utils/ogl/src/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 "basic.h"
  41 #include "basicp.h"
  42 #include "misc.h"
  43 #include "constrnt.h"
  44 #include "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 void wxOGLInitialize()
  59 {
  60   g_oglBullseyeCursor = new wxCursor(wxCURSOR_BULLSEYE);
  61
  62   g_oglNormalFont = new wxFont(10, wxSWISS, wxNORMAL, wxNORMAL);
  63
  64   g_oglBlackPen = new wxPen("BLACK", 1, wxSOLID);
  65
  66   g_oglWhiteBackgroundPen = new wxPen("WHITE", 1, wxSOLID);
  67   g_oglTransparentPen = new wxPen("WHITE", 1, wxTRANSPARENT);
  68   g_oglWhiteBackgroundBrush = new wxBrush("WHITE", wxSOLID);
  69   g_oglBlackForegroundPen = new wxPen("BLACK", 1, wxSOLID);
  70
  71   OGLInitializeConstraintTypes();
  72
  73   // Initialize big buffer used when writing images
  74   oglBuffer = new char[3000];
  75
  76   if (!oglPopupDivisionMenu)
  77   {
  78     oglPopupDivisionMenu = new wxMenu("", (wxFunction)oglGraphicsDivisionMenuProc);
  79     oglPopupDivisionMenu->Append(DIVISION_MENU_SPLIT_HORIZONTALLY, "Split horizontally");
  80     oglPopupDivisionMenu->Append(DIVISION_MENU_SPLIT_VERTICALLY, "Split vertically");
  81     oglPopupDivisionMenu->AppendSeparator();
  82     oglPopupDivisionMenu->Append(DIVISION_MENU_EDIT_LEFT_EDGE, "Edit left edge");
  83     oglPopupDivisionMenu->Append(DIVISION_MENU_EDIT_TOP_EDGE, "Edit top edge");
  84   }
  85 }
  86
  87 void wxOGLCleanUp()
  88 {
  89     if (oglBuffer)
  90     {
  91         delete[] oglBuffer;
  92         oglBuffer = NULL;
  93     }
  94     oglBuffer = NULL;
  95     if (oglPopupDivisionMenu)
  96     {
  97         delete oglPopupDivisionMenu;
  98         oglPopupDivisionMenu = NULL;
  99     }
 100     if (g_oglBullseyeCursor)
 101     {
 102         delete g_oglBullseyeCursor;
 103         g_oglBullseyeCursor = NULL;
 104     }
 105
 106     if (g_oglNormalFont)
 107     {
 108         delete g_oglNormalFont;
 109         g_oglNormalFont = NULL;
 110     }
 111     if (g_oglBlackPen)
 112     {
 113         delete g_oglBlackPen;
 114         g_oglBlackPen = NULL;
 115     }
 116     if (g_oglWhiteBackgroundPen)
 117     {
 118         delete g_oglWhiteBackgroundPen;
 119         g_oglWhiteBackgroundPen = NULL;
 120     }
 121     if (g_oglTransparentPen)
 122     {
 123         delete g_oglTransparentPen;
 124         g_oglTransparentPen = NULL;
 125     }
 126     if (g_oglWhiteBackgroundBrush)
 127     {
 128         delete g_oglWhiteBackgroundBrush;
 129         g_oglWhiteBackgroundBrush = NULL;
 130     }
 131     if (g_oglBlackForegroundPen)
 132     {
 133         delete g_oglBlackForegroundPen;
 134         g_oglBlackForegroundPen = NULL;
 135     }
 136
 137     OGLCleanUpConstraintTypes();
 138 }
 139
 140 wxFont *oglMatchFont(int point_size)
 141 {
 142   wxFont *font = wxTheFontList->FindOrCreateFont(point_size, wxSWISS, wxNORMAL, wxNORMAL);
 143 #if 0
 144   switch (point_size)
 145   {
 146     case 4:
 147       font = swiss_font_4;
 148       break;
 149     case 6:
 150       font = swiss_font_6;
 151       break;
 152     case 8:
 153       font = swiss_font_8;
 154       break;
 155     case 12:
 156       font = swiss_font_12;
 157       break;
 158     case 14:
 159       font = swiss_font_14;
 160       break;
 161     case 18:
 162       font = swiss_font_18;
 163       break;
 164     case 24:
 165       font = swiss_font_24;
 166       break;
 167     default:
 168     case 10:
 169       font = swiss_font_10;
 170       break;
 171   }
 172 #endif
 173   return font;
 174 }
 175
 176 int FontSizeDialog(wxFrame *parent, int old_size)
 177 {
 178   if (old_size <= 0)
 179     old_size = 10;
 180   char buf[40];
 181   sprintf(buf, "%d", old_size);
 182   wxString ans = wxGetTextFromUser("Enter point size", "Font size", buf, parent);
 183   if (ans == "")
 184     return 0;
 185
 186   int new_size = atoi(ans);
 187   if ((new_size <= 0) || (new_size > 40))
 188   {
 189     wxMessageBox("Invalid point size!", "Error", wxOK);
 190     return 0;
 191   }
 192   return new_size;
 193 /*
 194   char *strings[8];
 195   strings[0] = "4";
 196   strings[1] = "6";
 197   strings[2] = "8";
 198   strings[3] = "10";
 199   strings[4] = "12";
 200   strings[5] = "14";
 201   strings[6] = "18";
 202   strings[7] = "24";
 203   char *ans = wxGetSingleChoice("Choose", "Choose a font size", 8, strings, parent);
 204   if (ans)
 205   {
 206     int size;
 207     sscanf(ans, "%d", &size);
 208     return oglMatchFont(size);
 209   }
 210   else return NULL;
 211 */
 212 }
 213
 214 // Centre a list of strings in the given box. xOffset and yOffset are the
 215 // the positions that these lines should be relative to, and this might be
 216 // the same as m_xpos, m_ypos, but might be zero if formatting from left-justifying.
 217 void oglCentreText(wxDC& dc, wxList *text_list,
 218                 double m_xpos, double m_ypos, double width, double height,
 219                 int formatMode)
 220 {
 221   int n = text_list->Number();
 222
 223   if (!text_list || (n == 0))
 224     return;
 225
 226   // First, get maximum dimensions of box enclosing text
 227
 228   long char_height = 0;
 229   long max_width = 0;
 230   long current_width = 0;
 231
 232   // Store text extents for speed
 233   double *widths = new double[n];
 234
 235   wxNode *current = text_list->First();
 236   int i = 0;
 237   while (current)
 238   {
 239     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 240     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 241     widths[i] = current_width;
 242
 243     if (current_width > max_width)
 244       max_width = current_width;
 245     current = current->Next();
 246     i ++;
 247   }
 248
 249   double max_height = n*char_height;
 250
 251   double xoffset, yoffset, xOffset, yOffset;
 252
 253   if (formatMode & FORMAT_CENTRE_VERT)
 254   {
 255     if (max_height < height)
 256       yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 257     else
 258       yoffset = (double)(m_ypos - (height/2.0));
 259     yOffset = m_ypos;
 260   }
 261   else
 262   {
 263     yoffset = 0.0;
 264     yOffset = 0.0;
 265   }
 266
 267   if (formatMode & FORMAT_CENTRE_HORIZ)
 268   {
 269     xoffset = (double)(m_xpos - width/2.0);
 270     xOffset = m_xpos;
 271   }
 272   else
 273   {
 274     xoffset = 0.0;
 275     xOffset = 0.0;
 276   }
 277
 278   current = text_list->First();
 279   i = 0;
 280
 281   while (current)
 282   {
 283     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 284
 285     double x;
 286     if ((formatMode & FORMAT_CENTRE_HORIZ) && (widths[i] < width))
 287       x = (double)((width - widths[i])/2.0 + xoffset);
 288     else
 289       x = xoffset;
 290     double y = (double)(i*char_height + yoffset);
 291
 292     line->SetX( x - xOffset ); line->SetY( y - yOffset );
 293     current = current->Next();
 294     i ++;
 295   }
 296
 297   delete widths;
 298 }
 299
 300 // Centre a list of strings in the given box
 301 void oglCentreTextNoClipping(wxDC& dc, wxList *text_list,
 302                               double m_xpos, double m_ypos, double width, double height)
 303 {
 304   int n = text_list->Number();
 305
 306   if (!text_list || (n == 0))
 307     return;
 308
 309   // First, get maximum dimensions of box enclosing text
 310
 311   long char_height = 0;
 312   long max_width = 0;
 313   long current_width = 0;
 314
 315   // Store text extents for speed
 316   double *widths = new double[n];
 317
 318   wxNode *current = text_list->First();
 319   int i = 0;
 320   while (current)
 321   {
 322     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 323     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 324     widths[i] = current_width;
 325
 326     if (current_width > max_width)
 327       max_width = current_width;
 328     current = current->Next();
 329     i ++;
 330   }
 331
 332   double max_height = n*char_height;
 333
 334   double yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 335
 336   double xoffset = (double)(m_xpos - width/2.0);
 337
 338   current = text_list->First();
 339   i = 0;
 340
 341   while (current)
 342   {
 343     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 344
 345     double x = (double)((width - widths[i])/2.0 + xoffset);
 346     double y = (double)(i*char_height + yoffset);
 347
 348     line->SetX( x - m_xpos ); line->SetY( y - m_ypos );
 349     current = current->Next();
 350     i ++;
 351   }
 352   delete widths;
 353 }
 354
 355 void oglGetCentredTextExtent(wxDC& dc, wxList *text_list,
 356                               double m_xpos, double m_ypos, double width, double height,
 357                               double *actual_width, double *actual_height)
 358 {
 359   int n = text_list->Number();
 360
 361   if (!text_list || (n == 0))
 362   {
 363     *actual_width = 0;
 364     *actual_height = 0;
 365     return;
 366   }
 367
 368   // First, get maximum dimensions of box enclosing text
 369
 370   long char_height = 0;
 371   long max_width = 0;
 372   long current_width = 0;
 373
 374   wxNode *current = text_list->First();
 375   int i = 0;
 376   while (current)
 377   {
 378     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 379     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 380
 381     if (current_width > max_width)
 382       max_width = current_width;
 383     current = current->Next();
 384     i ++;
 385   }
 386
 387   *actual_height = n*char_height;
 388   *actual_width = max_width;
 389 }
 390
 391 // Format a string to a list of strings that fit in the given box.
 392 // Interpret %n and 10 or 13 as a new line.
 393 wxStringList *oglFormatText(wxDC& dc, const wxString& text, double width, double height, int formatMode)
 394 {
 395   // First, parse the string into a list of words
 396   wxStringList word_list;
 397
 398   // Make new lines into NULL strings at this point
 399   int i = 0; int j = 0; int len = strlen(text);
 400   char word[200]; word[0] = 0;
 401   bool end_word = FALSE; bool new_line = FALSE;
 402   while (i < len)
 403   {
 404     switch (text[i])
 405     {
 406       case '%':
 407       {
 408         i ++;
 409         if (i == len)
 410         { word[j] = '%'; j ++; }
 411         else
 412         {
 413           if (text[i] == 'n')
 414           { new_line = TRUE; end_word = TRUE; i++; }
 415           else
 416           { word[j] = '%'; j ++; word[j] = text[i]; j ++; i ++; }
 417         }
 418         break;
 419       }
 420       case 10:
 421       {
 422         new_line = TRUE; end_word = TRUE; i++;
 423         break;
 424       }
 425       case 13:
 426       {
 427         new_line = TRUE; end_word = TRUE; i++;
 428       }
 429       case ' ':
 430       {
 431         end_word = TRUE;
 432         i ++;
 433         break;
 434       }
 435       default:
 436       {
 437         word[j] = text[i];
 438         j ++; i ++;
 439         break;
 440       }
 441     }
 442     if (i == len) end_word = TRUE;
 443     if (end_word)
 444     {
 445       word[j] = 0;
 446       j = 0;
 447       word_list.Add(word);
 448       end_word = FALSE;
 449     }
 450     if (new_line)
 451     {
 452       word_list.Append(NULL);
 453       new_line = FALSE;
 454     }
 455   }
 456   // Now, make a list of strings which can fit in the box
 457   wxStringList *string_list = new wxStringList;
 458
 459   char buffer[400];
 460   buffer[0] = 0;
 461   wxNode *node = word_list.First();
 462   long x, y;
 463
 464   while (node)
 465   {
 466     wxString oldBuffer(buffer);
 467
 468     char *s = (char *)node->Data();
 469     if (!s)
 470     {
 471       // FORCE NEW LINE
 472       if (strlen(buffer) > 0)
 473         string_list->Add(buffer);
 474
 475       buffer[0] = 0;
 476     }
 477     else
 478     {
 479       if (buffer[0] != 0)
 480         strcat(buffer, " ");
 481
 482       strcat(buffer, s);
 483       dc.GetTextExtent(buffer, &x, &y);
 484
 485       // Don't fit within the bounding box if we're fitting shape to contents
 486       if ((x > width) && !(formatMode & FORMAT_SIZE_TO_CONTENTS))
 487       {
 488         // Deal with first word being wider than box
 489         if (oldBuffer.Length() > 0)
 490           string_list->Add(oldBuffer);
 491
 492         buffer[0] = 0;
 493         strcat(buffer, s);
 494       }
 495     }
 496
 497     node = node->Next();
 498   }
 499   if (buffer[0] != 0)
 500     string_list->Add(buffer);
 501
 502   return string_list;
 503 }
 504
 505 void oglDrawFormattedText(wxDC& dc, wxList *text_list,
 506                        double m_xpos, double m_ypos, double width, double height,
 507                        int formatMode)
 508 {
 509   double xoffset, yoffset;
 510   if (formatMode & FORMAT_CENTRE_HORIZ)
 511     xoffset = m_xpos;
 512   else
 513     xoffset = (double)(m_xpos - (width / 2.0));
 514
 515   if (formatMode & FORMAT_CENTRE_VERT)
 516     yoffset = m_ypos;
 517   else
 518     yoffset = (double)(m_ypos - (height / 2.0));
 519
 520   dc.SetClippingRegion(
 521                     (long)(m_xpos - width/2.0), (long)(m_ypos - height/2.0),
 522                     (long)width, (long)height);
 523
 524   wxNode *current = text_list->First();
 525   while (current)
 526   {
 527     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 528
 529     dc.DrawText(line->GetText(), WXROUND(xoffset + line->GetX()), WXROUND(yoffset + line->GetY()));
 530     current = current->Next();
 531   }
 532
 533   dc.DestroyClippingRegion();
 534 }
 535
 536 /*
 537  * Find centroid given list of points comprising polyline
 538  *
 539  */
 540
 541 void oglFindPolylineCentroid(wxList *points, double *x, double *y)
 542 {
 543   double xcount = 0;
 544   double ycount = 0;
 545
 546   wxNode *node = points->First();
 547   while (node)
 548   {
 549     wxRealPoint *point = (wxRealPoint *)node->Data();
 550     xcount += point->x;
 551     ycount += point->y;
 552     node = node->Next();
 553   }
 554
 555   *x = (xcount/points->Number());
 556   *y = (ycount/points->Number());
 557 }
 558
 559 /*
 560  * Check that (x1, y1) -> (x2, y2) hits (x3, y3) -> (x4, y4).
 561  * If so, ratio1 gives the proportion along the first line
 562  * that the intersection occurs (or something like that).
 563  * Used by functions below.
 564  *
 565  */
 566 void oglCheckLineIntersection(double x1, double y1, double x2, double y2,
 567                              double x3, double y3, double x4, double y4,
 568                              double *ratio1, double *ratio2)
 569 {
 570   double denominator_term = (y4 - y3)*(x2 - x1) - (y2 - y1)*(x4 - x3);
 571   double numerator_term = (x3 - x1)*(y4 - y3) + (x4 - x3)*(y1 - y3);
 572
 573   double line_constant;
 574   double length_ratio = 1.0;
 575   double k_line = 1.0;
 576
 577   // Check for parallel lines
 578   if ((denominator_term < 0.005) && (denominator_term > -0.005))
 579     line_constant = -1.0;
 580   else
 581     line_constant = numerator_term/denominator_term;
 582
 583   // Check for intersection
 584   if ((line_constant < 1.0) && (line_constant > 0.0))
 585   {
 586     // Now must check that other line hits
 587     if (((y4 - y3) < 0.005) && ((y4 - y3) > -0.005))
 588       k_line = ((x1 - x3) + line_constant*(x2 - x1))/(x4 - x3);
 589     else
 590       k_line = ((y1 - y3) + line_constant*(y2 - y1))/(y4 - y3);
 591
 592     if ((k_line >= 0.0) && (k_line < 1.0))
 593       length_ratio = line_constant;
 594     else
 595       k_line = 1.0;
 596   }
 597   *ratio1 = length_ratio;
 598   *ratio2 = k_line;
 599 }
 600
 601 /*
 602  * Find where (x1, y1) -> (x2, y2) hits one of the lines in xvec, yvec.
 603  * (*x3, *y3) is the point where it hits.
 604  *
 605  */
 606 void oglFindEndForPolyline(double n, double xvec[], double yvec[],
 607                            double x1, double y1, double x2, double y2, double *x3, double *y3)
 608 {
 609   int i;
 610   double lastx = xvec[0];
 611   double lasty = yvec[0];
 612
 613   double min_ratio = 1.0;
 614   double line_ratio;
 615   double other_ratio;
 616
 617   for (i = 1; i < n; i++)
 618   {
 619     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[i], yvec[i],
 620                             &line_ratio, &other_ratio);
 621     lastx = xvec[i];
 622     lasty = yvec[i];
 623
 624     if (line_ratio < min_ratio)
 625       min_ratio = line_ratio;
 626   }
 627
 628   // Do last (implicit) line if last and first doubles are not identical
 629   if (!(xvec[0] == lastx && yvec[0] == lasty))
 630   {
 631     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[0], yvec[0],
 632                             &line_ratio, &other_ratio);
 633
 634     if (line_ratio < min_ratio)
 635       min_ratio = line_ratio;
 636   }
 637
 638   *x3 = (x1 + (x2 - x1)*min_ratio);
 639   *y3 = (y1 + (y2 - y1)*min_ratio);
 640
 641 }
 642
 643 /*
 644  * Find where the line hits the box.
 645  *
 646  */
 647
 648 void oglFindEndForBox(double width, double height,
 649                       double x1, double y1,         // Centre of box (possibly)
 650                       double x2, double y2,         // other end of line
 651                       double *x3, double *y3)       // End on box edge
 652 {
 653   double xvec[5];
 654   double yvec[5];
 655
 656   xvec[0] = (double)(x1 - width/2.0);
 657   yvec[0] = (double)(y1 - height/2.0);
 658   xvec[1] = (double)(x1 - width/2.0);
 659   yvec[1] = (double)(y1 + height/2.0);
 660   xvec[2] = (double)(x1 + width/2.0);
 661   yvec[2] = (double)(y1 + height/2.0);
 662   xvec[3] = (double)(x1 + width/2.0);
 663   yvec[3] = (double)(y1 - height/2.0);
 664   xvec[4] = (double)(x1 - width/2.0);
 665   yvec[4] = (double)(y1 - height/2.0);
 666
 667   oglFindEndForPolyline(5, xvec, yvec, x2, y2, x1, y1, x3, y3);
 668 }
 669
 670 /*
 671  * Find where the line hits the circle.
 672  *
 673  */
 674
 675 void oglFindEndForCircle(double radius,
 676                          double x1, double y1,  // Centre of circle
 677                          double x2, double y2,  // Other end of line
 678                          double *x3, double *y3)
 679 {
 680   double H = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 681
 682   if (H == 0.0)
 683   {
 684     *x3 = x1;
 685     *y3 = y1;
 686   }
 687   else
 688   {
 689    *y3 = radius * (y2 - y1)/H + y1;
 690    *x3 = radius * (x2 - x1)/H + x1;
 691   }
 692 }
 693
 694 /*
 695  * Given the line (x1, y1) -> (x2, y2), and an arrow size of given length and width,
 696  * return the position of the tip of the arrow and the left and right vertices of the arrow.
 697  *
 698  */
 699
 700 void oglGetArrowPoints(double x1, double y1, double x2, double y2,
 701                       double length, double width,
 702                       double *tip_x, double *tip_y,
 703                       double *side1_x, double *side1_y,
 704                       double *side2_x, double *side2_y)
 705 {
 706   double l = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 707
 708   if (l < 0.01)
 709     l = (double) 0.01;
 710
 711   double i_bar = (x2 - x1)/l;
 712   double j_bar = (y2 - y1)/l;
 713
 714   double x3 = (- length*i_bar) + x2;
 715   double y3 = (- length*j_bar) + y2;
 716
 717   *side1_x = width*(-j_bar) + x3;
 718   *side1_y = width*i_bar + y3;
 719
 720   *side2_x = -width*(-j_bar) + x3;
 721   *side2_y = -width*i_bar + y3;
 722
 723   *tip_x = x2; *tip_y = y2;
 724 }
 725
 726 /*
 727  * Given an ellipse and endpoints of a line, returns the point at which
 728  * the line touches the ellipse in values x4, y4.
 729  * This function assumes that the centre of the ellipse is at x1, y1, and the
 730  * ellipse has a width of width1 and a height of height1. It also assumes you are
 731  * wanting to draw an arc FROM point x2, y2 TOWARDS point x3, y3.
 732  * This function calculates the x,y coordinates of the intersection point of
 733  * the arc with the ellipse.
 734  * Author: Ian Harrison
 735  */
 736
 737 void oglDrawArcToEllipse(double x1, double y1, double width1, double height1, double x2, double y2, double x3, double y3,
 738   double *x4, double *y4)
 739 {
 740   double a1 = (double)(width1/2.0);
 741   double b1 = (double)(height1/2.0);
 742
 743   // These are required to give top left x and y coordinates for DrawEllipse
 744 //  double top_left_x1 = (double)(x1 - a1);
 745 //  double top_left_y1 = (double)(y1 - b1);
 746 /*
 747   // Check for vertical line
 748   if (fabs(x2 - x3) < 0.05)
 749   {
 750     *x4 = x3;
 751     if (y2 < y3)
 752       *y4 = (double)(y1 - b1);
 753     else
 754       *y4 = (double)(y1 + b1);
 755     return;
 756   }
 757 */
 758   // Check that x2 != x3
 759   if (fabs(x2 - x3) < 0.05)
 760   {
 761     *x4 = x2;
 762     if (y3 > y2)
 763       *y4 = (double)(y1 - sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 764     else
 765       *y4 = (double)(y1 + sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 766     return;
 767   }
 768
 769   // Calculate the x and y coordinates of the point where arc intersects ellipse
 770
 771   double A, B, C, D, E, F, G, H, K;
 772   double ellipse1_x, ellipse1_y;
 773
 774   A = (double)(1/(a1 * a1));
 775   B = (double)((y3 - y2) * (y3 - y2)) / ((x3 - x2) * (x3 - x2) * b1 * b1);
 776   C = (double)(2 * (y3 - y2) * (y2 - y1)) / ((x3 - x2) * b1 * b1);
 777   D = (double)((y2 - y1) * (y2 - y1)) / (b1 * b1);
 778   E = (double)(A + B);
 779   F = (double)(C - (2 * A * x1) - (2 * B * x2));
 780   G = (double)((A * x1 * x1) + (B * x2 * x2) - (C * x2) + D - 1);
 781   H = (double)((y3 - y2) / (x3 - x2));
 782   K = (double)((F * F) - (4 * E * G));
 783
 784   if (K >= 0)
 785   // In this case the line intersects the ellipse, so calculate intersection
 786   {
 787     if(x2 >= x1)
 788     {
 789       ellipse1_x = (double)(((F * -1) + sqrt(K)) / (2 * E));
 790       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 791     }
 792     else
 793     {
 794       ellipse1_x = (double)(((F * -1) -  sqrt(K)) / (2 * E));
 795       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 796     }
 797   }
 798   else
 799   // in this case, arc does not intersect ellipse, so just draw arc
 800   {
 801     ellipse1_x = x3;
 802     ellipse1_y = y3;
 803   }
 804   *x4 = ellipse1_x;
 805   *y4 = ellipse1_y;
 806
 807 /*
 808   // Draw a little circle (radius = 2) at the end of the arc where it hits
 809   // the ellipse .
 810
 811   double circle_x = ellipse1_x - 2.0;
 812   double circle_y = ellipse1_y - 2.0;
 813   m_canvas->DrawEllipse(circle_x, circle_y, 4.0, 4.0);
 814 */
 815 }
 816
 817 // Update a list item from a list of strings
 818 void UpdateListBox(wxListBox *item, wxList *list)
 819 {
 820   item->Clear();
 821   if (!list)
 822     return;
 823
 824   wxNode *node = list->First();
 825   while (node)
 826   {
 827     char *s = (char *)node->Data();
 828     item->Append(s);
 829     node = node->Next();
 830   }
 831 }
 832
 833 bool oglRoughlyEqual(double val1, double val2, double tol)
 834 {
 835     return ( (val1 < (val2 + tol)) && (val1 > (val2 - tol)) &&
 836              (val2 < (val1 + tol)) && (val2 > (val1 - tol)));
 837 }
 838
 839 /*
 840  * Hex<->Dec conversion
 841  */
 842
 843 // Array used in DecToHex conversion routine.
 844 static char sg_HexArray[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B',
 845   'C', 'D', 'E', 'F' };
 846
 847 // Convert 2-digit hex number to decimal
 848 unsigned int oglHexToDec(char* buf)
 849 {
 850   int firstDigit, secondDigit;
 851
 852   if (buf[0] >= 'A')
 853     firstDigit = buf[0] - 'A' + 10;
 854   else
 855     firstDigit = buf[0] - '0';
 856
 857   if (buf[1] >= 'A')
 858     secondDigit = buf[1] - 'A' + 10;
 859   else
 860     secondDigit = buf[1] - '0';
 861
 862   return firstDigit * 16 + secondDigit;
 863 }
 864
 865 // Convert decimal integer to 2-character hex string
 866 void oglDecToHex(unsigned int dec, char *buf)
 867 {
 868     int firstDigit = (int)(dec/16.0);
 869     int secondDigit = (int)(dec - (firstDigit*16.0));
 870     buf[0] = sg_HexArray[firstDigit];
 871     buf[1] = sg_HexArray[secondDigit];
 872     buf[2] = 0;
 873 }
 874
 875 // 3-digit hex to wxColour
 876 wxColour oglHexToColour(const wxString& hex)
 877 {
 878     if (hex.Length() == 6)
 879         {
 880         char buf[7];
 881         strncpy(buf, hex, 7);
 882         unsigned int r = oglHexToDec((char *)buf);
 883         unsigned int g = oglHexToDec((char *)(buf+2));
 884         unsigned int b = oglHexToDec((char *)(buf+4));
 885         return wxColour(r, g, b);
 886         }
 887         else
 888             return wxColour(0,0,0);
 889 }
 890
 891 // RGB to 3-digit hex
 892 wxString oglColourToHex(const wxColour& colour)
 893 {
 894     char buf[7];
 895     unsigned int red = colour.Red();
 896     unsigned int green = colour.Green();
 897     unsigned int blue = colour.Blue();
 898
 899     oglDecToHex(red, buf);
 900     oglDecToHex(green, buf+2);
 901     oglDecToHex(blue, buf+4);
 902
 903     return wxString(buf);
 904 }
 905
 906