Re: Iterator

I am trying to make a series of sprites using an RSS feed. What I want to do is make n sprites where n is the number of items in the RSS feed. I used an iterator (set to iterate by the number of items in the RSS structure) to render the right number of sprites in different positions with different colours.

the problem that I have got is that when I put the text rendering stuff in the iterator, the animation runs quite slowly. I assume that this is because the text is rendering every frame, whereas it appears to render at the beginning of the animation only if the image with string is not in the iterator.

You're assumption is correct. I looked at the composition and the big problem is that the Image With String patch is generating an image from a string that changes for every iteration loop.

You can boost performance quite a bit by making sure the image has a fixed size instead of depending on the amount of text. I go from 8 to 20FPS if I set the Image Width and Image Height to a constant 1.0.

It's still very unoptimized at that point, as the composition is still drawing 10 fairly long texts per frame, but it's pretty much as far as you can go with the iterator approach.

So my question is how do I render an arbitrary number of text images without using the iterator, or is there any way of putting them in, but making sure that they are rendered only when the content of the RSS feed changes?

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Pierre-Olivier Latour email@hidden

Quartz Composer Architect Graphic & Imaging Team

References:
	>Iterator (From: Andrew Kearney <email@hidden>)