above information is useful because it allows the composition to know if the host is previewing the plug-in at reduced resolution, and it allows the composition to know exactly how much scaling has been performed.

Hosts will often preview a sequence at half- or quarter-resolution in order to provide faster feedback to the user. It may be necessary for your plug-in to take this scaling into consideration to ensure that the preview is consistent with the normal, unscaled output of the plug-in (i.e. when both scaleX and scaleY are equal to 1).

For your convenience, a Quartz Composer patch named “FxFactory Rendering Info” allows you to extract all values in the rendering info structure in one step: