/* [<][>][^][v][top][bottom][index][help] */
DEFINITIONS
This source file includes following definitions.
- draw_arc
- draw_single_stroke
- draw_stroke
- gfxpoly_from_stroke
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "../gfxdevice.h"
#include "../gfxtools.h"
#include "poly.h"
#include "wind.h"
#include "convert.h"
/* notice: left/right for a coordinate system where y goes up, not down */
typedef enum {LEFT=0, RIGHT=1} leftright_t;
/* factor that determines into how many line fragments a spline is converted */
#define SUBFRACTION (2.4)
// spline equation:
// s(t) = t*t*x2 + 2*t*(1-t)*cx + (1-t)*(1-t)*x1
//
// s(0.5) = 0.25*x2 + 0.5*cx + 0.25*x1
// ds(t)/dt = 2*t*x2 + (2-2t)*cx + (2t-2)*x1
// ds(0) = 2*(cx-x1)
static void draw_arc(gfxdrawer_t*draw, double x, double y, double a1, double a2, double r)
{
if(a2<a1) a2+=M_PI*2;
double d = (a2-a1);
int steps = ceil(8*d/(M_PI*2)); // we use 8 splines for a full circle
if(!steps) return;
int t;
double step = (a2-a1)/steps;
double lastx = x+cos(a1)*r;
double lasty = y+sin(a1)*r;
/* we could probably build a table for this- there are only 8
possible values for step */
double r2 = r*(2-sqrt(0.5+0.5*cos(step)));
draw->lineTo(draw, x+cos(a1)*r,y+sin(a1)*r);
for(t=1;t<=steps;t++) {
double a = a1 + t*step;
double c = cos(a)*r;
double s = sin(a)*r;
double xx = c + x;
double yy = s + y;
double dx = x + cos(a-step/2)*r2;
double dy = y + sin(a-step/2)*r2;
draw->splineTo(draw, dx, dy, xx, yy);
lastx = xx;
lasty = yy;
}
}
static void draw_single_stroke(gfxpoint_t*p, int num, gfxdrawer_t*draw, double width, gfx_capType cap, gfx_joinType join, double limit)
{
width/=2;
if(width<=0)
width = 0.05;
/* remove duplicate points */
int s=1,t;
gfxpoint_t last = p[0];
for(t=1;t<num;t++) {
if(p[t].x != last.x || p[t].y != last.y) {
p[s++] = last = p[t];
}
}
num = s;
char closed = (num>2 && p[0].x == p[num-1].x && p[0].y == p[num-1].y);
int start = 0;
int end = num-1;
int incr = 1;
int pos = 0;
double lastw=0;
/* iterate through the points two times: first forward, then backward,
adding a stroke outline to the right side and line caps after each
pass */
int pass;
for(pass=0;pass<2;pass++) {
if(closed) {
double dx = p[end].x - p[end-incr].x;
double dy = p[end].y - p[end-incr].y;
lastw = atan2(dy,dx);
if(lastw<0) lastw+=M_PI*2;
}
int pos;
for(pos=start;pos!=end;pos+=incr) {
//printf("%d) %.2f %.2f\n", pos, p[pos].x, p[pos].y);
double dx = p[pos+incr].x - p[pos].x;
double dy = p[pos+incr].y - p[pos].y;
double w = atan2(dy,dx);
if(w<0) w+=M_PI*2;
if(closed || pos!=start) {
double d = w-lastw;
leftright_t turn;
if(d>=0 && d<M_PI) turn=LEFT;
else if(d<0 && d>-M_PI) turn=RIGHT;
else if(d>=M_PI) {turn=RIGHT;}
else if(d<=-M_PI) {turn=LEFT;d+=M_PI*2;}
else {assert(0);}
if(turn!=LEFT || join==gfx_joinBevel) {
// nothing to do. bevel joins are easy
} else if(join==gfx_joinRound) {
draw_arc(draw, p[pos].x, p[pos].y, lastw-M_PI/2, w-M_PI/2, width);
} else if(join==gfx_joinMiter) {
double xw = M_PI/2 - d/2;
if(xw>0) {
double r2 = 1.0 / sin(M_PI/2-d/2);
if(r2 < limit) {
r2 *= width;
double addx = cos(lastw-M_PI/2+d/2)*r2;
double addy = sin(lastw-M_PI/2+d/2)*r2;
draw->lineTo(draw, p[pos].x+addx, p[pos].y+addy);
}
}
}
}
double addx = cos(w-M_PI/2)*width;
double addy = sin(w-M_PI/2)*width;
draw->lineTo(draw, p[pos].x+addx, p[pos].y+addy);
double px2 = p[pos+incr].x + addx;
double py2 = p[pos+incr].y + addy;
draw->lineTo(draw, p[pos+incr].x+addx, p[pos+incr].y+addy);
lastw = w;
}
if(closed) {
draw->close(draw);
} else {
/* draw stroke ends. We draw duplicates of some points here. The drawer
implementation should be smart enough to remove them. */
double c = cos(lastw-M_PI/2)*width;
double s = sin(lastw-M_PI/2)*width;
if(cap == gfx_capButt) {
draw->lineTo(draw, p[pos].x+c, p[pos].y+s);
draw->lineTo(draw, p[pos].x-c, p[pos].y-s);
} else if(cap == gfx_capRound) {
draw_arc(draw, p[pos].x, p[pos].y, lastw-M_PI/2, lastw+M_PI/2, width);
} else if(cap == gfx_capSquare) {
double c = cos(lastw-M_PI/2)*width;
double s = sin(lastw-M_PI/2)*width;
draw->lineTo(draw, p[pos].x+c, p[pos].y+s);
draw->lineTo(draw, p[pos].x+c-s, p[pos].y+s+c);
draw->lineTo(draw, p[pos].x-c-s, p[pos].y-s+c);
draw->lineTo(draw, p[pos].x-c, p[pos].y-s);
}
lastw += M_PI; // for dots
}
start=num-1;
end=0;
incr=-1;
}
if(!closed)
draw->close(draw);
}
void draw_stroke(gfxline_t*start, gfxdrawer_t*draw, double width, gfx_capType cap, gfx_joinType join, double miterLimit)
{
if(!start)
return;
assert(start->type == gfx_moveTo);
gfxline_t*line = start;
// measure array size
int size = 0;
int pos = 0;
double lastx,lasty;
while(line) {
if(line->type == gfx_moveTo) {
if(pos>size) size = pos;
pos++;
} else if(line->type == gfx_lineTo) {
pos++;
} else if(line->type == gfx_splineTo) {
int parts = (int)(sqrt(fabs(line->x-2*line->sx+lastx) + fabs(line->y-2*line->sy+lasty))*SUBFRACTION);
if(!parts) parts = 1;
pos+=parts+1;
}
lastx = line->x;
lasty = line->y;
line = line->next;
}
if(pos>size) size = pos;
if(!size) return;
gfxpoint_t* points = malloc(sizeof(gfxpoint_t)*size);
line = start;
pos = 0;
while(line) {
if(line->type == gfx_moveTo) {
if(pos)
draw_single_stroke(points, pos, draw, width, cap, join, miterLimit);
pos = 0;
} else if(line->type == gfx_splineTo) {
int parts = (int)(sqrt(fabs(line->x-2*line->sx+lastx) + fabs(line->y-2*line->sy+lasty))*SUBFRACTION);
if(!parts) parts = 1;
double stepsize = 1.0/parts;
int i;
for(i=0;i<parts;i++) {
double t = (double)i*stepsize;
points[pos].x = (line->x*t*t + 2*line->sx*t*(1-t) + lastx*(1-t)*(1-t));
points[pos].y = (line->y*t*t + 2*line->sy*t*(1-t) + lasty*(1-t)*(1-t));
pos++;
}
}
lastx = points[pos].x = line->x;
lasty = points[pos].y = line->y;
pos++;
line = line->next;
}
if(pos) draw_single_stroke(points, pos, draw, width, cap, join, miterLimit);
free(points);
}
static windcontext_t onepolygon = {1};
gfxpoly_t* gfxpoly_from_stroke(gfxline_t*line, gfxcoord_t width, gfx_capType cap_style, gfx_joinType joint_style, gfxcoord_t miterLimit, double gridsize)
{
gfxdrawer_t d;
gfxdrawer_target_poly(&d, gridsize);
draw_stroke(line, &d, width, cap_style, joint_style, miterLimit);
gfxpoly_t*poly = (gfxpoly_t*)d.result(&d);
assert(gfxpoly_check(poly, 1));
gfxpoly_t*poly2 = gfxpoly_process(poly, 0, &windrule_circular, &onepolygon);
gfxpoly_destroy(poly);
return poly2;
}