TransitionSetup.m

/*
     File: TransitionSetup.m
 Abstract: Category for the TransitionSelectorView that 
 gathers all transitions and sets them up for
 rendering.
  Version: 1.2
 
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#import "TransitionSelectorView.h"
 
 
@implementation TransitionSelectorView (TransitionSetup)
 
- (void)setupTransitions
{
    CIVector  *extent;
    int        i;
 
 
    if(!transitions)
    {
        // get all the transition filters
        NSArray *foundTransitions = [CIFilter filterNamesInCategories:[NSArray arrayWithObject:kCICategoryTransition]];
        
        if(!foundTransitions)
            return;
        i = [foundTransitions count];
 
        extent = [CIVector vectorWithX: 0  Y: 0  Z: thumbnailWidth  W: thumbnailHeight];
        transitions = [[NSMutableArray alloc] initWithCapacity:i];
        while(--i >= 0)
        {
            CIFilter    *theTransition = [CIFilter filterWithName:[foundTransitions objectAtIndex:i]];      // create the filter
            
            [theTransition setDefaults];    // initialize the filter with its defaults, as we might not set every value ourself
 
            // setup environment maps and other static parameters of the filters
            NSArray     *filterKeys = [theTransition inputKeys];
            NSDictionary    *filterAttributes = [theTransition attributes];
            if(filterKeys)
            {
                NSEnumerator    *enumerator = [filterKeys objectEnumerator];
                NSString        *currentKey;
                NSDictionary    *currentInputAttributes;
                
                while(currentKey = [enumerator nextObject]) 
                {
                    if([currentKey compare:@"inputExtent"] == NSOrderedSame)            // set the rendering extent to the size of the thumbnail
                        [theTransition setValue:extent forKey:currentKey];
                    else {
                        currentInputAttributes = [filterAttributes objectForKey:currentKey];
                        
                        NSString            *classType = [currentInputAttributes objectForKey:kCIAttributeClass];
                        
                        if([classType compare:@"CIImage"] == NSOrderedSame)
                        {
                            if([currentKey compare:@"inputShadingImage"] == NSOrderedSame)  // if there is a shading image, use our shading image
                                [theTransition setValue:[self shadingImage] forKey:currentKey];
                            else if ([currentKey compare:@"inputBacksideImage"] == NSOrderedSame)   // this is for the page curl transition
                                [theTransition setValue:[self sourceImage] forKey:currentKey];
                            else 
                                [theTransition setValue:[self maskImage] forKey:currentKey];
                        }
                    }
                }
            }
            [transitions addObject:theTransition];
        }
    }
}
 
@end