Question

我正在编写一个简单的绘图应用程序，每次用户将手指放下来绘制时，都会使用不同的颜色。如果我设置我的＆＃34;红色，绿色，蓝色＆＃34;值到特定值，然后它绘制它应该，但当我尝试使用CGFloat随机函数时，应用程序似乎忽略用户输入。我验证了随机函数功能只是在生成随机值时打印出来。

如果我发表评论，请在下面的代码中

red = randomCGFloat(min: 1, max: 254)
green = randomCGFloat(min: 1, max: 254)
blue = randomCGFloat(min: 1, max: 254)

并在setStrokeColor中使用默认值0表示红色，绿色，蓝色，然后绘图应用程序通常使用黑色作为笔触颜色。如果我取消注释随机数发生器，那么当我尝试绘制时应用程序不会显示任何内容。随机化器的限制设置正确（并在打印输出消息中验证），因此我不确定为什么setStrokeColor忽略这些值。

import UIKit
import Foundation

class ViewController: UIViewController {

@IBOutlet weak var mainImageView: UIImageView!

var lastPoint = CGPoint.zero
var red: CGFloat = 0
var green: CGFloat = 0
var blue: CGFloat = 0
var brushWidth: CGFloat = 30.0
var opacity: CGFloat = 1.0
var swiped = false

override func viewDidLoad() {
super.viewDidLoad()

}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    swiped = false

    red = randomCGFloat(min: 1, max: 254)
    green = randomCGFloat(min: 1, max: 254)
    blue = randomCGFloat(min: 1, max: 254)

    print("red: \(red)")
    print("green: \(green)")
    print("blue: \(blue)")

    if let touch = touches.first {
        lastPoint = touch.location(in: self.view)

    }
}

func drawLineFrom(from fromPoint: CGPoint, to toPoint: CGPoint) {
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, false, 0)

    mainImageView.image?.draw(in: view.bounds)

    let context = UIGraphicsGetCurrentContext()

    context?.move(to: fromPoint)
    context?.addLine(to: toPoint)

    context?.setLineCap(CGLineCap.round)
    context?.setLineWidth(brushWidth)
    context?.setStrokeColor(red: red, green: green, blue: blue, alpha: 1.0)
    context?.setBlendMode(CGBlendMode.normal)
    context?.strokePath()

    mainImageView.image = UIGraphicsGetImageFromCurrentImageContext()
    mainImageView.alpha = opacity
    UIGraphicsEndImageContext()
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    swiped = true
    if let touch = touches.first {
        let currentPoint = touch.location(in: view)
        drawLineFrom(from: lastPoint, to: currentPoint)

        lastPoint = currentPoint
    }
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    if !swiped {
        // draw a single point
        self.drawLineFrom(from: lastPoint, to: lastPoint)
    }
}

func randomCGFloat(min: CGFloat, max: CGFloat) -> CGFloat {
    return round(CGFloat(Float(arc4random()) / Float(UINT32_MAX)) * (max - min) + min)
}

任何建议都将不胜感激！

Answer 1

传递给setStrokeColor的红色/绿色/蓝色值需要介于0.0和1.0之间，而不是代码中的1到254.

绘图应用程序不会使用随机生成的CGfloats，但会使用静态CGfloats进行颜色生成

1 个答案: