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Sort horizontal edges

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Tsung-Po Sun 2021-01-31 14:09:42 +09:00 committed by Andrew Murray
parent 330f77ae7a
commit da1bf96b70
1 changed files with 24 additions and 7 deletions
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31
src/libImaging/Draw.c
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@ -411,20 +411,32 @@ x_cmp(const void *x0, const void *x1) {
}
}
static int
horiz_edge_cmp(const void *he0, const void *he1) {
int diff = (*(Edge **)he0)->xmin - (*(Edge **)he1)->xmin;
if (diff < 0) {
return -1;
} else if (diff > 0) {
return 1;
} else {
return 0;
}
}
static void
draw_horizontal_lines(
Imaging im, int n, Edge *e, int ink, int *x_pos, int y, hline_handler hline) {
Imaging im, int n, Edge **e, int ink, int *x_pos, int y, hline_handler hline) {
int i;
for (i = 0; i < n; i++) {
if (e[i].ymin == y && e[i].ymin == e[i].ymax) {
if (e[i]->ymin == y) {
int xmax;
int xmin = e[i].xmin;
int xmin = e[i]->xmin;
if (*x_pos < xmin) {
// Line would be after the current position
continue;
}
xmax = e[i].xmax;
xmax = e[i]->xmax;
if (*x_pos > xmin) {
// Line would be partway through x_pos, so increase the starting point
xmin = *x_pos;
@ -434,7 +446,7 @@ draw_horizontal_lines(
}
}
(*hline)(im, xmin, e[i].ymin, xmax, ink);
(*hline)(im, xmin, e[i]->ymin, xmax, ink);
*x_pos = xmax + 1;
}
}
@ -448,6 +460,7 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill, hline_handler h
Edge **edge_table;
float *xx;
int edge_count = 0;
int horiz_edge_count = 0;
int ymin = im->ysize - 1;
int ymax = 0;
int i;
@ -471,6 +484,7 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill, hline_handler h
ymax = e[i].ymax;
}
if (e[i].ymin == e[i].ymax) {
edge_table[n - 1 - (horiz_edge_count++)] = (e + i);
continue;
}
edge_table[edge_count++] = (e + i);
@ -482,6 +496,9 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill, hline_handler h
ymax = im->ysize;
}
Edge **horiz_e = (edge_table + edge_count);
qsort(horiz_e, horiz_edge_count, sizeof(Edge *), horiz_edge_cmp);
/* Process the edge table with a scan line searching for intersections */
/* malloc check ok, using calloc */
xx = calloc(edge_count * 2, sizeof(float));
@ -510,7 +527,7 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill, hline_handler h
// Line would be before the current position
continue;
}
draw_horizontal_lines(im, n, e, ink, &x_pos, ymin, hline);
draw_horizontal_lines(im, horiz_edge_count, horiz_e, ink, &x_pos, ymin, hline);
if (x_end < x_pos) {
// Line would be before the current position
continue;
@ -528,7 +545,7 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill, hline_handler h
(*hline)(im, x_start, ymin, x_end, ink);
x_pos = x_end + 1;
}
draw_horizontal_lines(im, n, e, ink, &x_pos, ymin, hline);
draw_horizontal_lines(im, horiz_edge_count, horiz_e, ink, &x_pos, ymin, hline);
}
free(xx);