我正在扫描二维码。我使用 UIView
将屏幕的背景颜色更改为半透明颜色。但是,我想把扫描二维码的地方的背景色做成透明的。我该怎么办?
class QRcodeScannerViewController : UIViewController, AVCaptureMetadataOutputObjectsDelegate {
@IBOutlet weak var qrcodeView: UIView!
@IBOutlet weak var header: UINavigationBar!
@IBOutlet weak var flash: UIButton!
@IBOutlet weak var qrcodeScanArea: UIImageView!
var previewLayer: AVCaptureVideoPreviewLayer!
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor.black
self.qrcodeView.backgroundColor = UIColor.black.withAlphaComponent(0.5)
view.layer.insertSublayer(previewLayer, at: 0)
view.bringSubviewToFront(flash)
view.bringSubviewToFront(header)
header.setBackgroundImage(UIImage(), for: UIBarMetrics.default)
header.isTranslucent = true
header.backgroundColor = UIColor.clear
header.shadowImage = UIImage()
当前我的二维码扫描 View
这是我想要的 View :
我不知道我反转的是哪一部分,但只有我想要的颜色是黑色,其余的是透明的。
view.addSubview(qrcodeView)
let shape = CGRect(x: 0, y: 0, width: 200, height: 200)
let maskLayer = CAShapeLayer()
maskLayer.path = UIBezierPath(roundedRect: shape, cornerRadius: 0).cgPath
maskLayer.backgroundColor = UIColor.clear.cgColor
maskLayer.fillRule = CAShapeLayerFillRule.evenOdd
qrcodeView.layer.mask = maskLayer
我引用下面的答案制作并应用了类(class)。但这对我不起作用。
let focusview = FocusView.init(frame: qrcodeView.frame)
focusview.areaBackground = UIColor.black
view.addSubview(focusview)
最佳答案
我做过类似的事情......实际上是前段时间做的几乎一样的事情。
我已经把我用的代码挖出来放在这里供大家引用
fileprivate let focusSize: CGSize = CGSize(width: 218, height: 150)
fileprivate let focusCornerRadius: CGFloat = 10.0
class FocusView: UIView {
var areaBackground: UIColor? {
set {
maskedFocusView.backgroundColor = newValue
}
get {
return maskedFocusView.backgroundColor
}
}
fileprivate let maskedFocusView: MaskedFocusView = {
return MaskedFocusView()
}()
let focusView: UIView = {
let view = UIView()
view.layer.borderColor = UIColor.white.cgColor
view.layer.borderWidth = 2
view.layer.cornerRadius = focusCornerRadius
// view.layer.shadowColor = UIColor.white.cgColor
// view.layer.shadowRadius = 5.0
// view.layer.shadowOpacity = 0.9
// view.layer.shadowOffset = CGSize.zero
view.layer.masksToBounds = true
return view
}()
override func awakeFromNib() {
super.awakeFromNib()
commonInit()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
func commonInit() {
backgroundColor = UIColor.darkGray.withAlphaComponent(0.5)
translatesAutoresizingMaskIntoConstraints = false
addSubview(maskedFocusView)
addSubview(focusView)
setupFocusViewConstraints()
setupMaskedFocusViewConstraints()
}
func setupFocusViewConstraints() {
NSLayoutConstraint.activate(
focusView.centerXAnchor.constraint(equalTo: centerXAnchor),
focusView.centerYAnchor.constraint(equalTo: centerYAnchor)
)
let regularFocusViewConstraints = [
focusView.widthAnchor.constraint(equalToConstant: focusSize.width),
focusView.heightAnchor.constraint(equalToConstant: focusSize.height)
]
NSLayoutConstraint.activate(regularFocusViewConstraints)
}
func setupMaskedFocusViewConstraints() {
NSLayoutConstraint.activate(
maskedFocusView.centerXAnchor.constraint(equalTo: centerXAnchor),
maskedFocusView.centerYAnchor.constraint(equalTo: centerYAnchor),
maskedFocusView.topAnchor.constraint(equalTo: topAnchor),
maskedFocusView.bottomAnchor.constraint(equalTo: bottomAnchor),
maskedFocusView.leadingAnchor.constraint(equalTo: leadingAnchor),
maskedFocusView.trailingAnchor.constraint(equalTo: trailingAnchor)
)
}
}
// MARK: - Masked focus view
fileprivate class MaskedFocusView: UIView {
let maskLayer: CAShapeLayer = CAShapeLayer()
override func awakeFromNib() {
super.awakeFromNib()
commonInit()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
func commonInit() {
backgroundColor = UIColor.darkGray.withAlphaComponent(0.5)
maskLayer.backgroundColor = UIColor.clear.cgColor
layer.mask = maskLayer
translatesAutoresizingMaskIntoConstraints = false
}
override func layoutSubviews() {
super.layoutSubviews()
let width = bounds.width
let height = bounds.height
let x = (width - focusSize.width) / 2
let y = (height - focusSize.height) / 2
let focusRect = CGRect(x: x, y: y, width: focusSize.width, height: focusSize.height)
let fullRect = CGRect(origin: bounds.origin, size: bounds.size)
let path = CGMutablePath()
path.addPath(UIBezierPath(rect: fullRect).cgPath)
path.addPath(UIBezierPath(roundedRect: focusRect, cornerRadius: focusCornerRadius).reversing().cgPath)
maskLayer.path = path
maskLayer.fillRule = .evenOdd
}
}
// MARK: - Layout constraints extension
extension NSLayoutConstraint {
/// A helper function to activate layout constraints.
static func activate(_ constraints: NSLayoutConstraint? ...) {
for case let constraint in constraints {
guard let constraint = constraint else {
continue
}
(constraint.firstItem as? UIView)?.translatesAutoresizingMaskIntoConstraints = false
constraint.isActive = true
}
}
}
extension Array where Element: NSLayoutConstraint {
func activate() {
forEach {
if !$0.isActive {
$0.isActive = true
}
}
}
func deactivate() {
forEach {
if $0.isActive {
$0.isActive = false
}
}
}
}
关于ios - 如何快速改变颜色的一小部分?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58815049/