/*

     File: ImageScrollView.m 

 Abstract: This scroll view allows the user to inspect the resulting image's levels of detail. 

  Version: 1.1 

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*/

#import "ImageScrollView.h"

#import "TiledImageView.h"

#import <QuartzCore/QuartzCore.h>

@implementation ImageScrollView;

@synthesize image, backTiledView;

- (void)dealloc {

    [frontTiledView release];

    self.backTiledView = nil;

    [backgroundImageView release];

    [image release];

    //--

    [super dealloc];

}

-(id)initWithFrame:(CGRect)frame image:(UIImage*)img {

    if((self = [super initWithFrame:frame])) {      

        // Set up the UIScrollView

        self.showsVerticalScrollIndicator = NO;

        self.showsHorizontalScrollIndicator = NO;

        self.bouncesZoom = YES;

        self.decelerationRate = UIScrollViewDecelerationRateFast;

        self.delegate = self;

        self.maximumZoomScale = 5.0f;

        self.minimumZoomScale = 0.25f;

        self.backgroundColor = [UIColor colorWithRed:0.4f green:0.2f blue:0.2f alpha:1.0f];

        // determine the size of the image

        self.image = img;

        CGRect imageRect = CGRectMake(0.0f,0.0f,CGImageGetWidth(image.CGImage),CGImageGetHeight(image.CGImage));

        imageScale = self.frame.size.width/imageRect.size.width;

        minimumScale = imageScale * 0.75f;

        NSLog(@"imageScale: %f",imageScale);

        imageRect.size = CGSizeMake(imageRect.size.width*imageScale, imageRect.size.height*imageScale);

        // Create a low res image representation of the image to display before the TiledImageView

        // renders its content.

        UIGraphicsBeginImageContext(imageRect.size);        

        CGContextRef context = UIGraphicsGetCurrentContext();       

        CGContextSaveGState(context);

        CGContextDrawImage(context, imageRect, image.CGImage);

        CGContextRestoreGState(context);        

        UIImage *backgroundImage = UIGraphicsGetImageFromCurrentImageContext();     

        UIGraphicsEndImageContext();        

        backgroundImageView = [[UIImageView alloc] initWithImage:backgroundImage];

        backgroundImageView.frame = imageRect;

        backgroundImageView.contentMode = UIViewContentModeScaleAspectFit;

        [self addSubview:backgroundImageView];

        [self sendSubviewToBack:backgroundImageView];

        // Create the TiledImageView based on the size of the image and scale it to fit the view.

        frontTiledView = [[TiledImageView alloc] initWithFrame:imageRect image:image scale:imageScale];

        [self addSubview:frontTiledView];

        [frontTiledView release];

    }

    return self;

}

#pragma mark -

#pragma mark Override layoutSubviews to center content

// We use layoutSubviews to center the image in the view

- (void)layoutSubviews {

    [super layoutSubviews];

    // center the image as it becomes smaller than the size of the screen

    CGSize boundsSize = self.bounds.size;

    CGRect frameToCenter = frontTiledView.frame;

    // center horizontally

    if (frameToCenter.size.width < boundsSize.width)

        frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;

    else

        frameToCenter.origin.x = 0;

    // center vertically

    if (frameToCenter.size.height < boundsSize.height)

        frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;

    else

        frameToCenter.origin.y = 0;

    frontTiledView.frame = frameToCenter;

    backgroundImageView.frame = frameToCenter;

    // to handle the interaction between CATiledLayer and high resolution screens, we need to manually set the

    // tiling view's contentScaleFactor to 1.0. (If we omitted this, it would be 2.0 on high resolution screens,

    // which would cause the CATiledLayer to ask us for tiles of the wrong scales.)

    frontTiledView.contentScaleFactor = 1.0;

}

#pragma mark -

#pragma mark UIScrollView delegate methods

// A UIScrollView delegate callback, called when the user starts zooming. 

// We return our current TiledImageView.

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {

    return frontTiledView;

}

// A UIScrollView delegate callback, called when the user stops zooming.  When the user stops zooming

// we create a new TiledImageView based on the new zoom level and draw it on top of the old TiledImageView.

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale {

    // set the new scale factor for the TiledImageView

    imageScale *=scale;

    if( imageScale < minimumScale ) imageScale = minimumScale;

    CGRect imageRect = CGRectMake(0.0f,0.0f,CGImageGetWidth(image.CGImage) * imageScale,CGImageGetHeight(image.CGImage) * imageScale);

    // Create a new TiledImageView based on new frame and scaling.

    frontTiledView = [[TiledImageView alloc] initWithFrame:imageRect image:image scale:imageScale]; 

    [self addSubview:frontTiledView];

    [frontTiledView release];

}

// A UIScrollView delegate callback, called when the user begins zooming.  When the user begins zooming

// we remove the old TiledImageView and set the current TiledImageView to be the old view so we can create a

// a new TiledImageView when the zooming ends.

- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view {

    // Remove back tiled view.

    [backTiledView removeFromSuperview];

    // Set the current TiledImageView to be the old view.

    self.backTiledView = frontTiledView;

}

@end