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487 lines
7.9 KiB
C
487 lines
7.9 KiB
C
![]() |
#include "fitz-base.h"
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#include "fitz-world.h"
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#include "fitz-draw.h"
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/*
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* Global Edge List -- list of straight path segments for scan conversion
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*
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* Stepping along the edges is with bresenham's line algorithm.
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*
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* See Mike Abrash -- Graphics Programming Black Book (notably chapter 40)
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*/
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fz_error *
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fz_newgel(fz_gel **gelp)
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{
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fz_gel *gel;
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gel = *gelp = fz_malloc(sizeof(fz_gel));
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if (!gel)
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return fz_outofmem;
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gel->edges = nil;
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gel->cap = 512;
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gel->len = 0;
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gel->edges = fz_malloc(sizeof(fz_edge) * gel->cap);
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if (!gel->edges) {
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fz_free(gel);
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return fz_outofmem;
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}
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gel->xmin = gel->ymin = INT_MAX;
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gel->xmax = gel->ymax = INT_MIN;
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gel->hs = 1;
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gel->vs = 1;
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return nil;
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}
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void
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fz_resetgel(fz_gel *gel, int hs, int vs)
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{
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gel->xmin = gel->ymin = INT_MAX;
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gel->xmax = gel->ymax = INT_MIN;
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gel->hs = hs;
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gel->vs = vs;
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gel->len = 0;
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}
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void
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fz_dropgel(fz_gel *gel)
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{
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fz_free(gel->edges);
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fz_free(gel);
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}
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fz_irect
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fz_boundgel(fz_gel *gel)
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{
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fz_irect bbox;
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bbox.x0 = fz_idiv(gel->xmin, gel->hs);
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bbox.y0 = fz_idiv(gel->ymin, gel->vs);
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bbox.x1 = fz_idiv(gel->xmax, gel->hs) + 1;
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bbox.y1 = fz_idiv(gel->ymax, gel->vs) + 1;
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return bbox;
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}
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fz_error *
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fz_insertgel(fz_gel *gel, float fx0, float fy0, float fx1, float fy1)
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{
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fz_edge *edge;
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int x0, y0, x1, y1;
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int dx, dy;
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int winding;
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int width;
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int tmp;
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fx0 *= gel->hs;
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fy0 *= gel->vs;
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fx1 *= gel->hs;
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fy1 *= gel->vs;
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/* TODO: should we round or truncate? */
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x0 = fx0 < 0 ? fx0 - 0.5 : fx0 + 0.5;
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y0 = fy0 < 0 ? fy0 - 0.5 : fy0 + 0.5;
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x1 = fx1 < 0 ? fx1 - 0.5 : fx1 + 0.5;
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y1 = fy1 < 0 ? fy1 - 0.5 : fy1 + 0.5;
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if (y0 == y1)
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return nil;
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if (y0 > y1) {
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winding = -1;
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tmp = x0; x0 = x1; x1 = tmp;
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tmp = y0; y0 = y1; y1 = tmp;
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}
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else
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winding = 1;
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if (x0 < gel->xmin) gel->xmin = x0;
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if (x0 > gel->xmax) gel->xmax = x0;
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if (x1 < gel->xmin) gel->xmin = x1;
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if (x1 > gel->xmax) gel->xmax = x1;
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if (y0 < gel->ymin) gel->ymin = y0;
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if (y1 > gel->ymax) gel->ymax = y1;
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if (gel->len + 1 == gel->cap) {
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int newcap = gel->cap + 512;
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fz_edge *newedges = fz_realloc(gel->edges, sizeof(fz_edge) * newcap);
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if (!newedges)
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return fz_outofmem;
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gel->cap = newcap;
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gel->edges = newedges;
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}
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edge = &gel->edges[gel->len++];
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dy = y1 - y0;
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dx = x1 - x0;
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width = dx < 0 ? -dx : dx;
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edge->xdir = dx > 0 ? 1 : -1;
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edge->ydir = winding;
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edge->x = x0;
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edge->y = y0;
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edge->h = dy;
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edge->adjdown = dy;
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/* initial error term going l->r and r->l */
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if (dx >= 0)
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edge->e = 0;
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else
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edge->e = -dy + 1;
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/* y-major edge */
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if (dy >= width) {
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edge->xmove = 0;
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edge->adjup = width;
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}
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/* x-major edge */
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else {
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edge->xmove = (width / dy) * edge->xdir;
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edge->adjup = width % dy;
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}
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return nil;
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}
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void
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fz_sortgel(fz_gel *gel)
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{
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fz_edge *a = gel->edges;
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int n = gel->len;
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int h, i, k;
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fz_edge t;
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h = 1;
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if (n < 14) {
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h = 1;
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}
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else {
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while (h < n)
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h = 3 * h + 1;
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h /= 3;
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h /= 3;
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}
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while (h > 0)
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{
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for (i = 0; i < n; i++) {
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t = a[i];
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k = i - h;
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/* TODO: sort on y major, x minor */
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while (k >= 0 && a[k].y > t.y) {
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a[k + h] = a[k];
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k -= h;
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}
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a[k + h] = t;
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}
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h /= 3;
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}
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}
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/*
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* Active Edge List -- keep track of active edges while sweeping
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*/
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fz_error *
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fz_newael(fz_ael **aelp)
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{
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fz_ael *ael;
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ael = *aelp = fz_malloc(sizeof(fz_ael));
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if (!ael)
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return fz_outofmem;
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ael->cap = 64;
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ael->len = 0;
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ael->edges = fz_malloc(sizeof(fz_edge*) * ael->cap);
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if (!ael->edges) {
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fz_free(ael);
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return fz_outofmem;
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}
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return nil;
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}
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void
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fz_dropael(fz_ael *ael)
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{
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fz_free(ael->edges);
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fz_free(ael);
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}
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static inline void
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sortael(fz_edge **a, int n)
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{
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int h, i, k;
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fz_edge *t;
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h = 1;
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if (n < 14) {
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h = 1;
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}
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else {
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while (h < n)
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h = 3 * h + 1;
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h /= 3;
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h /= 3;
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}
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while (h > 0)
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{
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for (i = 0; i < n; i++) {
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t = a[i];
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k = i - h;
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while (k >= 0 && a[k]->x > t->x) {
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a[k + h] = a[k];
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k -= h;
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}
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a[k + h] = t;
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}
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h /= 3;
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}
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}
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static fz_error *
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insertael(fz_ael *ael, fz_gel *gel, int y, int *e)
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{
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/* insert edges that start here */
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int e2 = *e;
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while (e2 < gel->len && gel->edges[e2].y == y) {
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if (ael->len + 1 == ael->cap) {
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int newcap = ael->cap + 256;
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fz_edge **newedges = fz_realloc(ael->edges, sizeof(fz_edge*) * newcap);
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if (!newedges)
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return fz_outofmem;
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ael->edges = newedges;
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ael->cap = newcap;
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}
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ael->edges[ael->len++] = &gel->edges[e2++];
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}
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*e = e2;
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/* shell-sort the edges by increasing x */
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sortael(ael->edges, ael->len);
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return nil;
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}
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static void
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advanceael(fz_ael *ael)
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{
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fz_edge *edge;
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int i = 0;
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while (i < ael->len)
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{
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edge = ael->edges[i];
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edge->h --;
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/* terminator! */
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if (edge->h == 0) {
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ael->edges[i] = ael->edges[--ael->len];
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}
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else {
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edge->x += edge->xmove;
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edge->e += edge->adjup;
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if (edge->e > 0) {
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edge->x += edge->xdir;
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edge->e -= edge->adjdown;
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}
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i ++;
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}
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}
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}
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/*
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* Scan convert
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*/
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static inline void
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addspan(unsigned char *list, int x0, int x1, int xofs, int hs)
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{
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int x0pix, x0sub;
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int x1pix, x1sub;
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if (x0 == x1)
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return;
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/* x between 0 and width of bbox */
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x0 -= xofs;
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x1 -= xofs;
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x0pix = x0 / hs;
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x0sub = x0 % hs;
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x1pix = x1 / hs;
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x1sub = x1 % hs;
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if (x0pix == x1pix)
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{
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list[x0pix] += x1sub - x0sub;
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list[x0pix+1] += x0sub - x1sub;
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}
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else
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{
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list[x0pix] += hs - x0sub;
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list[x0pix+1] += x0sub;
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list[x1pix] += x1sub - hs;
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list[x1pix+1] += -x1sub;
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}
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}
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static inline void
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nonzerowinding(fz_ael *ael, unsigned char *list, int xofs, int hs)
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{
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int winding = 0;
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int x = 0;
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int i;
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for (i = 0; i < ael->len; i++)
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{
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if (!winding && (winding + ael->edges[i]->ydir))
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x = ael->edges[i]->x;
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if (winding && !(winding + ael->edges[i]->ydir))
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addspan(list, x, ael->edges[i]->x, xofs, hs);
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winding += ael->edges[i]->ydir;
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}
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}
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static inline void
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evenodd(fz_ael *ael, unsigned char *list, int xofs, int hs)
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{
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int even = 0;
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int x = 0;
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int i;
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for (i = 0; i < ael->len; i++)
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{
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if (!even)
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x = ael->edges[i]->x;
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else
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addspan(list, x, ael->edges[i]->x, xofs, hs);
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even = !even;
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}
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}
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static inline void toalpha(unsigned char *list, int n)
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{
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int d = 0;
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while (n--)
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{
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d += *list;
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*list++ = d;
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}
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}
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static inline void blit(fz_pixmap *pix, int x, int y,
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unsigned char *list, int skipx, int len,
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unsigned char *rgb, int over)
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{
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unsigned char *dst;
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int cov;
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dst = pix->samples + ( (y - pix->y) * pix->w + (x - pix->x) ) * pix->n;
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cov = 0;
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while (skipx--)
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{
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cov += *list;
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*list = 0;
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++list;
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}
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if (rgb)
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fz_path_w3i1o4(rgb, list, cov, len, dst);
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else if (over)
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fz_path_1o1(list, cov, len, dst);
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else
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fz_path_1c1(list, cov, len, dst);
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}
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fz_error *
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fz_scanconvert(fz_gel *gel, fz_ael *ael, int eofill, fz_irect clip,
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fz_pixmap *pix, unsigned char *rgb, int over)
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{
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fz_error *error;
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unsigned char *deltas;
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int y, e;
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int yd, yc;
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int xmin = fz_idiv(gel->xmin, gel->hs);
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int xmax = fz_idiv(gel->xmax, gel->hs) + 1;
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int xofs = xmin * gel->hs;
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int hs = gel->hs;
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int vs = gel->vs;
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int skipx = clip.x0 - xmin;
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int clipn = clip.x1 - clip.x0;
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assert(clip.x0 >= xmin);
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assert(clip.x1 <= xmax);
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if (gel->len == 0)
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return nil;
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deltas = fz_malloc(xmax - xmin + 1);
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if (!deltas)
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return fz_outofmem;
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memset(deltas, 0, xmax - xmin + 1);
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e = 0;
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y = gel->edges[0].y;
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yc = fz_idiv(y, vs);
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yd = yc;
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while (ael->len > 0 || e < gel->len)
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{
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yc = fz_idiv(y, vs);
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if (yc != yd)
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{
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if (yd >= clip.y0 && yd < clip.y1)
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{
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blit(pix, xmin + skipx, yd, deltas, skipx, clipn, rgb, over);
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}
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}
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yd = yc;
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error = insertael(ael, gel, y, &e);
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if (error) {
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fz_free(deltas);
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return error;
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}
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if (yd >= clip.y0 && yd < clip.y1)
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{
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if (eofill)
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evenodd(ael, deltas, xofs, hs);
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else
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nonzerowinding(ael, deltas, xofs, hs);
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}
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advanceael(ael);
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|
if (ael->len > 0)
|
||
|
y ++;
|
||
|
else if (e < gel->len)
|
||
|
y = gel->edges[e].y;
|
||
|
}
|
||
|
|
||
|
if (yd >= clip.y0 && yd < clip.y1)
|
||
|
{
|
||
|
blit(pix, xmin + skipx, yd, deltas, skipx, clipn, rgb, over);
|
||
|
}
|
||
|
|
||
|
fz_free(deltas);
|
||
|
return nil;
|
||
|
}
|
||
|
|