带有乘法效果的Swift UIView [英] Swift UIView with multiply effect

问题描述

几个小时以来，我一直在努力实现以下目标:

What I've been trying to achieve for a couple of hours is something like the following:

我想在背景中有一个UIImage，然后最好是一个背景红色为UIView的红色，并具有某种乘法效果(红色区域).这可能吗?我已经看到了UIImage的一些扩展对其进行着色，但是只有当我希望我的WHOLE图像具有红色的多色效果时，该扩展才有用.

I would like to have a UIImage in the background and then preferably a UIView with a background color of red with some kind of multiply effect (the red area). Is this possible? I've seen a few extensions for UIImage that tints them, but that would only work if I wanted my WHOLE image to have a red multiply color effect.

谢谢

推荐答案

您可以在UIImageView顶部添加红色UIView.调整Alpha使其透明:

You could just add a red UIView to the top of your UIImageView. Adjust the alpha to make it transparent:

let someView = UIView(frame: someImageView.frame)
someView.backgroundColor = UIColor(colorLiteralRed: 255.0/255.0, green: 0, blue: 0, alpha: 0.5)
someImageView.addSubview(someView)

改为使用乘法:

let img = UIImage(named: "background")
let img2 = UIImage(named: "effect") //Make sure this is your red image same size as the background


let rect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)

UIGraphicsBeginImageContextWithOptions(img.size, true, 0)
let context = UIGraphicsGetCurrentContext()

// fill the background with white so that translucent colors get lighter
CGContextSetFillColorWithColor(context, UIColor.whiteColor().CGColor)
CGContextFillRect(context, rect)

img.drawInRect(rect, blendMode: .Normal, alpha: 1)
img2.drawInRect(rect, blendMode: .Multiply, alpha: 1)

// grab the finished image and return it
let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

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