1 #if HAVE_GD_BUNDLED
2 # include "gd.h"
3 #else
4 # include <gd.h>
5 #endif
6
7 #include "gd_intern.h"
8
9
10 /**
11 * Integer Ellipse functions (gdImageEllipse and gdImageFilledEllipse)
12 * Function added by Pierre-Alain Joye 02/08/2003 (paj@pearfr.org)
13 * See the ellipse function simplification for the equation
14 * as well as the midpoint algorithm.
15 */
16
gdImageEllipse(gdImagePtr im,int mx,int my,int w,int h,int c)17 void gdImageEllipse(gdImagePtr im, int mx, int my, int w, int h, int c)
18 {
19 int x=0,mx1=0,mx2=0,my1=0,my2=0;
20 long aq,bq,dx,dy,r,rx,ry,a,b;
21
22 a=w>>1;
23 b=h>>1;
24 gdImageSetPixel(im,mx+a, my, c);
25 gdImageSetPixel(im,mx-a, my, c);
26 mx1 = mx-a;my1 = my;
27 mx2 = mx+a;my2 = my;
28
29 aq = a * a;
30 bq = b * b;
31 dx = aq << 1;
32 dy = bq << 1;
33 r = a * bq;
34 rx = r << 1;
35 ry = 0;
36 x = a;
37 while (x > 0){
38 if (r > 0) {
39 my1++;my2--;
40 ry +=dx;
41 r -=ry;
42 }
43 if (r <= 0){
44 x--;
45 mx1++;mx2--;
46 rx -=dy;
47 r +=rx;
48 }
49 gdImageSetPixel(im,mx1, my1, c);
50 gdImageSetPixel(im,mx1, my2, c);
51 gdImageSetPixel(im,mx2, my1, c);
52 gdImageSetPixel(im,mx2, my2, c);
53 }
54 }
55
gdImageFilledEllipse(gdImagePtr im,int mx,int my,int w,int h,int c)56 void gdImageFilledEllipse (gdImagePtr im, int mx, int my, int w, int h, int c)
57 {
58 int x=0,mx1=0,mx2=0,my1=0,my2=0;
59 long aq,bq,dx,dy,r,rx,ry,a,b;
60 int i;
61 int old_y2;
62
63 a=w>>1;
64 b=h>>1;
65
66 for (x = mx-a; x <= mx+a; x++) {
67 gdImageSetPixel(im, x, my, c);
68 }
69
70 mx1 = mx-a;my1 = my;
71 mx2 = mx+a;my2 = my;
72
73 aq = a * a;
74 bq = b * b;
75 dx = aq << 1;
76 dy = bq << 1;
77 r = a * bq;
78 rx = r << 1;
79 ry = 0;
80 x = a;
81 old_y2=-2;
82 while (x > 0){
83 if (r > 0) {
84 my1++;my2--;
85 ry +=dx;
86 r -=ry;
87 }
88 if (r <= 0){
89 x--;
90 mx1++;mx2--;
91 rx -=dy;
92 r +=rx;
93 }
94 if(old_y2!=my2){
95 for(i=mx1;i<=mx2;i++){
96 gdImageSetPixel(im,i,my1,c);
97 gdImageSetPixel(im,i,my2,c);
98 }
99 }
100 old_y2 = my2;
101 }
102 }
103
104
105
