/*

 Copyright (C) 2015 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Main view controller for displaying the image, reflection and slider table.

 */

#import "MyViewController.h"

#import "SliderCell.h"

@interface MyViewController () <UITableViewDelegate, UITableViewDataSource>

@property (nonatomic, strong) IBOutlet UIImageView *imageView;

@property (nonatomic, strong) IBOutlet UIImageView *reflectionView;

@property (nonatomic, strong) IBOutlet UITableView *slidersTableView;

@property (nonatomic, strong) IBOutlet NSLayoutConstraint *reflectionViewHeightConstraint;

@end

#pragma mark -

@implementation MyViewController

// image reflection

static const CGFloat kDefaultReflectionFraction = 0.65;

static const CGFloat kDefaultReflectionOpacity = 0.40;

static NSString *kCellID = @"CellID";

- (void)viewDidLoad

{

    [super viewDidLoad];

    self.imageView.image = [UIImage imageNamed:@"scene.jpg"];

    [self.slidersTableView registerClass:[SliderCell class] forCellReuseIdentifier:kCellID];

    self.slidersTableView.backgroundColor = [UIColor whiteColor];

    self.view.autoresizesSubviews = YES;

    self.view.userInteractionEnabled = YES;

    // determine the size of the reflection to create

    int reflectionHeight = self.imageView.bounds.size.height * kDefaultReflectionFraction;

    // create the reflection image and assign it to the UIImageView

    self.reflectionView.image = [self reflectedImage:self.imageView withHeight:reflectionHeight];

    self.reflectionView.alpha = kDefaultReflectionOpacity;

}

#pragma mark - slider action methods

- (IBAction)sizeSlideAction:(id)sender

{

    UISlider *slider = (UISlider *)sender;

    CGFloat val = [slider value];

    // change the height constraint of our reflected image view

    NSInteger reflectionHeight = 180 * val;    // 180 is the original maximum height of the reflected image

    self.reflectionViewHeightConstraint.constant = reflectionHeight;

    // create the reflection image, assign it to the UIImageView and add the image view to the containerView

    self.reflectionView.image = [self reflectedImage:self.imageView withHeight:reflectionHeight];

    // get the alpha slider value, keep it set on the reflection

    UISlider *alphaSlider = (UISlider *)[[self.slidersTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:1 inSection:0]].contentView viewWithTag:kSliderTag];

    self.reflectionView.alpha = alphaSlider.value;

    UITableViewCell *sliderCell = [self.slidersTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];

    sliderCell.detailTextLabel.text = [NSString stringWithFormat:@"%0.2f", val];

}

- (IBAction)alphaSlideAction:(id)sender

{

    UISlider *slider = (UISlider *)sender;

    CGFloat val = [slider value];

    self.reflectionView.alpha = val;

    [self.slidersTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:1 inSection:0]].detailTextLabel.text = [NSString stringWithFormat:@"%0.2f", val];

}

#pragma mark - Image Reflection

CGImageRef CreateGradientImage(NSInteger pixelsWide, NSInteger pixelsHigh)

{

    CGImageRef theCGImage = NULL;

    // gradient is always black-white and the mask must be in the gray colorspace

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

    // create the bitmap context

    CGContextRef gradientBitmapContext = CGBitmapContextCreate(NULL, pixelsWide, pixelsHigh,

                                                               8, 0, colorSpace, kCGImageAlphaNone);

    // define the start and end grayscale values (with the alpha, even though

    // our bitmap context doesn't support alpha the gradient requires it)

    CGFloat colors[] = {0.0, 1.0, 1.0, 1.0};

    // create the CGGradient and then release the gray color space

    CGGradientRef grayScaleGradient = CGGradientCreateWithColorComponents(colorSpace, colors, NULL, 2);

    CGColorSpaceRelease(colorSpace);

    // create the start and end points for the gradient vector (straight down)

    CGPoint gradientStartPoint = CGPointZero;

    CGPoint gradientEndPoint = CGPointMake(0, pixelsHigh);

    // draw the gradient into the gray bitmap context

    CGContextDrawLinearGradient(gradientBitmapContext, grayScaleGradient, gradientStartPoint,

                                gradientEndPoint, kCGGradientDrawsAfterEndLocation);

    CGGradientRelease(grayScaleGradient);

    // convert the context into a CGImageRef and release the context

    theCGImage = CGBitmapContextCreateImage(gradientBitmapContext);

    CGContextRelease(gradientBitmapContext);

    // return the imageref containing the gradient

    return theCGImage;

}

CGContextRef MyCreateBitmapContext(NSInteger pixelsWide, NSInteger pixelsHigh)

{

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // create the bitmap context

    CGContextRef bitmapContext = CGBitmapContextCreate (NULL, pixelsWide, pixelsHigh, 8,

                                                        0, colorSpace,

                                                        // this will give us an optimal BGRA format for the device:

                                                        (kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst));

    CGColorSpaceRelease(colorSpace);

    return bitmapContext;

}

- (UIImage *)reflectedImage:(UIImageView *)fromImage withHeight:(NSInteger)height

{

    if (height == 0)

        return nil;

    // create a bitmap graphics context the size of the image

    CGContextRef mainViewContentContext = MyCreateBitmapContext(fromImage.bounds.size.width, height);

    // create a 2 bit CGImage containing a gradient that will be used for masking the

    // main view content to create the 'fade' of the reflection.  The CGImageCreateWithMask

    // function will stretch the bitmap image as required, so we can create a 1 pixel wide gradient

    CGImageRef gradientMaskImage = CreateGradientImage(1, height);

    // create an image by masking the bitmap of the mainView content with the gradient view

    // then release the  pre-masked content bitmap and the gradient bitmap

    CGContextClipToMask(mainViewContentContext, CGRectMake(0.0, 0.0, fromImage.bounds.size.width, height), gradientMaskImage);

    CGImageRelease(gradientMaskImage);

    // In order to grab the part of the image that we want to render, we move the context origin to the

    // height of the image that we want to capture, then we flip the context so that the image draws upside down.

    CGContextTranslateCTM(mainViewContentContext, 0.0, height);

    CGContextScaleCTM(mainViewContentContext, 1.0, -1.0);

    // draw the image into the bitmap context

    CGContextDrawImage(mainViewContentContext, fromImage.bounds, fromImage.image.CGImage);

    // create CGImageRef of the main view bitmap content, and then release that bitmap context

    CGImageRef reflectionImage = CGBitmapContextCreateImage(mainViewContentContext);

    CGContextRelease(mainViewContentContext);

    // convert the finished reflection image to a UIImage

    UIImage *theImage = [UIImage imageWithCGImage:reflectionImage];

    // image is retained by the property setting above, so we can release the original

    CGImageRelease(reflectionImage);

    return theImage;

}

#pragma mark - UITableViewDelegate

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section

{

    return 0.0;

}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath

{

    return 40.0;

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

{

    return 2;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{

    SliderCell *cell = [tableView dequeueReusableCellWithIdentifier:kCellID];

    UISlider *slider = (UISlider *)[cell.contentView viewWithTag:kSliderTag];

    if (indexPath.row == 0)

    {

        cell.textLabel.text = @"Size";

        slider.value = kDefaultReflectionFraction;

        [slider addTarget:self action:@selector(sizeSlideAction:) forControlEvents:UIControlEventValueChanged];

        cell.detailTextLabel.text = [NSString stringWithFormat:@"%0.2f", slider.value];

    }

    else

    {

        cell.textLabel.text = @"Alpha";

        slider.value = kDefaultReflectionOpacity;

        [slider addTarget:self action:@selector(alphaSlideAction:) forControlEvents:UIControlEventValueChanged];

        cell.detailTextLabel.text = [NSString stringWithFormat:@"%0.2f", slider.value];

    }

    return cell;

}

@end