xref: /plan9-contrib/sys/src/cmd/unix/drawterm/libmemdraw/line.c (revision 7dd7cddf99dd7472612f1413b4da293630e6b1bc)
1 #include "../lib9.h"
2 
3 #include "../libdraw/draw.h"
4 #include "../libmemdraw/memdraw.h"
5 #include "../libmemlayer/memlayer.h"
6 
7 enum
8 {
9 	Arrow1 = 8,
10 	Arrow2 = 10,
11 	Arrow3 = 3
12 };
13 
14 /*
15  * not used
16 static
17 int
18 lmin(int a, int b)
19 {
20 	if(a < b)
21 		return a;
22 	return b;
23 }
24 */
25 
26 static
27 int
28 lmax(int a, int b)
29 {
30 	if(a > b)
31 		return a;
32 	return b;
33 }
34 
35 /*
36  * Rather than line clip, we run the Bresenham loop over the full line,
37  * and clip on each pixel.  This is more expensive but means that
38  * lines look the same regardless of how the windowing has tiled them.
39  * For speed, we check for clipping outside the loop and make the
40  * test easy when possible.
41  */
42 
43 #ifdef NOTUSED
44 static
45 void
46 horline1(Memimage *dst, Point p0, Point p1, int srcval, Rectangle clipr)
47 {
48 	int x, y, dy, deltay, deltax, maxx;
49 	int dd, easy, e, bpp, m, m0;
50 	uchar *d;
51 
52 	deltax = p1.x - p0.x;
53 	deltay = p1.y - p0.y;
54 	dd = dst->width*sizeof(ulong);
55 	dy = 1;
56 	if(deltay < 0){
57 		dd = -dd;
58 		deltay = -deltay;
59 		dy = -1;
60 	}
61 	maxx = lmin(p1.x, clipr.max.x-1);
62 	bpp = dst->depth;
63 	m0 = 0xFF^(0xFF>>bpp);
64 	m = m0 >> (p0.x&(7/dst->depth))*bpp;
65 	easy = ptinrect(p0, clipr) && ptinrect(p1, clipr);
66 	e = 2*deltay - deltax;
67 	y = p0.y;
68 	d = byteaddr(dst, p0);
69 	deltay *= 2;
70 	deltax = deltay - 2*deltax;
71 	for(x=p0.x; x<=maxx; x++){
72 		if(easy || (clipr.min.x<=x && clipr.min.y<=y && y<clipr.max.y))
73 			*d ^= (*d^srcval) & m;
74 		if(e > 0){
75 			y += dy;
76 			d += dd;
77 			e += deltax;
78 		}else
79 			e += deltay;
80 		d++;
81 		m >>= bpp;
82 		if(m == 0)
83 			m = m0;
84 	}
85 }
86 
87 static
88 void
89 verline1(Memimage *dst, Point p0, Point p1, int srcval, Rectangle clipr)
90 {
91 	int x, y, deltay, deltax, maxy;
92 	int easy, e, bpp, m, m0, dd;
93 	uchar *d;
94 
95 	deltax = p1.x - p0.x;
96 	deltay = p1.y - p0.y;
97 	dd = 1;
98 	if(deltax < 0){
99 		dd = -1;
100 		deltax = -deltax;
101 	}
102 	maxy = lmin(p1.y, clipr.max.y-1);
103 	bpp = dst->depth;
104 	m0 = 0xFF^(0xFF>>bpp);
105 	m = m0 >> (p0.x&(7/dst->depth))*bpp;
106 	easy = ptinrect(p0, clipr) && ptinrect(p1, clipr);
107 	e = 2*deltax - deltay;
108 	x = p0.x;
109 	d = byteaddr(dst, p0);
110 	deltax *= 2;
111 	deltay = deltax - 2*deltay;
112 	for(y=p0.y; y<=maxy; y++){
113 		if(easy || (clipr.min.y<=y && clipr.min.x<=x && x<clipr.max.x))
114 			*d ^= (*d^srcval) & m;
115 		if(e > 0){
116 			x += dd;
117 			d += dd;
118 			e += deltay;
119 		}else
120 			e += deltax;
121 		d += dst->width*sizeof(ulong);
122 		m >>= bpp;
123 		if(m == 0)
124 			m = m0;
125 	}
126 }
127 
128 static
129 void
130 horliner(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
131 {
132 	int x, y, sx, sy, deltay, deltax, minx, maxx;
133 	int bpp, m, m0;
134 	uchar *d, *s;
135 
136 	deltax = p1.x - p0.x;
137 	deltay = p1.y - p0.y;
138 	sx = drawreplxy(src->r.min.x, src->r.max.x, p0.x+dsrc.x);
139 	minx = lmax(p0.x, clipr.min.x);
140 	maxx = lmin(p1.x, clipr.max.x-1);
141 	bpp = dst->depth;
142 	m0 = 0xFF^(0xFF>>bpp);
143 	m = m0 >> (minx&(7/dst->depth))*bpp;
144 	for(x=minx; x<=maxx; x++){
145 		y = p0.y + (deltay*(x-p0.x)+deltax/2)/deltax;
146 		if(clipr.min.y<=y && y<clipr.max.y){
147 			d = byteaddr(dst, Pt(x, y));
148 			sy = drawreplxy(src->r.min.y, src->r.max.y, y+dsrc.y);
149 			s = byteaddr(src, Pt(sx, sy));
150 			*d ^= (*d^*s) & m;
151 		}
152 		if(++sx >= src->r.max.x)
153 			sx = src->r.min.x;
154 		m >>= bpp;
155 		if(m == 0)
156 			m = m0;
157 	}
158 }
159 
160 static
161 void
162 verliner(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
163 {
164 	int x, y, sx, sy, deltay, deltax, miny, maxy;
165 	int bpp, m, m0;
166 	uchar *d, *s;
167 
168 	deltax = p1.x - p0.x;
169 	deltay = p1.y - p0.y;
170 	sy = drawreplxy(src->r.min.y, src->r.max.y, p0.y+dsrc.y);
171 	miny = lmax(p0.y, clipr.min.y);
172 	maxy = lmin(p1.y, clipr.max.y-1);
173 	bpp = dst->depth;
174 	m0 = 0xFF^(0xFF>>bpp);
175 	for(y=miny; y<=maxy; y++){
176 		if(deltay == 0)	/* degenerate line */
177 			x = p0.x;
178 		else
179 			x = p0.x + (deltax*(y-p0.y)+deltay/2)/deltay;
180 		if(clipr.min.x<=x && x<clipr.max.x){
181 			m = m0 >> (x&(7/dst->depth))*bpp;
182 			d = byteaddr(dst, Pt(x, y));
183 			sx = drawreplxy(src->r.min.x, src->r.max.x, x+dsrc.x);
184 			s = byteaddr(src, Pt(sx, sy));
185 			*d ^= (*d^*s) & m;
186 		}
187 		if(++sy >= src->r.max.y)
188 			sy = src->r.min.y;
189 	}
190 }
191 
192 static
193 void
194 horline(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
195 {
196 	int x, y, deltay, deltax, minx, maxx;
197 	int bpp, m, m0;
198 	uchar *d, *s;
199 
200 	deltax = p1.x - p0.x;
201 	deltay = p1.y - p0.y;
202 	minx = lmax(p0.x, clipr.min.x);
203 	maxx = lmin(p1.x, clipr.max.x-1);
204 	bpp = dst->depth;
205 	m0 = 0xFF^(0xFF>>bpp);
206 	m = m0 >> (minx&(7/dst->depth))*bpp;
207 	for(x=minx; x<=maxx; x++){
208 		y = p0.y + (deltay*(x-p0.x)+deltay/2)/deltax;
209 		if(clipr.min.y<=y && y<clipr.max.y){
210 			d = byteaddr(dst, Pt(x, y));
211 			s = byteaddr(src, addpt(dsrc, Pt(x, y)));
212 			*d ^= (*d^*s) & m;
213 		}
214 		m >>= bpp;
215 		if(m == 0)
216 			m = m0;
217 	}
218 }
219 
220 static
221 void
222 verline(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
223 {
224 	int x, y, deltay, deltax, miny, maxy;
225 	int bpp, m, m0;
226 	uchar *d, *s;
227 
228 	deltax = p1.x - p0.x;
229 	deltay = p1.y - p0.y;
230 	miny = lmax(p0.y, clipr.min.y);
231 	maxy = lmin(p1.y, clipr.max.y-1);
232 	bpp = dst->depth;
233 	m0 = 0xFF^(0xFF>>bpp);
234 	for(y=miny; y<=maxy; y++){
235 		if(deltay == 0)	/* degenerate line */
236 			x = p0.x;
237 		else
238 			x = p0.x + deltax*(y-p0.y)/deltay;
239 		if(clipr.min.x<=x && x<clipr.max.x){
240 			m = m0 >> (x&(7/dst->depth))*bpp;
241 			d = byteaddr(dst, Pt(x, y));
242 			s = byteaddr(src, addpt(dsrc, Pt(x, y)));
243 			*d ^= (*d^*s) & m;
244 		}
245 	}
246 }
247 #endif /* NOTUSED */
248 
249 Memimage*
250 membrush(int radius)
251 {
252 	static Memimage *brush;
253 	static int brushradius;
254 
255 	if(brush==nil || brushradius!=radius){
256 		freememimage(brush);
257 		brush = allocmemimage(Rect(0, 0, 2*radius+1, 2*radius+1), memopaque->chan);
258 		if(brush != nil){
259 			memfillcolor(brush, DTransparent);	/* zeros */
260 			memellipse(brush, Pt(radius, radius), radius, radius, -1, memopaque, Pt(radius, radius));
261 		}
262 		brushradius = radius;
263 	}
264 	return brush;
265 }
266 
267 static
268 void
269 discend(Point p, int radius, Memimage *dst, Memimage *src, Point dsrc)
270 {
271 	Memimage *disc;
272 	Rectangle r;
273 
274 	disc = membrush(radius);
275 	if(disc != nil){
276 		r.min.x = p.x - radius;
277 		r.min.y = p.y - radius;
278 		r.max.x = p.x + radius+1;
279 		r.max.y = p.y + radius+1;
280 		memdraw(dst, r, src, addpt(r.min, dsrc), disc, Pt(0,0));
281 	}
282 }
283 
284 static
285 void
286 arrowend(Point tip, Point *pp, int end, int sin, int cos, int radius)
287 {
288 	int x1, x2, x3;
289 
290 	/* before rotation */
291 	if(end == Endarrow){
292 		x1 = Arrow1;
293 		x2 = Arrow2;
294 		x3 = Arrow3;
295 	}else{
296 		x1 = (end>>5) & 0x1FF;	/* distance along line from end of line to tip */
297 		x2 = (end>>14) & 0x1FF;	/* distance along line from barb to tip */
298 		x3 = (end>>23) & 0x1FF;	/* distance perpendicular from edge of line to barb */
299 	}
300 
301 	/* comments follow track of right-facing arrowhead */
302 	pp->x = tip.x+((2*radius+1)*sin/2-x1*cos);		/* upper side of shaft */
303 	pp->y = tip.y-((2*radius+1)*cos/2+x1*sin);
304 	pp++;
305 	pp->x = tip.x+((2*radius+2*x3+1)*sin/2-x2*cos);		/* upper barb */
306 	pp->y = tip.y-((2*radius+2*x3+1)*cos/2+x2*sin);
307 	pp++;
308 	pp->x = tip.x;
309 	pp->y = tip.y;
310 	pp++;
311 	pp->x = tip.x+(-(2*radius+2*x3+1)*sin/2-x2*cos);	/* lower barb */
312 	pp->y = tip.y-(-(2*radius+2*x3+1)*cos/2+x2*sin);
313 	pp++;
314 	pp->x = tip.x+(-(2*radius+1)*sin/2-x1*cos);		/* lower side of shaft */
315 	pp->y = tip.y+((2*radius+1)*cos/2-x1*sin);
316 }
317 
318 void
319 _memimageline(Memimage *dst, Point p0, Point p1, int end0, int end1, int radius, Memimage *src, Point sp, Rectangle clipr)
320 {
321 	/*
322 	 * BUG: We should really really pick off purely horizontal and purely
323 	 * vertical lines and handle them separately with calls to memimagedraw
324 	 * on rectangles.
325 	 */
326 
327 	int hor;
328 	int sin, cos, dx, dy, t;
329 	Rectangle oclipr;
330 	Point q, pts[10], *pp, d;
331 
332 	if(radius < 0)
333 		return;
334 	if(rectclip(&clipr, dst->r) == 0)
335 		return;
336 	if(rectclip(&clipr, dst->clipr) == 0)
337 		return;
338 	d = subpt(sp, p0);
339 	if(rectclip(&clipr, rectsubpt(src->clipr, d)) == 0)
340 		return;
341 	if((src->flags&Frepl)==0 && rectclip(&clipr, rectsubpt(src->r, d))==0)
342 		return;
343 	/* this means that only verline() handles degenerate lines (p0==p1) */
344 	hor = (abs(p1.x-p0.x) > abs(p1.y-p0.y));
345 	/*
346 	 * Clipping is a little peculiar.  We can't use Sutherland-Cohen
347 	 * clipping because lines are wide.  But this is probably just fine:
348 	 * we do all math with the original p0 and p1, but clip when deciding
349 	 * what pixels to draw.  This means the layer code can call this routine,
350 	 * using clipr to define the region being written, and get the same set
351 	 * of pixels regardless of the dicing.
352 	 */
353 	if((hor && p0.x>p1.x) || (!hor && p0.y>p1.y)){
354 		q = p0;
355 		p0 = p1;
356 		p1 = q;
357 		t = end0;
358 		end0 = end1;
359 		end1 = t;
360 	}
361 
362 /*    Hard: */
363 	/* draw thick line using polygon fill */
364 	icossin2(p1.x-p0.x, p1.y-p0.y, &cos, &sin);
365 	dx = (sin*(2*radius+1))/2;
366 	dy = (cos*(2*radius+1))/2;
367 	pp = pts;
368 	oclipr = dst->clipr;
369 	dst->clipr = clipr;
370 	q.x = ICOSSCALE*p0.x+ICOSSCALE/2-cos/2;
371 	q.y = ICOSSCALE*p0.y+ICOSSCALE/2-sin/2;
372 	switch(end0 & 0x1F){
373 	case Enddisc:
374 		discend(p0, radius, dst, src, d);
375 		/* fall through */
376 	case Endsquare:
377 	default:
378 		pp->x = q.x-dx;
379 		pp->y = q.y+dy;
380 		pp++;
381 		pp->x = q.x+dx;
382 		pp->y = q.y-dy;
383 		pp++;
384 		break;
385 	case Endarrow:
386 		arrowend(q, pp, end0, -sin, -cos, radius);
387 		memfillpolysc(dst, pts, 5, ~0, src, addpt(pts[0], mulpt(d, ICOSSCALE)), 1, 10, 1);
388 		pp[1] = pp[4];
389 		pp += 2;
390 	}
391 	q.x = ICOSSCALE*p1.x+ICOSSCALE/2+cos/2;
392 	q.y = ICOSSCALE*p1.y+ICOSSCALE/2+sin/2;
393 	switch(end1 & 0x1F){
394 	case Enddisc:
395 		discend(p1, radius, dst, src, d);
396 		/* fall through */
397 	case Endsquare:
398 	default:
399 		pp->x = q.x+dx;
400 		pp->y = q.y-dy;
401 		pp++;
402 		pp->x = q.x-dx;
403 		pp->y = q.y+dy;
404 		pp++;
405 		break;
406 	case Endarrow:
407 		arrowend(q, pp, end1, sin, cos, radius);
408 		memfillpolysc(dst, pp, 5, ~0, src, addpt(pts[0], mulpt(d, ICOSSCALE)), 1, 10, 1);
409 		pp[1] = pp[4];
410 		pp += 2;
411 	}
412 	memfillpolysc(dst, pts, pp-pts, ~0, src, addpt(pts[0], mulpt(d, ICOSSCALE)), 0, 10, 1);
413 	dst->clipr = oclipr;
414 	return;
415 }
416 
417 void
418 memimageline(Memimage *dst, Point p0, Point p1, int end0, int end1, int radius, Memimage *src, Point sp)
419 {
420 	_memimageline(dst, p0, p1, end0, end1, radius, src, sp, dst->clipr);
421 }
422 
423 /*
424  * Simple-minded conservative code to compute bounding box of line.
425  * Result is probably a little larger than it needs to be.
426  */
427 static
428 void
429 addbbox(Rectangle *r, Point p)
430 {
431 	if(r->min.x > p.x)
432 		r->min.x = p.x;
433 	if(r->min.y > p.y)
434 		r->min.y = p.y;
435 	if(r->max.x < p.x+1)
436 		r->max.x = p.x+1;
437 	if(r->max.y < p.y+1)
438 		r->max.y = p.y+1;
439 }
440 
441 int
442 memlineendsize(int end)
443 {
444 	int x3;
445 
446 	if((end&0x3F) != Endarrow)
447 		return 0;
448 	if(end == Endarrow)
449 		x3 = Arrow3;
450 	else
451 		x3 = (end>>23) & 0x1FF;
452 	return x3;
453 }
454 
455 Rectangle
456 memlinebbox(Point p0, Point p1, int end0, int end1, int radius)
457 {
458 	Rectangle r, r1;
459 	int extra;
460 
461 	r.min.x = 10000000;
462 	r.min.y = 10000000;
463 	r.max.x = -10000000;
464 	r.max.y = -10000000;
465 	extra = lmax(memlineendsize(end0), memlineendsize(end1));
466 	r1 = insetrect(canonrect(Rpt(p0, p1)), -(radius+extra));
467 	addbbox(&r, r1.min);
468 	addbbox(&r, r1.max);
469 	return r;
470 }
471