Question

可能是一个简单的问题。我正在尝试制作一个可以绘制直线的应用程序：水平垂直线和对角线。我也正在尝试对线路进行测量（还不行。）

我已确定我可以画线，但不能画直线（就像没有尺子的铅笔一样）在网上找不到任何文档来绘制直线）

import UIKit
import Foundation
class tekengedeelte: UIViewController, UITextFieldDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate  {


    @IBOutlet weak var tekenview: UIView!

    var path = UIBezierPath()
    var startPoint = CGPoint()
    var touchPoint = CGPoint()
    var setSigImage: ((_ data: UIImage) -> ())?
    var setcameraimage: ((_ data: UIImage) -> ())?

    override func viewDidLoad() {
        super.viewDidLoad()
        tekenview.layer.shadowOpacity = 1
        tekenview.layer.shadowRadius = 10
        tekenview.layer.shadowOffset = CGSize(width: 1, height: 1)
        tekenview.layer.shadowColor = UIColor.black.cgColor
        //tekenview.layer.shadowPath = UIBezierPath(rect: tekenview.bounds).cgPath
        tekenview.layer.shadowPath = CGPath(rect: tekenview.bounds, transform: nil)
        tekenview.layer.shouldRasterize = true

        tekenview.clipsToBounds = true
        tekenview.isMultipleTouchEnabled = false
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        let touch = touches.first
        if let point = touch?.location(in: tekenview) {
            startPoint = point
        }
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        let touch = touches.first
        if let point = touch?.location(in: tekenview) {
            touchPoint = point
        }

        path.move(to: startPoint)
        path.addLine(to: touchPoint)
        startPoint = touchPoint

        draw()
    }

    func draw() {
        let strokeLayer = CAShapeLayer()
        strokeLayer.fillColor = UIColor.black.cgColor
        strokeLayer.lineWidth = 5
        strokeLayer.strokeColor = UIColor.black.cgColor
        strokeLayer.path = path.cgPath
        tekenview.layer.addSublayer(strokeLayer)
        tekenview.setNeedsDisplay()
    }

    @IBAction func clearPressed(_ sender: UIButton) {
        path.removeAllPoints()
        tekenview.layer.sublayers = nil
        tekenview.setNeedsDisplay()
    }

    @IBAction func setPressed(_ sender: UIButton) {

        // Convert CanvasView to UIImage
        let renderer = UIGraphicsImageRenderer(size: tekenview.bounds.size)
        let image = renderer.image { ctx in
            view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
        }

        // Send image back to onboarding screen
        setSigImage?(image)

        // Rotate device back to portrait mode
        //let appDelegate = UIApplication.shared.delegate as! AppDelegate
       //appDelegate.r = .portrait


        // Close modal window
        dismiss(animated: true)
    }
    //foto maken
    @IBAction func camera(_ sender: UIButton) {
        if UIImagePickerController.isSourceTypeAvailable(UIImagePickerController.SourceType.camera){
            let imagePicker = UIImagePickerController()
            imagePicker.delegate = self
            imagePicker.sourceType = UIImagePickerController.SourceType.camera;
            imagePicker.allowsEditing = false
            self.present(imagePicker, animated: true, completion: nil)
        }
    }

    @IBAction func photolibraryaction(_ sender: UIButton) {
        if UIImagePickerController.isSourceTypeAvailable(UIImagePickerController.SourceType.photoLibrary) {
            let imagepicker = UIImagePickerController()
            imagepicker.delegate = self
            imagepicker.sourceType = UIImagePickerController.SourceType.photoLibrary;
            imagepicker.allowsEditing = true
            self.present(imagepicker, animated: true, completion: nil)
        }

    }
}

Answer 1

Reinier Melian解释了使用核心图形绘制直线。触摸结束后，使用CGContext绘制保存图像以在UIImageView中显示。

您需要保持当前的context 直到画线过程结束，之后您需要保留当前图像并清除{{1} }，再次绘制保存的图像，然后绘制新行。触摸结束时，请清除当前context并保存当前图像，然后再次开始新的线条绘制过程。

context

画直线快4

1 个答案: