使用图层(borderWidth,borderColor等)向UIImageView添加边框非常容易。是否有可能为图像添加边框,而不是图像视图?有人知道吗?
更新
我尝试按照以下建议使用extension
。谢谢你,但我没有得到理想的结果。这是我的代码。有什么问题?
import UIKit
class ViewController: UIViewController {
var imageView: UIImageView!
var sizeW = CGFloat()
var sizeH = CGFloat()
override func viewDidLoad() {
super.viewDidLoad()
sizeW = view.frame.width
sizeH = view.frame.height
setImage()
}
func setImage(){
//add image view
imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: sizeW/2, height: sizeH/2))
imageView.center = view.center
imageView.tintColor = UIColor.orange
imageView.contentMode = UIViewContentMode.scaleAspectFit
let imgOriginal = UIImage(named: "plum")!.withRenderingMode(.alwaysTemplate)
let borderImage = imgOriginal.imageWithBorder(width: 2, color: UIColor.blue)
imageView.image = borderImage
view.addSubview(imageView)
}
}
extension UIImage {
func imageWithBorder(width: CGFloat, color: UIColor) -> UIImage? {
let square = CGSize(width: min(size.width, size.height) + width * 2, height: min(size.width, size.height) + width * 2)
let imageView = UIImageView(frame: CGRect(origin: CGPoint(x: 0, y: 0), size: square))
imageView.contentMode = .center
imageView.image = self
imageView.layer.borderWidth = width
imageView.layer.borderColor = color.cgColor
UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, false, scale)
guard let context = UIGraphicsGetCurrentContext() else { return nil }
imageView.layer.render(in: context)
let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return result
}
}
带有红色边框的第二张图片或多或少是我需要的:
答案 0 :(得分:5)
在@ herme5的大力启发下,重构为更紧凑的Swift 5 / iOS12 +代码,如下所示(也解决了垂直翻转问题):
public extension UIImage {
/**
Returns the flat colorized version of the image, or self when something was wrong
- Parameters:
- color: The colors to user. By defaut, uses the ``UIColor.white`
- Returns: the flat colorized version of the image, or the self if something was wrong
*/
func colorized(with color: UIColor = .white) -> UIImage {
UIGraphicsBeginImageContextWithOptions(size, false, scale)
defer {
UIGraphicsEndImageContext()
}
guard let context = UIGraphicsGetCurrentContext(), let cgImage = cgImage else { return self }
let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
color.setFill()
context.translateBy(x: 0, y: size.height)
context.scaleBy(x: 1.0, y: -1.0)
context.clip(to: rect, mask: cgImage)
context.fill(rect)
guard let colored = UIGraphicsGetImageFromCurrentImageContext() else { return self }
return colored
}
/**
Returns the stroked version of the fransparent image with the given stroke color and the thickness.
- Parameters:
- color: The colors to user. By defaut, uses the ``UIColor.white`
- thickness: the thickness of the border. Default to `2`
- quality: The number of degrees (out of 360): the smaller the best, but the slower. Defaults to `10`.
- Returns: the stroked version of the image, or self if something was wrong
*/
func stroked(with color: UIColor = .white, thickness: CGFloat = 2, quality: CGFloat = 10) -> UIImage {
guard let cgImage = cgImage else { return self }
// Colorize the stroke image to reflect border color
let strokeImage = colorized(with: color)
guard let strokeCGImage = strokeImage.cgImage else { return self }
/// Rendering quality of the stroke
let step = quality == 0 ? 10 : abs(quality)
let oldRect = CGRect(x: thickness, y: thickness, width: size.width, height: size.height).integral
let newSize = CGSize(width: size.width + 2 * thickness, height: size.height + 2 * thickness)
let translationVector = CGPoint(x: thickness, y: 0)
UIGraphicsBeginImageContextWithOptions(newSize, false, scale)
guard let context = UIGraphicsGetCurrentContext() else { return self }
defer {
UIGraphicsEndImageContext()
}
context.translateBy(x: 0, y: newSize.height)
context.scaleBy(x: 1.0, y: -1.0)
context.interpolationQuality = .high
for angle: CGFloat in stride(from: 0, to: 360, by: step) {
let vector = translationVector.rotated(around: .zero, byDegrees: angle)
let transform = CGAffineTransform(translationX: vector.x, y: vector.y)
context.concatenate(transform)
context.draw(strokeCGImage, in: oldRect)
let resetTransform = CGAffineTransform(translationX: -vector.x, y: -vector.y)
context.concatenate(resetTransform)
}
context.draw(cgImage, in: oldRect)
guard let stroked = UIGraphicsGetImageFromCurrentImageContext() else { return self }
return stroked
}
}
extension CGPoint {
/**
Rotates the point from the center `origin` by `byDegrees` degrees along the Z axis.
- Parameters:
- origin: The center of he rotation;
- byDegrees: Amount of degrees to rotate around the Z axis.
- Returns: The rotated point.
*/
func rotated(around origin: CGPoint, byDegrees: CGFloat) -> CGPoint {
let dx = x - origin.x
let dy = y - origin.y
let radius = sqrt(dx * dx + dy * dy)
let azimuth = atan2(dy, dx) // in radians
let newAzimuth = azimuth + byDegrees * .pi / 180.0 // to radians
let x = origin.x + radius * cos(newAzimuth)
let y = origin.y + radius * sin(newAzimuth)
return CGPoint(x: x, y: y)
}
}
答案 1 :(得分:3)
以下是实现这一目标的方法:
将以下extension
添加到您的代码中:
extension UIImage {
func imageWithBorder(width: CGFloat, color: UIColor) -> UIImage? {
let square = CGSize(width: min(size.width, size.height) + width * 2, height: min(size.width, size.height) + width * 2)
let imageView = UIImageView(frame: CGRect(origin: CGPoint(x: 0, y: 0), size: square))
imageView.contentMode = .center
imageView.image = self
imageView.layer.borderWidth = width
imageView.layer.borderColor = color.cgColor
UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, false, scale)
guard let context = UIGraphicsGetCurrentContext() else { return nil }
imageView.layer.render(in: context)
let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return result
}
}
你可以这样使用它:
let imgOriginal = UIImage.init(named: "Richie_Rich")
img.image = imgOriginal?.imageWithBorder(width: 2, color: UIColor.blue)
结果将是:
Here是圆角的原始帖子,但我删除了该代码,因为您没有要求它。
答案 2 :(得分:1)
这是我在Swift 4中编写的UIImage扩展。正如IOSDealBreaker所说,这全都与图像处理有关,并且可能会发生某些特殊情况。您应该具有透明背景的png图像,并且如果尺寸大于原始尺寸,则要进行管理。
(0,0)
周围的距离就是边界粗细)我的方法使用许多util方法和类扩展。以下是一些数学运算,可以使向量(实际上是一个点)围绕另一个点旋转:Rotating a CGPoint around another CGPoint
extension CGPoint {
func rotated(around origin: CGPoint, byDegrees: CGFloat) -> CGPoint {
let dx = self.x - origin.x
let dy = self.y - origin.y
let radius = sqrt(dx * dx + dy * dy)
let azimuth = atan2(dy, dx) // in radians
let newAzimuth = azimuth + (byDegrees * CGFloat.pi / 180.0) // convert it to radians
let x = origin.x + radius * cos(newAzimuth)
let y = origin.y + radius * sin(newAzimuth)
return CGPoint(x: x, y: y)
}
}
我编写了自定义CIFilter来给具有透明背景的图像着色:Colorize a UIImage in Swift
class ColorFilter: CIFilter {
var inputImage: CIImage?
var inputColor: CIColor?
private let kernel: CIColorKernel = {
let kernelString =
"""
kernel vec4 colorize(__sample pixel, vec4 color) {
pixel.rgb = pixel.a * color.rgb;
pixel.a *= color.a;
return pixel;
}
"""
return CIColorKernel(source: kernelString)!
}()
override var outputImage: CIImage? {
guard let inputImage = inputImage, let inputColor = inputColor else { return nil }
let inputs = [inputImage, inputColor] as [Any]
return kernel.apply(extent: inputImage.extent, arguments: inputs)
}
}
extension UIImage {
func colorized(with color: UIColor) -> UIImage {
guard let cgInput = self.cgImage else {
return self
}
let colorFilter = ColorFilter()
colorFilter.inputImage = CIImage(cgImage: cgInput)
colorFilter.inputColor = CIColor(color: color)
if let ciOutputImage = colorFilter.outputImage {
let context = CIContext(options: nil)
let cgImg = context.createCGImage(ciOutputImage, from: ciOutputImage.extent)
return UIImage(cgImage: cgImg!, scale: self.scale, orientation: self.imageOrientation).alpha(color.rgba.alpha).withRenderingMode(self.renderingMode)
} else {
return self
}
}
在这一点上,您应该拥有一切来完成这项工作:
extension UIImage {
func stroked(with color: UIColor, size: CGFloat) -> UIImage {
let strokeImage = self.colorized(with: color)
let oldRect = CGRect(x: size, y: size, width: self.size.width, height: self.size.height).integral
let newSize = CGSize(width: self.size.width + (2*size), height: self.size.height + (2*size))
let translationVector = CGPoint(x: size, y: 0)
UIGraphicsBeginImageContextWithOptions(newSize, false, self.scale)
if let context = UIGraphicsGetCurrentContext() {
context.interpolationQuality = .high
let step = 10 // reduce the step to increase quality
for angle in stride(from: 0, to: 360, by: step) {
let vector = translationVector.rotated(around: .zero, byDegrees: CGFloat(angle))
let transform = CGAffineTransform(translationX: vector.x, y: vector.y)
context.concatenate(transform)
context.draw(strokeImage.cgImage!, in: oldRect)
let resetTransform = CGAffineTransform(translationX: -vector.x, y: -vector.y)
context.concatenate(resetTransform)
}
context.draw(self.cgImage!, in: oldRect)
let newImage = UIImage(cgImage: context.makeImage()!, scale: self.scale, orientation: self.imageOrientation)
UIGraphicsEndImageContext()
return newImage.withRenderingMode(self.renderingMode)
}
UIGraphicsEndImageContext()
return self
}
}
答案 3 :(得分:0)
图像的边框属于iOS的图像处理区域。这对于UIView而言并不容易,但它非常深,但如果你愿意去远方,这里有一个图书馆和一个旅程提示 https://github.com/BradLarson/GPUImage
尝试使用GPUImageThresholdEdgeDetectionFilter
或尝试OpenCV https://docs.opencv.org/2.4/doc/tutorials/ios/image_manipulation/image_manipulation.html
答案 4 :(得分:-1)
将此简单扩展用于UIImage
app.get('/test/xyz/:xyz_name?', test);
它将为您提供带粉红色边框的图像。