如何在UIImage中使用过滤器，CGBitmapContextCreate和CGBitmapInfo？

Question

我想在iOS 8上应用Core Image过滤器在Swift中对UIImage对象进行各种CG操作，但是我在使用CGBitmapContextCreate（）方面遇到了一些困难，特别是对于CGBitmapInfo参数，我希望将其设置为与Swift兼容的等效项目标C使用的常量kCGImageAlphaPremultipliedLast的变量

我想要一些如何做这些事情的工作实例。

Answer 1

这是一个如何通过拳头创建CGBItmapContext对图像执行CG操作的示例...

func setImageMaskColor(srcImage: UIImage, color: UIColor) -> UIImage {
    var bounds = CGRectMake(0, 0, srcImage.size.width, srcImage.size.height)
    var colorSpace = CGColorSpaceCreateDeviceRGB()
    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedFirst.rawValue)
    var ctx = CGBitmapContextCreate(nil,
                    CGImageGetWidth(srcImage.CGImage),
                    CGImageGetHeight(srcImage.CGImage),
                    CGImageGetBitsPerComponent(srcImage.CGImage),
                    CGImageGetBytesPerRow(srcImage.CGImage),
                    CGImageGetColorSpace(srcImage.CGImage),
                    bitmapInfo)!
    CGContextDrawImage(ctx, bounds, srcImage.CGImage)
    CGContextSetBlendMode(ctx, kCGBlendModeSourceAtop)
    CGContextSetFillColorWithColor(ctx, color.CGColor)
    CGContextFillRect(ctx, bounds);
    var resultCGimage = CGBitmapContextCreateImage(ctx)
    CGContextDrawImage(ctx, bounds, resultCGimage)
    return UIImage(CGImage: resultCGimage)!
}

Answer 2

以下是如何对UIIimage执行Core Image过滤器的示例...

func imageAdjustHue(srcImage: UIImage, hue: CGFloat) -> UIImage {
    var colorParam = [ kCIInputAngleKey : hue ]
    var ciimage = CIImage(CGImage: srcImage.CGImage)
    let filteredImage = ciimage.imageByApplyingFilter("CIHueAdjust", withInputParameters: colorParam)
    return UIImage(CIImage: filteredImage!)!
}