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