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Port insertion sort improvement of libgd 2.0.26 #17342

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Jan 4, 2025
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Port insertion sort improvement of libgd 2.0.26 #17342

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26 changes: 17 additions & 9 deletions ext/gd/libgd/gd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2715,8 +2715,6 @@ void gdImageOpenPolygon (gdImagePtr im, gdPointPtr p, int n, int c)
}
}

int gdCompareInt (const void *a, const void *b);

/* THANKS to Kirsten Schulz for the polygon fixes! */

/* The intersection finding technique of this code could be improved
Expand All @@ -2728,6 +2726,8 @@ int gdCompareInt (const void *a, const void *b);
void gdImageFilledPolygon (gdImagePtr im, gdPointPtr p, int n, int c)
{
int i;
int j;
int index;
int y;
int miny, maxy, pmaxy;
int x1, y1;
Expand Down Expand Up @@ -2832,8 +2832,21 @@ void gdImageFilledPolygon (gdImagePtr im, gdPointPtr p, int n, int c)
im->polyInts[ints++] = x2;
}
}
qsort(im->polyInts, ints, sizeof(int), gdCompareInt);

/*
2.0.26: polygons pretty much always have less than 100 points,
and most of the time they have considerably less. For such trivial
cases, insertion sort is a good choice. Also a good choice for
future implementations that may wish to indirect through a table.
*/
for (i = 1; (i < ints); i++) {
index = im->polyInts[i];
j = i;
while ((j > 0) && (im->polyInts[j - 1] > index)) {
im->polyInts[j] = im->polyInts[j - 1];
j--;
}
im->polyInts[j] = index;
}
for (i = 0; i < ints - 1; i += 2) {
gdImageLine(im, im->polyInts[i], y, im->polyInts[i + 1], y, fill_color);
}
Expand All @@ -2845,11 +2858,6 @@ void gdImageFilledPolygon (gdImagePtr im, gdPointPtr p, int n, int c)
}
}

int gdCompareInt (const void *a, const void *b)
{
return (*(const int *) a) - (*(const int *) b);
}

void gdImageSetStyle (gdImagePtr im, int *style, int noOfPixels)
{
if (im->style) {
Expand Down
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