1 /*
2  * rotate an image 180° in O(log Dx + log Dy) /dev/draw writes,
3  * using an extra buffer same size as the image.
4  *
5  * the basic concept is that you can invert an array by inverting
6  * the top half, inverting the bottom half, and then swapping them.
7  * the code does this slightly backwards to ensure O(log n) runtime.
8  * (If you do it wrong, you can get O(log² n) runtime.)
9  *
10  * This is usually overkill, but it speeds up slow remote
11  * connections quite a bit.
12  */
13 
14 #include <u.h>
15 #include <libc.h>
16 #include <bio.h>
17 #include <draw.h>
18 #include <thread.h>
19 #include <cursor.h>
20 #include "page.h"
21 
22 int ndraw = 0;
23 enum {
24 	Xaxis = 0,
25 	Yaxis = 1,
26 };
27 
28 Image *mtmp;
29 
30 void
31 writefile(char *name, Image *im, int gran)
32 {
33 	static int c = 100;
34 	int fd;
35 	char buf[200];
36 
37 	snprint(buf, sizeof buf, "%d%s%d", c++, name, gran);
38 	fd = create(buf, OWRITE, 0666);
39 	if(fd < 0)
40 		return;
41 	writeimage(fd, im, 0);
42 	close(fd);
43 }
44 
45 void
46 moveup(Image *im, Image *tmp, int a, int b, int c, int axis)
47 {
48 	Rectangle range;
49 	Rectangle dr0, dr1;
50 	Point p0, p1;
51 
52 	if(a == b || b == c)
53 		return;
54 
55 	drawop(tmp, tmp->r, im, nil, im->r.min, S);
56 
57 	switch(axis){
58 	case Xaxis:
59 		range = Rect(a, im->r.min.y,  c, im->r.max.y);
60 		dr0 = range;
61 		dr0.max.x = dr0.min.x+(c-b);
62 		p0 = Pt(b, im->r.min.y);
63 
64 		dr1 = range;
65 		dr1.min.x = dr1.max.x-(b-a);
66 		p1 = Pt(a, im->r.min.y);
67 		break;
68 	case Yaxis:
69 	default:
70 		range = Rect(im->r.min.x, a,  im->r.max.x, c);
71 		dr0 = range;
72 		dr0.max.y = dr0.min.y+(c-b);
73 		p0 = Pt(im->r.min.x, b);
74 
75 		dr1 = range;
76 		dr1.min.y = dr1.max.y-(b-a);
77 		p1 = Pt(im->r.min.x, a);
78 		break;
79 	}
80 	drawop(im, dr0, tmp, nil, p0, S);
81 	drawop(im, dr1, tmp, nil, p1, S);
82 }
83 
84 void
85 interlace(Image *im, Image *tmp, int axis, int n, Image *mask, int gran)
86 {
87 	Point p0, p1;
88 	Rectangle r0;
89 
90 	r0 = im->r;
91 	switch(axis) {
92 	case Xaxis:
93 		r0.max.x = n;
94 		p0 = (Point){gran, 0};
95 		p1 = (Point){-gran, 0};
96 		break;
97 	case Yaxis:
98 	default:
99 		r0.max.y = n;
100 		p0 = (Point){0, gran};
101 		p1 = (Point){0, -gran};
102 		break;
103 	}
104 
105 	drawop(tmp, im->r, im, display->opaque, im->r.min, S);
106 	gendrawop(im, r0, tmp, p0, mask, mask->r.min, S);
107 	gendrawop(im, r0, tmp, p1, mask, p1, S);
108 }
109 
110 /*
111  * Halve the grating period in the mask.
112  * The grating currently looks like
113  * ####____####____####____####____
114  * where #### is opacity.
115  *
116  * We want
117  * ##__##__##__##__##__##__##__##__
118  * which is achieved by shifting the mask
119  * and drawing on itself through itself.
120  * Draw doesn't actually allow this, so
121  * we have to copy it first.
122  *
123  *     ####____####____####____####____ (dst)
124  * +   ____####____####____####____#### (src)
125  * in  __####____####____####____####__ (mask)
126  * ===========================================
127  *     ##__##__##__##__##__##__##__##__
128  */
129 int
130 nextmask(Image *mask, int axis, int maskdim)
131 {
132 	Point o;
133 
134 	o = axis==Xaxis ? Pt(maskdim,0) : Pt(0,maskdim);
135 	drawop(mtmp, mtmp->r, mask, nil, mask->r.min, S);
136 	gendrawop(mask, mask->r, mtmp, o, mtmp, divpt(o,-2), S);
137 //	writefile("mask", mask, maskdim/2);
138 	return maskdim/2;
139 }
140 
141 void
142 shuffle(Image *im, Image *tmp, int axis, int n, Image *mask, int gran,
143 	int lastnn)
144 {
145 	int nn, left;
146 
147 	if(gran == 0)
148 		return;
149 	left = n%(2*gran);
150 	nn = n - left;
151 
152 	interlace(im, tmp, axis, nn, mask, gran);
153 //	writefile("interlace", im, gran);
154 
155 	gran = nextmask(mask, axis, gran);
156 	shuffle(im, tmp, axis, n, mask, gran, nn);
157 //	writefile("shuffle", im, gran);
158 	moveup(im, tmp, lastnn, nn, n, axis);
159 //	writefile("move", im, gran);
160 }
161 
162 void
163 rot180(Image *im)
164 {
165 	Image *tmp, *tmp0;
166 	Image *mask;
167 	Rectangle rmask;
168 	int gran;
169 
170 	if(chantodepth(im->chan) < 8){
171 		/* this speeds things up dramatically; draw is too slow on sub-byte pixel sizes */
172 		tmp0 = xallocimage(display, im->r, CMAP8, 0, DNofill);
173 		drawop(tmp0, tmp0->r, im, nil, im->r.min, S);
174 	}else
175 		tmp0 = im;
176 
177 	tmp = xallocimage(display, tmp0->r, tmp0->chan, 0, DNofill);
178 	if(tmp == nil){
179 		if(tmp0 != im)
180 			freeimage(tmp0);
181 		return;
182 	}
183 	for(gran=1; gran<Dx(im->r); gran *= 2)
184 		;
185 	gran /= 4;
186 
187 	rmask.min = ZP;
188 	rmask.max = (Point){2*gran, 100};
189 
190 	mask = xallocimage(display, rmask, GREY1, 1, DTransparent);
191 	mtmp = xallocimage(display, rmask, GREY1, 1, DTransparent);
192 	if(mask == nil || mtmp == nil) {
193 		fprint(2, "out of memory during rot180: %r\n");
194 		wexits("memory");
195 	}
196 	rmask.max.x = gran;
197 	drawop(mask, rmask, display->opaque, nil, ZP, S);
198 //	writefile("mask", mask, gran);
199 	shuffle(im, tmp, Xaxis, Dx(im->r), mask, gran, 0);
200 	freeimage(mask);
201 	freeimage(mtmp);
202 
203 	for(gran=1; gran<Dy(im->r); gran *= 2)
204 		;
205 	gran /= 4;
206 	rmask.max = (Point){100, 2*gran};
207 	mask = xallocimage(display, rmask, GREY1, 1, DTransparent);
208 	mtmp = xallocimage(display, rmask, GREY1, 1, DTransparent);
209 	if(mask == nil || mtmp == nil) {
210 		fprint(2, "out of memory during rot180: %r\n");
211 		wexits("memory");
212 	}
213 	rmask.max.y = gran;
214 	drawop(mask, rmask, display->opaque, nil, ZP, S);
215 	shuffle(im, tmp, Yaxis, Dy(im->r), mask, gran, 0);
216 	freeimage(mask);
217 	freeimage(mtmp);
218 	freeimage(tmp);
219 	if(tmp0 != im)
220 		freeimage(tmp0);
221 }
222 
223 /* rotates an image 90 degrees clockwise */
224 Image *
225 rot90(Image *im)
226 {
227 	Image *tmp;
228 	int i, j, dx, dy;
229 
230 	dx = Dx(im->r);
231 	dy = Dy(im->r);
232 	tmp = xallocimage(display, Rect(0, 0, dy, dx), im->chan, 0, DCyan);
233 	if(tmp == nil) {
234 		fprint(2, "out of memory during rot90: %r\n");
235 		wexits("memory");
236 	}
237 
238 	for(j = 0; j < dx; j++) {
239 		for(i = 0; i < dy; i++) {
240 			drawop(tmp, Rect(i, j, i+1, j+1), im, nil, Pt(j, dy-(i+1)), S);
241 		}
242 	}
243 	freeimage(im);
244 
245 	return(tmp);
246 }
247 
248 /* rotates an image 270 degrees clockwise */
249 Image *
250 rot270(Image *im)
251 {
252 	Image *tmp;
253 	int i, j, dx, dy;
254 
255 	dx = Dx(im->r);
256 	dy = Dy(im->r);
257 	tmp = xallocimage(display, Rect(0, 0, dy, dx), im->chan, 0, DCyan);
258 	if(tmp == nil) {
259 		fprint(2, "out of memory during rot270: %r\n");
260 		wexits("memory");
261 	}
262 
263 	for(i = 0; i < dy; i++) {
264 		for(j = 0; j < dx; j++) {
265 			drawop(tmp, Rect(i, j, i+1, j+1), im, nil, Pt(dx-(j+1), i), S);
266 		}
267 	}
268 	freeimage(im);
269 
270 	return(tmp);
271 }
272 
273 /* from resample.c -- resize from → to using interpolation */
274 
275 
276 #define K2 7	/* from -.7 to +.7 inclusive, meaning .2 into each adjacent pixel */
277 #define NK (2*K2+1)
278 double K[NK];
279 
280 double
281 fac(int L)
282 {
283 	int i, f;
284 
285 	f = 1;
286 	for(i=L; i>1; --i)
287 		f *= i;
288 	return f;
289 }
290 
291 /*
292  * i0(x) is the modified Bessel function, Σ (x/2)^2L / (L!)²
293  * There are faster ways to calculate this, but we precompute
294  * into a table so let's keep it simple.
295  */
296 double
297 i0(double x)
298 {
299 	double v;
300 	int L;
301 
302 	v = 1.0;
303 	for(L=1; L<10; L++)
304 		v += pow(x/2., 2*L)/pow(fac(L), 2);
305 	return v;
306 }
307 
308 double
309 kaiser(double x, double t, double a)
310 {
311 	if(fabs(x) > t)
312 		return 0.;
313 	return i0(a*sqrt(1-(x*x/(t*t))))/i0(a);
314 }
315 
316 
317 void
318 resamplex(uchar *in, int off, int d, int inx, uchar *out, int outx)
319 {
320 	int i, x, k;
321 	double X, xx, v, rat;
322 
323 
324 	rat = (double)inx/(double)outx;
325 	for(x=0; x<outx; x++){
326 		if(inx == outx){
327 			/* don't resample if size unchanged */
328 			out[off+x*d] = in[off+x*d];
329 			continue;
330 		}
331 		v = 0.0;
332 		X = x*rat;
333 		for(k=-K2; k<=K2; k++){
334 			xx = X + rat*k/10.;
335 			i = xx;
336 			if(i < 0)
337 				i = 0;
338 			if(i >= inx)
339 				i = inx-1;
340 			v += in[off+i*d] * K[K2+k];
341 		}
342 		out[off+x*d] = v;
343 	}
344 }
345 
346 void
347 resampley(uchar **in, int off, int iny, uchar **out, int outy)
348 {
349 	int y, i, k;
350 	double Y, yy, v, rat;
351 
352 	rat = (double)iny/(double)outy;
353 	for(y=0; y<outy; y++){
354 		if(iny == outy){
355 			/* don't resample if size unchanged */
356 			out[y][off] = in[y][off];
357 			continue;
358 		}
359 		v = 0.0;
360 		Y = y*rat;
361 		for(k=-K2; k<=K2; k++){
362 			yy = Y + rat*k/10.;
363 			i = yy;
364 			if(i < 0)
365 				i = 0;
366 			if(i >= iny)
367 				i = iny-1;
368 			v += in[i][off] * K[K2+k];
369 		}
370 		out[y][off] = v;
371 	}
372 
373 }
374 
375 Image*
376 resample(Image *from, Image *to)
377 {
378 	int i, j, bpl, nchan;
379 	uchar **oscan, **nscan;
380 	char tmp[20];
381 	int xsize, ysize;
382 	double v;
383 	Image *t1, *t2;
384 	ulong tchan;
385 
386 	for(i=-K2; i<=K2; i++){
387 		K[K2+i] = kaiser(i/10., K2/10., 4.);
388 	}
389 
390 	/* normalize */
391 	v = 0.0;
392 	for(i=0; i<NK; i++)
393 		v += K[i];
394 	for(i=0; i<NK; i++)
395 		K[i] /= v;
396 
397 	switch(from->chan){
398 	case GREY8:
399 	case RGB24:
400 	case RGBA32:
401 	case ARGB32:
402 	case XRGB32:
403 		break;
404 
405 	case CMAP8:
406 	case RGB15:
407 	case RGB16:
408 		tchan = RGB24;
409 		goto Convert;
410 
411 	case GREY1:
412 	case GREY2:
413 	case GREY4:
414 		tchan = GREY8;
415 	Convert:
416 		/* use library to convert to byte-per-chan form, then convert back */
417 		t1 = xallocimage(display, Rect(0, 0, Dx(from->r), Dy(from->r)), tchan, 0, DNofill);
418 		if(t1 == nil) {
419 			fprint(2, "out of memory for temp image 1 in resample: %r\n");
420 			wexits("memory");
421 		}
422 		drawop(t1, t1->r, from, nil, ZP, S);
423 		t2 = xallocimage(display, to->r, tchan, 0, DNofill);
424 		if(t2 == nil) {
425 			fprint(2, "out of memory temp image 2 in resample: %r\n");
426 			wexits("memory");
427 		}
428 		resample(t1, t2);
429 		drawop(to, to->r, t2, nil, ZP, S);
430 		freeimage(t1);
431 		freeimage(t2);
432 		return to;
433 
434 	default:
435 		sysfatal("can't handle channel type %s", chantostr(tmp, from->chan));
436 	}
437 
438 	xsize = Dx(to->r);
439 	ysize = Dy(to->r);
440 	oscan = malloc(Dy(from->r)*sizeof(uchar*));
441 	nscan = malloc(max(ysize, Dy(from->r))*sizeof(uchar*));
442 	if(oscan == nil || nscan == nil)
443 		sysfatal("can't allocate: %r");
444 
445 	/* unload original image into scan lines */
446 	bpl = bytesperline(from->r, from->depth);
447 	for(i=0; i<Dy(from->r); i++){
448 		oscan[i] = malloc(bpl);
449 		if(oscan[i] == nil)
450 			sysfatal("can't allocate: %r");
451 		j = unloadimage(from, Rect(from->r.min.x, from->r.min.y+i, from->r.max.x, from->r.min.y+i+1), oscan[i], bpl);
452 		if(j != bpl)
453 			sysfatal("unloadimage");
454 	}
455 
456 	/* allocate scan lines for destination. we do y first, so need at least Dy(from->r) lines */
457 	bpl = bytesperline(Rect(0, 0, xsize, Dy(from->r)), from->depth);
458 	for(i=0; i<max(ysize, Dy(from->r)); i++){
459 		nscan[i] = malloc(bpl);
460 		if(nscan[i] == nil)
461 			sysfatal("can't allocate: %r");
462 	}
463 
464 	/* resample in X */
465 	nchan = from->depth/8;
466 	for(i=0; i<Dy(from->r); i++){
467 		for(j=0; j<nchan; j++){
468 			if(j==0 && from->chan==XRGB32)
469 				continue;
470 			resamplex(oscan[i], j, nchan, Dx(from->r), nscan[i], xsize);
471 		}
472 		free(oscan[i]);
473 		oscan[i] = nscan[i];
474 		nscan[i] = malloc(bpl);
475 		if(nscan[i] == nil)
476 			sysfatal("can't allocate: %r");
477 	}
478 
479 	/* resample in Y */
480 	for(i=0; i<xsize; i++)
481 		for(j=0; j<nchan; j++)
482 			resampley(oscan, nchan*i+j, Dy(from->r), nscan, ysize);
483 
484 	/* pack data into destination */
485 	bpl = bytesperline(to->r, from->depth);
486 	for(i=0; i<ysize; i++){
487 		j = loadimage(to, Rect(0, i, xsize, i+1), nscan[i], bpl);
488 		if(j != bpl)
489 			sysfatal("loadimage: %r");
490 	}
491 
492 	for(i=0; i<Dy(from->r); i++){
493 		free(oscan[i]);
494 		free(nscan[i]);
495 	}
496 	free(oscan);
497 	free(nscan);
498 
499 	return to;
500 }