git.maemo.org Git - navit-package/blob - navit/transform.c

   1 /**
   2  * Navit, a modular navigation system.
   3  * Copyright (C) 2005-2008 Navit Team
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * version 2 as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the
  16  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  * Boston, MA  02110-1301, USA.
  18  */
  19
  20 #include <assert.h>
  21 #include <stdio.h>
  22 #include <math.h>
  23 #include <limits.h>
  24 #include <glib.h>
  25 #include <string.h>
  26 #include "config.h"
  27 #include "coord.h"
  28 #include "debug.h"
  29 #include "map.h"
  30 #include "transform.h"
  31 #include "projection.h"
  32 #include "point.h"
  33 #include "item.h"
  34
  35 struct transformation {
  36         int angle;              /* Rotation angle */
  37         double cos_val,sin_val; /* cos and sin of rotation angle */
  38         struct map_selection *map_sel;
  39         struct map_selection *screen_sel;
  40         struct point screen_center;
  41         struct coord map_center;        /* Center of source rectangle */
  42         enum projection pro;
  43         long scale;             /* Scale factor */
  44 };
  45
  46 struct transformation *
  47 transform_new(void)
  48 {
  49         struct transformation *this_;
  50
  51         this_=g_new0(struct transformation, 1);
  52
  53         return this_;
  54 }
  55
  56 static const double gar2geo_units = 360.0/(1<<24);
  57 static const double geo2gar_units = 1/(360.0/(1<<24));
  58
  59 void
  60 transform_to_geo(enum projection pro, struct coord *c, struct coord_geo *g)
  61 {
  62         switch (pro) {
  63         case projection_mg:
  64                 g->lng=c->x/6371000.0/M_PI*180;
  65                 g->lat=atan(exp(c->y/6371000.0))/M_PI*360-90;
  66                 break;
  67         case projection_garmin:
  68                 g->lng=c->x*gar2geo_units;
  69                 g->lat=c->y*gar2geo_units;
  70                 break;
  71         default:
  72                 break;
  73         }
  74 }
  75
  76 void
  77 transform_from_geo(enum projection pro, struct coord_geo *g, struct coord *c)
  78 {
  79         switch (pro) {
  80         case projection_mg:
  81                 c->x=g->lng*6371000.0*M_PI/180;
  82                 c->y=log(tan(M_PI_4+g->lat*M_PI/360))*6371000.0;
  83                 break;
  84         case projection_garmin:
  85                 c->x=g->lng*geo2gar_units;
  86                 c->y=g->lat*geo2gar_units;
  87                 break;
  88         default:
  89                 break;
  90         }
  91 }
  92
  93 void
  94 transform_from_to(struct coord *cfrom, enum projection from, struct coord *cto, enum projection to)
  95 {
  96         struct coord_geo g;
  97         transform_to_geo(from, cfrom, &g);
  98         transform_from_geo(to, &g, cto);
  99 }
 100
 101 void
 102 transform_geo_to_cart(struct coord_geo *geo, double a, double b, struct coord_geo_cart *cart)
 103 {
 104         double n,ee=1-b*b/(a*a);
 105         n = a/sqrt(1-ee*sin(geo->lat)*sin(geo->lat));
 106         cart->x=n*cos(geo->lat)*cos(geo->lng);
 107         cart->y=n*cos(geo->lat)*sin(geo->lng);
 108         cart->z=n*(1-ee)*sin(geo->lat);
 109 }
 110
 111 void
 112 transform_cart_to_geo(struct coord_geo_cart *cart, double a, double b, struct coord_geo *geo)
 113 {
 114         double lat,lati,n,ee=1-b*b/(a*a), lng = atan(cart->y/cart->x);
 115
 116         lat = atan(cart->z / sqrt((cart->x * cart->x) + (cart->y * cart->y)));
 117         do
 118         {
 119                 lati = lat;
 120
 121                 n = a / sqrt(1-ee*sin(lat)*sin(lat));
 122                 lat = atan((cart->z + ee * n * sin(lat)) / sqrt(cart->x * cart->x + cart->y * cart->y));
 123         }
 124         while (fabs(lat - lati) >= 0.000000000000001);
 125
 126         geo->lng=lng/M_PI*180;
 127         geo->lat=lat/M_PI*180;
 128 }
 129
 130
 131 void
 132 transform_datum(struct coord_geo *from, enum map_datum from_datum, struct coord_geo *to, enum map_datum to_datum)
 133 {
 134 }
 135
 136 int
 137 transform(struct transformation *t, enum projection pro, struct coord *c, struct point *p, int count, int unique)
 138 {
 139         struct coord c1;
 140         int xcn, ycn;
 141         struct coord_geo g;
 142 #ifdef AVOID_FLOAT
 143         int xc,yc;
 144 #else
 145         double xc,yc;
 146 #endif
 147         int i,j = 0;
 148         for (i=0; i < count; i++) {
 149                 if (pro == t->pro) {
 150                         xc=c[i].x;
 151                         yc=c[i].y;
 152                 } else {
 153                         transform_to_geo(pro, &c[i], &g);
 154                         transform_from_geo(t->pro, &g, &c1);
 155                         xc=c1.x;
 156                         yc=c1.y;
 157                 }
 158 //              dbg(2,"0x%x, 0x%x - 0x%x,0x%x contains 0x%x,0x%x\n", t->r.lu.x, t->r.lu.y, t->r.rl.x, t->r.rl.y, c->x, c->y);
 159 //              ret=coord_rect_contains(&t->r, c);
 160                 xc-=t->map_center.x;
 161                 yc-=t->map_center.y;
 162                 yc=-yc;
 163                 if (t->angle) {
 164                         xcn=xc*t->cos_val+yc*t->sin_val;
 165                         ycn=-xc*t->sin_val+yc*t->cos_val;
 166                         xc=xcn;
 167                         yc=ycn;
 168                 }
 169                 xc=xc*16;
 170                 yc=yc*16;
 171 #ifndef AVOID_FLOAT
 172                 if (t->scale!=1) {
 173                         xc=xc/(double)(t->scale);
 174                         yc=yc/(double)(t->scale);
 175                 }
 176 #else
 177                 if (t->scale!=1) {
 178                         xc=xc/t->scale;
 179                         yc=yc/t->scale;
 180                 }
 181 #endif
 182                 xc+=t->screen_center.x;
 183                 yc+=t->screen_center.y;
 184                 if (xc < -0x8000)
 185                         xc=-0x8000;
 186                 if (xc > 0x7fff) {
 187                         xc=0x7fff;
 188                 }
 189                 if (yc < -0x8000)
 190                         yc=-0x8000;
 191                 if (yc > 0x7fff)
 192                         yc=0x7fff;
 193                 if (j == 0 || !unique || p[j-1].x != xc || p[j-1].y != yc) {
 194                         p[j].x=xc;
 195                         p[j].y=yc;
 196                         j++;
 197                 }
 198         }
 199         return j;
 200 }
 201
 202 void
 203 transform_reverse(struct transformation *t, struct point *p, struct coord *c)
 204 {
 205         int xc,yc;
 206         xc=p->x;
 207         yc=p->y;
 208         xc-=t->screen_center.x;
 209         yc-=t->screen_center.y;
 210         xc=xc*t->scale/16;
 211         yc=-yc*t->scale/16;
 212         if (t->angle) {
 213                 int xcn, ycn;
 214                 xcn=xc*t->cos_val+yc*t->sin_val;
 215                 ycn=-xc*t->sin_val+yc*t->cos_val;
 216                 xc=xcn;
 217                 yc=ycn;
 218         }
 219         c->x=t->map_center.x+xc;
 220         c->y=t->map_center.y+yc;
 221 }
 222
 223 enum projection
 224 transform_get_projection(struct transformation *this_)
 225 {
 226         return this_->pro;
 227 }
 228
 229 void
 230 transform_set_projection(struct transformation *this_, enum projection pro)
 231 {
 232         this_->pro=pro;
 233 }
 234
 235 static int
 236 min4(int v1,int v2, int v3, int v4)
 237 {
 238         int res=v1;
 239         if (v2 < res)
 240                 res=v2;
 241         if (v3 < res)
 242                 res=v3;
 243         if (v4 < res)
 244                 res=v4;
 245         return res;
 246 }
 247
 248 static int
 249 max4(int v1,int v2, int v3, int v4)
 250 {
 251         int res=v1;
 252         if (v2 > res)
 253                 res=v2;
 254         if (v3 > res)
 255                 res=v3;
 256         if (v4 > res)
 257                 res=v4;
 258         return res;
 259 }
 260
 261 struct map_selection *
 262 transform_get_selection(struct transformation *this_, enum projection pro, int order)
 263 {
 264
 265         struct map_selection *ret,*curri,*curro;
 266         struct coord_geo g;
 267         int i;
 268
 269         ret=map_selection_dup(this_->map_sel);
 270         curri=this_->map_sel;
 271         curro=ret;
 272         while (curri) {
 273                 if (this_->pro != pro) {
 274                         transform_to_geo(this_->pro, &curri->u.c_rect.lu, &g);
 275                         transform_from_geo(pro, &g, &curro->u.c_rect.lu);
 276                         dbg(1,"%f,%f", g.lat, g.lng);
 277                         transform_to_geo(this_->pro, &curri->u.c_rect.rl, &g);
 278                         transform_from_geo(pro, &g, &curro->u.c_rect.rl);
 279                         dbg(1,": - %f,%f\n", g.lat, g.lng);
 280                 }
 281                 dbg(1,"transform rect for %d is %d,%d - %d,%d\n", pro, curro->u.c_rect.lu.x, curro->u.c_rect.lu.y, curro->u.c_rect.rl.x, curro->u.c_rect.rl.y);
 282                 for (i = 0 ; i < layer_end ; i++)
 283                         curro->order[i]+=order;
 284                 curri=curri->next;
 285                 curro=curro->next;
 286         }
 287         return ret;
 288 }
 289
 290 struct coord *
 291 transform_center(struct transformation *this_)
 292 {
 293         return &this_->map_center;
 294 }
 295
 296 void
 297 transform_set_angle(struct transformation *t,int angle)
 298 {
 299         t->angle=angle;
 300         t->cos_val=cos(M_PI*t->angle/180);
 301         t->sin_val=sin(M_PI*t->angle/180);
 302 }
 303
 304 int
 305 transform_get_angle(struct transformation *this_,int angle)
 306 {
 307         return this_->angle;
 308 }
 309
 310 void
 311 transform_set_screen_selection(struct transformation *t, struct map_selection *sel)
 312 {
 313         map_selection_destroy(t->screen_sel);
 314         t->screen_sel=map_selection_dup(sel);
 315         if (sel) {
 316                 t->screen_center.x=(sel->u.p_rect.rl.x-sel->u.p_rect.lu.x)/2;
 317                 t->screen_center.y=(sel->u.p_rect.rl.y-sel->u.p_rect.lu.y)/2;
 318         }
 319 }
 320
 321 void
 322 transform_set_screen_center(struct transformation *t, struct point *p)
 323 {
 324         t->screen_center=*p;
 325 }
 326
 327 #if 0
 328 void
 329 transform_set_size(struct transformation *t, int width, int height)
 330 {
 331         t->width=width;
 332         t->height=height;
 333 }
 334 #endif
 335
 336 void
 337 transform_get_size(struct transformation *t, int *width, int *height)
 338 {
 339         struct point_rect *r;
 340         if (t->screen_sel) {
 341                 r=&t->screen_sel->u.p_rect;
 342                 *width=r->rl.x-r->lu.x;
 343                 *height=r->rl.y-r->lu.y;
 344         }
 345 }
 346
 347 void
 348 transform_setup(struct transformation *t, struct pcoord *c, int scale, int angle)
 349 {
 350         t->pro=c->pro;
 351         t->map_center.x=c->x;
 352         t->map_center.y=c->y;
 353         t->scale=scale;
 354         transform_set_angle(t, angle);
 355 }
 356
 357 #if 0
 358
 359 void
 360 transform_setup_source_rect_limit(struct transformation *t, struct coord *center, int limit)
 361 {
 362         t->center=*center;
 363         t->scale=1;
 364         t->angle=0;
 365         t->r.lu.x=center->x-limit;
 366         t->r.rl.x=center->x+limit;
 367         t->r.rl.y=center->y-limit;
 368         t->r.lu.y=center->y+limit;
 369 }
 370 #endif
 371
 372 void
 373 transform_setup_source_rect(struct transformation *t)
 374 {
 375         int i;
 376         struct coord screen[4];
 377         struct point screen_pnt[4];
 378         struct point_rect *pr;
 379         struct map_selection *ms,*msm,*next,**msm_last;
 380         ms=t->map_sel;
 381         while (ms) {
 382                 next=ms->next;
 383                 g_free(ms);
 384                 ms=next;
 385         }
 386         t->map_sel=NULL;
 387         msm_last=&t->map_sel;
 388         ms=t->screen_sel;
 389         while (ms) {
 390                 msm=g_new0(struct map_selection, 1);
 391                 *msm=*ms;
 392                 pr=&ms->u.p_rect;
 393                 screen_pnt[0].x=pr->lu.x;
 394                 screen_pnt[0].y=pr->lu.y;
 395                 screen_pnt[1].x=pr->rl.x;
 396                 screen_pnt[1].y=pr->lu.y;
 397                 screen_pnt[2].x=pr->lu.x;
 398                 screen_pnt[2].y=pr->rl.y;
 399                 screen_pnt[3].x=pr->rl.x;
 400                 screen_pnt[3].y=pr->rl.y;
 401                 for (i = 0 ; i < 4 ; i++) {
 402                         transform_reverse(t, &screen_pnt[i], &screen[i]);
 403                 }
 404                 msm->u.c_rect.lu.x=min4(screen[0].x,screen[1].x,screen[2].x,screen[3].x);
 405                 msm->u.c_rect.rl.x=max4(screen[0].x,screen[1].x,screen[2].x,screen[3].x);
 406                 msm->u.c_rect.rl.y=min4(screen[0].y,screen[1].y,screen[2].y,screen[3].y);
 407                 msm->u.c_rect.lu.y=max4(screen[0].y,screen[1].y,screen[2].y,screen[3].y);
 408                 *msm_last=msm;
 409                 msm_last=&msm->next;
 410                 ms=ms->next;
 411         }
 412 }
 413
 414 long
 415 transform_get_scale(struct transformation *t)
 416 {
 417         return t->scale;
 418 }
 419
 420 void
 421 transform_set_scale(struct transformation *t, long scale)
 422 {
 423         t->scale=scale;
 424 }
 425
 426
 427 int
 428 transform_get_order(struct transformation *t)
 429 {
 430         int scale=t->scale;
 431         int order=0;
 432         while (scale > 1) {
 433                 order++;
 434                 scale>>=1;
 435         }
 436         order=18-order;
 437         if (order < 0)
 438                 order=0;
 439         return order;
 440 }
 441
 442
 443
 444 #define TWOPI (M_PI*2)
 445 #define GC2RAD(c) ((c) * TWOPI/(1<<24))
 446 #define minf(a,b) ((a) < (b) ? (a) : (b))
 447
 448 static double
 449 transform_distance_garmin(struct coord *c1, struct coord *c2)
 450 {
 451 #ifdef USE_HALVESINE
 452         static const int earth_radius = 6371*1000; //m change accordingly
 453 // static const int earth_radius  = 3960; //miles
 454
 455 //Point 1 cords
 456         float lat1  = GC2RAD(c1->y);
 457         float long1 = GC2RAD(c1->x);
 458
 459 //Point 2 cords
 460         float lat2  = GC2RAD(c2->y);
 461         float long2 = GC2RAD(c2->x);
 462
 463 //Haversine Formula
 464         float dlong = long2-long1;
 465         float dlat  = lat2-lat1;
 466
 467         float sinlat  = sinf(dlat/2);
 468         float sinlong = sinf(dlong/2);
 469
 470         float a=(sinlat*sinlat)+cosf(lat1)*cosf(lat2)*(sinlong*sinlong);
 471         float c=2*asinf(minf(1,sqrt(a)));
 472 #ifdef AVOID_FLOAT
 473         return round(earth_radius*c);
 474 #else
 475         return earth_radius*c;
 476 #endif
 477 #else
 478 #define GMETER 2.3887499999999999
 479         double dx,dy;
 480         dx=c1->x-c2->x;
 481         dy=c1->y-c2->y;
 482         return sqrt(dx*dx+dy*dy)*GMETER;
 483 #undef GMETER
 484 #endif
 485 }
 486
 487 double
 488 transform_scale(int y)
 489 {
 490         struct coord c;
 491         struct coord_geo g;
 492         c.x=0;
 493         c.y=y;
 494         transform_to_geo(projection_mg, &c, &g);
 495         return 1/cos(g.lat/180*M_PI);
 496 }
 497
 498 #ifdef AVOID_FLOAT
 499 static int
 500 tab_sqrt[]={14142,13379,12806,12364,12018,11741,11517,11333,11180,11051,10943,10850,10770,10701,10640,10587,10540,10499,10462,10429,10400,10373,10349,10327,10307,10289,10273,10257,10243,10231,10219,10208};
 501 #endif
 502
 503 double
 504 transform_distance(enum projection pro, struct coord *c1, struct coord *c2)
 505 {
 506         if (pro == projection_mg) {
 507 #ifndef AVOID_FLOAT
 508         double dx,dy,scale=transform_scale((c1->y+c2->y)/2);
 509         dx=c1->x-c2->x;
 510         dy=c1->y-c2->y;
 511         return sqrt(dx*dx+dy*dy)/scale;
 512 #else
 513         int dx,dy,f,scale=15539;
 514         dx=c1->x-c2->x;
 515         dy=c1->y-c2->y;
 516         if (dx < 0)
 517                 dx=-dx;
 518         if (dy < 0)
 519                 dy=-dy;
 520         while (dx > 20000 || dy > 20000) {
 521                 dx/=10;
 522                 dy/=10;
 523                 scale/=10;
 524         }
 525         if (! dy)
 526                 return dx*10000/scale;
 527         if (! dx)
 528                 return dy*10000/scale;
 529         if (dx > dy) {
 530                 f=dx*8/dy-8;
 531                 if (f >= 32)
 532                         return dx*10000/scale;
 533                 return dx*tab_sqrt[f]/scale;
 534         } else {
 535                 f=dy*8/dx-8;
 536                 if (f >= 32)
 537                         return dy*10000/scale;
 538                 return dy*tab_sqrt[f]/scale;
 539         }
 540 #endif
 541         } else if (pro == projection_garmin) {
 542                 return transform_distance_garmin(c1, c2);
 543         } else {
 544                 dbg(0,"Unknown projection: %d\n", pro);
 545                 return 0;
 546         }
 547 }
 548
 549 double
 550 transform_polyline_length(enum projection pro, struct coord *c, int count)
 551 {
 552         double ret=0;
 553         int i;
 554
 555         for (i = 0 ; i < count-1 ; i++)
 556                 ret+=transform_distance(pro, &c[i], &c[i+1]);
 557         return ret;
 558 }
 559
 560 int
 561 transform_distance_sq(struct coord *c1, struct coord *c2)
 562 {
 563         int dx=c1->x-c2->x;
 564         int dy=c1->y-c2->y;
 565
 566         if (dx > 32767 || dy > 32767 || dx < -32767 || dy < -32767)
 567                 return INT_MAX;
 568         else
 569                 return dx*dx+dy*dy;
 570 }
 571
 572 int
 573 transform_distance_sq_pc(struct pcoord *c1, struct pcoord *c2)
 574 {
 575         struct coord p1,p2;
 576         p1.x = c1->x; p1.y = c1->y;
 577         p2.x = c2->x; p2.y = c2->y;
 578         return transform_distance_sq(&p1, &p2);
 579 }
 580
 581 int
 582 transform_distance_line_sq(struct coord *l0, struct coord *l1, struct coord *ref, struct coord *lpnt)
 583 {
 584         int vx,vy,wx,wy;
 585         int c1,c2;
 586         int climit=1000000;
 587         struct coord l;
 588
 589         vx=l1->x-l0->x;
 590         vy=l1->y-l0->y;
 591         wx=ref->x-l0->x;
 592         wy=ref->y-l0->y;
 593
 594         c1=vx*wx+vy*wy;
 595         if ( c1 <= 0 ) {
 596                 if (lpnt)
 597                         *lpnt=*l0;
 598                 return transform_distance_sq(l0, ref);
 599         }
 600         c2=vx*vx+vy*vy;
 601         if ( c2 <= c1 ) {
 602                 if (lpnt)
 603                         *lpnt=*l1;
 604                 return transform_distance_sq(l1, ref);
 605         }
 606         while (c1 > climit || c2 > climit) {
 607                 c1/=256;
 608                 c2/=256;
 609         }
 610         l.x=l0->x+vx*c1/c2;
 611         l.y=l0->y+vy*c1/c2;
 612         if (lpnt)
 613                 *lpnt=l;
 614         return transform_distance_sq(&l, ref);
 615 }
 616
 617 int
 618 transform_distance_polyline_sq(struct coord *c, int count, struct coord *ref, struct coord *lpnt, int *pos)
 619 {
 620         int i,dist,distn;
 621         struct coord lp;
 622         if (count < 2)
 623                 return INT_MAX;
 624         if (pos)
 625                 *pos=0;
 626         dist=transform_distance_line_sq(&c[0], &c[1], ref, lpnt);
 627         for (i=2 ; i < count ; i++) {
 628                 distn=transform_distance_line_sq(&c[i-1], &c[i], ref, &lp);
 629                 if (distn < dist) {
 630                         dist=distn;
 631                         if (lpnt)
 632                                 *lpnt=lp;
 633                         if (pos)
 634                                 *pos=i-1;
 635                 }
 636         }
 637         return dist;
 638 }
 639
 640
 641 void
 642 transform_print_deg(double deg)
 643 {
 644         printf("%2.0f:%2.0f:%2.4f", floor(deg), fmod(deg*60,60), fmod(deg*3600,60));
 645 }
 646
 647 #ifdef AVOID_FLOAT
 648 static int tab_atan[]={0,262,524,787,1051,1317,1584,1853,2126,2401,2679,2962,3249,3541,3839,4142,4452,4770,5095,5430,5774,6128,6494,6873,7265,7673,8098,8541,9004,9490,10000,10538};
 649
 650 static int
 651 atan2_int_lookup(int val)
 652 {
 653         int len=sizeof(tab_atan)/sizeof(int);
 654         int i=len/2;
 655         int p=i-1;
 656         for (;;) {
 657                 i>>=1;
 658                 if (val < tab_atan[p])
 659                         p-=i;
 660                 else
 661                         if (val < tab_atan[p+1])
 662                                 return p+(p>>1);
 663                         else
 664                                 p+=i;
 665         }
 666 }
 667
 668 static int
 669 atan2_int(int dx, int dy)
 670 {
 671         int f,mul=1,add=0,ret;
 672         if (! dx) {
 673                 return dy < 0 ? 180 : 0;
 674         }
 675         if (! dy) {
 676                 return dx < 0 ? -90 : 90;
 677         }
 678         if (dx < 0) {
 679                 dx=-dx;
 680                 mul=-1;
 681         }
 682         if (dy < 0) {
 683                 dy=-dy;
 684                 add=180*mul;
 685                 mul*=-1;
 686         }
 687         while (dx > 20000 || dy > 20000) {
 688                 dx/=10;
 689                 dy/=10;
 690         }
 691         if (dx > dy) {
 692                 ret=90-atan2_int_lookup(dy*10000/dx);
 693         } else {
 694                 ret=atan2_int_lookup(dx*10000/dy);
 695         }
 696         return ret*mul+add;
 697 }
 698 #endif
 699
 700 int
 701 transform_get_angle_delta(struct coord *c1, struct coord *c2, int dir)
 702 {
 703         int dx=c2->x-c1->x;
 704         int dy=c2->y-c1->y;
 705 #ifndef AVOID_FLOAT
 706         double angle;
 707         angle=atan2(dx,dy);
 708         angle*=180/M_PI;
 709 #else
 710         int angle;
 711         angle=atan2_int(dx,dy);
 712 #endif
 713         if (dir == -1)
 714                 angle=angle-180;
 715         if (angle < 0)
 716                 angle+=360;
 717         return angle;
 718 }
 719
 720 int
 721 transform_within_border(struct transformation *this_, struct point *p, int border)
 722 {
 723         struct map_selection *ms=this_->screen_sel;
 724         while (ms) {
 725                 struct point_rect *r=&ms->u.p_rect;
 726                 if (p->x >= r->lu.x+border && p->x <= r->rl.x-border &&
 727                     p->y >= r->lu.y+border && p->y <= r->rl.y-border)
 728                         return 1;
 729                 ms=ms->next;
 730         }
 731         return 0;
 732 }
 733
 734 int
 735 transform_within_dist_point(struct coord *ref, struct coord *c, int dist)
 736 {
 737         if (c->x-dist > ref->x)
 738                 return 0;
 739         if (c->x+dist < ref->x)
 740                 return 0;
 741         if (c->y-dist > ref->y)
 742                 return 0;
 743         if (c->y+dist < ref->y)
 744                 return 0;
 745         if ((c->x-ref->x)*(c->x-ref->x) + (c->y-ref->y)*(c->y-ref->y) <= dist*dist)
 746                 return 1;
 747         return 0;
 748 }
 749
 750 int
 751 transform_within_dist_line(struct coord *ref, struct coord *c0, struct coord *c1, int dist)
 752 {
 753         int vx,vy,wx,wy;
 754         int n1,n2;
 755         struct coord lc;
 756
 757         if (c0->x < c1->x) {
 758                 if (c0->x-dist > ref->x)
 759                         return 0;
 760                 if (c1->x+dist < ref->x)
 761                         return 0;
 762         } else {
 763                 if (c1->x-dist > ref->x)
 764                         return 0;
 765                 if (c0->x+dist < ref->x)
 766                         return 0;
 767         }
 768         if (c0->y < c1->y) {
 769                 if (c0->y-dist > ref->y)
 770                         return 0;
 771                 if (c1->y+dist < ref->y)
 772                         return 0;
 773         } else {
 774                 if (c1->y-dist > ref->y)
 775                         return 0;
 776                 if (c0->y+dist < ref->y)
 777                         return 0;
 778         }
 779         vx=c1->x-c0->x;
 780         vy=c1->y-c0->y;
 781         wx=ref->x-c0->x;
 782         wy=ref->y-c0->y;
 783
 784         n1=vx*wx+vy*wy;
 785         if ( n1 <= 0 )
 786                 return transform_within_dist_point(ref, c0, dist);
 787         n2=vx*vx+vy*vy;
 788         if ( n2 <= n1 )
 789                 return transform_within_dist_point(ref, c1, dist);
 790
 791         lc.x=c0->x+vx*n1/n2;
 792         lc.y=c0->y+vy*n1/n2;
 793         return transform_within_dist_point(ref, &lc, dist);
 794 }
 795
 796 int
 797 transform_within_dist_polyline(struct coord *ref, struct coord *c, int count, int close, int dist)
 798 {
 799         int i;
 800         for (i = 0 ; i < count-1 ; i++) {
 801                 if (transform_within_dist_line(ref,c+i,c+i+1,dist)) {
 802                         return 1;
 803                 }
 804         }
 805         if (close)
 806                 return (transform_within_dist_line(ref,c,c+count-1,dist));
 807         return 0;
 808 }
 809
 810 int
 811 transform_within_dist_polygon(struct coord *ref, struct coord *c, int count, int dist)
 812 {
 813         int i, j, ci = 0;
 814         for (i = 0, j = count-1; i < count; j = i++) {
 815                 if ((((c[i].y <= ref->y) && ( ref->y < c[j].y )) ||
 816                 ((c[j].y <= ref->y) && ( ref->y < c[i].y))) &&
 817                 (ref->x < (c[j].x - c[i].x) * (ref->y - c[i].y) / (c[j].y - c[i].y) + c[i].x))
 818                         ci = !ci;
 819         }
 820         if (! ci) {
 821                 if (dist)
 822                         return transform_within_dist_polyline(ref, c, count, dist, 1);
 823                 else
 824                         return 0;
 825         }
 826         return 1;
 827 }
 828
 829 int
 830 transform_within_dist_item(struct coord *ref, enum item_type type, struct coord *c, int count, int dist)
 831 {
 832         if (type < type_line)
 833                 return transform_within_dist_point(ref, c, dist);
 834         if (type < type_area)
 835                 return transform_within_dist_polyline(ref, c, count, 0, dist);
 836         return transform_within_dist_polygon(ref, c, count, dist);
 837 }
 838
 839 void
 840 transform_destroy(struct transformation *t)
 841 {
 842         g_free(t);
 843 }
 844
 845
 846 /*
 847 Note: there are many mathematically equivalent ways to express these formulas. As usual, not all of them are computationally equivalent.
 848
 849 L = latitude in radians (positive north)
 850 Lo = longitude in radians (positive east)
 851 E = easting (meters)
 852 N = northing (meters)
 853
 854 For the sphere
 855
 856 E = r Lo
 857 N = r ln [ tan (pi/4 + L/2) ]
 858
 859 where
 860
 861 r = radius of the sphere (meters)
 862 ln() is the natural logarithm
 863
 864 For the ellipsoid
 865
 866 E = a Lo
 867 N = a * ln ( tan (pi/4 + L/2) * ( (1 - e * sin (L)) / (1 + e * sin (L))) ** (e/2)  )
 868
 869
 870                                                e
 871                                                -
 872                    pi     L     1 - e sin(L)   2
 873     =  a ln( tan( ---- + ---) (--------------)   )
 874                    4      2     1 + e sin(L)
 875
 876
 877 where
 878
 879 a = the length of the semi-major axis of the ellipsoid (meters)
 880 e = the first eccentricity of the ellipsoid
 881
 882
 883 */
 884
 885