/* |
File: AssetBrowserItem.m |
Abstract: Represents an asset in AssetBrowserController. |
Version: 1.3 |
|
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The Apple Software is provided by Apple on an "AS IS" basis. APPLE |
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IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL |
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Copyright (C) 2014 Apple Inc. All Rights Reserved. |
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*/ |
|
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#import "AssetBrowserItem.h" |
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#import <AVFoundation/AVFoundation.h> |
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#include <AssertMacros.h> |
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@interface AssetBrowserItem () |
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- (AVAsset*)copyAssetIfCreated; |
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@property (nonatomic, copy) NSString *title; |
@property (nonatomic, strong) UIImage *thumbnailImage; |
@property (nonatomic, readonly) BOOL canGenerateThumbnails; |
@property (nonatomic, readonly) BOOL audioOnly; |
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@end |
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@implementation AssetBrowserItem |
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@synthesize URL = assetURL, title = assetTitle, haveRichestTitle; |
@synthesize thumbnailImage, canGenerateThumbnails, audioOnly; |
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- (id)initWithURL:(NSURL*)URL |
{ |
return [self initWithURL:URL title:nil]; |
} |
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- (id)initWithURL:(NSURL*)URL title:(NSString*)title |
{ |
if ((self = [super init])) { |
assetURL = URL; |
if (assetURL == nil) { |
return nil; |
} |
haveRichestTitle = title ? YES : NO; |
assetTitle = title ? [title copy] : [[URL lastPathComponent] stringByDeletingPathExtension]; |
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// Assume we can generate a thumb unless we have loaded the assets or tried already and know otherwise. |
canGenerateThumbnails = YES; |
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// Assets can only be accessed from one thread at a time. |
assetQueue = dispatch_queue_create("Asset Queue", DISPATCH_QUEUE_SERIAL); |
} |
return self; |
} |
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- (id)initWithAssetItem:(AssetBrowserItem*)browserItem |
{ |
if ((self = [super init])) { |
// Inititialization time properties. |
assetURL = browserItem.URL; |
|
// May have been an initialization time property. |
assetTitle = browserItem.title; |
haveRichestTitle = browserItem.haveRichestTitle; |
|
thumbnailImage = browserItem.thumbnailImage; |
asset = [browserItem copyAssetIfCreated]; |
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canGenerateThumbnails = browserItem.canGenerateThumbnails; |
audioOnly = browserItem.audioOnly; |
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assetQueue = dispatch_queue_create("Asset Queue", DISPATCH_QUEUE_SERIAL); |
} |
return self; |
} |
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- (id)copyWithZone:(NSZone *)zone |
{ |
AssetBrowserItem *copy = [[AssetBrowserItem allocWithZone:zone] initWithAssetItem:self]; |
return copy; |
} |
|
// Do simple equality based on the item's URL. |
- (BOOL)isEqual:(id)anObject |
{ |
if (self == anObject) |
return YES; |
|
if ([anObject isKindOfClass:[AssetBrowserItem class]]) { |
AssetBrowserItem *item = anObject; |
NSURL *myURL = self.URL; |
NSURL *theirURL = item.URL; |
if (myURL && theirURL) { |
return [myURL isEqual:theirURL]; |
} |
return NO; |
} |
return NO; |
} |
|
- (NSUInteger)hash |
{ |
if (self.URL) { |
return [self.URL hash]; |
} |
else { |
return [super hash]; |
} |
} |
|
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// Must be called on assetQueue. Will handle lazy asset creation. |
- (AVAsset*)getAssetInternal |
{ |
check( dispatch_get_current_queue() == assetQueue ); |
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if (asset == nil) { |
asset = [[AVURLAsset alloc] initWithURL:assetURL options:nil]; |
} |
return asset; |
} |
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// Our public accessor always copies the asset since assets can only safely be accessed from one thread at a time. |
- (AVAsset*)asset |
{ |
__block AVAsset *theAsset = nil; |
dispatch_sync(assetQueue, ^(void) { |
theAsset = [[self getAssetInternal] copy]; |
}); |
|
return theAsset; |
} |
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- (AVAsset*)copyAssetIfCreated |
{ |
__block AVAsset *theAsset = nil; |
dispatch_sync(assetQueue, ^(void) { |
theAsset = [asset copy]; |
}); |
return theAsset; |
} |
|
- (void)generateTitleFromMetadataAsynchronouslyWithCompletionHandler:(void (^)(NSString *title))handler |
{ |
if (haveRichestTitle) { |
dispatch_async(dispatch_get_main_queue(), ^(void) { |
if (handler) |
handler(self.title); |
}); |
return; |
} |
dispatch_async(assetQueue, ^(void) { |
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AVAsset *titleAsset = [self getAssetInternal]; |
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[titleAsset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"commonMetadata"] completionHandler:^{ |
dispatch_async(assetQueue, ^(void) { |
NSString* title = nil; |
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NSArray *titles = [AVMetadataItem metadataItemsFromArray:[titleAsset commonMetadata] withKey:AVMetadataCommonKeyTitle keySpace:AVMetadataKeySpaceCommon]; |
if ([titles count] > 0) |
{ |
// Try to get a title that matches one of the user's preferred languages. |
NSArray *preferredLanguages = [NSLocale preferredLanguages]; |
|
for (NSString *thisLanguage in preferredLanguages) |
{ |
NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:thisLanguage]; |
NSArray *titlesForLocale = [AVMetadataItem metadataItemsFromArray:titles withLocale:locale]; |
if ([titlesForLocale count] > 0) |
{ |
title = [[titlesForLocale objectAtIndex:0] stringValue]; |
break; |
} |
} |
|
// No matches in any of the preferred languages. Just use the primary title metadata we find. |
if (title == nil) |
{ |
title = [[titles objectAtIndex:0] stringValue]; |
} |
} |
|
dispatch_async(dispatch_get_main_queue(), ^{ |
haveRichestTitle = YES; |
if (title) |
self.title = title; |
if (handler) |
handler(self.title); |
}); |
}); |
}]; |
}); |
} |
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CGRect makeRectWithAspectRatioOutsideRect(CGSize aspectRatio, CGRect containerRect) |
{ |
CGSize scale = CGSizeMake(containerRect.size.width / aspectRatio.width, containerRect.size.height / aspectRatio.height); |
CGFloat maxScale = fmax(scale.width, scale.height); |
|
CGPoint centerPoint = CGPointMake(CGRectGetMidX(containerRect), CGRectGetMidY(containerRect)); |
CGSize size = CGSizeMake(aspectRatio.width * maxScale, aspectRatio.height * maxScale); |
return CGRectMake(centerPoint.x - 0.5f * size.width, centerPoint.y - 0.5f * size.height, size.width, size.height); |
} |
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- (CGSize)maxSizeForImageGeneratorToCropAsset:(AVAsset*)thumbnailAsset toSize:(CGSize)size |
{ |
CGSize naturalSize = CGSizeZero; |
CGSize naturalSizeTransformed = CGSizeZero; |
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NSArray *videoTracks = [thumbnailAsset tracksWithMediaType:AVMediaTypeVideo]; |
if ( ([videoTracks count] > 0) ) { |
AVAssetTrack *videoTrack = [videoTracks objectAtIndex:0]; |
NSArray *formatDescriptions = [videoTrack formatDescriptions]; |
if ([formatDescriptions count] > 0) { |
CMVideoFormatDescriptionRef videoFormatDescription = (__bridge CMFormatDescriptionRef)[formatDescriptions objectAtIndex:0]; |
naturalSize = CMVideoFormatDescriptionGetPresentationDimensions(videoFormatDescription, YES, YES); |
naturalSizeTransformed = CGSizeApplyAffineTransform (naturalSize, videoTrack.preferredTransform); |
naturalSizeTransformed.width = fabs(naturalSizeTransformed.width); |
naturalSizeTransformed.height = fabs(naturalSizeTransformed.height); |
} |
else { |
return CGSizeZero; |
} |
} |
else { |
return CGSizeZero; |
} |
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CGRect croppedRect = CGRectZero; |
croppedRect.size = size; |
CGRect containerRect = makeRectWithAspectRatioOutsideRect(naturalSizeTransformed, croppedRect); |
containerRect.origin = CGPointZero; |
containerRect = CGRectIntegral(containerRect); |
|
return containerRect.size; |
} |
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- (UIImage*)copyImageFromCGImage:(CGImageRef)image croppedToSize:(CGSize)size |
{ |
UIImage *thumbUIImage = nil; |
|
CGRect thumbRect = CGRectMake(0.0, 0.0, CGImageGetWidth(image), CGImageGetHeight(image)); |
CGRect cropRect = AVMakeRectWithAspectRatioInsideRect(size, thumbRect); |
cropRect.origin.x = round(cropRect.origin.x); |
cropRect.origin.y = round(cropRect.origin.y); |
cropRect = CGRectIntegral(cropRect); |
CGImageRef croppedThumbImage = CGImageCreateWithImageInRect(image, cropRect); |
thumbUIImage = [[UIImage alloc] initWithCGImage:croppedThumbImage]; |
CGImageRelease(croppedThumbImage); |
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return thumbUIImage; |
} |
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// Must be called on assetQueue. |
- (BOOL)assetHasVideoTrack:(AVAsset*)thumbnailAsset |
{ |
check( dispatch_get_current_queue() == assetQueue ); |
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NSArray *videoTracks = [thumbnailAsset tracksWithMediaType:AVMediaTypeVideo]; |
if ([videoTracks count] == 0) { |
canGenerateThumbnails = NO; |
NSArray *audioTracks = [thumbnailAsset tracksWithMediaType:AVMediaTypeAudio]; |
if ([audioTracks count] != 0) { |
audioOnly = YES; |
} |
return NO; |
} |
return YES; |
} |
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// Must be called on assetQueue. |
- (void)generateNonVideoThumbnailWithSize:(CGSize)size fillMode:(AssetBrowserItemFillMode)mode completionHandler:(void (^)(UIImage *thumbnail))handler |
{ |
check( dispatch_get_current_queue() == assetQueue ); |
|
UIImage *thumb = nil; |
if (audioOnly) { |
thumb = [UIImage imageNamed:@"Browser-AudioOnly"]; |
} |
else { |
thumb = [UIImage imageNamed:@"Browser-ErrorLoading"]; |
} |
|
if ( mode == AssetBrowserItemFillModeCrop ) { |
CGRect boundingRect = CGRectZero; |
boundingRect.size = thumb.size; |
boundingRect.size.width *= thumb.scale; |
boundingRect.size.height *= thumb.scale; |
|
CGSize cropSize = AVMakeRectWithAspectRatioInsideRect(size, boundingRect).size; |
if ( !CGSizeEqualToSize(cropSize, size) ) { |
thumb = [self copyImageFromCGImage:[thumb CGImage] croppedToSize:cropSize]; |
} |
} |
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dispatch_async(dispatch_get_main_queue(), ^(void) { |
self.thumbnailImage = thumb; |
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if (handler) { |
handler(thumb); |
} |
}); |
} |
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// Must be called on assetQueue. |
- (void)generateThumbnailFromAsset:(AVAsset*)thumbnailAsset withSize:(CGSize)size fillMode:(AssetBrowserItemFillMode)mode completionHandler:(void (^)(UIImage *thumbnail))handler |
{ |
check( dispatch_get_current_queue() == assetQueue ); |
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AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:thumbnailAsset]; |
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imageGenerator.appliesPreferredTrackTransform = YES; |
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if ( mode == AssetBrowserItemFillModeAspectFit ) |
imageGenerator.maximumSize = size; |
if ( mode == AssetBrowserItemFillModeCrop ) |
imageGenerator.maximumSize = [self maxSizeForImageGeneratorToCropAsset:thumbnailAsset toSize:size]; |
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NSValue *imageTimeValue = [NSValue valueWithCMTime:CMTimeMake(2, 1)]; |
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[imageGenerator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:imageTimeValue] completionHandler: |
^(CMTime requestedTime, CGImageRef image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error) |
{ |
if (result == AVAssetImageGeneratorFailed) { |
dispatch_sync(assetQueue, ^(void) { |
canGenerateThumbnails = NO; |
[self generateNonVideoThumbnailWithSize:size fillMode:mode completionHandler:handler]; |
}); |
} |
else { |
UIImage *thumbUIImage = nil; |
if (image) { |
if (mode == AssetBrowserItemFillModeCrop) { |
thumbUIImage = [self copyImageFromCGImage:image croppedToSize:size]; |
} |
else { |
thumbUIImage = [[UIImage alloc] initWithCGImage:image]; |
} |
} |
dispatch_async(dispatch_get_main_queue(), ^{ |
self.thumbnailImage = thumbUIImage; |
|
if (handler) { |
handler(self.thumbnailImage); |
} |
}); |
} |
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}]; |
} |
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- (void)generateThumbnailAsynchronouslyWithSize:(CGSize)size fillMode:(AssetBrowserItemFillMode)mode completionHandler:(void (^)(UIImage *thumbnail))handler |
{ |
dispatch_async(assetQueue, ^(void) { |
if (!canGenerateThumbnails) { |
[self generateNonVideoThumbnailWithSize:size fillMode:mode completionHandler:handler]; |
return; |
} |
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AVAsset *thumbnailAsset = [self getAssetInternal]; |
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[thumbnailAsset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler:^(void) { |
dispatch_async(assetQueue, ^(void) { |
AVKeyValueStatus postLoadingStatus = [thumbnailAsset statusOfValueForKey:@"tracks" error:NULL]; |
if ((postLoadingStatus == AVKeyValueStatusLoaded) && [self assetHasVideoTrack:thumbnailAsset]) { |
[self generateThumbnailFromAsset:thumbnailAsset withSize:size fillMode:mode completionHandler:handler]; |
} |
else { |
canGenerateThumbnails = NO; |
[self generateNonVideoThumbnailWithSize:size fillMode:mode completionHandler:handler]; |
} |
}); |
}]; |
}); |
} |
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- (UIImage*)placeHolderImage |
{ |
return [UIImage imageNamed:@"Browser-Placeholder"]; |
} |
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- (void)clearThumbnailCache |
{ |
self.thumbnailImage = nil; |
} |
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- (void)clearAssetCache |
{ |
dispatch_sync(assetQueue, ^(void) { |
asset = nil; |
}); |
} |
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- (NSString*)description |
{ |
return [NSString stringWithFormat:@"<AssetBrowserItem: %p, '%@'>", self, self.title]; |
} |
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@end |
