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Refactor image source helpers

This commit is contained in:
Reda Lemeden 2014-12-13 11:35:00 +01:00
parent 8013faea87
commit 2951bb60a1
1 changed files with 45 additions and 25 deletions
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68
Source/ImageSourceHelpers.swift
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@ -2,33 +2,53 @@ import UIKit
import ImageIO import ImageIO
import MobileCoreServices import MobileCoreServices
private func CGImageSourceContainsAnimatedGIF(imageSource: CGImageSource) -> Bool { internal typealias GIFProperties = [String : Double]
let isTypeGIF = UTTypeConformsTo(CGImageSourceGetType(imageSource), kUTTypeGIF) private let defaultDuration: Double = 0
let imageCount = CGImageSourceGetCount(imageSource)
func CGImageSourceGIFFrameDuration(imageSource: CGImageSource, index: Int) -> NSTimeInterval {
if !imageSource.isAnimatedGIF { return 0.0 }
let duration = imageSource.GIFPropertiesAtIndex(UInt(index))
>>- durationFromGIFProperties
>>- capDuration
return duration ?? defaultDuration
}
private func capDuration(duration: Double) -> Double? {
if duration < 0 { return .None }
let threshold = 0.02 - Double(FLT_EPSILON)
let cappedDuration = duration < threshold ? 0.1 : duration
return cappedDuration
}
private func durationFromGIFProperties(properties: GIFProperties) -> Double? {
let unclampedDelayTime = properties[String(kCGImagePropertyGIFUnclampedDelayTime)]
let delayTime = properties[String(kCGImagePropertyGIFDelayTime)]
return duration <^> unclampedDelayTime <*> delayTime
}
private func duration(unclampedDelayTime: Double)(delayTime: Double) -> Double {
let delayArray = [unclampedDelayTime, delayTime]
return delayArray.filter(isPositive).first ?? defaultDuration
}
private func isPositive(value: Double) -> Bool {
return value >= 0
}
extension CGImageSourceRef {
var isAnimatedGIF: Bool {
let isTypeGIF = UTTypeConformsTo(CGImageSourceGetType(self), kUTTypeGIF)
let imageCount = CGImageSourceGetCount(self)
return isTypeGIF != 0 && imageCount > 1 return isTypeGIF != 0 && imageCount > 1
} }
func CGImageSourceGIFFrameDuration(imageSource: CGImageSource, index: Int) -> NSTimeInterval { func GIFPropertiesAtIndex(index: UInt) -> GIFProperties? {
let containsAnimatedGIF = CGImageSourceContainsAnimatedGIF(imageSource) if !isAnimatedGIF { return .None }
if !containsAnimatedGIF { return 0.0 }
var duration = 0.0 let imageProperties = CGImageSourceCopyPropertiesAtIndex(self, index, nil) as Dictionary
let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, UInt(index), nil) as NSDictionary return imageProperties[String(kCGImagePropertyGIFDictionary)] as? GIFProperties
let GIFProperties: NSDictionary? = imageProperties.objectForKey(kCGImagePropertyGIFDictionary) as? NSDictionary
if let properties = GIFProperties {
duration = properties.valueForKey(kCGImagePropertyGIFUnclampedDelayTime) as Double
if duration <= 0 {
duration = properties.valueForKey(kCGImagePropertyGIFDelayTime) as Double
} }
} }
let threshold = 0.02 - Double(FLT_EPSILON)
if duration > 0 && duration < threshold {
duration = 0.1
}
return duration
}