检测点是否在SVG路径中 [英] Detecting wether a point is inside a SVG Path
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 这里是 通过以下两个函数，程序集中的Xcode和 编辑2： p> 我发布了新问题 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： 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 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。 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: I'm aware of the CoreGraphics's How can I do this by writing my own method? EDIT: I'm trying to avoid Here are some examples of paths where Xcode breaks with and EDIT 2: I posted a new question about the 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: Creates an Path with only Line-Elements, quality is the number of segments a curve is split into Does CGPathContainsPoint and Interpolation in one step, quality is again the number of segments a curve is split into. Here is the implementation.
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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。
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 pre>
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
get_y_inflections get_cubic_coefficients 。
containsPoint：问题。
$ b $ p code $ CGPathRef CGPathCreatePolygonPath（CGPathRef path，int quality）;
BOOL CGPathContainsPointInterpolated（CGPathRef path，const CGAffineTransform * m，CGPoint point，bool eoFill，int quality）;
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;
}
"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:"
containsPoint: method, but I'd like to avoid using this method.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.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"
EXC_BAD_ACCESS in the assembly by the following two functions: get_y_inflections and get_cubic_coefficients.containsPoint: problem.CGPathRef CGPathCreatePolygonPath(CGPathRef path, int quality);BOOL CGPathContainsPointInterpolated(CGPathRef path, const CGAffineTransform *m, CGPoint point, bool eoFill, int quality);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;
}
