将 BezierPath 转换为 SVG 文件

Question

我有一个从下面的代码生成的 NSBezierPath，我想将此路径转换为一个 svg 文件（请参阅下面的 svg 代码），我可以将其导入 Adob​​e Illustrator。任何想法如何做到这一点？

贝塞尔路径描述

NSColor* color0 = [NSColor colorWithCalibratedRed: 0 green: 0 blue: 0 alpha: 1];

{
    //// Bezier Drawing
    NSBezierPath* bezierPath = [NSBezierPath bezierPath];
    [bezierPath moveToPoint: NSMakePoint(2, 30.41)];
    [bezierPath curveToPoint: NSMakePoint(8.41, 1.91) controlPoint1: NSMakePoint(5.73, 41.21) controlPoint2: NSMakePoint(17.37, 63.33)];
    [bezierPath curveToPoint: NSMakePoint(49.79, 1.53) controlPoint1: NSMakePoint(45.32, 94.95) controlPoint2: NSMakePoint(41.89, 1.26)];
    [bezierPath setMiterLimit: 4];
    [bezierPath setLineCapStyle: NSRoundLineCapStyle];
    [bezierPath setLineJoinStyle: NSRoundLineJoinStyle];
    [color0 setStroke];
    [bezierPath setLineWidth: 3];
    [bezierPath stroke];
}

svg 描述

<?xml version="1.0" encoding="utf-8"?>
<!-- Generator: Adobe Illustrator 16.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
     width="200px" height="200px" viewBox="0 0 200 200" enable-background="new 0 0 200 200" xml:space="preserve">
<g id="n1">
    <path fill="none" stroke="#000000" stroke-width="3" stroke-linecap="round" stroke-linejoin="round" d="M2,169.585
        c3.73-10.794,15.369-32.913,6.406,28.508c36.91-93.04,33.489,0.644,41.384,0.381"/>
</g>
</svg>

一些观察

BezierPath 使用 [NSBezierPath bezierPath] 表示路径数据的开始，而 svg 使用 d = "path data"。

BezierPath 使用 moveToPoint，而 svg 使用 M。

BezierPath 使用 curveToPoint 而 svg 使用 c。

svg 不使用空格，而是使用非常紧凑的形式。

BezierPath 使用绝对坐标，而 svg 使用相对坐标。

对于曲线，BezierPath 使用“point, controlPoint1, controlPoint2”的顺序，而 svg 使用“controlPoint1, controlPoint2, point”的顺序。

请注意，我们正在将路径嵌入到 svg 中 width="200px" height="200px" 的框中。

使用这些观察，我们可以将 BezierPath 描述转换为 svg 描述，如下所示：

1. moveToPoint: NSMakePoint(2, 30.41)]

被翻译成 M2,169.59 (M=MoveToPoint, 2=2, 200-30.41=169.59)

1. curveToPoint: NSMakePoint(8.41, 1.91) controlPoint1: NSMakePoint(5.73, 41.21) controlPoint2: NSMakePoint(17.37, 63.33)]

被翻译成

c3.73-10.794,15.369-32.913,6.406,28.508

(c=curveToPoint, 3.73=5.73-2, -10.8=30.41-41.21, 15.37=17.37-2, 32.89=63.3-30.41, 6.41=8.41-2, 28.5=30.41-1.91))

等等

我想我可以使用这些观察来进行我自己的翻译，但如果已经有我可以使用的编写代码会更好，更通用。

Answer 1

这是解决我的问题的一种解决方案。但它只适用于贝塞尔路径。请注意，我只是在填写路径数据。这必须以下面的一些静态文本开头。如果有人有更通用或更好的解决方案，我想听听。

<?xml version="1.0" encoding="utf-8"?>
 ...
stroke-linejoin="round

还请注意，我使用的是 200x200 的画布（因此翻转 y 坐标时为 200）。

-(NSString *)svgFromBezierPath:(NSBezierPath *)path {
    int numElements = (int) [path elementCount];
    if (numElements == 0) {
        return nil;
    }

    NSString *result = @"d=\"";
    NSPoint points[3];
    NSString *xStr;
    NSString *yStr;
    NSString *xCp1;
    NSString *yCp1;
    NSString *xCp2;
    NSString *yCp2;
    NSString *temp;
    double yValue;

    for (int i=0; i < numElements; i++)
    {
        switch ([path elementAtIndex:i associatedPoints:points])
        {
            case NSMoveToBezierPathElement:
                xStr = [NSString stringWithFormat:@"%0.2f", points[0].x];
                yValue = 200 - points[0].y;
                yStr = [NSString stringWithFormat:@"%0.2f", yValue];

                temp = [NSString stringWithFormat:@"M%@,%@,",xStr, yStr];
                result = [result stringByAppendingString:temp];
                break;

            case NSLineToBezierPathElement:
                xStr = [NSString stringWithFormat:@"%0.2f", points[0].x];
                yValue = 200 - points[0].y;
                yStr = [NSString stringWithFormat:@"%0.2f", yValue];

                temp = [NSString stringWithFormat:@"L%@,%@,",xStr, yStr];
                result = [result stringByAppendingString:temp];
                break;

            case NSCurveToBezierPathElement:
                xStr = [NSString stringWithFormat:@"%0.2f", points[0].x];
                yValue = 200 - points[0].y;
                yStr = [NSString stringWithFormat:@"%0.2f", yValue];

                xCp1 = [NSString stringWithFormat:@"%0.2f", points[1].x];
                yValue = 200 - points[1].y;
                yCp1= [NSString stringWithFormat:@"%0.2f", yValue];

                xCp2 = [NSString stringWithFormat:@"%0.2f", points[2].x];
                yValue = 200 - points[2].y;
                yCp2= [NSString stringWithFormat:@"%0.2f", yValue];

                temp = [NSString stringWithFormat:@"C%@,%@,%@,%@,%@,%@,", xStr, yStr, xCp1, yCp1,xCp2, yCp2];
                result = [result stringByAppendingString:temp];
                break;

            case NSClosePathBezierPathElement:
                result = [result stringByAppendingString:@"z,"];
                break;
        }
    }

    result = [result substringToIndex:result.length-1]; // delete the trailing comma
    result = [result stringByAppendingString:@"\"/></svg>"];
    return result;
}