ios - 如何在 iOS 上的 Google map 中徒手绘制？

Question

在绘图应用程序中，我们可以识别用户何时开始绘图并移动手指以绘制线条/形状。我想在 map 上做同样的事情，我该怎么做？

Answer 1

基本步骤将包括:

1)每当用户开始绘图时添加一个叠加 View 。

lazy var canvasView:CanvasView = {

    var overlayView = CanvasView(frame: self.googleMapView.frame)
    overlayView.isUserInteractionEnabled = true
    overlayView.delegate = self
    return overlayView

}()
@IBAction func drawActn(_ sender: AnyObject?) {

    self.coordinates.removeAll()
    self.view.addSubview(canvasView)
    let origImage = UIImage(named: "pen")
    let tintedImage = origImage?.withRenderingMode(UIImageRenderingMode.alwaysTemplate)
    drawBtn.setImage(tintedImage, for: .normal)
    drawBtn.tintColor = UIColor.white
    drawBtn.backgroundColor = UIColor.red

}

2)在叠加 View 中自由手绘。

class CanvasView: UIImageView {

    weak var delegate:NotifyTouchEvents?
    var lastPoint = CGPoint.zero
    let brushWidth:CGFloat = 3.0
    let opacity :CGFloat = 1.0


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


        if let touch = touches.first {

            self.delegate?.touchBegan(touch: touch)
            lastPoint = touch.location(in: self)
        }
    }


    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {

        if let touch = touches.first  {

            self.delegate?.touchMoved(touch: touch)
            let currentPoint = touch.location(in: self)
            drawLineFrom(fromPoint: lastPoint, toPoint: currentPoint)
            lastPoint = currentPoint
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

        if let touch = touches.first  {

            self.delegate?.touchEnded(touch: touch)

        }
    }

    func drawLineFrom(fromPoint: CGPoint, toPoint: CGPoint) {

        UIGraphicsBeginImageContext(self.frame.size)
        let context = UIGraphicsGetCurrentContext()
        self.image?.draw(in: CGRect(x: 0, y: 0, width: self.frame.size.width, height: self.frame.size.height))

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

        context?.setLineCap(.round)
        context?.setLineWidth(brushWidth)
        context?.setStrokeColor(UIColor.black.cgColor)
        context?.setBlendMode(.normal)
        context?.strokePath()

        self.image = UIGraphicsGetImageFromCurrentImageContext()
        self.alpha = opacity
        UIGraphicsEndImageContext()

    }

}

3)使用委托(delegate)模式从OverlayView获取数组中的所有坐标到Controller

//MARK: GET DRAWABLE COORDINATES
extension ViewController:NotifyTouchEvents{

    func touchBegan(touch:UITouch){

        let location = touch.location(in: self.googleMapView)
        let coordinate = self.googleMapView.projection.coordinate(for: location)
        self.coordinates.append(coordinate)

    }

    func touchMoved(touch:UITouch){

        let location = touch.location(in: self.googleMapView)
        let coordinate = self.googleMapView.projection.coordinate(for: location)
        self.coordinates.append(coordinate)

    }

    func touchEnded(touch:UITouch){

        let location = touch.location(in: self.googleMapView)
        let coordinate = self.googleMapView.projection.coordinate(for: location)
        self.coordinates.append(coordinate)
        createPolygonFromTheDrawablePoints()
    }
}

4)将该坐标更改为多边形。

   func createPolygonFromTheDrawablePoints(){

        let numberOfPoints = self.coordinates.count
        //do not draw in mapview a single point
        if numberOfPoints > 2 { addPolyGonInMapView(drawableLoc: coordinates) }//neglects a single touch
        coordinates = []
        self.canvasView.image = nil
        self.canvasView.removeFromSuperview()

        let origImage = UIImage(named: "pen")
        let tintedImage = origImage?.withRenderingMode(UIImageRenderingMode.alwaysTemplate)
        drawBtn.setImage(tintedImage, for: .normal)
        drawBtn.tintColor = UIColor.red
        drawBtn.backgroundColor = UIColor.white

    }

    func  addPolyGonInMapView( drawableLoc:[CLLocationCoordinate2D]){

        isDrawingModeEnabled = true
        let path = GMSMutablePath()
        for loc in drawableLoc{

            path.add(loc)

        }
        let newpolygon = GMSPolygon(path: path)
        newpolygon.strokeWidth = 3
        newpolygon.strokeColor = UIColor.black
        newpolygon.fillColor = UIColor.black.withAlphaComponent(0.5)
        newpolygon.map = googleMapView
        if cancelDrawingBtn.isHidden == true{ cancelDrawingBtn.isHidden = false }
        userDrawablePolygons.append(newpolygon)
        addPolygonDeleteAnnotation(endCoordinate: drawableLoc.last!,polygon: newpolygon)
    }

我创建了一个演示项目，用于在 Swift 3 中的 Google map 上绘制/删除多个多边形 here .

请记住在 AppDelegate 中设置 API key 并更改包标识符以运行项目。