Standard version: 1.5

Major Change

(sept 23, 2016): This to be co-addressed with Spatial Formats are broken

Generators, as conceived, are not very good. They need to be broken into two types…..

• generators that determine their own formats, e.g. a file reading plug-in
• generators that leave format determination to the host application, eg: a spatial noise generator that can make noise anywhere on the image plane.

Unfortunately there is probably some degree of interplay between what a plug-in might want to produce and what a host can accept. This needs to be thought about, but can almost certainly accommodated with a careful use of the get RoD/spatial format/data format calls.

This goes hand in hand with fixing the broken spatial format. 

The generator context needs to advertise if it determines its own pixel and spatial format (eg: an image file reader), or should be told what pixel and spatial format it should produce. To do that it needs a new property on the effect descriptor...

• kOfxImageEffectPropGeneratorType - a string property that takes one of two values...
• kOfxImageEffectGeneratorFormatMaster
• kOfxImageEffectGeneratorFormatSlave

A generator of type kOfxImageEffectGeneratorFormatMaster will have the kOfxImageEffectActionGetImageFormat action called to determine the format of the clip being created, while a kOfxImageEffectGeneratorFormatSlave will not. A slave will have the format determined for it by the host and the relevant properties available on the output clip.

In both cases all the other calls are standard, eg: the get region of definition call. 

Note, a generator plugin may be asked to render a region that is not congruent to the output format, as with all other effect types.