GridDemoViewController.m

//
//  GridDemoViewController.m
//  JNWCollectionViewDemo
//
//  Created by Jonathan Willing on 4/15/13.
//  Copyright (c) 2013 AppJon. All rights reserved.
//

#import "GridDemoViewController.h"
#import "GridCell.h"
#import "ListHeader.h"

@interface GridDemoViewController()
@property (nonatomic, strong) NSArray *images;
@property (nonatomic, strong) IBOutlet NSSlider *sizeSlider;
@end

static NSString * const identifier = @"CELL";
static NSString * const headerIdentifier = @"HEADER";

@implementation GridDemoViewController

- (id)init {
	return [self initWithNibName:NSStringFromClass(self.class) bundle:nil];
}

- (void)awakeFromNib {
	[self generateImages];
	
	JNWCollectionViewGridLayout *gridLayout = [[JNWCollectionViewGridLayout alloc] init];
	gridLayout.delegate = self;
	gridLayout.verticalSpacing = 10.f;
	
	self.collectionView.collectionViewLayout = gridLayout;
	self.collectionView.dataSource = self;
	self.collectionView.animatesSelection = NO; // (this is the default option)
	
	[self.collectionView registerClass:GridCell.class forCellWithReuseIdentifier:identifier];
	[self.collectionView registerClass:ListHeader.class forSupplementaryViewOfKind:JNWCollectionViewListLayoutHeaderKind withReuseIdentifier:headerIdentifier];

	
	[self.collectionView reloadData];
}

- (IBAction)updateSizeSliderValue:(id)sender {
	[self.collectionView.collectionViewLayout invalidateLayout];
}

#pragma mark Data source

- (JNWCollectionViewCell *)collectionView:(JNWCollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
	GridCell *cell = (GridCell *)[collectionView dequeueReusableCellWithIdentifier:identifier];
	cell.image = self.images[indexPath.jnw_item % self.images.count];
	return cell;
}

- (NSInteger)numberOfSectionsInCollectionView:(JNWCollectionView *)collectionView {
	return 5;
}

- (NSUInteger)collectionView:(JNWCollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
	return 4;
}

- (CGFloat)collectionView:(JNWCollectionView *)collectionView heightForHeaderInSection:(NSInteger)index
{
	return 24.f;
}

- (JNWCollectionViewReusableView *)collectionView:(JNWCollectionView *)collectionView viewForSupplementaryViewOfKind:(NSString *)kind inSection:(NSInteger)section {

	ListHeader *header = (ListHeader *)[collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifer:headerIdentifier];
	header.headerLabelText = [NSString stringWithFormat:@"Header %ld", section];
	return header;
}

- (CGSize)sizeForItemInCollectionView:(JNWCollectionView *)collectionView {
	CGFloat sizeSliderValue = self.sizeSlider.floatValue;
	return CGSizeMake(sizeSliderValue, sizeSliderValue);
}

#pragma mark Image creation

// To simulate at least something realistic, this just generates some randomly tinted images so that not every
// cell has the same image.
- (void)generateImages {
	NSInteger numberOfImages = 30;
	NSMutableArray *images = [NSMutableArray array];
	
	for (int i = 0; i < numberOfImages; i++) {
		
		// Just get a randomly-tinted template image.
		NSImage *image = [NSImage imageWithSize:CGSizeMake(150.f, 150.f) flipped:NO drawingHandler:^BOOL(NSRect dstRect) {
			[[NSImage imageNamed:NSImageNameUser] drawInRect:dstRect fromRect:CGRectZero operation:NSCompositeSourceOver fraction:1];
			
			CGFloat hue = arc4random() % 256 / 256.0;
			CGFloat saturation = arc4random() % 128 / 256.0 + 0.5;
			CGFloat brightness = arc4random() % 128 / 256.0 + 0.5;
			NSColor *color = [NSColor colorWithCalibratedHue:hue saturation:saturation brightness:brightness alpha:1];
			
			[color set];
			NSRectFillUsingOperation(dstRect, NSCompositeDestinationAtop);
			
			return YES;
		}];
		
		[images addObject:image];
	}
	
	self.images = images.copy;
}

@end