| rsc | 324891a | 2006-06-25 18:58:06 +0000 | [diff] [blame] | 1 | #include <u.h> |
| 2 | #include <libc.h> |
| 3 | #include <draw.h> |
| 4 | #include <memdraw.h> |
| 5 | |
| 6 | /* |
| 7 | * elarc(dst,c,a,b,t,src,sp,alpha,phi) |
| 8 | * draws the part of an ellipse between rays at angles alpha and alpha+phi |
| 9 | * measured counterclockwise from the positive x axis. other |
| 10 | * arguments are as for ellipse(dst,c,a,b,t,src,sp) |
| 11 | */ |
| 12 | |
| 13 | enum |
| 14 | { |
| 15 | R, T, L, B /* right, top, left, bottom */ |
| 16 | }; |
| 17 | |
| 18 | static |
| 19 | Point corners[] = { |
| 20 | {1,1}, |
| 21 | {-1,1}, |
| 22 | {-1,-1}, |
| 23 | {1,-1} |
| 24 | }; |
| 25 | |
| 26 | static |
| 27 | Point p00; |
| 28 | |
| 29 | /* |
| 30 | * make a "wedge" mask covering the desired angle and contained in |
| 31 | * a surrounding square; draw a full ellipse; intersect that with the |
| 32 | * wedge to make a mask through which to copy src to dst. |
| 33 | */ |
| 34 | void |
| 35 | memarc(Memimage *dst, Point c, int a, int b, int t, Memimage *src, Point sp, int alpha, int phi, int op) |
| 36 | { |
| 37 | int i, w, beta, tmp, c1, c2, m, m1; |
| 38 | Rectangle rect; |
| 39 | Point p, bnd[8]; |
| 40 | Memimage *wedge, *figure, *mask; |
| 41 | |
| 42 | if(a < 0) |
| 43 | a = -a; |
| 44 | if(b < 0) |
| 45 | b = -b; |
| 46 | w = t; |
| 47 | if(w < 0) |
| 48 | w = 0; |
| 49 | alpha = -alpha; /* compensate for upside-down coords */ |
| 50 | phi = -phi; |
| 51 | beta = alpha + phi; |
| 52 | if(phi < 0){ |
| 53 | tmp = alpha; |
| 54 | alpha = beta; |
| 55 | beta = tmp; |
| 56 | phi = -phi; |
| 57 | } |
| 58 | if(phi >= 360){ |
| 59 | memellipse(dst, c, a, b, t, src, sp, op); |
| 60 | return; |
| 61 | } |
| 62 | while(alpha < 0) |
| 63 | alpha += 360; |
| 64 | while(beta < 0) |
| 65 | beta += 360; |
| 66 | c1 = alpha/90 & 3; /* number of nearest corner */ |
| 67 | c2 = beta/90 & 3; |
| 68 | /* |
| 69 | * icossin returns point at radius ICOSSCALE. |
| 70 | * multiplying by m1 moves it outside the ellipse |
| 71 | */ |
| 72 | rect = Rect(-a-w, -b-w, a+w+1, b+w+1); |
| 73 | m = rect.max.x; /* inradius of bounding square */ |
| 74 | if(m < rect.max.y) |
| 75 | m = rect.max.y; |
| 76 | m1 = (m+ICOSSCALE-1) >> 10; |
| 77 | m = m1 << 10; /* assure m1*cossin is inside */ |
| 78 | i = 0; |
| 79 | bnd[i++] = Pt(0,0); |
| 80 | icossin(alpha, &p.x, &p.y); |
| 81 | bnd[i++] = mulpt(p, m1); |
| 82 | for(;;) { |
| 83 | bnd[i++] = mulpt(corners[c1], m); |
| 84 | if(c1==c2 && phi<180) |
| 85 | break; |
| 86 | c1 = (c1+1) & 3; |
| 87 | phi -= 90; |
| 88 | } |
| 89 | icossin(beta, &p.x, &p.y); |
| 90 | bnd[i++] = mulpt(p, m1); |
| 91 | |
| 92 | figure = nil; |
| 93 | mask = nil; |
| 94 | wedge = allocmemimage(rect, GREY1); |
| 95 | if(wedge == nil) |
| 96 | goto Return; |
| 97 | memfillcolor(wedge, DTransparent); |
| 98 | memfillpoly(wedge, bnd, i, ~0, memopaque, p00, S); |
| 99 | figure = allocmemimage(rect, GREY1); |
| 100 | if(figure == nil) |
| 101 | goto Return; |
| 102 | memfillcolor(figure, DTransparent); |
| 103 | memellipse(figure, p00, a, b, t, memopaque, p00, S); |
| 104 | mask = allocmemimage(rect, GREY1); |
| 105 | if(mask == nil) |
| 106 | goto Return; |
| 107 | memfillcolor(mask, DTransparent); |
| 108 | memimagedraw(mask, rect, figure, rect.min, wedge, rect.min, S); |
| 109 | c = subpt(c, dst->r.min); |
| 110 | memdraw(dst, dst->r, src, subpt(sp, c), mask, subpt(p00, c), op); |
| 111 | |
| 112 | Return: |
| 113 | freememimage(wedge); |
| 114 | freememimage(figure); |
| 115 | freememimage(mask); |
| 116 | } |
