检测点是否在SVG路径中

检测点是否在SVG路径中

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检测点是否在SVG路径中

本文介绍了检测点是否在SVG路径中的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我试图检测一个给定的点是否在Objective-C的封闭SVG路径中。我无法弄清楚如何做数学运算。



我有一个路径坐标，我想确定一个随机点位于路径的内部还是外部。



以下是路径坐标的示例： 

 M673 460 c2 0 4 -1 5 -2 1 -1 2 -2 2 -4 0 -2 0 -3 0 -3 0 0 -3 1 -5 1 -3 1 -5 2 -5 3 0 1 0 3 0 4 1 0 2 1 3 1z：

我知道CoreGraphics的 containsPoint：方法，但我想避免使用这种方法。



如何通过编写我自己的方法来实现这一点？



编辑：

我试图避免 containsPoint ：，因为该函数在使用时似乎会在某些坐标/路径上崩溃。它看起来相当随机，当它崩溃，当它不。



这里是 containsPoint：使应用程序崩溃：

 M661 446 c1 -1 3 -1 4 -1 1 -1 2 -2 2  - 4 0 -2 0 -2 -2 -2 0 1 -2 1 -3 1 -2 0 -3 1 -3 2 0 1 0 2 0 3 0 0 1 1 2 1z
M535 460 c0 0 1 -1 1 -2 1 -2 0 -3 -1 -3 0 0 -1 0 -2 1 0 1 0 2 0 3 1 0 1 1 2 1z
  pre> 
 
 
通过以下两个函数，程序集中的Xcode和 EXC_BAD_ACCESS ： get_y_inflections 和 get_cubic_coefficients 。
 
 
 
 编辑2： p> 
 
 
我发布了  containsPoint：问题。 
 
解决方案
所以，因为我需要一个Polygon /从弯曲的路径插入我自己，我可能也有解决您的问题的方法：
 
 
 
这两个'Public'函数：
 $ b $ p code $ CGPathRef CGPathCreatePolygonPath（CGPathRef path，int quality）;  
 
 
 
创建一个仅包含线元素的路径，质量是曲线分成的线段数量
 
 
  BOOL CGPathContainsPointInterpolated（CGPathRef path，const CGAffineTransform * m，CGPoint point，bool eoFill，int quality）;   
 
 
 CGPathContainsPoint和Interpolation在一个步骤中，质量又是一条曲线分成的段的数量。
 
 
 
这是实现。
  typedef struct {
 CGMutablePathRef path; 
诠释质量; 
} InterpolationInfo; 
 
 static inline float cubeInterp（float t，float p0，float p1，float p2，float p3）{
 return powf（1-t，3）* p0 + 3 * powf（1 -t，2）* t * p1 + 3 *（1-t）* powf（t，2）* p2 + powf（t，3）* p3; 
} 
 
 static void pointsForCubeCurve（CGPoint cp0，CGPoint cp1，CGPoint cp2，CGPoint ep，CGPoint * buffer，int numberPoints）{
 for（int i = 0; i< numberPoints; i ++）{
 float t =（i + 1）/（float）numberPoints; 
 buffer [i] = CGPointMake（cubeInterp（t，cp0.x，cp1.x，cp2.x，ep.x），cubeInterp（t，cp0.y，cp1.y，cp2.y，ep。 Y））; 
 
 
 
 static int inline float quadInterp（float t，float p0，float p1，float p2）{
 return powf（1-t，2）* p0 + 2 *（1-t）* t * p1 + powf（t，2）* p2; 
 
 
 static void pointsForQuadCurve（CGPoint cp0，CGPoint cp，CGPoint ep，CGPoint * buffer，int numberPoints）{
 for（int i = 0; i< numberPoints; i ++ ）{
 float t =（i + 1）/（float）numberPoints; 
 buffer [i] = CGPointMake（quadInterp（t，cp0.x，cp.x，ep.x），quadInterp（t，cp0.x，cp.x，ep.x））; 
 
 
 
 static void CGPathElementConvertToPolygon（void * info，const CGPathElement * element）{
 InterpolationInfo * interpInfo = info; 
 switch（element-> type）{
 case kCGPathElementMoveToPoint：
 CGPathMoveToPoint（interpInfo-> path，NULL，element-> points [0] .x，element-> points [0] .Y）; 
休息; 
 case kCGPathElementAddLineToPoint：
 CGPathAddLineToPoint（interpInfo-> path，NULL，element-> points [0] .x，element-> points [0] .y）; 
休息; 
 case kCGPathElementAddQuadCurveToPoint：{
 int nr = interpInfo-> quality; 
 CGPoint缓冲区[nr]; 
 pointsForQuadCurve（CGPathGetCurrentPoint（interpInfo->路径），element-> points [0]，element-> points [1]，buffer，nr）; 
 for（int i = 0; i< nr; i ++）{
 CGPathAddLineToPoint（interpInfo-> path，NULL，buffer [i] .x，buffer [i] .y）; 
} 
 break; 
} 
 case kCGPathElementAddCurveToPoint：{
 int nr = interpInfo-> quality; 
 CGPoint缓冲区[nr]; （CGPathGetCurrentPoint（interpInfo->路径），元素 - >点[0]，元素 - >点[1]，元素 - >点[2]，缓冲区，nr）。 
 for（int i = 0; i< nr; i ++）{
 CGPathAddLineToPoint（interpInfo-> path，NULL，buffer [i] .x，buffer [i] .y）; 
} 
 break; 
} 
 case kCGPathElementCloseSubpath：
 CGPathCloseSubpath（interpInfo-> path）; 
休息; 
默认值：
 break; 
 
 
 
 static CGPathRef CGPathCreatePolygonPath（CGPathRef path，int quality）{
 CGMutablePathRef newPath = CGPathCreateMutable（）; 
 InterpolationInfo info; 
 info.path = newPath; 
 info.quality = quality; 
 CGPathApply（path，& info，CGPathElementConvertToPolygon）; 
返回newPath; 
} 
 
 static BOOL CGPathContainsPointInterpolated（CGPathRef path，const CGAffineTransform * m，CGPoint point，bool eoFill，int quality）{
 CGPathRef polygon = CGPathCreatePolygonPath（path，quality）; 
 BOOL returnValue = CGPathContainsPoint（polygon，m，point，eoFill）; 
 CGPathRelease（polygon）; 
返回returnValue; 
} 
  
 
I'm trying to detecting wether a given point is inside a closed SVG path in Objective-C. I'm having trouble figuring out how to do the math.
I have a path's coordinates and I'd like to determine wether a random point is inside or outside the path.
Here's an example of a path's coordinates:
"M673 460 c2 0 4 -1 5 -2 1 -1 2 -2 2 -4 0 -2 0 -3 0 -3 0 0 -3 1 -5 1 -3 1 -5 2 -5 3 0 1 0 3 0 4 1 0 2 1 3 1z:"

I'm aware of the CoreGraphics's containsPoint: method, but I'd like to avoid using this method.
How can I do this by writing my own method?
EDIT:
I'm trying to avoid containsPoint: because the function seems to crash on some coordinates / paths when using it. It looks quite random when it crashes and when it doesn't.
Here are some examples of paths where containsPoint: makes the app crash:
"M661 446 c1 -1 3 -1 4 -1 1 -1 2 -2 2 -4 0 -2 0 -2 -2 -2 0 1 -2 1 -3 1 -2 0 -3 1 -3 2 0 1 0 2 0 3 0 0 1 1 2 1z"
"M535 460 c0 0 1 -1 1 -2 1 -2 0 -3 -1 -3 0 0 -1 0 -2 1 0 1 0 2 0 3 1 0 1 1 2 1z"

Xcode breaks with and EXC_BAD_ACCESS in the assembly by the following two functions: get_y_inflections and get_cubic_coefficients.
EDIT 2:
I posted a new question about the containsPoint: problem.
 解决方案 
So, as i needed a Polygon/Interpolation from a Curved Path myself, i might have a solution for your problem as well: 
The two 'Public' Functions:
CGPathRef CGPathCreatePolygonPath(CGPathRef path, int quality);
Creates an Path with only Line-Elements, quality is the number of segments a curve is split into
BOOL CGPathContainsPointInterpolated(CGPathRef path, const CGAffineTransform *m, CGPoint point, bool eoFill, int quality);
Does CGPathContainsPoint and Interpolation in one step, quality is again the number of segments a curve is split into.
Here is the implementation.
typedef struct {
    CGMutablePathRef path;
    int quality;
} InterpolationInfo;

static inline float cubeInterp(float t, float p0, float p1, float p2, float p3) {
    return powf(1-t, 3)*p0 + 3*powf(1-t, 2)*t*p1 + 3*(1-t)*powf(t, 2)*p2 + powf(t, 3)*p3;
}

static void pointsForCubeCurve(CGPoint cp0, CGPoint cp1, CGPoint cp2, CGPoint ep, CGPoint *buffer, int numberPoints) {
    for (int i = 0; i<numberPoints; i++) {
        float t = (i+1)/(float)numberPoints;
        buffer[i] = CGPointMake(cubeInterp(t, cp0.x, cp1.x, cp2.x, ep.x), cubeInterp(t, cp0.y, cp1.y, cp2.y, ep.y));
    }
}

static inline float quadInterp(float t, float p0, float p1, float p2) {
    return powf(1-t, 2)*p0 + 2*(1-t)*t*p1 + powf(t, 2)*p2;
}

static void pointsForQuadCurve(CGPoint cp0, CGPoint cp, CGPoint ep, CGPoint *buffer, int numberPoints) {
    for (int i = 0; i<numberPoints; i++) {
        float t = (i+1)/(float)numberPoints;
        buffer[i] = CGPointMake(quadInterp(t, cp0.x, cp.x, ep.x), quadInterp(t, cp0.x, cp.x, ep.x));
    }
}

static void CGPathElementConvertToPolygon(void *info, const CGPathElement *element) {
    InterpolationInfo *interpInfo = info;
    switch (element->type) {
        case kCGPathElementMoveToPoint:
            CGPathMoveToPoint(interpInfo->path, NULL, element->points[0].x, element->points[0].y);
            break;
        case kCGPathElementAddLineToPoint:
            CGPathAddLineToPoint(interpInfo->path, NULL, element->points[0].x, element->points[0].y);
            break;
        case kCGPathElementAddQuadCurveToPoint: {
            int nr = interpInfo->quality;
            CGPoint buffer[nr];
            pointsForQuadCurve(CGPathGetCurrentPoint(interpInfo->path), element->points[0], element->points[1], buffer, nr);
            for (int i = 0; i<nr; i++) {
                CGPathAddLineToPoint(interpInfo->path, NULL, buffer[i].x, buffer[i].y);
            }
            break;
        }
        case kCGPathElementAddCurveToPoint: {
            int nr = interpInfo->quality;
            CGPoint buffer[nr];
            pointsForCubeCurve(CGPathGetCurrentPoint(interpInfo->path), element->points[0], element->points[1], element->points[2], buffer, nr);
            for (int i = 0; i<nr; i++) {
                CGPathAddLineToPoint(interpInfo->path, NULL, buffer[i].x, buffer[i].y);
            }
            break;
        }
        case kCGPathElementCloseSubpath:
            CGPathCloseSubpath(interpInfo->path);
            break;
        default:
            break;
    }
}

static CGPathRef CGPathCreatePolygonPath(CGPathRef path, int quality) {
    CGMutablePathRef newPath = CGPathCreateMutable();
    InterpolationInfo info;
    info.path = newPath;
    info.quality = quality;
    CGPathApply(path, &info, CGPathElementConvertToPolygon);
    return newPath;
}

static BOOL CGPathContainsPointInterpolated(CGPathRef path, const CGAffineTransform *m, CGPoint point, bool eoFill, int quality) {
    CGPathRef polygon = CGPathCreatePolygonPath(path, quality);
    BOOL returnValue = CGPathContainsPoint(polygon, m, point, eoFill);
    CGPathRelease(polygon);
    return returnValue;
}

                        
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08-20 11:27
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