Ios 当渐变重新启动时,如何在swift中使用图像时固定文本上的渐变
我试图在文本上创建一个渐变,我使用UIGraphics来使用渐变图像来创建这个。我遇到的问题是梯度正在重新开始。有人知道如何缩放渐变以延伸到文本吗 文本位于线框上,将被更改几次。有时它是完美的,但有时它不是 渐变应该从黄色变为蓝色,但会重新启动,请参见下图: 每次标签大小更改时,您都必须重新绘制图像 这是因为图案Ios 当渐变重新启动时,如何在swift中使用图像时固定文本上的渐变,ios,swift,uilabel,core-graphics,gradient,Ios,Swift,Uilabel,Core Graphics,Gradient,我试图在文本上创建一个渐变,我使用UIGraphics来使用渐变图像来创建这个。我遇到的问题是梯度正在重新开始。有人知道如何缩放渐变以延伸到文本吗 文本位于线框上,将被更改几次。有时它是完美的,但有时它不是 渐变应该从黄色变为蓝色,但会重新启动,请参见下图: 每次标签大小更改时,您都必须重新绘制图像 这是因为图案UIColor仅平铺。发件人: 在绘制过程中,图案颜色的图像根据需要平铺以覆盖给定区域 因此,当标签的边界发生变化时,您需要自己更改图像大小,因为图案图像不支持拉伸。为此,可以将UIL
UIColor
仅平铺。发件人:
在绘制过程中,图案颜色的图像根据需要平铺以覆盖给定区域
因此,当标签的边界发生变化时,您需要自己更改图像大小,因为图案图像不支持拉伸。为此,可以将UILabel
子类化,并覆盖layoutSubviews
方法。这样做应该可以达到预期的效果:
class GradientLabel: UILabel {
let gradientImage = UIImage(named:"gradient.png")
override func layoutSubviews() {
guard let grad = gradientImage else { // skip re-drawing gradient if it doesn't exist
return
}
// redraw your gradient image
UIGraphicsBeginImageContext(frame.size)
grad.drawInRect(bounds)
let myGradient = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
// update text color
textColor = UIColor(patternImage: myGradient)
}
}
虽然值得一提的是,我总是更喜欢自己画一个渐变,因为你可以有更多的灵活性(比如说你想在以后添加另一种颜色)。此外,当您以不同的大小重新绘制图像时,图像的质量可能会降低(尽管由于渐变的性质,这应该是相当小的) 只需覆盖
UILabel
子类的drawRect
,就可以绘制自己的渐变。例如:
override func drawRect(rect: CGRect) {
// begin new image context to let the superclass draw the text in (so we can use it as a mask)
UIGraphicsBeginImageContextWithOptions(bounds.size, false, 0.0)
do {
// get your image context
let ctx = UIGraphicsGetCurrentContext()
// flip context
CGContextScaleCTM(ctx, 1, -1)
CGContextTranslateCTM(ctx, 0, -bounds.size.height)
// get the superclass to draw text
super.drawRect(rect)
}
// get image and end context
let img = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
// get drawRect context
let ctx = UIGraphicsGetCurrentContext()
// clip context to image
CGContextClipToMask(ctx, bounds, img.CGImage)
// define your colors and locations
let colors = [UIColor.orangeColor().CGColor, UIColor.redColor().CGColor, UIColor.purpleColor().CGColor, UIColor.blueColor().CGColor]
let locs:[CGFloat] = [0.0, 0.3, 0.6, 1.0]
// create your gradient
let grad = CGGradientCreateWithColors(CGColorSpaceCreateDeviceRGB(), colors, locs)
// draw gradient
CGContextDrawLinearGradient(ctx, grad, CGPoint(x: 0, y:bounds.size.height*0.5), CGPoint(x:bounds.size.width, y:bounds.size.height*0.5), CGGradientDrawingOptions(rawValue: 0))
}
输出:
swift4&as子类
@OliverCanagh您需要在故事板中选择标签,然后进入身份检查器。然后可以将类字段更改为自定义类()。很高兴我的回答能帮上忙,请:)嗨,谢谢你回复我,现在效果很好!非常感谢你的帮助。抱歉,我无意中删除了我以前关于如何将渐变应用于标签的评论。下面是使用Swift 3的
NSTextView
示例:
override func drawRect(rect: CGRect) {
// begin new image context to let the superclass draw the text in (so we can use it as a mask)
UIGraphicsBeginImageContextWithOptions(bounds.size, false, 0.0)
do {
// get your image context
let ctx = UIGraphicsGetCurrentContext()
// flip context
CGContextScaleCTM(ctx, 1, -1)
CGContextTranslateCTM(ctx, 0, -bounds.size.height)
// get the superclass to draw text
super.drawRect(rect)
}
// get image and end context
let img = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
// get drawRect context
let ctx = UIGraphicsGetCurrentContext()
// clip context to image
CGContextClipToMask(ctx, bounds, img.CGImage)
// define your colors and locations
let colors = [UIColor.orangeColor().CGColor, UIColor.redColor().CGColor, UIColor.purpleColor().CGColor, UIColor.blueColor().CGColor]
let locs:[CGFloat] = [0.0, 0.3, 0.6, 1.0]
// create your gradient
let grad = CGGradientCreateWithColors(CGColorSpaceCreateDeviceRGB(), colors, locs)
// draw gradient
CGContextDrawLinearGradient(ctx, grad, CGPoint(x: 0, y:bounds.size.height*0.5), CGPoint(x:bounds.size.width, y:bounds.size.height*0.5), CGGradientDrawingOptions(rawValue: 0))
}
class GradientLabel: UILabel {
// MARK: - Colors to create gradient from
@IBInspectable open var gradientFrom: UIColor?
@IBInspectable open var gradientTo: UIColor?
override func draw(_ rect: CGRect) {
// begin new image context to let the superclass draw the text in (so we can use it as a mask)
UIGraphicsBeginImageContextWithOptions(bounds.size, false, 0.0)
do {
// get your image context
guard let ctx = UIGraphicsGetCurrentContext() else { super.draw(rect); return }
// flip context
ctx.scaleBy(x: 1, y: -1)
ctx.translateBy(x: 0, y: -bounds.size.height)
// get the superclass to draw text
super.draw(rect)
}
// get image and end context
guard let img = UIGraphicsGetImageFromCurrentImageContext(), img.cgImage != nil else { return }
UIGraphicsEndImageContext()
// get drawRect context
guard let ctx = UIGraphicsGetCurrentContext() else { return }
// clip context to image
ctx.clip(to: bounds, mask: img.cgImage!)
// define your colors and locations
let colors: [CGColor] = [UIColor.orange.cgColor, UIColor.red.cgColor, UIColor.purple.cgColor, UIColor.blue.cgColor]
let locs: [CGFloat] = [0.0, 0.3, 0.6, 1.0]
// create your gradient
guard let grad = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: colors as CFArray, locations: locs) else { return }
// draw gradient
ctx.drawLinearGradient(grad, start: CGPoint(x: 0, y: bounds.size.height*0.5), end: CGPoint(x:bounds.size.width, y: bounds.size.height*0.5), options: CGGradientDrawingOptions(rawValue: 0))
}
}