Re: Issues with CIFilters and CALayers
Re: Issues with CIFilters and CALayers
- Subject: Re: Issues with CIFilters and CALayers
- From: Gordon Apple <email@hidden>
- Date: Mon, 24 Feb 2014 11:28:55 -0600
- Thread-topic: Issues with CIFilters and CALayers
Apparently, my comment about not understanding this construct for
setValueForKeyPath was correct. It actually works. I finally got the
highlighting filter to work and update properly. Now I¹m trying to do
something much simpler, i.e., construct a freezeFilter. Nothing I¹ve tried
so far works. Apparently, a CIFilter is expected to be stateless function
such as outputImage = f(inputImage, parameters). Not accepting this premiss,
I decided to try caching the first output image ( from the outputImage
method), then return the cashed image thereafter, an ultra simple concept,
except that it does not work. Any reason, besides what I postulated, why
this shouldn¹t work?
On 2/23/14 3:06 PM, "Gordon Apple" <email@hidden> wrote:
> We have run into a number is issues trying to use CIFilters with CALayers:
>
> 1. When a layer is hidden, its filters, especially background filters, should
> be temporarily removed, or at least bypassed. Hiding the layer should make if
> effectively non-existent in the displayed layer stack.
>
> 2. The docs should tell you that in a CIFilter you cannot auto-synthesize
> filter input parameters. This simply does not work, especially for inputImage.
>
> 3. The docs for CALayer filters and background filters say you should name
> your filters for use in changing parameters. I.e., filter.name = @²myFilter².
> Amazingly, this works, in spite of the fact that there is no public property
> called ³name² for a CIFilter.
>
> 4. The example keyPath makes no sense whatsoever, unless we just don¹t
> understand keyPaths:
>
> [layer setValue:XXX forKeyPath:@²backgroundFilters.myFilter.filterParam²];
>
> backgroundFilters is an array of filters. myFilter is a property value of some
> element of the array. (huh?)
>
> 5. We need some decent documentation of what in GL Shading Language is
> actually relevant to writing ciKernels, besides the one page addendum
> provided.
>
> 6. And, of course, the problem we have already mentioned in a previous post
> about getting a CALayer to update when a filter parameter is changed.
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