HTRasterView.m

//
//  HTRasterView.m
//  HotelTonight
//
//  Created by Jacob Jennings on 11/29/12.
//  Copyright (c) 2013 HotelTonight
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

//  The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#import "HTRasterView.h"
#import "NSObject+HTPropertyHash.h"
#import "MSCachedAsyncViewDrawing.h"
#import "UIView+HTRaster.h"
#import <QuartzCore/QuartzCore.h>

// Uncommenting this SLOWS THINGS DOWN A LOT and will save all images to disk
//#define HT_DEBUG_SAVEFILES 1

//#define HT_DEBUG_RASTERLEVEL 1
//#define HT_DEBUG_RASTERLEVEL 2
//#define HT_DEBUG_RASTERLEVEL 3

@interface HTRasterView ()

@property (nonatomic, assign) BOOL implementsShouldRasterize;
@property (nonatomic, assign) BOOL implementsUseMinimumSizeForCaps;
@property (nonatomic, assign) BOOL implementsCapEdgeInsets;
@property (nonatomic, assign) BOOL implementsShadowPath;
@property (nonatomic, assign) BOOL implementsPlaceholderImage;
@property (nonatomic, strong) UIImageView *placeholderImageView;
@property (atomic, strong) NSOperation *drawingOperation;
@property (atomic, strong) NSString *currentRenderingCacheKey; // For avoiding race conditions while drawsOnMainThread = NO
@property (nonatomic, strong) UIView<HTRasterizableView> *rasterizableViewAsSubview;
@property (nonatomic, strong) UIImageView *imageView;
@property (nonatomic, assign) BOOL loaded;

@end

@implementation HTRasterView
@dynamic image;

- (id)initWithFrame:(CGRect)frame
{
    self = ([super initWithFrame:frame]);
    if (self)
    {
        _kvoEnabled = YES;
        _drawsOnMainThread = YES;
        _rasterized = YES;
        _imageView = [[UIImageView alloc] init];
        _imageView.opaque = YES;
        _loaded = YES;
        [self addSubview:_imageView];
    }
    return self;
}

- (void)layoutSubviews
{
    [super layoutSubviews];

    if (self.rasterizableView)
    {
        [self layoutRasterizableView];
        [self regenerateImage:nil];
    }
    self.rasterizableViewAsSubview.frame = self.bounds;
    self.imageView.frame = self.bounds;
    self.placeholderImageView.frame = self.bounds;
    [self.imageView layoutIfNeeded];

    if (self.implementsShadowPath)
    {
        self.layer.shadowPath = [self.rasterizableView rasterViewShadowPathForBounds:self.bounds].CGPath;
    }
}

- (void)layoutRasterizableView;
{
    CGSize size = self.bounds.size;
    UIEdgeInsets edgeInsets = [self capEdgeInsets];

    if ([self useMinimumCapSize])
    {
#if HT_DEBUG_RASTERLEVEL >= 3
        NSLog(@"Using minimum cap size for %@", NSStringFromClass([self.rasterizableView class]));
#endif
        size = CGSizeMake(edgeInsets.left + edgeInsets.right + 1, edgeInsets.top + edgeInsets.bottom + 1);
    }

    self.rasterizableView.frame = (CGRect){ .origin = CGPointZero, .size = size };
    [self.rasterizableView layoutIfNeeded];
}

- (void)dealloc
{
    [self removeAllObservers];
    _rasterizableView.htRasterImageView = nil;
    self.delegate = nil;
}

#pragma mark - Properties

- (void)setRasterizableView:(UIView<HTRasterizableView> *)rasterizableView
{
    [self setRasterizableView:rasterizableView generatePlaceholder:YES];
}

- (void)setRasterizableView:(UIView<HTRasterizableView> *)rasterizableView generatePlaceholder:(BOOL)generatePlaceholder
{
    [self removeAllObservers];
    _rasterizableView.htRasterImageView = nil;
    _rasterizableView = rasterizableView;
    if (!rasterizableView)
    {
        return;
    }
    _rasterizableView.htRasterImageView = self;

    self.implementsShouldRasterize = [self.rasterizableView respondsToSelector:@selector(shouldRegenerateRaster)];
    self.implementsUseMinimumSizeForCaps = [self.rasterizableView respondsToSelector:@selector(useMinimumFrameForCaps)];
    self.implementsCapEdgeInsets = [self.rasterizableView respondsToSelector:@selector(capEdgeInsets)];
    self.implementsShadowPath = [self.rasterizableView respondsToSelector:@selector(rasterViewShadowPathForBounds:)];
    self.implementsPlaceholderImage = [self.rasterizableView respondsToSelector:@selector(placeholderImage)];

    if (generatePlaceholder)
    {
        [self generatePlaceholder];
    }

    if (self.implementsShadowPath)
    {
        self.layer.shadowRadius = self.rasterizableView.layer.shadowRadius;
        self.layer.shadowOffset = self.rasterizableView.layer.shadowOffset;
        self.layer.shadowColor = self.rasterizableView.layer.shadowColor;
        self.layer.shadowOpacity = self.rasterizableView.layer.shadowOpacity;
    }
    else
    {
        self.layer.shadowOpacity = 0;
    }

    rasterizableView.shouldTrackState = YES;
    [rasterizableView addObserver:self forKeyPath:@"stateHash" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:nil];

    [self setNeedsLayout];
}

- (void)generatePlaceholder
{
    if (self.implementsPlaceholderImage)
    {
        [self.placeholderImageView removeFromSuperview];
        self.placeholderImageView = [[UIImageView alloc] initWithImage:[self.rasterizableView placeholderImage]];
        [self insertSubview:self.placeholderImageView atIndex:0];
        self.imageView.image = nil;
    }
}

- (void)setRasterized:(BOOL)rasterized
{
    if (_rasterized == rasterized)
    {
        return;
    }
    _rasterized = rasterized;
    if (rasterized)
    {
        [self.rasterizableViewAsSubview removeFromSuperview];
        [self setRasterizableView:self.rasterizableViewAsSubview generatePlaceholder:NO];
        self.rasterizableViewAsSubview = nil;
    }
    else
    {
        self.rasterizableViewAsSubview = self.rasterizableView;
        [self addSubview:self.rasterizableViewAsSubview];
        self.rasterizableView = nil;
        [self setNeedsLayout];
    }
    self.imageView.hidden = !rasterized;
}

- (UIImage *)image
{
    return self.imageView.image;
}

#pragma mark - Private

- (void)removeAllObservers;
{
    [_rasterizableView removeObserver:self forKeyPath:@"stateHash"];
    _rasterizableView.shouldTrackState = NO;
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (!self.kvoEnabled)
    {
        return;
    }
    [self regenerateImage:nil];
}

- (UIEdgeInsets)capEdgeInsets
{
    UIEdgeInsets edgeInsets = UIEdgeInsetsZero;
    if (self.implementsCapEdgeInsets)
    {
        edgeInsets = [self.rasterizableView capEdgeInsets];
    }
    return edgeInsets;
}

- (BOOL)useMinimumCapSize
{
    return self.implementsUseMinimumSizeForCaps && [self.rasterizableView useMinimumFrameForCaps];
}

- (void)regenerateImage:(HTSARIVVoidBlock)complete
{
    if (!self.rasterizableView)
    {
        return;
    }
    if (self.implementsShouldRasterize)
    {
        if (![self.rasterizableView shouldRegenerateRaster])
        {
#if HT_DEBUG_RASTERLEVEL >= 3
            NSLog(@"Cancelled regenerate via shouldRegenerateRaster: %@", NSStringFromClass([self.rasterizableView class]));
#endif
            return;
        }
    }
    [self layoutRasterizableView];
    CGSize size = self.rasterizableView.bounds.size;
    if ((size.width < 1 || size.height < 1))
    {
#if HT_DEBUG_RASTERLEVEL >= 3
        NSLog(@"Too small %@", NSStringFromClass([self.rasterizableView class]));
#endif
        return;
    }
    __block NSString *cacheKey = [self cacheKey];
#if HT_DEBUG_RASTERLEVEL >= 2
        NSLog(@"%d Maybe drawing cache instance: %d\n", (int)self, (int)cacheKey);
#endif
    __weak HTRasterView *wSelf = self;
    MSCachedAsyncViewDrawingDrawBlock drawBlock = ^ BOOL (CGRect frame, CGContextRef context)
    {
        if (cacheKey != self.currentRenderingCacheKey || cacheKey != [self cacheKey])
        {
            return NO;
        }
        if ([wSelf.delegate respondsToSelector:@selector(rasterViewWillRegenerateImage:)])
        {
            [wSelf.delegate rasterViewWillRegenerateImage:wSelf];
        }
        [wSelf.rasterizableView drawRect:frame inContext:context];
        if (cacheKey != self.currentRenderingCacheKey || cacheKey != [self cacheKey])
        {
            return NO;
        }
#if HT_DEBUG_RASTERLEVEL >= 2
        NSLog(@"%d Drawing: key instance: %d\n\n", (int)wSelf, (int)cacheKey);
#endif
        return YES;
    };

    MSCachedAsyncViewDrawingCompletionBlock completionBlock = ^(UIImage *drawnImage)
    {
        if (self.currentRenderingCacheKey != cacheKey)
        {
            return;
        }
        if (!drawnImage)
        {
            return;
        }
        if (drawnImage != wSelf.imageView.image)
        {
#if HT_DEBUG_RASTERLEVEL >= 1
            NSLog(@"%d Using key instance: %d, Key: \n%@\n\n", (int)wSelf, (int)cacheKey, cacheKey);
#endif

            wSelf.imageView.image = drawnImage;
            if (wSelf.placeholderImageView)
            {
                wSelf.imageView.alpha = 0;
                [UIView animateWithDuration:0.25
                                      delay:0
                                    options:UIViewAnimationOptionCurveEaseInOut
                                 animations:^{
                                     self.imageView.alpha = 1;
                                 }
                                 completion:^(BOOL finished) {
                                     wSelf.placeholderImageView = nil;
                                 }];
            }
        }
        self.loaded = YES;
        if ([wSelf.delegate respondsToSelector:@selector(rasterViewImageLoaded:)])
        {
            [wSelf.delegate rasterViewImageLoaded:wSelf];
        }

#if HT_DEBUG_SAVEFILES
        NSString *fileName = [NSString stringWithFormat:@"/%@-%u.png", NSStringFromClass([wSelf.rasterizableView class]), [cacheKey hash]];
        NSData *imageData = UIImagePNGRepresentation(drawnImage);
        NSString *imagePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]
                               stringByAppendingPathComponent:fileName];
        [imageData writeToFile:imagePath atomically:YES];
#endif

        if (complete) complete();
    };

    [self.drawingOperation cancel];
#if HT_DEBUG_RASTERLEVEL >= 3
    NSLog(@"actual regen %@ size: %@", NSStringFromClass([self.rasterizableView class]), NSStringFromCGSize(size));
#endif
    self.currentRenderingCacheKey = cacheKey;
    self.loaded = NO;
    self.drawingOperation = [[MSCachedAsyncViewDrawing sharedInstance] drawViewSynchronous:self.drawsOnMainThread
                                                                              withCacheKey:cacheKey
                                                                                      size:size
                                                                           backgroundColor:[UIColor clearColor]
                                                                             capEdgeInsets:[self capEdgeInsets]
                                                                                 drawBlock:drawBlock
                                                                           completionBlock:completionBlock];
}

- (NSString *)cacheKey
{
    NSString *cacheString = [self.rasterizableView stateHash];
    return cacheString;
}

- (void)willMoveToWindow:(UIWindow *)newWindow
{
    [self regenerateImage:nil];
}

- (NSString *)description
{
    return [[super description] stringByAppendingFormat:@", rasterizableView: %@, image: %@", NSStringFromClass([self.rasterizableView class]), self.imageView.image];
}

@end