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 #ifdef PROLOGIO
  28 #include <wx/wxexpr.h>
  29 #endif
  30
  31 #include <wx/types.h>
  32
  33 #if USE_IOSTREAMH
  34 #include <iostream.h>
  35 #else
  36 #include <iostream>
  37 #endif
  38 #include <ctype.h>
  39 #include <math.h>
  40 #include <stdlib.h>
  41
  42 #include "basic.h"
  43 #include "basicp.h"
  44 #include "misc.h"
  45 #include "constrnt.h"
  46 #include "composit.h"
  47
  48 wxFont*         g_oglNormalFont;
  49 wxPen*          g_oglBlackPen;
  50 wxPen*          g_oglWhiteBackgroundPen;
  51 wxPen*          g_oglTransparentPen;
  52 wxBrush*        g_oglWhiteBackgroundBrush;
  53 wxPen*          g_oglBlackForegroundPen;
  54 wxCursor*       g_oglBullseyeCursor = NULL;
  55
  56 char*           oglBuffer = NULL;
  57
  58 wxList          oglObjectCopyMapping(wxKEY_INTEGER);
  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   if (!oglPopupDivisionMenu)
  79   {
  80     oglPopupDivisionMenu = new wxMenu("", (wxFunction)oglGraphicsDivisionMenuProc);
  81     oglPopupDivisionMenu->Append(DIVISION_MENU_SPLIT_HORIZONTALLY, "Split horizontally");
  82     oglPopupDivisionMenu->Append(DIVISION_MENU_SPLIT_VERTICALLY, "Split vertically");
  83     oglPopupDivisionMenu->AppendSeparator();
  84     oglPopupDivisionMenu->Append(DIVISION_MENU_EDIT_LEFT_EDGE, "Edit left edge");
  85     oglPopupDivisionMenu->Append(DIVISION_MENU_EDIT_TOP_EDGE, "Edit top edge");
  86   }
  87 }
  88
  89 void wxOGLCleanUp()
  90 {
  91     if (oglBuffer)
  92     {
  93         delete[] oglBuffer;
  94         oglBuffer = NULL;
  95     }
  96     oglBuffer = NULL;
  97     if (oglPopupDivisionMenu)
  98     {
  99         delete oglPopupDivisionMenu;
 100         oglPopupDivisionMenu = NULL;
 101     }
 102     if (g_oglBullseyeCursor)
 103     {
 104         delete g_oglBullseyeCursor;
 105         g_oglBullseyeCursor = NULL;
 106     }
 107
 108     if (g_oglNormalFont)
 109     {
 110         delete g_oglNormalFont;
 111         g_oglNormalFont = NULL;
 112     }
 113     if (g_oglBlackPen)
 114     {
 115         delete g_oglBlackPen;
 116         g_oglBlackPen = NULL;
 117     }
 118     if (g_oglWhiteBackgroundPen)
 119     {
 120         delete g_oglWhiteBackgroundPen;
 121         g_oglWhiteBackgroundPen = NULL;
 122     }
 123     if (g_oglTransparentPen)
 124     {
 125         delete g_oglTransparentPen;
 126         g_oglTransparentPen = NULL;
 127     }
 128     if (g_oglWhiteBackgroundBrush)
 129     {
 130         delete g_oglWhiteBackgroundBrush;
 131         g_oglWhiteBackgroundBrush = NULL;
 132     }
 133     if (g_oglBlackForegroundPen)
 134     {
 135         delete g_oglBlackForegroundPen;
 136         g_oglBlackForegroundPen = NULL;
 137     }
 138
 139     OGLCleanUpConstraintTypes();
 140 }
 141
 142 wxFont *oglMatchFont(int point_size)
 143 {
 144   wxFont *font = wxTheFontList->FindOrCreateFont(point_size, wxSWISS, wxNORMAL, wxNORMAL);
 145 #if 0
 146   switch (point_size)
 147   {
 148     case 4:
 149       font = swiss_font_4;
 150       break;
 151     case 6:
 152       font = swiss_font_6;
 153       break;
 154     case 8:
 155       font = swiss_font_8;
 156       break;
 157     case 12:
 158       font = swiss_font_12;
 159       break;
 160     case 14:
 161       font = swiss_font_14;
 162       break;
 163     case 18:
 164       font = swiss_font_18;
 165       break;
 166     case 24:
 167       font = swiss_font_24;
 168       break;
 169     default:
 170     case 10:
 171       font = swiss_font_10;
 172       break;
 173   }
 174 #endif
 175   return font;
 176 }
 177
 178 int FontSizeDialog(wxFrame *parent, int old_size)
 179 {
 180   if (old_size <= 0)
 181     old_size = 10;
 182   char buf[40];
 183   sprintf(buf, "%d", old_size);
 184   wxString ans = wxGetTextFromUser("Enter point size", "Font size", buf, parent);
 185   if (ans == "")
 186     return 0;
 187
 188   int new_size = atoi(ans);
 189   if ((new_size <= 0) || (new_size > 40))
 190   {
 191     wxMessageBox("Invalid point size!", "Error", wxOK);
 192     return 0;
 193   }
 194   return new_size;
 195 /*
 196   char *strings[8];
 197   strings[0] = "4";
 198   strings[1] = "6";
 199   strings[2] = "8";
 200   strings[3] = "10";
 201   strings[4] = "12";
 202   strings[5] = "14";
 203   strings[6] = "18";
 204   strings[7] = "24";
 205   char *ans = wxGetSingleChoice("Choose", "Choose a font size", 8, strings, parent);
 206   if (ans)
 207   {
 208     int size;
 209     sscanf(ans, "%d", &size);
 210     return oglMatchFont(size);
 211   }
 212   else return NULL;
 213 */
 214 }
 215
 216 // Centre a list of strings in the given box. xOffset and yOffset are the
 217 // the positions that these lines should be relative to, and this might be
 218 // the same as m_xpos, m_ypos, but might be zero if formatting from left-justifying.
 219 void oglCentreText(wxDC& dc, wxList *text_list,
 220                 double m_xpos, double m_ypos, double width, double height,
 221                 int formatMode)
 222 {
 223   int n = text_list->Number();
 224
 225   if (!text_list || (n == 0))
 226     return;
 227
 228   // First, get maximum dimensions of box enclosing text
 229
 230   long char_height = 0;
 231   long max_width = 0;
 232   long current_width = 0;
 233
 234   // Store text extents for speed
 235   double *widths = new double[n];
 236
 237   wxNode *current = text_list->First();
 238   int i = 0;
 239   while (current)
 240   {
 241     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 242     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 243     widths[i] = current_width;
 244
 245     if (current_width > max_width)
 246       max_width = current_width;
 247     current = current->Next();
 248     i ++;
 249   }
 250
 251   double max_height = n*char_height;
 252
 253   double xoffset, yoffset, xOffset, yOffset;
 254
 255   if (formatMode & FORMAT_CENTRE_VERT)
 256   {
 257     if (max_height < height)
 258       yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 259     else
 260       yoffset = (double)(m_ypos - (height/2.0));
 261     yOffset = m_ypos;
 262   }
 263   else
 264   {
 265     yoffset = 0.0;
 266     yOffset = 0.0;
 267   }
 268
 269   if (formatMode & FORMAT_CENTRE_HORIZ)
 270   {
 271     xoffset = (double)(m_xpos - width/2.0);
 272     xOffset = m_xpos;
 273   }
 274   else
 275   {
 276     xoffset = 0.0;
 277     xOffset = 0.0;
 278   }
 279
 280   current = text_list->First();
 281   i = 0;
 282
 283   while (current)
 284   {
 285     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 286
 287     double x;
 288     if ((formatMode & FORMAT_CENTRE_HORIZ) && (widths[i] < width))
 289       x = (double)((width - widths[i])/2.0 + xoffset);
 290     else
 291       x = xoffset;
 292     double y = (double)(i*char_height + yoffset);
 293
 294     line->SetX( x - xOffset ); line->SetY( y - yOffset );
 295     current = current->Next();
 296     i ++;
 297   }
 298
 299   delete widths;
 300 }
 301
 302 // Centre a list of strings in the given box
 303 void oglCentreTextNoClipping(wxDC& dc, wxList *text_list,
 304                               double m_xpos, double m_ypos, double width, double height)
 305 {
 306   int n = text_list->Number();
 307
 308   if (!text_list || (n == 0))
 309     return;
 310
 311   // First, get maximum dimensions of box enclosing text
 312
 313   long char_height = 0;
 314   long max_width = 0;
 315   long current_width = 0;
 316
 317   // Store text extents for speed
 318   double *widths = new double[n];
 319
 320   wxNode *current = text_list->First();
 321   int i = 0;
 322   while (current)
 323   {
 324     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 325     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 326     widths[i] = current_width;
 327
 328     if (current_width > max_width)
 329       max_width = current_width;
 330     current = current->Next();
 331     i ++;
 332   }
 333
 334   double max_height = n*char_height;
 335
 336   double yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 337
 338   double xoffset = (double)(m_xpos - width/2.0);
 339
 340   current = text_list->First();
 341   i = 0;
 342
 343   while (current)
 344   {
 345     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 346
 347     double x = (double)((width - widths[i])/2.0 + xoffset);
 348     double y = (double)(i*char_height + yoffset);
 349
 350     line->SetX( x - m_xpos ); line->SetY( y - m_ypos );
 351     current = current->Next();
 352     i ++;
 353   }
 354   delete widths;
 355 }
 356
 357 void oglGetCentredTextExtent(wxDC& dc, wxList *text_list,
 358                               double m_xpos, double m_ypos, double width, double height,
 359                               double *actual_width, double *actual_height)
 360 {
 361   int n = text_list->Number();
 362
 363   if (!text_list || (n == 0))
 364   {
 365     *actual_width = 0;
 366     *actual_height = 0;
 367     return;
 368   }
 369
 370   // First, get maximum dimensions of box enclosing text
 371
 372   long char_height = 0;
 373   long max_width = 0;
 374   long current_width = 0;
 375
 376   wxNode *current = text_list->First();
 377   int i = 0;
 378   while (current)
 379   {
 380     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 381     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 382
 383     if (current_width > max_width)
 384       max_width = current_width;
 385     current = current->Next();
 386     i ++;
 387   }
 388
 389   *actual_height = n*char_height;
 390   *actual_width = max_width;
 391 }
 392
 393 // Format a string to a list of strings that fit in the given box.
 394 // Interpret %n and 10 or 13 as a new line.
 395 wxStringList *oglFormatText(wxDC& dc, const wxString& text, double width, double height, int formatMode)
 396 {
 397   // First, parse the string into a list of words
 398   wxStringList word_list;
 399
 400   // Make new lines into NULL strings at this point
 401   int i = 0; int j = 0; int len = strlen(text);
 402   char word[200]; word[0] = 0;
 403   bool end_word = FALSE; bool new_line = FALSE;
 404   while (i < len)
 405   {
 406     switch (text[i])
 407     {
 408       case '%':
 409       {
 410         i ++;
 411         if (i == len)
 412         { word[j] = '%'; j ++; }
 413         else
 414         {
 415           if (text[i] == 'n')
 416           { new_line = TRUE; end_word = TRUE; i++; }
 417           else
 418           { word[j] = '%'; j ++; word[j] = text[i]; j ++; i ++; }
 419         }
 420         break;
 421       }
 422       case 10:
 423       {
 424         new_line = TRUE; end_word = TRUE; i++;
 425         break;
 426       }
 427       case 13:
 428       {
 429         new_line = TRUE; end_word = TRUE; i++;
 430       }
 431       case ' ':
 432       {
 433         end_word = TRUE;
 434         i ++;
 435         break;
 436       }
 437       default:
 438       {
 439         word[j] = text[i];
 440         j ++; i ++;
 441         break;
 442       }
 443     }
 444     if (i == len) end_word = TRUE;
 445     if (end_word)
 446     {
 447       word[j] = 0;
 448       j = 0;
 449       word_list.Append((wxObject *)copystring(word));
 450       end_word = FALSE;
 451     }
 452     if (new_line)
 453     {
 454       word_list.Append((wxObject *)NULL);
 455       new_line = FALSE;
 456     }
 457   }
 458   // Now, make a list of strings which can fit in the box
 459   wxStringList *string_list = new wxStringList;
 460
 461   char buffer[400];
 462   buffer[0] = 0;
 463   wxNode *node = word_list.First();
 464   long x, y;
 465
 466   while (node)
 467   {
 468     wxString oldBuffer(buffer);
 469
 470     char *s = (char *)node->Data();
 471     if (!s)
 472     {
 473       // FORCE NEW LINE
 474       if (strlen(buffer) > 0)
 475         string_list->Add(buffer);
 476
 477       buffer[0] = 0;
 478     }
 479     else
 480     {
 481       if (buffer[0] != 0)
 482         strcat(buffer, " ");
 483
 484       strcat(buffer, s);
 485       dc.GetTextExtent(buffer, &x, &y);
 486
 487       // Don't fit within the bounding box if we're fitting shape to contents
 488       if ((x > width) && !(formatMode & FORMAT_SIZE_TO_CONTENTS))
 489       {
 490         // Deal with first word being wider than box
 491         if (oldBuffer.Length() > 0)
 492           string_list->Add(oldBuffer);
 493
 494         buffer[0] = 0;
 495         strcat(buffer, s);
 496       }
 497     }
 498
 499     node = node->Next();
 500   }
 501   if (buffer[0] != 0)
 502     string_list->Add(buffer);
 503
 504   return string_list;
 505 }
 506
 507 void oglDrawFormattedText(wxDC& dc, wxList *text_list,
 508                        double m_xpos, double m_ypos, double width, double height,
 509                        int formatMode)
 510 {
 511   double xoffset, yoffset;
 512   if (formatMode & FORMAT_CENTRE_HORIZ)
 513     xoffset = m_xpos;
 514   else
 515     xoffset = (double)(m_xpos - (width / 2.0));
 516
 517   if (formatMode & FORMAT_CENTRE_VERT)
 518     yoffset = m_ypos;
 519   else
 520     yoffset = (double)(m_ypos - (height / 2.0));
 521
 522   dc.SetClippingRegion(
 523                     (double)(m_xpos - width/2.0), (double)(m_ypos - height/2.0),
 524                     (double)width, (double)height);
 525
 526   wxNode *current = text_list->First();
 527   while (current)
 528   {
 529     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 530
 531     dc.DrawText(line->GetText(), WXROUND(xoffset + line->GetX()), WXROUND(yoffset + line->GetY()));
 532     current = current->Next();
 533   }
 534
 535   dc.DestroyClippingRegion();
 536 }
 537
 538 /*
 539  * Find centroid given list of points comprising polyline
 540  *
 541  */
 542
 543 void oglFindPolylineCentroid(wxList *points, double *x, double *y)
 544 {
 545   double xcount = 0;
 546   double ycount = 0;
 547
 548   wxNode *node = points->First();
 549   while (node)
 550   {
 551     wxRealPoint *point = (wxRealPoint *)node->Data();
 552     xcount += point->x;
 553     ycount += point->y;
 554     node = node->Next();
 555   }
 556
 557   *x = (xcount/points->Number());
 558   *y = (ycount/points->Number());
 559 }
 560
 561 /*
 562  * Check that (x1, y1) -> (x2, y2) hits (x3, y3) -> (x4, y4).
 563  * If so, ratio1 gives the proportion along the first line
 564  * that the intersection occurs (or something like that).
 565  * Used by functions below.
 566  *
 567  */
 568 void oglCheckLineIntersection(double x1, double y1, double x2, double y2,
 569                              double x3, double y3, double x4, double y4,
 570                              double *ratio1, double *ratio2)
 571 {
 572   double denominator_term = (y4 - y3)*(x2 - x1) - (y2 - y1)*(x4 - x3);
 573   double numerator_term = (x3 - x1)*(y4 - y3) + (x4 - x3)*(y1 - y3);
 574
 575   double line_constant;
 576   double length_ratio = 1.0;
 577   double k_line = 1.0;
 578
 579   // Check for parallel lines
 580   if ((denominator_term < 0.005) && (denominator_term > -0.005))
 581     line_constant = -1.0;
 582   else
 583     line_constant = numerator_term/denominator_term;
 584
 585   // Check for intersection
 586   if ((line_constant < 1.0) && (line_constant > 0.0))
 587   {
 588     // Now must check that other line hits
 589     if (((y4 - y3) < 0.005) && ((y4 - y3) > -0.005))
 590       k_line = ((x1 - x3) + line_constant*(x2 - x1))/(x4 - x3);
 591     else
 592       k_line = ((y1 - y3) + line_constant*(y2 - y1))/(y4 - y3);
 593
 594     if ((k_line >= 0.0) && (k_line < 1.0))
 595       length_ratio = line_constant;
 596     else
 597       k_line = 1.0;
 598   }
 599   *ratio1 = length_ratio;
 600   *ratio2 = k_line;
 601 }
 602
 603 /*
 604  * Find where (x1, y1) -> (x2, y2) hits one of the lines in xvec, yvec.
 605  * (*x3, *y3) is the point where it hits.
 606  *
 607  */
 608 void oglFindEndForPolyline(double n, double xvec[], double yvec[],
 609                            double x1, double y1, double x2, double y2, double *x3, double *y3)
 610 {
 611   int i;
 612   double lastx = xvec[0];
 613   double lasty = yvec[0];
 614
 615   double min_ratio = 1.0;
 616   double line_ratio;
 617   double other_ratio;
 618
 619   for (i = 1; i < n; i++)
 620   {
 621     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[i], yvec[i],
 622                             &line_ratio, &other_ratio);
 623     lastx = xvec[i];
 624     lasty = yvec[i];
 625
 626     if (line_ratio < min_ratio)
 627       min_ratio = line_ratio;
 628   }
 629
 630   // Do last (implicit) line if last and first doubles are not identical
 631   if (!(xvec[0] == lastx && yvec[0] == lasty))
 632   {
 633     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[0], yvec[0],
 634                             &line_ratio, &other_ratio);
 635
 636     if (line_ratio < min_ratio)
 637       min_ratio = line_ratio;
 638   }
 639
 640   *x3 = (x1 + (x2 - x1)*min_ratio);
 641   *y3 = (y1 + (y2 - y1)*min_ratio);
 642
 643 }
 644
 645 /*
 646  * Find where the line hits the box.
 647  *
 648  */
 649
 650 void oglFindEndForBox(double width, double height,
 651                       double x1, double y1,         // Centre of box (possibly)
 652                       double x2, double y2,         // other end of line
 653                       double *x3, double *y3)       // End on box edge
 654 {
 655   double xvec[5];
 656   double yvec[5];
 657
 658   xvec[0] = (double)(x1 - width/2.0);
 659   yvec[0] = (double)(y1 - height/2.0);
 660   xvec[1] = (double)(x1 - width/2.0);
 661   yvec[1] = (double)(y1 + height/2.0);
 662   xvec[2] = (double)(x1 + width/2.0);
 663   yvec[2] = (double)(y1 + height/2.0);
 664   xvec[3] = (double)(x1 + width/2.0);
 665   yvec[3] = (double)(y1 - height/2.0);
 666   xvec[4] = (double)(x1 - width/2.0);
 667   yvec[4] = (double)(y1 - height/2.0);
 668
 669   oglFindEndForPolyline(5, xvec, yvec, x2, y2, x1, y1, x3, y3);
 670 }
 671
 672 /*
 673  * Find where the line hits the circle.
 674  *
 675  */
 676
 677 void oglFindEndForCircle(double radius,
 678                          double x1, double y1,  // Centre of circle
 679                          double x2, double y2,  // Other end of line
 680                          double *x3, double *y3)
 681 {
 682   double H = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 683
 684   if (H == 0.0)
 685   {
 686     *x3 = x1;
 687     *y3 = y1;
 688   }
 689   else
 690   {
 691    *y3 = radius * (y2 - y1)/H + y1;
 692    *x3 = radius * (x2 - x1)/H + x1;
 693   }
 694 }
 695
 696 /*
 697  * Given the line (x1, y1) -> (x2, y2), and an arrow size of given length and width,
 698  * return the position of the tip of the arrow and the left and right vertices of the arrow.
 699  *
 700  */
 701
 702 void oglGetArrowPoints(double x1, double y1, double x2, double y2,
 703                       double length, double width,
 704                       double *tip_x, double *tip_y,
 705                       double *side1_x, double *side1_y,
 706                       double *side2_x, double *side2_y)
 707 {
 708   double l = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 709
 710   if (l < 0.01)
 711     l = (double) 0.01;
 712
 713   double i_bar = (x2 - x1)/l;
 714   double j_bar = (y2 - y1)/l;
 715
 716   double x3 = (- length*i_bar) + x2;
 717   double y3 = (- length*j_bar) + y2;
 718
 719   *side1_x = width*(-j_bar) + x3;
 720   *side1_y = width*i_bar + y3;
 721
 722   *side2_x = -width*(-j_bar) + x3;
 723   *side2_y = -width*i_bar + y3;
 724
 725   *tip_x = x2; *tip_y = y2;
 726 }
 727
 728 /*
 729  * Given an ellipse and endpoints of a line, returns the point at which
 730  * the line touches the ellipse in values x4, y4.
 731  * This function assumes that the centre of the ellipse is at x1, y1, and the
 732  * ellipse has a width of width1 and a height of height1. It also assumes you are
 733  * wanting to draw an arc FROM point x2, y2 TOWARDS point x3, y3.
 734  * This function calculates the x,y coordinates of the intersection point of
 735  * the arc with the ellipse.
 736  * Author: Ian Harrison
 737  */
 738
 739 void oglDrawArcToEllipse(double x1, double y1, double width1, double height1, double x2, double y2, double x3, double y3,
 740   double *x4, double *y4)
 741 {
 742   double a1 = (double)(width1/2.0);
 743   double b1 = (double)(height1/2.0);
 744
 745   // These are required to give top left x and y coordinates for DrawEllipse
 746 //  double top_left_x1 = (double)(x1 - a1);
 747 //  double top_left_y1 = (double)(y1 - b1);
 748 /*
 749   // Check for vertical line
 750   if (fabs(x2 - x3) < 0.05)
 751   {
 752     *x4 = x3;
 753     if (y2 < y3)
 754       *y4 = (double)(y1 - b1);
 755     else
 756       *y4 = (double)(y1 + b1);
 757     return;
 758   }
 759 */
 760   // Check that x2 != x3
 761   if (fabs(x2 - x3) < 0.05)
 762   {
 763     *x4 = x2;
 764     if (y3 > y2)
 765       *y4 = (double)(y1 - sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 766     else
 767       *y4 = (double)(y1 + sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 768     return;
 769   }
 770
 771   // Calculate the x and y coordinates of the point where arc intersects ellipse
 772
 773   double A, B, C, D, E, F, G, H, K;
 774   double ellipse1_x, ellipse1_y;
 775
 776   A = (double)(1/(a1 * a1));
 777   B = (double)((y3 - y2) * (y3 - y2)) / ((x3 - x2) * (x3 - x2) * b1 * b1);
 778   C = (double)(2 * (y3 - y2) * (y2 - y1)) / ((x3 - x2) * b1 * b1);
 779   D = (double)((y2 - y1) * (y2 - y1)) / (b1 * b1);
 780   E = (double)(A + B);
 781   F = (double)(C - (2 * A * x1) - (2 * B * x2));
 782   G = (double)((A * x1 * x1) + (B * x2 * x2) - (C * x2) + D - 1);
 783   H = (double)((y3 - y2) / (x3 - x2));
 784   K = (double)((F * F) - (4 * E * G));
 785
 786   if (K >= 0)
 787   // In this case the line intersects the ellipse, so calculate intersection
 788   {
 789     if(x2 >= x1)
 790     {
 791       ellipse1_x = (double)(((F * -1) + sqrt(K)) / (2 * E));
 792       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 793     }
 794     else
 795     {
 796       ellipse1_x = (double)(((F * -1) -  sqrt(K)) / (2 * E));
 797       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 798     }
 799   }
 800   else
 801   // in this case, arc does not intersect ellipse, so just draw arc
 802   {
 803     ellipse1_x = x3;
 804     ellipse1_y = y3;
 805   }
 806   *x4 = ellipse1_x;
 807   *y4 = ellipse1_y;
 808
 809 /*
 810   // Draw a little circle (radius = 2) at the end of the arc where it hits
 811   // the ellipse .
 812
 813   double circle_x = ellipse1_x - 2.0;
 814   double circle_y = ellipse1_y - 2.0;
 815   m_canvas->DrawEllipse(circle_x, circle_y, 4.0, 4.0);
 816 */
 817 }
 818
 819 // Update a list item from a list of strings
 820 void UpdateListBox(wxListBox *item, wxList *list)
 821 {
 822   item->Clear();
 823   if (!list)
 824     return;
 825
 826   wxNode *node = list->First();
 827   while (node)
 828   {
 829     char *s = (char *)node->Data();
 830     item->Append(s);
 831     node = node->Next();
 832   }
 833 }
 834
 835 bool oglRoughlyEqual(double val1, double val2, double tol)
 836 {
 837     return ( (val1 < (val2 + tol)) && (val1 > (val2 - tol)) &&
 838              (val2 < (val1 + tol)) && (val2 > (val1 - tol)));
 839 }
 840
 841 /*
 842  * Hex<->Dec conversion
 843  */
 844
 845 // Array used in DecToHex conversion routine.
 846 static char sg_HexArray[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B',
 847   'C', 'D', 'E', 'F' };
 848
 849 // Convert 2-digit hex number to decimal
 850 unsigned int oglHexToDec(char* buf)
 851 {
 852   int firstDigit, secondDigit;
 853
 854   if (buf[0] >= 'A')
 855     firstDigit = buf[0] - 'A' + 10;
 856   else
 857     firstDigit = buf[0] - '0';
 858
 859   if (buf[1] >= 'A')
 860     secondDigit = buf[1] - 'A' + 10;
 861   else
 862     secondDigit = buf[1] - '0';
 863
 864   return firstDigit * 16 + secondDigit;
 865 }
 866
 867 // Convert decimal integer to 2-character hex string
 868 void oglDecToHex(unsigned int dec, char *buf)
 869 {
 870     int firstDigit = (int)(dec/16.0);
 871     int secondDigit = (int)(dec - (firstDigit*16.0));
 872     buf[0] = sg_HexArray[firstDigit];
 873     buf[1] = sg_HexArray[secondDigit];
 874     buf[2] = 0;
 875 }
 876
 877 // 3-digit hex to wxColour
 878 wxColour oglHexToColour(const wxString& hex)
 879 {
 880     if (hex.Length() == 6)
 881         {
 882         char buf[7];
 883         strncpy(buf, hex, 7);
 884         unsigned int r = oglHexToDec((char *)buf);
 885         unsigned int g = oglHexToDec((char *)(buf+2));
 886         unsigned int b = oglHexToDec((char *)(buf+4));
 887         return wxColour(r, g, b);
 888         }
 889         else
 890             return wxColour(0,0,0);
 891 }
 892
 893 // RGB to 3-digit hex
 894 wxString oglColourToHex(const wxColour& colour)
 895 {
 896     char buf[7];
 897     unsigned int red = colour.Red();
 898     unsigned int green = colour.Green();
 899     unsigned int blue = colour.Blue();
 900
 901     oglDecToHex(red, buf);
 902     oglDecToHex(green, buf+2);
 903     oglDecToHex(blue, buf+4);
 904
 905     return wxString(buf);
 906 }
 907
 908