contrib/src/ogl/oglmisc.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 #if wxUSE_PROLOGIO
  28 #include <wx/deprecated/wxexpr.h>
  29 #endif
  30
  31 #include <wx/types.h>
  32
  33 #ifdef new
  34 #undef new
  35 #endif
  36
  37 #include <ctype.h>
  38 #include <math.h>
  39 #include <stdlib.h>
  40
  41 #include "wx/ogl/ogl.h"
  42
  43
  44 wxFont*         g_oglNormalFont;
  45 wxPen*          g_oglBlackPen;
  46 wxPen*          g_oglWhiteBackgroundPen;
  47 wxPen*          g_oglTransparentPen;
  48 wxBrush*        g_oglWhiteBackgroundBrush;
  49 wxPen*          g_oglBlackForegroundPen;
  50 wxCursor*       g_oglBullseyeCursor = NULL;
  51
  52 wxChar*           oglBuffer = NULL;
  53
  54 wxList          oglObjectCopyMapping(wxKEY_INTEGER);
  55
  56
  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(wxT("BLACK"), 1, wxSOLID);
  65
  66   g_oglWhiteBackgroundPen = new wxPen(wxT("WHITE"), 1, wxSOLID);
  67   g_oglTransparentPen = new wxPen(wxT("WHITE"), 1, wxTRANSPARENT);
  68   g_oglWhiteBackgroundBrush = new wxBrush(wxT("WHITE"), wxSOLID);
  69   g_oglBlackForegroundPen = new wxPen(wxT("BLACK"), 1, wxSOLID);
  70
  71   OGLInitializeConstraintTypes();
  72
  73   // Initialize big buffer used when writing images
  74   oglBuffer = new wxChar[3000];
  75
  76 }
  77
  78 void wxOGLCleanUp()
  79 {
  80     if (oglBuffer)
  81     {
  82         delete[] oglBuffer;
  83         oglBuffer = NULL;
  84     }
  85     oglBuffer = NULL;
  86
  87     if (g_oglBullseyeCursor)
  88     {
  89         delete g_oglBullseyeCursor;
  90         g_oglBullseyeCursor = NULL;
  91     }
  92
  93     if (g_oglNormalFont)
  94     {
  95         delete g_oglNormalFont;
  96         g_oglNormalFont = NULL;
  97     }
  98     if (g_oglBlackPen)
  99     {
 100         delete g_oglBlackPen;
 101         g_oglBlackPen = NULL;
 102     }
 103     if (g_oglWhiteBackgroundPen)
 104     {
 105         delete g_oglWhiteBackgroundPen;
 106         g_oglWhiteBackgroundPen = NULL;
 107     }
 108     if (g_oglTransparentPen)
 109     {
 110         delete g_oglTransparentPen;
 111         g_oglTransparentPen = NULL;
 112     }
 113     if (g_oglWhiteBackgroundBrush)
 114     {
 115         delete g_oglWhiteBackgroundBrush;
 116         g_oglWhiteBackgroundBrush = NULL;
 117     }
 118     if (g_oglBlackForegroundPen)
 119     {
 120         delete g_oglBlackForegroundPen;
 121         g_oglBlackForegroundPen = NULL;
 122     }
 123
 124     OGLCleanUpConstraintTypes();
 125 }
 126
 127 wxFont *oglMatchFont(int point_size)
 128 {
 129   wxFont *font = wxTheFontList->FindOrCreateFont(point_size, wxSWISS, wxNORMAL, wxNORMAL);
 130 #if 0
 131   switch (point_size)
 132   {
 133     case 4:
 134       font = swiss_font_4;
 135       break;
 136     case 6:
 137       font = swiss_font_6;
 138       break;
 139     case 8:
 140       font = swiss_font_8;
 141       break;
 142     case 12:
 143       font = swiss_font_12;
 144       break;
 145     case 14:
 146       font = swiss_font_14;
 147       break;
 148     case 18:
 149       font = swiss_font_18;
 150       break;
 151     case 24:
 152       font = swiss_font_24;
 153       break;
 154     default:
 155     case 10:
 156       font = swiss_font_10;
 157       break;
 158   }
 159 #endif
 160   return font;
 161 }
 162
 163 int FontSizeDialog(wxFrame *parent, int old_size)
 164 {
 165   if (old_size <= 0)
 166     old_size = 10;
 167   wxString buf;
 168   buf << old_size;
 169   wxString ans = wxGetTextFromUser(wxT("Enter point size"), wxT("Font size"), buf, parent);
 170   if (ans.Length() == 0)
 171     return 0;
 172
 173   long new_size = 0;
 174   ans.ToLong(&new_size);
 175   if ((new_size <= 0) || (new_size > 40))
 176   {
 177     wxMessageBox(wxT("Invalid point size!"), wxT("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->GetCount();
 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   wxObjectList::compatibility_iterator current = text_list->GetFirst();
 224   int i = 0;
 225   while (current)
 226   {
 227     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 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->GetNext();
 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->GetFirst();
 267   i = 0;
 268
 269   while (current)
 270   {
 271     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 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->GetNext();
 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->GetCount();
 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   wxObjectList::compatibility_iterator current = text_list->GetFirst();
 307   int i = 0;
 308   while (current)
 309   {
 310     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 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->GetNext();
 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->GetFirst();
 327   i = 0;
 328
 329   while (current)
 330   {
 331     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 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->GetNext();
 338     i ++;
 339   }
 340   delete widths;
 341 }
 342
 343 void oglGetCentredTextExtent(wxDC& dc, wxList *text_list,
 344                               double WXUNUSED(m_xpos), double WXUNUSED(m_ypos), double WXUNUSED(width), double WXUNUSED(height),
 345                               double *actual_width, double *actual_height)
 346 {
 347   int n = text_list->GetCount();
 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   wxObjectList::compatibility_iterator current = text_list->GetFirst();
 363   while (current)
 364   {
 365     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 366     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 367
 368     if (current_width > max_width)
 369       max_width = current_width;
 370     current = current->GetNext();
 371   }
 372
 373   *actual_height = n*char_height;
 374   *actual_width = max_width;
 375 }
 376
 377 // Format a string to a list of strings that fit in the given box.
 378 // Interpret %n and 10 or 13 as a new line.
 379 wxStringList *oglFormatText(wxDC& dc, const wxString& text, double width, double WXUNUSED(height), int formatMode)
 380 {
 381   // First, parse the string into a list of words
 382   wxStringList word_list;
 383
 384   // Make new lines into NULL strings at this point
 385   int i = 0; int j = 0; int len = text.Length();
 386   wxChar word[400]; word[0] = 0;
 387   bool end_word = false; bool new_line = false;
 388   while (i < len)
 389   {
 390     switch (text[i])
 391     {
 392       case wxT('%'):
 393       {
 394         i ++;
 395         if (i == len)
 396         { word[j] = wxT('%'); j ++; }
 397         else
 398         {
 399           if (text[i] == wxT('n'))
 400           { new_line = true; end_word = true; i++; }
 401           else
 402           { word[j] = wxT('%'); j ++; word[j] = text[i]; j ++; i ++; }
 403         }
 404         break;
 405       }
 406       case 10:
 407       {
 408         new_line = true; end_word = true; i++;
 409         break;
 410       }
 411       case 13:
 412       {
 413         new_line = true; end_word = true; i++;
 414         break;
 415       }
 416       case wxT(' '):
 417       {
 418         end_word = true;
 419         i ++;
 420         break;
 421       }
 422       default:
 423       {
 424         word[j] = text[i];
 425         j ++; i ++;
 426         break;
 427       }
 428     }
 429     if (i == len) end_word = true;
 430     if (end_word)
 431     {
 432       word[j] = 0;
 433       j = 0;
 434       word_list.Add(word);
 435       end_word = false;
 436     }
 437     if (new_line)
 438     {
 439       word_list.Append(NULL);
 440       new_line = false;
 441     }
 442   }
 443   // Now, make a list of strings which can fit in the box
 444   wxStringList *string_list = new wxStringList;
 445
 446   wxString buffer;
 447   wxStringList::compatibility_iterator node = word_list.GetFirst();
 448   long x, y;
 449
 450   while (node)
 451   {
 452     wxString oldBuffer(buffer);
 453
 454     wxString s = node->GetData();
 455     if (s.empty())
 456     {
 457       // FORCE NEW LINE
 458       if (buffer.Length() > 0)
 459         string_list->Add(buffer);
 460
 461       buffer.Empty();
 462     }
 463     else
 464     {
 465       if (buffer.Length() != 0)
 466         buffer += wxT(" ");
 467
 468       buffer += s;
 469       dc.GetTextExtent(buffer, &x, &y);
 470
 471       // Don't fit within the bounding box if we're fitting shape to contents
 472       if ((x > width) && !(formatMode & FORMAT_SIZE_TO_CONTENTS))
 473       {
 474         // Deal with first word being wider than box
 475         if (oldBuffer.Length() > 0)
 476           string_list->Add(oldBuffer);
 477
 478         buffer.Empty();
 479         buffer += s;
 480       }
 481     }
 482
 483     node = node->GetNext();
 484   }
 485   if (buffer.Length() != 0)
 486     string_list->Add(buffer);
 487
 488   return string_list;
 489 }
 490
 491 void oglDrawFormattedText(wxDC& dc, wxList *text_list,
 492                        double m_xpos, double m_ypos, double width, double height,
 493                        int formatMode)
 494 {
 495   double xoffset, yoffset;
 496   if (formatMode & FORMAT_CENTRE_HORIZ)
 497     xoffset = m_xpos;
 498   else
 499     xoffset = (double)(m_xpos - (width / 2.0));
 500
 501   if (formatMode & FORMAT_CENTRE_VERT)
 502     yoffset = m_ypos;
 503   else
 504     yoffset = (double)(m_ypos - (height / 2.0));
 505
 506   dc.SetClippingRegion(
 507                     (long)(m_xpos - width/2.0), (long)(m_ypos - height/2.0),
 508                     (long)width+1, (long)height+1); // +1 to allow for rounding errors
 509
 510   wxObjectList::compatibility_iterator current = text_list->GetFirst();
 511   while (current)
 512   {
 513     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 514
 515     dc.DrawText(line->GetText(), WXROUND(xoffset + line->GetX()), WXROUND(yoffset + line->GetY()));
 516     current = current->GetNext();
 517   }
 518
 519   dc.DestroyClippingRegion();
 520 }
 521
 522 /*
 523  * Find centroid given list of points comprising polyline
 524  *
 525  */
 526
 527 void oglFindPolylineCentroid(wxList *points, double *x, double *y)
 528 {
 529   double xcount = 0;
 530   double ycount = 0;
 531
 532   wxObjectList::compatibility_iterator node = points->GetFirst();
 533   while (node)
 534   {
 535     wxRealPoint *point = (wxRealPoint *)node->GetData();
 536     xcount += point->x;
 537     ycount += point->y;
 538     node = node->GetNext();
 539   }
 540
 541   *x = (xcount/points->GetCount());
 542   *y = (ycount/points->GetCount());
 543 }
 544
 545 /*
 546  * Check that (x1, y1) -> (x2, y2) hits (x3, y3) -> (x4, y4).
 547  * If so, ratio1 gives the proportion along the first line
 548  * that the intersection occurs (or something like that).
 549  * Used by functions below.
 550  *
 551  */
 552 void oglCheckLineIntersection(double x1, double y1, double x2, double y2,
 553                              double x3, double y3, double x4, double y4,
 554                              double *ratio1, double *ratio2)
 555 {
 556   double denominator_term = (y4 - y3)*(x2 - x1) - (y2 - y1)*(x4 - x3);
 557   double numerator_term = (x3 - x1)*(y4 - y3) + (x4 - x3)*(y1 - y3);
 558
 559   double line_constant;
 560   double length_ratio = 1.0;
 561   double k_line = 1.0;
 562
 563   // Check for parallel lines
 564   if ((denominator_term < 0.005) && (denominator_term > -0.005))
 565     line_constant = -1.0;
 566   else
 567     line_constant = numerator_term/denominator_term;
 568
 569   // Check for intersection
 570   if ((line_constant < 1.0) && (line_constant > 0.0))
 571   {
 572     // Now must check that other line hits
 573     if (((y4 - y3) < 0.005) && ((y4 - y3) > -0.005))
 574       k_line = ((x1 - x3) + line_constant*(x2 - x1))/(x4 - x3);
 575     else
 576       k_line = ((y1 - y3) + line_constant*(y2 - y1))/(y4 - y3);
 577
 578     if ((k_line >= 0.0) && (k_line < 1.0))
 579       length_ratio = line_constant;
 580     else
 581       k_line = 1.0;
 582   }
 583   *ratio1 = length_ratio;
 584   *ratio2 = k_line;
 585 }
 586
 587 /*
 588  * Find where (x1, y1) -> (x2, y2) hits one of the lines in xvec, yvec.
 589  * (*x3, *y3) is the point where it hits.
 590  *
 591  */
 592 void oglFindEndForPolyline(double n, double xvec[], double yvec[],
 593                            double x1, double y1, double x2, double y2, double *x3, double *y3)
 594 {
 595   int i;
 596   double lastx = xvec[0];
 597   double lasty = yvec[0];
 598
 599   double min_ratio = 1.0;
 600   double line_ratio;
 601   double other_ratio;
 602
 603   for (i = 1; i < n; i++)
 604   {
 605     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[i], yvec[i],
 606                             &line_ratio, &other_ratio);
 607     lastx = xvec[i];
 608     lasty = yvec[i];
 609
 610     if (line_ratio < min_ratio)
 611       min_ratio = line_ratio;
 612   }
 613
 614   // Do last (implicit) line if last and first doubles are not identical
 615   if (!(xvec[0] == lastx && yvec[0] == lasty))
 616   {
 617     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[0], yvec[0],
 618                             &line_ratio, &other_ratio);
 619
 620     if (line_ratio < min_ratio)
 621       min_ratio = line_ratio;
 622   }
 623
 624   *x3 = (x1 + (x2 - x1)*min_ratio);
 625   *y3 = (y1 + (y2 - y1)*min_ratio);
 626
 627 }
 628
 629 /*
 630  * Find where the line hits the box.
 631  *
 632  */
 633
 634 void oglFindEndForBox(double width, double height,
 635                       double x1, double y1,         // Centre of box (possibly)
 636                       double x2, double y2,         // other end of line
 637                       double *x3, double *y3)       // End on box edge
 638 {
 639   double xvec[5];
 640   double yvec[5];
 641
 642   xvec[0] = (double)(x1 - width/2.0);
 643   yvec[0] = (double)(y1 - height/2.0);
 644   xvec[1] = (double)(x1 - width/2.0);
 645   yvec[1] = (double)(y1 + height/2.0);
 646   xvec[2] = (double)(x1 + width/2.0);
 647   yvec[2] = (double)(y1 + height/2.0);
 648   xvec[3] = (double)(x1 + width/2.0);
 649   yvec[3] = (double)(y1 - height/2.0);
 650   xvec[4] = (double)(x1 - width/2.0);
 651   yvec[4] = (double)(y1 - height/2.0);
 652
 653   oglFindEndForPolyline(5, xvec, yvec, x2, y2, x1, y1, x3, y3);
 654 }
 655
 656 /*
 657  * Find where the line hits the circle.
 658  *
 659  */
 660
 661 void oglFindEndForCircle(double radius,
 662                          double x1, double y1,  // Centre of circle
 663                          double x2, double y2,  // Other end of line
 664                          double *x3, double *y3)
 665 {
 666   double H = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 667
 668   if (H == 0.0)
 669   {
 670     *x3 = x1;
 671     *y3 = y1;
 672   }
 673   else
 674   {
 675    *y3 = radius * (y2 - y1)/H + y1;
 676    *x3 = radius * (x2 - x1)/H + x1;
 677   }
 678 }
 679
 680 /*
 681  * Given the line (x1, y1) -> (x2, y2), and an arrow size of given length and width,
 682  * return the position of the tip of the arrow and the left and right vertices of the arrow.
 683  *
 684  */
 685
 686 void oglGetArrowPoints(double x1, double y1, double x2, double y2,
 687                       double length, double width,
 688                       double *tip_x, double *tip_y,
 689                       double *side1_x, double *side1_y,
 690                       double *side2_x, double *side2_y)
 691 {
 692   double l = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 693
 694   if (l < 0.01)
 695     l = (double) 0.01;
 696
 697   double i_bar = (x2 - x1)/l;
 698   double j_bar = (y2 - y1)/l;
 699
 700   double x3 = (- length*i_bar) + x2;
 701   double y3 = (- length*j_bar) + y2;
 702
 703   *side1_x = width*(-j_bar) + x3;
 704   *side1_y = width*i_bar + y3;
 705
 706   *side2_x = -width*(-j_bar) + x3;
 707   *side2_y = -width*i_bar + y3;
 708
 709   *tip_x = x2; *tip_y = y2;
 710 }
 711
 712 /*
 713  * Given an ellipse and endpoints of a line, returns the point at which
 714  * the line touches the ellipse in values x4, y4.
 715  * This function assumes that the centre of the ellipse is at x1, y1, and the
 716  * ellipse has a width of width1 and a height of height1. It also assumes you are
 717  * wanting to draw an arc FROM point x2, y2 TOWARDS point x3, y3.
 718  * This function calculates the x,y coordinates of the intersection point of
 719  * the arc with the ellipse.
 720  * Author: Ian Harrison
 721  */
 722
 723 void oglDrawArcToEllipse(double x1, double y1, double width1, double height1, double x2, double y2, double x3, double y3,
 724   double *x4, double *y4)
 725 {
 726   double a1 = (double)(width1/2.0);
 727   double b1 = (double)(height1/2.0);
 728
 729   // These are required to give top left x and y coordinates for DrawEllipse
 730 //  double top_left_x1 = (double)(x1 - a1);
 731 //  double top_left_y1 = (double)(y1 - b1);
 732 /*
 733   // Check for vertical line
 734   if (fabs(x2 - x3) < 0.05)
 735   {
 736     *x4 = x3;
 737     if (y2 < y3)
 738       *y4 = (double)(y1 - b1);
 739     else
 740       *y4 = (double)(y1 + b1);
 741     return;
 742   }
 743 */
 744   // Check that x2 != x3
 745   if (fabs(x2 - x3) < 0.05)
 746   {
 747     *x4 = x2;
 748     if (y3 > y2)
 749       *y4 = (double)(y1 - sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 750     else
 751       *y4 = (double)(y1 + sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 752     return;
 753   }
 754
 755   // Calculate the x and y coordinates of the point where arc intersects ellipse
 756
 757   double A, B, C, D, E, F, G, H, K;
 758   double ellipse1_x, ellipse1_y;
 759
 760   A = (double)(1/(a1 * a1));
 761   B = (double)((y3 - y2) * (y3 - y2)) / ((x3 - x2) * (x3 - x2) * b1 * b1);
 762   C = (double)(2 * (y3 - y2) * (y2 - y1)) / ((x3 - x2) * b1 * b1);
 763   D = (double)((y2 - y1) * (y2 - y1)) / (b1 * b1);
 764   E = (double)(A + B);
 765   F = (double)(C - (2 * A * x1) - (2 * B * x2));
 766   G = (double)((A * x1 * x1) + (B * x2 * x2) - (C * x2) + D - 1);
 767   H = (double)((y3 - y2) / (x3 - x2));
 768   K = (double)((F * F) - (4 * E * G));
 769
 770   if (K >= 0)
 771   // In this case the line intersects the ellipse, so calculate intersection
 772   {
 773     if(x2 >= x1)
 774     {
 775       ellipse1_x = (double)(((F * -1) + sqrt(K)) / (2 * E));
 776       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 777     }
 778     else
 779     {
 780       ellipse1_x = (double)(((F * -1) -  sqrt(K)) / (2 * E));
 781       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 782     }
 783   }
 784   else
 785   // in this case, arc does not intersect ellipse, so just draw arc
 786   {
 787     ellipse1_x = x3;
 788     ellipse1_y = y3;
 789   }
 790   *x4 = ellipse1_x;
 791   *y4 = ellipse1_y;
 792
 793 /*
 794   // Draw a little circle (radius = 2) at the end of the arc where it hits
 795   // the ellipse .
 796
 797   double circle_x = ellipse1_x - 2.0;
 798   double circle_y = ellipse1_y - 2.0;
 799   m_canvas->DrawEllipse(circle_x, circle_y, 4.0, 4.0);
 800 */
 801 }
 802
 803 // Update a list item from a list of strings
 804 void UpdateListBox(wxListBox *item, wxList *list)
 805 {
 806   item->Clear();
 807   if (!list)
 808     return;
 809
 810   wxObjectList::compatibility_iterator node = list->GetFirst();
 811   while (node)
 812   {
 813     wxChar *s = (wxChar *)node->GetData();
 814     item->Append(s);
 815     node = node->GetNext();
 816   }
 817 }
 818
 819 bool oglRoughlyEqual(double val1, double val2, double tol)
 820 {
 821     return ( (val1 < (val2 + tol)) && (val1 > (val2 - tol)) &&
 822              (val2 < (val1 + tol)) && (val2 > (val1 - tol)));
 823 }
 824
 825 /*
 826  * Hex<->Dec conversion
 827  */
 828
 829 // Array used in DecToHex conversion routine.
 830 static wxChar sg_HexArray[] = { wxT('0'), wxT('1'), wxT('2'), wxT('3'),
 831                                 wxT('4'), wxT('5'), wxT('6'), wxT('7'),
 832                                 wxT('8'), wxT('9'), wxT('A'), wxT('B'),
 833                                 wxT('C'), wxT('D'), wxT('E'), wxT('F')
 834 };
 835
 836 // Convert 2-digit hex number to decimal
 837 unsigned int oglHexToDec(wxChar* buf)
 838 {
 839   int firstDigit, secondDigit;
 840
 841   if (buf[0] >= wxT('A'))
 842     firstDigit = buf[0] - wxT('A') + 10;
 843   else
 844     firstDigit = buf[0] - wxT('0');
 845
 846   if (buf[1] >= wxT('A'))
 847     secondDigit = buf[1] - wxT('A') + 10;
 848   else
 849     secondDigit = buf[1] - wxT('0');
 850
 851   return firstDigit * 16 + secondDigit;
 852 }
 853
 854 // Convert decimal integer to 2-character hex string
 855 void oglDecToHex(unsigned int dec, wxChar *buf)
 856 {
 857     int firstDigit = (int)(dec/16.0);
 858     int secondDigit = (int)(dec - (firstDigit*16.0));
 859     buf[0] = sg_HexArray[firstDigit];
 860     buf[1] = sg_HexArray[secondDigit];
 861     buf[2] = 0;
 862 }
 863
 864 // 3-digit hex to wxColour
 865 wxColour oglHexToColour(const wxString& hex)
 866 {
 867     if (hex.Length() == 6)
 868     {
 869         long r, g, b;
 870         r = g = b = 0;
 871         hex.Mid(0,2).ToLong(&r, 16);
 872         hex.Mid(2,2).ToLong(&g, 16);
 873         hex.Mid(4,2).ToLong(&b, 16);
 874         return wxColour((unsigned char)r,
 875                         (unsigned char)g,
 876                         (unsigned char)b);
 877     }
 878     else
 879         return *wxBLACK;
 880 }
 881
 882 // RGB to 3-digit hex
 883 wxString oglColourToHex(const wxColour& colour)
 884 {
 885     wxChar buf[7];
 886     unsigned int red = colour.Red();
 887     unsigned int green = colour.Green();
 888     unsigned int blue = colour.Blue();
 889
 890     oglDecToHex(red, buf);
 891     oglDecToHex(green, buf+2);
 892     oglDecToHex(blue, buf+4);
 893
 894     return wxString(buf);
 895 }
 896
 897