为什么这个 CoreGraphics 绘图代码很慢？

Question

我根据我的其他一些开源程序编写了此绘图代码。

它根据用户名将线分成几层。

有效，只是速度很慢。我认为这是因为我正在添加图层并在我绘制的同一图层上循环遍历它们。这在 C++ 和 Javascript 中很快，但在 Swift.

中很慢

忽略 send_point，因为它不会减慢绘图代码的速度。（Crystal 服务器非常快，目前也忽略该命令。）

如何优化此代码？

//
//  GlobalDrawController.swift
//  GlobalChat
//
//  Created by Jonathan Silverman on 7/9/20.
//  Copyright © 2020 Jonathan Silverman. All rights reserved.
//

import Cocoa

class GlobalDrawController: NSViewController {
    
    @IBOutlet weak var drawing_view: NSView!
    
    var gcc: GlobalChatController?

    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do view setup here.
        print("viewDidLoad: gdc")
    }
    
}

class LineDrawer : NSView {
    var newLinear = NSBezierPath()
    
    
    var points : [[String : Any]] = []
    
    var nameHash : [String : Int] = [:] // which layer is this handle on
    
    var layerOrder : [String] = [] // which order to draw layers
    
    var layers : [String : Any] = [:] // which points are in a layer
    
//    var username : String = ""
    
    var scribbling : Bool = false
    var pen_color : NSColor = NSColor.black.usingColorSpace(NSColorSpace.deviceRGB)!
    var pen_width : CGFloat = CGFloat(1)
    
    func addClick(_ x: CGFloat, y: CGFloat, dragging: Bool, red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat, width: CGFloat, clickName: String) {
        var point : [String : Any] = [:]
        point["x"] = x
        point["y"] = y
        point["dragging"] = dragging
        point["red"] = red
        point["green"] = green
        point["blue"] = blue
        point["alpha"] = alpha
        point["width"] = width
        point["clickName"] = clickName
        points.append(point)
        
        var layerName : String = ""
        
        if(nameHash[clickName] == nil) {
            let layer = 0
            nameHash[clickName] = layer
            layerName = "\(clickName)_\(layer)"
            let layerArray : [[String : Any]] = []
            layers[layerName] = layerArray
        } else {
            if(dragging == false) {
                let layer = nameHash[clickName]! + 1
                nameHash[clickName] = layer
                layerName = "\(clickName)_\(layer)"
                let layerArray : [[String : Any]] = []
                layers[layerName] = layerArray
            } else {
                let layer = nameHash[clickName]!
                layerName = "\(clickName)_\(layer)"
            }
        }
        
        var tempLayers = layers[layerName] as! [[String : Any]]
        tempLayers.append(point)
        layers[layerName] = tempLayers
        
        if(!layerOrder.contains(layerName)) {
            layerOrder.append(layerName)
        }
        
    }
    
    func drawLineTo(_ lastPoint : CGPoint, _ endPoint : CGPoint, _ penColor : NSColor, _ penWidth : CGFloat) {
        newLinear.move(to: lastPoint)
        newLinear.line(to: endPoint)
        penColor.set()
        newLinear.lineWidth = penWidth
        newLinear.stroke()
    }
    
    
    func redraw() {
        NSColor.white.setFill() // allow configuration of this later
        bounds.fill()
        
        for layer in layerOrder {
            let layerArray = layers[layer] as! [[String : Any]]
            for i in 1...layerArray.count - 1 {
                let lastObj = layerArray[i - 1] as [String : Any]
                var lastPoint : CGPoint = CGPoint()
                lastPoint.x = lastObj["x"] as! CGFloat
                lastPoint.y = lastObj["y"] as! CGFloat
                let thisObj = layerArray[i] as [String : Any]
                var thisPoint : CGPoint = CGPoint()
                thisPoint.x = thisObj["x"] as! CGFloat
                thisPoint.y = thisObj["y"] as! CGFloat
                if(thisObj["dragging"] as! Bool && lastObj["dragging"] as! Bool) {
                    let red = lastObj["red"] as! CGFloat
                    let green = lastObj["green"] as! CGFloat
                    let blue = lastObj["blue"] as! CGFloat
                    let alpha = lastObj["alpha"] as! CGFloat
                    let penColor : NSColor = NSColor.init(red: red, green: green, blue: blue, alpha: alpha)
                    let penWidth = lastObj["width"] as! CGFloat
                    drawLineTo(lastPoint, thisPoint, penColor, penWidth)
                }
            }
        }
    }

    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
        let objectFrame: NSRect = self.frame
        if self.needsToDraw(objectFrame) {
            // drawing code for object
            redraw()
        }
    }

    override func mouseDown(with event: NSEvent) {
        let gdc = self.window?.contentViewController as! GlobalDrawController
        super.mouseDown(with: event)
        scribbling = true
        
        var lastPt = convert(event.locationInWindow, from: nil)
        lastPt.x -= frame.origin.x
        lastPt.y -= frame.origin.y
        
        addClick(lastPt.x, y: lastPt.y, dragging: false, red: pen_color.redComponent, green: pen_color.greenComponent, blue: pen_color.blueComponent, alpha: pen_color.alphaComponent, width: pen_width, clickName: gdc.gcc!.handle)
        
        send_point(lastPt.x, y: lastPt.y, dragging: false, red: pen_color.redComponent, green: pen_color.greenComponent, blue: pen_color.blueComponent, alpha: pen_color.alphaComponent, width: pen_width, clickName: gdc.gcc!.handle)
        
    }

    override func mouseDragged(with event: NSEvent) {
        let gdc = self.window?.contentViewController as! GlobalDrawController
        super.mouseDragged(with: event)
        var newPt = convert(event.locationInWindow, from: nil)
        newPt.x -= frame.origin.x
        newPt.y -= frame.origin.y
        
        addClick(newPt.x, y: newPt.y, dragging: true, red: pen_color.redComponent, green: pen_color.greenComponent, blue: pen_color.blueComponent, alpha: pen_color.alphaComponent, width: pen_width, clickName: gdc.gcc!.handle)
        
        
        send_point(newPt.x, y: newPt.y, dragging: true, red: pen_color.redComponent, green: pen_color.greenComponent, blue: pen_color.blueComponent, alpha: pen_color.alphaComponent, width: pen_width, clickName: gdc.gcc!.handle)

        needsDisplay = true
        
    }
    
    override func mouseUp(with event: NSEvent) {
        super.mouseUp(with: event)
        scribbling = false
        
    }
    
    
    func send_point(_ x: CGFloat, y: CGFloat, dragging: Bool, red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat, width: CGFloat, clickName: String) {
        let gdc = self.window?.contentViewController as! GlobalDrawController
        var point : [String] = []
        point.append(String(x.description))
        point.append(String(y.description))
        point.append(String(dragging.description))
        point.append(String(red.description))
        point.append(String(green.description))
        point.append(String(blue.description))
        point.append(String(alpha.description))
        point.append(String(width.description))
        point.append(String(gdc.gcc!.chat_token))
        gdc.gcc?.send_message("POINT", args: point)
    }
    
}

Answer 1

它很慢，因为我使用了 NSBezierPath。

这是一个更快的 DrawLineTo 方法。

    func drawLineTo(_ lastPoint : CGPoint, _ endPoint : CGPoint, _ penColor : NSColor, _ penWidth : CGFloat) {
        
        guard let context = NSGraphicsContext.current?.cgContext else { return }
        context.setStrokeColor(penColor.cgColor)
        context.setLineWidth(penWidth)
        context.move(to: lastPoint)
        context.addLine(to: endPoint)
        context.strokePath()
        
    }

为什么这个 CoreGraphics 绘图代码很慢？

Why is this CoreGraphics drawing code slow?

cocoa

core-graphics

swift