/
draw.c
1986 lines (1576 loc) · 44.4 KB
/
draw.c
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#include "imager.h"
#include "draw.h"
#include "log.h"
#include "imageri.h"
#include "imrender.h"
#include <limits.h>
int
i_ppix_norm(i_img *im, i_img_dim x, i_img_dim y, i_color const *col) {
i_color src;
i_color work;
int dest_alpha;
int remains;
if (!col->channel[3])
return 0;
switch (im->channels) {
case 1:
work = *col;
i_adapt_colors(2, 4, &work, 1);
i_gpix(im, x, y, &src);
remains = 255 - work.channel[1];
src.channel[0] = (src.channel[0] * remains
+ work.channel[0] * work.channel[1]) / 255;
return i_ppix(im, x, y, &src);
case 2:
work = *col;
i_adapt_colors(2, 4, &work, 1);
i_gpix(im, x, y, &src);
remains = 255 - work.channel[1];
dest_alpha = work.channel[1] + remains * src.channel[1] / 255;
if (work.channel[1] == 255) {
return i_ppix(im, x, y, &work);
}
else {
src.channel[0] = (work.channel[1] * work.channel[0]
+ remains * src.channel[0] * src.channel[1] / 255) / dest_alpha;
src.channel[1] = dest_alpha;
return i_ppix(im, x, y, &src);
}
case 3:
work = *col;
i_gpix(im, x, y, &src);
remains = 255 - work.channel[3];
src.channel[0] = (src.channel[0] * remains
+ work.channel[0] * work.channel[3]) / 255;
src.channel[1] = (src.channel[1] * remains
+ work.channel[1] * work.channel[3]) / 255;
src.channel[2] = (src.channel[2] * remains
+ work.channel[2] * work.channel[3]) / 255;
return i_ppix(im, x, y, &src);
case 4:
work = *col;
i_gpix(im, x, y, &src);
remains = 255 - work.channel[3];
dest_alpha = work.channel[3] + remains * src.channel[3] / 255;
if (work.channel[3] == 255) {
return i_ppix(im, x, y, &work);
}
else {
src.channel[0] = (work.channel[3] * work.channel[0]
+ remains * src.channel[0] * src.channel[3] / 255) / dest_alpha;
src.channel[1] = (work.channel[3] * work.channel[1]
+ remains * src.channel[1] * src.channel[3] / 255) / dest_alpha;
src.channel[2] = (work.channel[3] * work.channel[2]
+ remains * src.channel[2] * src.channel[3] / 255) / dest_alpha;
src.channel[3] = dest_alpha;
return i_ppix(im, x, y, &src);
}
}
return 0;
}
static void
cfill_from_btm(i_img *im, i_fill_t *fill, struct i_bitmap *btm,
i_img_dim bxmin, i_img_dim bxmax, i_img_dim bymin, i_img_dim bymax);
void
i_mmarray_cr(i_mmarray *ar,i_img_dim l) {
i_img_dim i;
size_t alloc_size;
ar->lines=l;
alloc_size = sizeof(minmax) * l;
/* check for overflow */
if (alloc_size / l != sizeof(minmax)) {
fprintf(stderr, "overflow calculating memory allocation");
exit(3);
}
ar->data=mymalloc(alloc_size); /* checked 5jul05 tonyc */
for(i=0;i<l;i++) { ar->data[i].max=-1; ar->data[i].min=MAXINT; }
}
void
i_mmarray_dst(i_mmarray *ar) {
ar->lines=0;
if (ar->data != NULL) { myfree(ar->data); ar->data=NULL; }
}
void
i_mmarray_add(i_mmarray *ar,i_img_dim x,i_img_dim y) {
if (y>-1 && y<ar->lines)
{
if (x<ar->data[y].min) ar->data[y].min=x;
if (x>ar->data[y].max) ar->data[y].max=x;
}
}
int
i_mmarray_gmin(i_mmarray *ar,i_img_dim y) {
if (y>-1 && y<ar->lines) return ar->data[y].min;
else return -1;
}
int
i_mmarray_getm(i_mmarray *ar,i_img_dim y) {
if (y>-1 && y<ar->lines) return ar->data[y].max;
else return MAXINT;
}
#if 0
/* unused? */
void
i_mmarray_render(i_img *im,i_mmarray *ar,i_color *val) {
i_img_dim i,x;
for(i=0;i<ar->lines;i++) if (ar->data[i].max!=-1) for(x=ar->data[i].min;x<ar->data[i].max;x++) i_ppix(im,x,i,val);
}
#endif
static
void
i_arcdraw(i_img_dim x1, i_img_dim y1, i_img_dim x2, i_img_dim y2, i_mmarray *ar) {
double alpha;
double dsec;
i_img_dim temp;
alpha=(double)(y2-y1)/(double)(x2-x1);
if (fabs(alpha) <= 1)
{
if (x2<x1) { temp=x1; x1=x2; x2=temp; temp=y1; y1=y2; y2=temp; }
dsec=y1;
while(x1<=x2)
{
i_mmarray_add(ar,x1,(i_img_dim)(dsec+0.5));
dsec+=alpha;
x1++;
}
}
else
{
alpha=1/alpha;
if (y2<y1) { temp=x1; x1=x2; x2=temp; temp=y1; y1=y2; y2=temp; }
dsec=x1;
while(y1<=y2)
{
i_mmarray_add(ar,(i_img_dim)(dsec+0.5),y1);
dsec+=alpha;
y1++;
}
}
}
void
i_mmarray_info(i_mmarray *ar) {
i_img_dim i;
for(i=0;i<ar->lines;i++)
if (ar->data[i].max!=-1)
printf("line %"i_DF ": min=%" i_DF ", max=%" i_DF ".\n",
i_DFc(i), i_DFc(ar->data[i].min), i_DFc(ar->data[i].max));
}
static void
i_arc_minmax(i_int_hlines *hlines,i_img_dim x,i_img_dim y, double rad,float d1,float d2) {
i_mmarray dot;
double f,fx,fy;
i_img_dim x1,y1;
i_mmarray_cr(&dot, hlines->limit_y);
x1=(i_img_dim)(x+0.5+rad*cos(d1*PI/180.0));
y1=(i_img_dim)(y+0.5+rad*sin(d1*PI/180.0));
fx=(float)x1; fy=(float)y1;
/* printf("x1: %d.\ny1: %d.\n",x1,y1); */
i_arcdraw(x, y, x1, y1, &dot);
x1=(i_img_dim)(x+0.5+rad*cos(d2*PI/180.0));
y1=(i_img_dim)(y+0.5+rad*sin(d2*PI/180.0));
for(f=d1;f<=d2;f+=0.01)
i_mmarray_add(&dot,(i_img_dim)(x+0.5+rad*cos(f*PI/180.0)),(i_img_dim)(y+0.5+rad*sin(f*PI/180.0)));
/* printf("x1: %d.\ny1: %d.\n",x1,y1); */
i_arcdraw(x, y, x1, y1, &dot);
/* render the minmax values onto the hlines */
for (y = 0; y < dot.lines; y++) {
if (dot.data[y].max!=-1) {
i_img_dim minx, width;
minx = dot.data[y].min;
width = dot.data[y].max - dot.data[y].min + 1;
i_int_hlines_add(hlines, y, minx, width);
}
}
/* dot.info(); */
i_mmarray_dst(&dot);
}
static void
i_arc_hlines(i_int_hlines *hlines,i_img_dim x,i_img_dim y,double rad,float d1,float d2) {
if (d1 <= d2) {
i_arc_minmax(hlines, x, y, rad, d1, d2);
}
else {
i_arc_minmax(hlines, x, y, rad, d1, 360);
i_arc_minmax(hlines, x, y, rad, 0, d2);
}
}
/*
=item i_arc(im, x, y, rad, d1, d2, color)
=category Drawing
=synopsis i_arc(im, 50, 50, 20, 45, 135, &color);
Fills an arc centered at (x,y) with radius I<rad> covering the range
of angles in degrees from d1 to d2, with the color.
=cut
*/
void
i_arc(i_img *im, i_img_dim x, i_img_dim y,double rad,double d1,double d2,const i_color *val) {
i_int_hlines hlines;
i_int_init_hlines_img(&hlines, im);
i_arc_hlines(&hlines, x, y, rad, d1, d2);
i_int_hlines_fill_color(im, &hlines, val);
i_int_hlines_destroy(&hlines);
}
/*
=item i_arc_cfill(im, x, y, rad, d1, d2, fill)
=category Drawing
=synopsis i_arc_cfill(im, 50, 50, 35, 90, 135, fill);
Fills an arc centered at (x,y) with radius I<rad> covering the range
of angles in degrees from d1 to d2, with the fill object.
=cut
*/
#define MIN_CIRCLE_STEPS 8
#define MAX_CIRCLE_STEPS 360
void
i_arc_cfill(i_img *im, i_img_dim x, i_img_dim y,double rad,double d1,double d2,i_fill_t *fill) {
i_int_hlines hlines;
i_int_init_hlines_img(&hlines, im);
i_arc_hlines(&hlines, x, y, rad, d1, d2);
i_int_hlines_fill_fill(im, &hlines, fill);
i_int_hlines_destroy(&hlines);
}
static void
arc_poly(int *count, double **xvals, double **yvals,
double x, double y, double rad, double d1, double d2) {
double d1_rad, d2_rad;
double circum;
i_img_dim steps, point_count;
double angle_inc;
/* normalize the angles */
d1 = fmod(d1, 360);
if (d1 == 0) {
if (d2 >= 360) { /* default is 361 */
d2 = 360;
}
else {
d2 = fmod(d2, 360);
if (d2 < d1)
d2 += 360;
}
}
else {
d2 = fmod(d2, 360);
if (d2 < d1)
d2 += 360;
}
d1_rad = d1 * PI / 180;
d2_rad = d2 * PI / 180;
/* how many segments for the curved part?
we do a maximum of one per degree, with a minimum of 8/circle
we try to aim at having about one segment per 2 pixels
Work it out per circle to get a step size.
I was originally making steps = circum/2 but that looked horrible.
I think there might be an issue in the polygon filler.
*/
circum = 2 * PI * rad;
steps = circum;
if (steps > MAX_CIRCLE_STEPS)
steps = MAX_CIRCLE_STEPS;
else if (steps < MIN_CIRCLE_STEPS)
steps = MIN_CIRCLE_STEPS;
angle_inc = 2 * PI / steps;
point_count = steps + 5; /* rough */
/* point_count is always relatively small, so allocation won't overflow */
*xvals = mymalloc(point_count * sizeof(double)); /* checked 17feb2005 tonyc */
*yvals = mymalloc(point_count * sizeof(double)); /* checked 17feb2005 tonyc */
/* from centre to edge at d1 */
(*xvals)[0] = x;
(*yvals)[0] = y;
(*xvals)[1] = x + rad * cos(d1_rad);
(*yvals)[1] = y + rad * sin(d1_rad);
*count = 2;
/* step around the curve */
while (d1_rad < d2_rad) {
(*xvals)[*count] = x + rad * cos(d1_rad);
(*yvals)[*count] = y + rad * sin(d1_rad);
++*count;
d1_rad += angle_inc;
}
/* finish off the curve */
(*xvals)[*count] = x + rad * cos(d2_rad);
(*yvals)[*count] = y + rad * sin(d2_rad);
++*count;
}
/*
=item i_arc_aa(im, x, y, rad, d1, d2, color)
=category Drawing
=synopsis i_arc_aa(im, 50, 50, 35, 90, 135, &color);
Anti-alias fills an arc centered at (x,y) with radius I<rad> covering
the range of angles in degrees from d1 to d2, with the color.
=cut
*/
void
i_arc_aa(i_img *im, double x, double y, double rad, double d1, double d2,
const i_color *val) {
double *xvals, *yvals;
int count;
arc_poly(&count, &xvals, &yvals, x, y, rad, d1, d2);
i_poly_aa(im, count, xvals, yvals, val);
myfree(xvals);
myfree(yvals);
}
/*
=item i_arc_aa_cfill(im, x, y, rad, d1, d2, fill)
=category Drawing
=synopsis i_arc_aa_cfill(im, 50, 50, 35, 90, 135, fill);
Anti-alias fills an arc centered at (x,y) with radius I<rad> covering
the range of angles in degrees from d1 to d2, with the fill object.
=cut
*/
void
i_arc_aa_cfill(i_img *im, double x, double y, double rad, double d1, double d2,
i_fill_t *fill) {
double *xvals, *yvals;
int count;
arc_poly(&count, &xvals, &yvals, x, y, rad, d1, d2);
i_poly_aa_cfill(im, count, xvals, yvals, fill);
myfree(xvals);
myfree(yvals);
}
/* Temporary AA HACK */
typedef i_img_dim frac;
static frac float_to_frac(double x) { return (frac)(0.5+x*16.0); }
static
void
polar_to_plane(double cx, double cy, float angle, double radius, frac *x, frac *y) {
*x = float_to_frac(cx+radius*cos(angle));
*y = float_to_frac(cy+radius*sin(angle));
}
static
void
make_minmax_list(i_mmarray *dot, double x, double y, double radius) {
float angle = 0.0;
float astep = radius>0.1 ? .5/radius : 10;
frac cx, cy, lx, ly, sx, sy;
mm_log((1, "make_minmax_list(dot %p, x %.2f, y %.2f, radius %.2f)\n", dot, x, y, radius));
polar_to_plane(x, y, angle, radius, &sx, &sy);
for(angle = 0.0; angle<361; angle +=astep) {
lx = sx; ly = sy;
polar_to_plane(x, y, angle, radius, &cx, &cy);
sx = cx; sy = cy;
if (fabs(cx-lx) > fabs(cy-ly)) {
int ccx, ccy;
if (lx>cx) {
ccx = lx; lx = cx; cx = ccx;
ccy = ly; ly = cy; cy = ccy;
}
for(ccx=lx; ccx<=cx; ccx++) {
ccy = ly + ((cy-ly)*(ccx-lx))/(cx-lx);
i_mmarray_add(dot, ccx, ccy);
}
} else {
int ccx, ccy;
if (ly>cy) {
ccy = ly; ly = cy; cy = ccy;
ccx = lx; lx = cx; cx = ccx;
}
for(ccy=ly; ccy<=cy; ccy++) {
if (cy-ly) ccx = lx + ((cx-lx)*(ccy-ly))/(cy-ly); else ccx = lx;
i_mmarray_add(dot, ccx, ccy);
}
}
}
}
/* Get the number of subpixels covered */
static
int
i_pixel_coverage(i_mmarray *dot, i_img_dim x, i_img_dim y) {
frac minx = x*16;
frac maxx = minx+15;
frac cy;
int cnt = 0;
for(cy=y*16; cy<(y+1)*16; cy++) {
frac tmin = dot->data[cy].min;
frac tmax = dot->data[cy].max;
if (tmax == -1 || tmin > maxx || tmax < minx) continue;
if (tmin < minx) tmin = minx;
if (tmax > maxx) tmax = maxx;
cnt+=1+tmax-tmin;
}
return cnt;
}
/*
=item i_circle_aa(im, x, y, rad, color)
=category Drawing
=synopsis i_circle_aa(im, 50, 50, 45, &color);
Anti-alias fills a circle centered at (x,y) for radius I<rad> with
color.
=cut
*/
void
i_circle_aa(i_img *im, double x, double y, double rad, const i_color *val) {
i_mmarray dot;
i_color temp;
i_img_dim ly;
mm_log((1, "i_circle_aa(im %p, centre(" i_DFp "), rad %.2f, val %p)\n",
im, i_DFcp(x, y), rad, val));
i_mmarray_cr(&dot,16*im->ysize);
make_minmax_list(&dot, x, y, rad);
for(ly = 0; ly<im->ysize; ly++) {
int ix, cy, minx = INT_MAX, maxx = INT_MIN;
/* Find the left/rightmost set subpixels */
for(cy = 0; cy<16; cy++) {
frac tmin = dot.data[ly*16+cy].min;
frac tmax = dot.data[ly*16+cy].max;
if (tmax == -1) continue;
if (minx > tmin) minx = tmin;
if (maxx < tmax) maxx = tmax;
}
if (maxx == INT_MIN) continue; /* no work to be done for this row of pixels */
minx /= 16;
maxx /= 16;
for(ix=minx; ix<=maxx; ix++) {
int cnt = i_pixel_coverage(&dot, ix, ly);
if (cnt>255) cnt = 255;
if (cnt) { /* should never be true */
int ch;
float ratio = (float)cnt/255.0;
i_gpix(im, ix, ly, &temp);
for(ch=0;ch<im->channels; ch++) temp.channel[ch] = (unsigned char)((float)val->channel[ch]*ratio + (float)temp.channel[ch]*(1.0-ratio));
i_ppix(im, ix, ly, &temp);
}
}
}
i_mmarray_dst(&dot);
}
/*
=item i_circle_out(im, x, y, r, col)
=category Drawing
=synopsis i_circle_out(im, 50, 50, 45, &color);
Draw a circle outline centered at (x,y) with radius r,
non-anti-aliased.
Parameters:
=over
=item *
(x, y) - the center of the circle
=item *
r - the radius of the circle in pixels, must be non-negative
=back
Returns non-zero on success.
Implementation:
=cut
*/
int
i_circle_out(i_img *im, i_img_dim xc, i_img_dim yc, i_img_dim r,
const i_color *col) {
i_img_dim x, y;
i_img_dim dx, dy;
int error;
i_clear_error();
if (r < 0) {
i_push_error(0, "circle: radius must be non-negative");
return 0;
}
i_ppix(im, xc+r, yc, col);
i_ppix(im, xc-r, yc, col);
i_ppix(im, xc, yc+r, col);
i_ppix(im, xc, yc-r, col);
x = 0;
y = r;
dx = 1;
dy = -2 * r;
error = 1 - r;
while (x < y) {
if (error >= 0) {
--y;
dy += 2;
error += dy;
}
++x;
dx += 2;
error += dx;
i_ppix(im, xc + x, yc + y, col);
i_ppix(im, xc + x, yc - y, col);
i_ppix(im, xc - x, yc + y, col);
i_ppix(im, xc - x, yc - y, col);
if (x != y) {
i_ppix(im, xc + y, yc + x, col);
i_ppix(im, xc + y, yc - x, col);
i_ppix(im, xc - y, yc + x, col);
i_ppix(im, xc - y, yc - x, col);
}
}
return 1;
}
/*
=item arc_seg(angle)
Convert an angle in degrees into an angle measure we can generate
simply from the numbers we have when drawing the circle.
=back
*/
static i_img_dim
arc_seg(double angle, int scale) {
i_img_dim seg = (angle + 45) / 90;
double remains = angle - seg * 90; /* should be in the range [-45,45] */
while (seg > 4)
seg -= 4;
if (seg == 4 && remains > 0)
seg = 0;
return scale * (seg * 2 + sin(remains * PI/180));
}
/*
=item i_arc_out(im, x, y, r, d1, d2, col)
=category Drawing
=synopsis i_arc_out(im, 50, 50, 45, 45, 135, &color);
Draw an arc outline centered at (x,y) with radius r, non-anti-aliased
over the angle range d1 through d2 degrees.
Parameters:
=over
=item *
(x, y) - the center of the circle
=item *
r - the radius of the circle in pixels, must be non-negative
=item *
d1, d2 - the range of angles to draw the arc over, in degrees.
=back
Returns non-zero on success.
Implementation:
=cut
*/
int
i_arc_out(i_img *im, i_img_dim xc, i_img_dim yc, i_img_dim r,
double d1, double d2, const i_color *col) {
i_img_dim x, y;
i_img_dim dx, dy;
int error;
i_img_dim segs[2][2];
int seg_count;
i_img_dim sin_th;
i_img_dim seg_d1, seg_d2;
int seg_num;
i_img_dim scale = r + 1;
i_img_dim seg1 = scale * 2;
i_img_dim seg2 = scale * 4;
i_img_dim seg3 = scale * 6;
i_img_dim seg4 = scale * 8;
i_clear_error();
if (r <= 0) {
i_push_error(0, "arc: radius must be non-negative");
return 0;
}
if (d1 + 360 <= d2)
return i_circle_out(im, xc, yc, r, col);
if (d1 < 0)
d1 += 360 * floor((-d1 + 359) / 360);
if (d2 < 0)
d2 += 360 * floor((-d2 + 359) / 360);
d1 = fmod(d1, 360);
d2 = fmod(d2, 360);
seg_d1 = arc_seg(d1, scale);
seg_d2 = arc_seg(d2, scale);
if (seg_d2 < seg_d1) {
/* split into two segments */
segs[0][0] = 0;
segs[0][1] = seg_d2;
segs[1][0] = seg_d1;
segs[1][1] = seg4;
seg_count = 2;
}
else {
segs[0][0] = seg_d1;
segs[0][1] = seg_d2;
seg_count = 1;
}
for (seg_num = 0; seg_num < seg_count; ++seg_num) {
i_img_dim seg_start = segs[seg_num][0];
i_img_dim seg_end = segs[seg_num][1];
if (seg_start == 0)
i_ppix(im, xc+r, yc, col);
if (seg_start <= seg1 && seg_end >= seg1)
i_ppix(im, xc, yc+r, col);
if (seg_start <= seg2 && seg_end >= seg2)
i_ppix(im, xc-r, yc, col);
if (seg_start <= seg3 && seg_end >= seg3)
i_ppix(im, xc, yc-r, col);
y = 0;
x = r;
dy = 1;
dx = -2 * r;
error = 1 - r;
while (y < x) {
if (error >= 0) {
--x;
dx += 2;
error += dx;
}
++y;
dy += 2;
error += dy;
sin_th = y;
if (seg_start <= sin_th && seg_end >= sin_th)
i_ppix(im, xc + x, yc + y, col);
if (seg_start <= seg1 - sin_th && seg_end >= seg1 - sin_th)
i_ppix(im, xc + y, yc + x, col);
if (seg_start <= seg1 + sin_th && seg_end >= seg1 + sin_th)
i_ppix(im, xc - y, yc + x, col);
if (seg_start <= seg2 - sin_th && seg_end >= seg2 - sin_th)
i_ppix(im, xc - x, yc + y, col);
if (seg_start <= seg2 + sin_th && seg_end >= seg2 + sin_th)
i_ppix(im, xc - x, yc - y, col);
if (seg_start <= seg3 - sin_th && seg_end >= seg3 - sin_th)
i_ppix(im, xc - y, yc - x, col);
if (seg_start <= seg3 + sin_th && seg_end >= seg3 + sin_th)
i_ppix(im, xc + y, yc - x, col);
if (seg_start <= seg4 - sin_th && seg_end >= seg4 - sin_th)
i_ppix(im, xc + x, yc - y, col);
}
}
return 1;
}
static double
cover(i_img_dim r, i_img_dim j) {
double rjsqrt = sqrt(r*r - j*j);
return ceil(rjsqrt) - rjsqrt;
}
/*
=item i_circle_out_aa(im, xc, yc, r, col)
=synopsis i_circle_out_aa(im, 50, 50, 45, &color);
Draw a circle outline centered at (x,y) with radius r, anti-aliased.
Parameters:
=over
=item *
(xc, yc) - the center of the circle
=item *
r - the radius of the circle in pixels, must be non-negative
=item *
col - an i_color for the color to draw in.
=back
Returns non-zero on success.
=cut
Based on "Fast Anti-Aliased Circle Generation", Xiaolin Wu, Graphics
Gems.
I use floating point for I<D> since for large circles the precision of
a [0,255] value isn't sufficient when approaching the end of the
octant.
*/
int
i_circle_out_aa(i_img *im, i_img_dim xc, i_img_dim yc, i_img_dim r, const i_color *col) {
i_img_dim i, j;
double t;
i_color workc = *col;
int orig_alpha = col->channel[3];
i_clear_error();
if (r <= 0) {
i_push_error(0, "arc: radius must be non-negative");
return 0;
}
i = r;
j = 0;
t = 0;
i_ppix_norm(im, xc+i, yc+j, col);
i_ppix_norm(im, xc-i, yc+j, col);
i_ppix_norm(im, xc+j, yc+i, col);
i_ppix_norm(im, xc+j, yc-i, col);
while (i > j+1) {
double d;
int cv, inv_cv;
j++;
d = cover(r, j);
cv = (int)(d * 255 + 0.5);
inv_cv = 255-cv;
if (d < t) {
--i;
}
if (inv_cv) {
workc.channel[3] = orig_alpha * inv_cv / 255;
i_ppix_norm(im, xc+i, yc+j, &workc);
i_ppix_norm(im, xc-i, yc+j, &workc);
i_ppix_norm(im, xc+i, yc-j, &workc);
i_ppix_norm(im, xc-i, yc-j, &workc);
if (i != j) {
i_ppix_norm(im, xc+j, yc+i, &workc);
i_ppix_norm(im, xc-j, yc+i, &workc);
i_ppix_norm(im, xc+j, yc-i, &workc);
i_ppix_norm(im, xc-j, yc-i, &workc);
}
}
if (cv && i > j) {
workc.channel[3] = orig_alpha * cv / 255;
i_ppix_norm(im, xc+i-1, yc+j, &workc);
i_ppix_norm(im, xc-i+1, yc+j, &workc);
i_ppix_norm(im, xc+i-1, yc-j, &workc);
i_ppix_norm(im, xc-i+1, yc-j, &workc);
if (j != i-1) {
i_ppix_norm(im, xc+j, yc+i-1, &workc);
i_ppix_norm(im, xc-j, yc+i-1, &workc);
i_ppix_norm(im, xc+j, yc-i+1, &workc);
i_ppix_norm(im, xc-j, yc-i+1, &workc);
}
}
t = d;
}
return 1;
}
/*
=item i_arc_out_aa(im, xc, yc, r, d1, d2, col)
=synopsis i_arc_out_aa(im, 50, 50, 45, 45, 125, &color);
Draw a circle arc outline centered at (x,y) with radius r, from angle
d1 degrees through angle d2 degrees, anti-aliased.
Parameters:
=over
=item *
(xc, yc) - the center of the circle
=item *
r - the radius of the circle in pixels, must be non-negative
=item *
d1, d2 - the range of angle in degrees to draw the arc through. If
d2-d1 >= 360 a full circle is drawn.
=back
Returns non-zero on success.
=cut
Based on "Fast Anti-Aliased Circle Generation", Xiaolin Wu, Graphics
Gems.
*/
int
i_arc_out_aa(i_img *im, i_img_dim xc, i_img_dim yc, i_img_dim r, double d1, double d2, const i_color *col) {
i_img_dim i, j;
double t;
i_color workc = *col;
i_img_dim segs[2][2];
int seg_count;
i_img_dim sin_th;
i_img_dim seg_d1, seg_d2;
int seg_num;
int orig_alpha = col->channel[3];
i_img_dim scale = r + 1;
i_img_dim seg1 = scale * 2;
i_img_dim seg2 = scale * 4;
i_img_dim seg3 = scale * 6;
i_img_dim seg4 = scale * 8;
i_clear_error();
if (r <= 0) {
i_push_error(0, "arc: radius must be non-negative");
return 0;
}
if (d1 + 360 <= d2)
return i_circle_out_aa(im, xc, yc, r, col);
if (d1 < 0)
d1 += 360 * floor((-d1 + 359) / 360);
if (d2 < 0)
d2 += 360 * floor((-d2 + 359) / 360);
d1 = fmod(d1, 360);
d2 = fmod(d2, 360);
seg_d1 = arc_seg(d1, scale);
seg_d2 = arc_seg(d2, scale);
if (seg_d2 < seg_d1) {
/* split into two segments */
segs[0][0] = 0;
segs[0][1] = seg_d2;
segs[1][0] = seg_d1;
segs[1][1] = seg4;
seg_count = 2;
}
else {
segs[0][0] = seg_d1;
segs[0][1] = seg_d2;
seg_count = 1;
}
for (seg_num = 0; seg_num < seg_count; ++seg_num) {
i_img_dim seg_start = segs[seg_num][0];
i_img_dim seg_end = segs[seg_num][1];
i = r;
j = 0;
t = 0;
if (seg_start == 0)
i_ppix_norm(im, xc+i, yc+j, col);
if (seg_start <= seg1 && seg_end >= seg1)
i_ppix_norm(im, xc+j, yc+i, col);
if (seg_start <= seg2 && seg_end >= seg2)
i_ppix_norm(im, xc-i, yc+j, col);
if (seg_start <= seg3 && seg_end >= seg3)
i_ppix_norm(im, xc+j, yc-i, col);
while (i > j+1) {
int cv, inv_cv;
double d;
j++;
d = cover(r, j);
cv = (int)(d * 255 + 0.5);
inv_cv = 255-cv;
if (d < t) {
--i;
}
sin_th = j;
if (inv_cv) {
workc.channel[3] = orig_alpha * inv_cv / 255;
if (seg_start <= sin_th && seg_end >= sin_th)
i_ppix_norm(im, xc+i, yc+j, &workc);
if (seg_start <= seg2 - sin_th && seg_end >= seg2 - sin_th)
i_ppix_norm(im, xc-i, yc+j, &workc);
if (seg_start <= seg4 - sin_th && seg_end >= seg4 - sin_th)
i_ppix_norm(im, xc+i, yc-j, &workc);