/*

     File: FilteredImageView.m 

 Abstract: UIView subclass that renders a UIImage with a set of filters applied.

 The filters are requested from it's data source. 

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 */

#import "FilteredImageView.h"

@implementation FilteredImageView

@synthesize datasource;

@synthesize inputImage = _inputImage;

//

// Requests the list of filters from the data source and applies each filter

// in order to the _inputImage.

- (void)reloadData

{

    if (!_inputImage)

        return;

    // Create a CIImage from the _inputImage.  While UIImage has a property returning

    // a CIImage representation of it, there are cases where it will not work.  This is the

    // most compatible route.

    _filteredImage = [[CIImage alloc] initWithCGImage:_inputImage.CGImage options:nil];

    // Retrieve the list of CIFilters to apply from our datasource.

    NSArray *filters = [self.datasource filtersToApply];

    if (filters)

        // Iterate through each filter setting our CIImage as the input and re-assigning

        // the filter's output back to our CIImage.  This creates a chaining effect.

        for(CIFilter *filter in filters) {

            [filter setValue:_filteredImage forKey:@"inputImage"];

            // Certain filters place restrictions on their input values that we may not have accounted for

            // in the configuration method.  For example, CIColorCube requires its parameter to be a power

            // of 2.  In such as case, the filter will throw an exception when we ask it generate and image.

            // Catch the exception and pretend nothing happened thereby bypassing the filter.

            @try {

                _filteredImage = filter.outputImage;

            }

            @catch (NSException* e) { }

        }

    // Inform UIKit that we need to be redrawn.

    [self setNeedsDisplay];

}

- (void)drawRect:(CGRect)rect

{

    [super drawRect:rect];

    if (!_filteredImage)

        return;

    // This is the rect we'll draw our final image into.  By making it a bit smaller than our bounds

    // we'll get a nice border.

    CGRect innerBounds = CGRectMake(5, 5, self.bounds.size.width - 10, self.bounds.size.height - 10);

    // To display the image, convert it back to a UIImage and draw it in our rect.  UIImage takes

    // into account the orientation of an image when drawing which we would have needed to worry about

    // when drawing it directly with Core Image and Core Graphics calls.

    [[UIImage imageWithCIImage:_filteredImage] drawInRect:innerBounds];

}

- (void)setInputImage:(UIImage *)inputImage

{

    // Since Core Image filters must be operate on every pixel in an image, you may want to

    // consider resizing an input image to the view size before applying any filters.

    //

    _inputImage = inputImage;

    [self reloadData];

}

@end