contrib/src/ogl/misc.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        misc.cpp
   3 // Purpose:     Miscellaneous OGL support functions
   4 // Author:      Julian Smart
   5 // Modified by:
   6 // Created:     12/07/98
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Julian Smart
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifdef __GNUG__
  13 #pragma implementation "misc.h"
  14 #endif
  15
  16 // For compilers that support precompilation, includes "wx.h".
  17 #include <wx/wxprec.h>
  18
  19 #ifdef __BORLANDC__
  20 #pragma hdrstop
  21 #endif
  22
  23 #ifndef WX_PRECOMP
  24 #include <wx/wx.h>
  25 #endif
  26
  27 #include <wx/wxexpr.h>
  28
  29 #include <wx/types.h>
  30
  31 #if wxUSE_IOSTREAMH
  32 #include <iostream.h>
  33 #else
  34 #include <iostream>
  35 #endif
  36 #include <ctype.h>
  37 #include <math.h>
  38 #include <stdlib.h>
  39
  40 #include <wx/ogl/basic.h>
  41 #include <wx/ogl/basicp.h>
  42 #include <wx/ogl/misc.h>
  43 #include <wx/ogl/constrnt.h>
  44 #include <wx/ogl/composit.h>
  45
  46 wxFont*         g_oglNormalFont;
  47 wxPen*          g_oglBlackPen;
  48 wxPen*          g_oglWhiteBackgroundPen;
  49 wxPen*          g_oglTransparentPen;
  50 wxBrush*        g_oglWhiteBackgroundBrush;
  51 wxPen*          g_oglBlackForegroundPen;
  52 wxCursor*       g_oglBullseyeCursor = NULL;
  53
  54 char*           oglBuffer = NULL;
  55
  56 wxList          oglObjectCopyMapping(wxKEY_INTEGER);
  57
  58
  59
  60 void wxOGLInitialize()
  61 {
  62   g_oglBullseyeCursor = new wxCursor(wxCURSOR_BULLSEYE);
  63
  64   g_oglNormalFont = new wxFont(10, wxSWISS, wxNORMAL, wxNORMAL);
  65
  66   g_oglBlackPen = new wxPen("BLACK", 1, wxSOLID);
  67
  68   g_oglWhiteBackgroundPen = new wxPen("WHITE", 1, wxSOLID);
  69   g_oglTransparentPen = new wxPen("WHITE", 1, wxTRANSPARENT);
  70   g_oglWhiteBackgroundBrush = new wxBrush("WHITE", wxSOLID);
  71   g_oglBlackForegroundPen = new wxPen("BLACK", 1, wxSOLID);
  72
  73   OGLInitializeConstraintTypes();
  74
  75   // Initialize big buffer used when writing images
  76   oglBuffer = new char[3000];
  77
  78 }
  79
  80 void wxOGLCleanUp()
  81 {
  82     if (oglBuffer)
  83     {
  84         delete[] oglBuffer;
  85         oglBuffer = NULL;
  86     }
  87     oglBuffer = NULL;
  88     if (g_oglBullseyeCursor)
  89     {
  90         delete g_oglBullseyeCursor;
  91         g_oglBullseyeCursor = NULL;
  92     }
  93
  94     if (g_oglNormalFont)
  95     {
  96         delete g_oglNormalFont;
  97         g_oglNormalFont = NULL;
  98     }
  99     if (g_oglBlackPen)
 100     {
 101         delete g_oglBlackPen;
 102         g_oglBlackPen = NULL;
 103     }
 104     if (g_oglWhiteBackgroundPen)
 105     {
 106         delete g_oglWhiteBackgroundPen;
 107         g_oglWhiteBackgroundPen = NULL;
 108     }
 109     if (g_oglTransparentPen)
 110     {
 111         delete g_oglTransparentPen;
 112         g_oglTransparentPen = NULL;
 113     }
 114     if (g_oglWhiteBackgroundBrush)
 115     {
 116         delete g_oglWhiteBackgroundBrush;
 117         g_oglWhiteBackgroundBrush = NULL;
 118     }
 119     if (g_oglBlackForegroundPen)
 120     {
 121         delete g_oglBlackForegroundPen;
 122         g_oglBlackForegroundPen = NULL;
 123     }
 124
 125     OGLCleanUpConstraintTypes();
 126 }
 127
 128 wxFont *oglMatchFont(int point_size)
 129 {
 130   wxFont *font = wxTheFontList->FindOrCreateFont(point_size, wxSWISS, wxNORMAL, wxNORMAL);
 131 #if 0
 132   switch (point_size)
 133   {
 134     case 4:
 135       font = swiss_font_4;
 136       break;
 137     case 6:
 138       font = swiss_font_6;
 139       break;
 140     case 8:
 141       font = swiss_font_8;
 142       break;
 143     case 12:
 144       font = swiss_font_12;
 145       break;
 146     case 14:
 147       font = swiss_font_14;
 148       break;
 149     case 18:
 150       font = swiss_font_18;
 151       break;
 152     case 24:
 153       font = swiss_font_24;
 154       break;
 155     default:
 156     case 10:
 157       font = swiss_font_10;
 158       break;
 159   }
 160 #endif
 161   return font;
 162 }
 163
 164 int FontSizeDialog(wxFrame *parent, int old_size)
 165 {
 166   if (old_size <= 0)
 167     old_size = 10;
 168   char buf[40];
 169   sprintf(buf, "%d", old_size);
 170   wxString ans = wxGetTextFromUser("Enter point size", "Font size", buf, parent);
 171   if (ans == "")
 172     return 0;
 173
 174   int new_size = atoi(ans);
 175   if ((new_size <= 0) || (new_size > 40))
 176   {
 177     wxMessageBox("Invalid point size!", "Error", wxOK);
 178     return 0;
 179   }
 180   return new_size;
 181 /*
 182   char *strings[8];
 183   strings[0] = "4";
 184   strings[1] = "6";
 185   strings[2] = "8";
 186   strings[3] = "10";
 187   strings[4] = "12";
 188   strings[5] = "14";
 189   strings[6] = "18";
 190   strings[7] = "24";
 191   char *ans = wxGetSingleChoice("Choose", "Choose a font size", 8, strings, parent);
 192   if (ans)
 193   {
 194     int size;
 195     sscanf(ans, "%d", &size);
 196     return oglMatchFont(size);
 197   }
 198   else return NULL;
 199 */
 200 }
 201
 202 // Centre a list of strings in the given box. xOffset and yOffset are the
 203 // the positions that these lines should be relative to, and this might be
 204 // the same as m_xpos, m_ypos, but might be zero if formatting from left-justifying.
 205 void oglCentreText(wxDC& dc, wxList *text_list,
 206                 double m_xpos, double m_ypos, double width, double height,
 207                 int formatMode)
 208 {
 209   int n = text_list->Number();
 210
 211   if (!text_list || (n == 0))
 212     return;
 213
 214   // First, get maximum dimensions of box enclosing text
 215
 216   long char_height = 0;
 217   long max_width = 0;
 218   long current_width = 0;
 219
 220   // Store text extents for speed
 221   double *widths = new double[n];
 222
 223   wxNode *current = text_list->First();
 224   int i = 0;
 225   while (current)
 226   {
 227     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 228     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 229     widths[i] = current_width;
 230
 231     if (current_width > max_width)
 232       max_width = current_width;
 233     current = current->Next();
 234     i ++;
 235   }
 236
 237   double max_height = n*char_height;
 238
 239   double xoffset, yoffset, xOffset, yOffset;
 240
 241   if (formatMode & FORMAT_CENTRE_VERT)
 242   {
 243     if (max_height < height)
 244       yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 245     else
 246       yoffset = (double)(m_ypos - (height/2.0));
 247     yOffset = m_ypos;
 248   }
 249   else
 250   {
 251     yoffset = 0.0;
 252     yOffset = 0.0;
 253   }
 254
 255   if (formatMode & FORMAT_CENTRE_HORIZ)
 256   {
 257     xoffset = (double)(m_xpos - width/2.0);
 258     xOffset = m_xpos;
 259   }
 260   else
 261   {
 262     xoffset = 0.0;
 263     xOffset = 0.0;
 264   }
 265
 266   current = text_list->First();
 267   i = 0;
 268
 269   while (current)
 270   {
 271     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 272
 273     double x;
 274     if ((formatMode & FORMAT_CENTRE_HORIZ) && (widths[i] < width))
 275       x = (double)((width - widths[i])/2.0 + xoffset);
 276     else
 277       x = xoffset;
 278     double y = (double)(i*char_height + yoffset);
 279
 280     line->SetX( x - xOffset ); line->SetY( y - yOffset );
 281     current = current->Next();
 282     i ++;
 283   }
 284
 285   delete widths;
 286 }
 287
 288 // Centre a list of strings in the given box
 289 void oglCentreTextNoClipping(wxDC& dc, wxList *text_list,
 290                               double m_xpos, double m_ypos, double width, double height)
 291 {
 292   int n = text_list->Number();
 293
 294   if (!text_list || (n == 0))
 295     return;
 296
 297   // First, get maximum dimensions of box enclosing text
 298
 299   long char_height = 0;
 300   long max_width = 0;
 301   long current_width = 0;
 302
 303   // Store text extents for speed
 304   double *widths = new double[n];
 305
 306   wxNode *current = text_list->First();
 307   int i = 0;
 308   while (current)
 309   {
 310     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 311     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 312     widths[i] = current_width;
 313
 314     if (current_width > max_width)
 315       max_width = current_width;
 316     current = current->Next();
 317     i ++;
 318   }
 319
 320   double max_height = n*char_height;
 321
 322   double yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 323
 324   double xoffset = (double)(m_xpos - width/2.0);
 325
 326   current = text_list->First();
 327   i = 0;
 328
 329   while (current)
 330   {
 331     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 332
 333     double x = (double)((width - widths[i])/2.0 + xoffset);
 334     double y = (double)(i*char_height + yoffset);
 335
 336     line->SetX( x - m_xpos ); line->SetY( y - m_ypos );
 337     current = current->Next();
 338     i ++;
 339   }
 340   delete widths;
 341 }
 342
 343 void oglGetCentredTextExtent(wxDC& dc, wxList *text_list,
 344                               double m_xpos, double m_ypos, double width, double height,
 345                               double *actual_width, double *actual_height)
 346 {
 347   int n = text_list->Number();
 348
 349   if (!text_list || (n == 0))
 350   {
 351     *actual_width = 0;
 352     *actual_height = 0;
 353     return;
 354   }
 355
 356   // First, get maximum dimensions of box enclosing text
 357
 358   long char_height = 0;
 359   long max_width = 0;
 360   long current_width = 0;
 361
 362   wxNode *current = text_list->First();
 363   int i = 0;
 364   while (current)
 365   {
 366     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 367     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 368
 369     if (current_width > max_width)
 370       max_width = current_width;
 371     current = current->Next();
 372     i ++;
 373   }
 374
 375   *actual_height = n*char_height;
 376   *actual_width = max_width;
 377 }
 378
 379 // Format a string to a list of strings that fit in the given box.
 380 // Interpret %n and 10 or 13 as a new line.
 381 wxStringList *oglFormatText(wxDC& dc, const wxString& text, double width, double height, int formatMode)
 382 {
 383   // First, parse the string into a list of words
 384   wxStringList word_list;
 385
 386   // Make new lines into NULL strings at this point
 387   int i = 0; int j = 0; int len = strlen(text);
 388   char word[200]; word[0] = 0;
 389   bool end_word = FALSE; bool new_line = FALSE;
 390   while (i < len)
 391   {
 392     switch (text[i])
 393     {
 394       case '%':
 395       {
 396         i ++;
 397         if (i == len)
 398         { word[j] = '%'; j ++; }
 399         else
 400         {
 401           if (text[i] == 'n')
 402           { new_line = TRUE; end_word = TRUE; i++; }
 403           else
 404           { word[j] = '%'; j ++; word[j] = text[i]; j ++; i ++; }
 405         }
 406         break;
 407       }
 408       case 10:
 409       {
 410         new_line = TRUE; end_word = TRUE; i++;
 411         break;
 412       }
 413       case 13:
 414       {
 415         new_line = TRUE; end_word = TRUE; i++;
 416       }
 417       case ' ':
 418       {
 419         end_word = TRUE;
 420         i ++;
 421         break;
 422       }
 423       default:
 424       {
 425         word[j] = text[i];
 426         j ++; i ++;
 427         break;
 428       }
 429     }
 430     if (i == len) end_word = TRUE;
 431     if (end_word)
 432     {
 433       word[j] = 0;
 434       j = 0;
 435       word_list.Add(word);
 436       end_word = FALSE;
 437     }
 438     if (new_line)
 439     {
 440       word_list.Append(NULL);
 441       new_line = FALSE;
 442     }
 443   }
 444   // Now, make a list of strings which can fit in the box
 445   wxStringList *string_list = new wxStringList;
 446
 447   char buffer[400];
 448   buffer[0] = 0;
 449   wxNode *node = word_list.First();
 450   long x, y;
 451
 452   while (node)
 453   {
 454     wxString oldBuffer(buffer);
 455
 456     char *s = (char *)node->Data();
 457     if (!s)
 458     {
 459       // FORCE NEW LINE
 460       if (strlen(buffer) > 0)
 461         string_list->Add(buffer);
 462
 463       buffer[0] = 0;
 464     }
 465     else
 466     {
 467       if (buffer[0] != 0)
 468         strcat(buffer, " ");
 469
 470       strcat(buffer, s);
 471       dc.GetTextExtent(buffer, &x, &y);
 472
 473       // Don't fit within the bounding box if we're fitting shape to contents
 474       if ((x > width) && !(formatMode & FORMAT_SIZE_TO_CONTENTS))
 475       {
 476         // Deal with first word being wider than box
 477         if (oldBuffer.Length() > 0)
 478           string_list->Add(oldBuffer);
 479
 480         buffer[0] = 0;
 481         strcat(buffer, s);
 482       }
 483     }
 484
 485     node = node->Next();
 486   }
 487   if (buffer[0] != 0)
 488     string_list->Add(buffer);
 489
 490   return string_list;
 491 }
 492
 493 void oglDrawFormattedText(wxDC& dc, wxList *text_list,
 494                        double m_xpos, double m_ypos, double width, double height,
 495                        int formatMode)
 496 {
 497   double xoffset, yoffset;
 498   if (formatMode & FORMAT_CENTRE_HORIZ)
 499     xoffset = m_xpos;
 500   else
 501     xoffset = (double)(m_xpos - (width / 2.0));
 502
 503   if (formatMode & FORMAT_CENTRE_VERT)
 504     yoffset = m_ypos;
 505   else
 506     yoffset = (double)(m_ypos - (height / 2.0));
 507
 508   dc.SetClippingRegion(
 509                     (long)(m_xpos - width/2.0), (long)(m_ypos - height/2.0),
 510                     (long)width, (long)height);
 511
 512   wxNode *current = text_list->First();
 513   while (current)
 514   {
 515     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 516
 517     dc.DrawText(line->GetText(), WXROUND(xoffset + line->GetX()), WXROUND(yoffset + line->GetY()));
 518     current = current->Next();
 519   }
 520
 521   dc.DestroyClippingRegion();
 522 }
 523
 524 /*
 525  * Find centroid given list of points comprising polyline
 526  *
 527  */
 528
 529 void oglFindPolylineCentroid(wxList *points, double *x, double *y)
 530 {
 531   double xcount = 0;
 532   double ycount = 0;
 533
 534   wxNode *node = points->First();
 535   while (node)
 536   {
 537     wxRealPoint *point = (wxRealPoint *)node->Data();
 538     xcount += point->x;
 539     ycount += point->y;
 540     node = node->Next();
 541   }
 542
 543   *x = (xcount/points->Number());
 544   *y = (ycount/points->Number());
 545 }
 546
 547 /*
 548  * Check that (x1, y1) -> (x2, y2) hits (x3, y3) -> (x4, y4).
 549  * If so, ratio1 gives the proportion along the first line
 550  * that the intersection occurs (or something like that).
 551  * Used by functions below.
 552  *
 553  */
 554 void oglCheckLineIntersection(double x1, double y1, double x2, double y2,
 555                              double x3, double y3, double x4, double y4,
 556                              double *ratio1, double *ratio2)
 557 {
 558   double denominator_term = (y4 - y3)*(x2 - x1) - (y2 - y1)*(x4 - x3);
 559   double numerator_term = (x3 - x1)*(y4 - y3) + (x4 - x3)*(y1 - y3);
 560
 561   double line_constant;
 562   double length_ratio = 1.0;
 563   double k_line = 1.0;
 564
 565   // Check for parallel lines
 566   if ((denominator_term < 0.005) && (denominator_term > -0.005))
 567     line_constant = -1.0;
 568   else
 569     line_constant = numerator_term/denominator_term;
 570
 571   // Check for intersection
 572   if ((line_constant < 1.0) && (line_constant > 0.0))
 573   {
 574     // Now must check that other line hits
 575     if (((y4 - y3) < 0.005) && ((y4 - y3) > -0.005))
 576       k_line = ((x1 - x3) + line_constant*(x2 - x1))/(x4 - x3);
 577     else
 578       k_line = ((y1 - y3) + line_constant*(y2 - y1))/(y4 - y3);
 579
 580     if ((k_line >= 0.0) && (k_line < 1.0))
 581       length_ratio = line_constant;
 582     else
 583       k_line = 1.0;
 584   }
 585   *ratio1 = length_ratio;
 586   *ratio2 = k_line;
 587 }
 588
 589 /*
 590  * Find where (x1, y1) -> (x2, y2) hits one of the lines in xvec, yvec.
 591  * (*x3, *y3) is the point where it hits.
 592  *
 593  */
 594 void oglFindEndForPolyline(double n, double xvec[], double yvec[],
 595                            double x1, double y1, double x2, double y2, double *x3, double *y3)
 596 {
 597   int i;
 598   double lastx = xvec[0];
 599   double lasty = yvec[0];
 600
 601   double min_ratio = 1.0;
 602   double line_ratio;
 603   double other_ratio;
 604
 605   for (i = 1; i < n; i++)
 606   {
 607     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[i], yvec[i],
 608                             &line_ratio, &other_ratio);
 609     lastx = xvec[i];
 610     lasty = yvec[i];
 611
 612     if (line_ratio < min_ratio)
 613       min_ratio = line_ratio;
 614   }
 615
 616   // Do last (implicit) line if last and first doubles are not identical
 617   if (!(xvec[0] == lastx && yvec[0] == lasty))
 618   {
 619     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[0], yvec[0],
 620                             &line_ratio, &other_ratio);
 621
 622     if (line_ratio < min_ratio)
 623       min_ratio = line_ratio;
 624   }
 625
 626   *x3 = (x1 + (x2 - x1)*min_ratio);
 627   *y3 = (y1 + (y2 - y1)*min_ratio);
 628
 629 }
 630
 631 /*
 632  * Find where the line hits the box.
 633  *
 634  */
 635
 636 void oglFindEndForBox(double width, double height,
 637                       double x1, double y1,         // Centre of box (possibly)
 638                       double x2, double y2,         // other end of line
 639                       double *x3, double *y3)       // End on box edge
 640 {
 641   double xvec[5];
 642   double yvec[5];
 643
 644   xvec[0] = (double)(x1 - width/2.0);
 645   yvec[0] = (double)(y1 - height/2.0);
 646   xvec[1] = (double)(x1 - width/2.0);
 647   yvec[1] = (double)(y1 + height/2.0);
 648   xvec[2] = (double)(x1 + width/2.0);
 649   yvec[2] = (double)(y1 + height/2.0);
 650   xvec[3] = (double)(x1 + width/2.0);
 651   yvec[3] = (double)(y1 - height/2.0);
 652   xvec[4] = (double)(x1 - width/2.0);
 653   yvec[4] = (double)(y1 - height/2.0);
 654
 655   oglFindEndForPolyline(5, xvec, yvec, x2, y2, x1, y1, x3, y3);
 656 }
 657
 658 /*
 659  * Find where the line hits the circle.
 660  *
 661  */
 662
 663 void oglFindEndForCircle(double radius,
 664                          double x1, double y1,  // Centre of circle
 665                          double x2, double y2,  // Other end of line
 666                          double *x3, double *y3)
 667 {
 668   double H = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 669
 670   if (H == 0.0)
 671   {
 672     *x3 = x1;
 673     *y3 = y1;
 674   }
 675   else
 676   {
 677    *y3 = radius * (y2 - y1)/H + y1;
 678    *x3 = radius * (x2 - x1)/H + x1;
 679   }
 680 }
 681
 682 /*
 683  * Given the line (x1, y1) -> (x2, y2), and an arrow size of given length and width,
 684  * return the position of the tip of the arrow and the left and right vertices of the arrow.
 685  *
 686  */
 687
 688 void oglGetArrowPoints(double x1, double y1, double x2, double y2,
 689                       double length, double width,
 690                       double *tip_x, double *tip_y,
 691                       double *side1_x, double *side1_y,
 692                       double *side2_x, double *side2_y)
 693 {
 694   double l = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 695
 696   if (l < 0.01)
 697     l = (double) 0.01;
 698
 699   double i_bar = (x2 - x1)/l;
 700   double j_bar = (y2 - y1)/l;
 701
 702   double x3 = (- length*i_bar) + x2;
 703   double y3 = (- length*j_bar) + y2;
 704
 705   *side1_x = width*(-j_bar) + x3;
 706   *side1_y = width*i_bar + y3;
 707
 708   *side2_x = -width*(-j_bar) + x3;
 709   *side2_y = -width*i_bar + y3;
 710
 711   *tip_x = x2; *tip_y = y2;
 712 }
 713
 714 /*
 715  * Given an ellipse and endpoints of a line, returns the point at which
 716  * the line touches the ellipse in values x4, y4.
 717  * This function assumes that the centre of the ellipse is at x1, y1, and the
 718  * ellipse has a width of width1 and a height of height1. It also assumes you are
 719  * wanting to draw an arc FROM point x2, y2 TOWARDS point x3, y3.
 720  * This function calculates the x,y coordinates of the intersection point of
 721  * the arc with the ellipse.
 722  * Author: Ian Harrison
 723  */
 724
 725 void oglDrawArcToEllipse(double x1, double y1, double width1, double height1, double x2, double y2, double x3, double y3,
 726   double *x4, double *y4)
 727 {
 728   double a1 = (double)(width1/2.0);
 729   double b1 = (double)(height1/2.0);
 730
 731   // These are required to give top left x and y coordinates for DrawEllipse
 732 //  double top_left_x1 = (double)(x1 - a1);
 733 //  double top_left_y1 = (double)(y1 - b1);
 734 /*
 735   // Check for vertical line
 736   if (fabs(x2 - x3) < 0.05)
 737   {
 738     *x4 = x3;
 739     if (y2 < y3)
 740       *y4 = (double)(y1 - b1);
 741     else
 742       *y4 = (double)(y1 + b1);
 743     return;
 744   }
 745 */
 746   // Check that x2 != x3
 747   if (fabs(x2 - x3) < 0.05)
 748   {
 749     *x4 = x2;
 750     if (y3 > y2)
 751       *y4 = (double)(y1 - sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 752     else
 753       *y4 = (double)(y1 + sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 754     return;
 755   }
 756
 757   // Calculate the x and y coordinates of the point where arc intersects ellipse
 758
 759   double A, B, C, D, E, F, G, H, K;
 760   double ellipse1_x, ellipse1_y;
 761
 762   A = (double)(1/(a1 * a1));
 763   B = (double)((y3 - y2) * (y3 - y2)) / ((x3 - x2) * (x3 - x2) * b1 * b1);
 764   C = (double)(2 * (y3 - y2) * (y2 - y1)) / ((x3 - x2) * b1 * b1);
 765   D = (double)((y2 - y1) * (y2 - y1)) / (b1 * b1);
 766   E = (double)(A + B);
 767   F = (double)(C - (2 * A * x1) - (2 * B * x2));
 768   G = (double)((A * x1 * x1) + (B * x2 * x2) - (C * x2) + D - 1);
 769   H = (double)((y3 - y2) / (x3 - x2));
 770   K = (double)((F * F) - (4 * E * G));
 771
 772   if (K >= 0)
 773   // In this case the line intersects the ellipse, so calculate intersection
 774   {
 775     if(x2 >= x1)
 776     {
 777       ellipse1_x = (double)(((F * -1) + sqrt(K)) / (2 * E));
 778       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 779     }
 780     else
 781     {
 782       ellipse1_x = (double)(((F * -1) -  sqrt(K)) / (2 * E));
 783       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 784     }
 785   }
 786   else
 787   // in this case, arc does not intersect ellipse, so just draw arc
 788   {
 789     ellipse1_x = x3;
 790     ellipse1_y = y3;
 791   }
 792   *x4 = ellipse1_x;
 793   *y4 = ellipse1_y;
 794
 795 /*
 796   // Draw a little circle (radius = 2) at the end of the arc where it hits
 797   // the ellipse .
 798
 799   double circle_x = ellipse1_x - 2.0;
 800   double circle_y = ellipse1_y - 2.0;
 801   m_canvas->DrawEllipse(circle_x, circle_y, 4.0, 4.0);
 802 */
 803 }
 804
 805 // Update a list item from a list of strings
 806 void UpdateListBox(wxListBox *item, wxList *list)
 807 {
 808   item->Clear();
 809   if (!list)
 810     return;
 811
 812   wxNode *node = list->First();
 813   while (node)
 814   {
 815     char *s = (char *)node->Data();
 816     item->Append(s);
 817     node = node->Next();
 818   }
 819 }
 820
 821 bool oglRoughlyEqual(double val1, double val2, double tol)
 822 {
 823     return ( (val1 < (val2 + tol)) && (val1 > (val2 - tol)) &&
 824              (val2 < (val1 + tol)) && (val2 > (val1 - tol)));
 825 }
 826
 827 /*
 828  * Hex<->Dec conversion
 829  */
 830
 831 // Array used in DecToHex conversion routine.
 832 static char sg_HexArray[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B',
 833   'C', 'D', 'E', 'F' };
 834
 835 // Convert 2-digit hex number to decimal
 836 unsigned int oglHexToDec(char* buf)
 837 {
 838   int firstDigit, secondDigit;
 839
 840   if (buf[0] >= 'A')
 841     firstDigit = buf[0] - 'A' + 10;
 842   else
 843     firstDigit = buf[0] - '0';
 844
 845   if (buf[1] >= 'A')
 846     secondDigit = buf[1] - 'A' + 10;
 847   else
 848     secondDigit = buf[1] - '0';
 849
 850   return firstDigit * 16 + secondDigit;
 851 }
 852
 853 // Convert decimal integer to 2-character hex string
 854 void oglDecToHex(unsigned int dec, char *buf)
 855 {
 856     int firstDigit = (int)(dec/16.0);
 857     int secondDigit = (int)(dec - (firstDigit*16.0));
 858     buf[0] = sg_HexArray[firstDigit];
 859     buf[1] = sg_HexArray[secondDigit];
 860     buf[2] = 0;
 861 }
 862
 863 // 3-digit hex to wxColour
 864 wxColour oglHexToColour(const wxString& hex)
 865 {
 866     if (hex.Length() == 6)
 867         {
 868         char buf[7];
 869         strncpy(buf, hex, 7);
 870         unsigned int r = oglHexToDec((char *)buf);
 871         unsigned int g = oglHexToDec((char *)(buf+2));
 872         unsigned int b = oglHexToDec((char *)(buf+4));
 873         return wxColour(r, g, b);
 874         }
 875         else
 876             return wxColour(0,0,0);
 877 }
 878
 879 // RGB to 3-digit hex
 880 wxString oglColourToHex(const wxColour& colour)
 881 {
 882     char buf[7];
 883     unsigned int red = colour.Red();
 884     unsigned int green = colour.Green();
 885     unsigned int blue = colour.Blue();
 886
 887     oglDecToHex(red, buf);
 888     oglDecToHex(green, buf+2);
 889     oglDecToHex(blue, buf+4);
 890
 891     return wxString(buf);
 892 }
 893
 894