fltk/src/fl_arci.cxx

//
// "$Id$"
//
// Arc (integer) drawing functions for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2008 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//

/**
  \file fl_arci.cxx
  \brief Utility functions for drawing circles using integers
*/

// "integer" circle drawing functions.  These draw the limited
// circle types provided by X and NT graphics.  The advantage of
// these is that small ones draw quite nicely (probably due to stored
// hand-drawn bitmaps of small circles!) and may be implemented by
// hardware and thus are fast.

// Probably should add fl_chord.

// 3/10/98: created

#include <FL/fl_draw.H>
#include <FL/x.H>
#ifdef WIN32
#  include <FL/math.h>
#endif
#ifdef __APPLE__
#  include <config.h>
#endif

/**
  Draw ellipse sections using integer coordinates.
  
  These functions match the rather limited circle drawing code provided by X
  and WIN32. The advantage over using fl_arc with floating point coordinates
  is that they are faster because they often use the hardware, and they draw
  much nicer small circles, since the small sizes are often hard-coded bitmaps.

  If a complete circle is drawn it will fit inside the passed bounding box.
  The two angles are measured in degrees counterclockwise from 3'oclock and
  are the starting and ending angle of the arc, a2 must be greater or equal
  to a1.

  fl_arc() draws a series of lines to approximate the arc. Notice that the
  integer version of fl_arc() has a different number of arguments than the
  double version fl_arc(double x, double y, double r, double start, double a)

  \param[in] x,y,w,h bounding box of complete circle
  \param[in] a1,a2 start and end angles of arc measured in degrees
             counter-clockwise from 3 o'clock.  a2 must be greater
	     than or equal to a1.
*/
void fl_arc(int x,int y,int w,int h,double a1,double a2) {
  if (w <= 0 || h <= 0) return;

#if defined(USE_X11)
  XDrawArc(fl_display, fl_window, fl_gc, x,y,w-1,h-1, int(a1*64),int((a2-a1)*64));
#elif defined(WIN32)
  int xa = x+w/2+int(w*cos(a1/180.0*M_PI));
  int ya = y+h/2-int(h*sin(a1/180.0*M_PI));
  int xb = x+w/2+int(w*cos(a2/180.0*M_PI));
  int yb = y+h/2-int(h*sin(a2/180.0*M_PI));
  if (fabs(a1 - a2) < 90) {
    if (xa == xb && ya == yb) SetPixel(fl_gc, xa, ya, fl_RGB());
    else Arc(fl_gc, x, y, x+w, y+h, xa, ya, xb, yb);
  } else Arc(fl_gc, x, y, x+w, y+h, xa, ya, xb, yb);
#elif defined(__APPLE_QUARTZ__)
  a1 = (-a1)/180.0f*M_PI; a2 = (-a2)/180.0f*M_PI;
  float cx = x + 0.5f*w - 0.5f, cy = y + 0.5f*h - 0.5f;
  if (w!=h) {
    CGContextSaveGState(fl_gc);
    CGContextTranslateCTM(fl_gc, cx, cy);
    CGContextScaleCTM(fl_gc, w-1.0f, h-1.0f);
    CGContextAddArc(fl_gc, 0, 0, 0.5, a1, a2, 1);
    CGContextRestoreGState(fl_gc);
  } else {
    float r = (w+h)*0.25f-0.5f;
    CGContextAddArc(fl_gc, cx, cy, r, a1, a2, 1);
  }
  CGContextStrokePath(fl_gc);
#else
# error unsupported platform
#endif
}

/**
  Draw filled ellipse sections using integer coordinates.
  
  Like fl_arc, but fl_pie() draws a filled-in pie slice.
  This slice may extend outside the line drawn by fl_arc;
  to avoid this use w - 1 and h - 1.

  \param[in] x,y,w,h bounding box of complete circle
  \param[in] a1,a2 start and end angles of arc measured in degrees
             counter-clockwise from 3 o'clock.  a2 must be greater
	     than or equal to a1.
*/
void fl_pie(int x,int y,int w,int h,double a1,double a2) {
  if (w <= 0 || h <= 0) return;

#if defined(USE_X11)
  XFillArc(fl_display, fl_window, fl_gc, x,y,w-1,h-1, int(a1*64),int((a2-a1)*64));
#elif defined(WIN32)
  if (a1 == a2) return;
  int xa = x+w/2+int(w*cos(a1/180.0*M_PI));
  int ya = y+h/2-int(h*sin(a1/180.0*M_PI));
  int xb = x+w/2+int(w*cos(a2/180.0*M_PI));
  int yb = y+h/2-int(h*sin(a2/180.0*M_PI));
  SelectObject(fl_gc, fl_brush());
  if (fabs(a1 - a2) < 90) {
    if (xa == xb && ya == yb) {
      MoveToEx(fl_gc, x+w/2, y+h/2, 0L); 
      LineTo(fl_gc, xa, ya);
      SetPixel(fl_gc, xa, ya, fl_RGB());
    } else Pie(fl_gc, x, y, x+w, y+h, xa, ya, xb, yb);
  } else Pie(fl_gc, x, y, x+w, y+h, xa, ya, xb, yb); 
#elif defined(__APPLE_QUARTZ__)
  a1 = (-a1)/180.0f*M_PI; a2 = (-a2)/180.0f*M_PI;
  float cx = x + 0.5f*w - 0.5f, cy = y + 0.5f*h - 0.5f;
  if (w!=h) {
    CGContextSaveGState(fl_gc);
    CGContextTranslateCTM(fl_gc, cx, cy);
    CGContextScaleCTM(fl_gc, w, h);
    CGContextAddArc(fl_gc, 0, 0, 0.5, a1, a2, 1);
    CGContextAddLineToPoint(fl_gc, 0, 0);
    CGContextClosePath(fl_gc);
    CGContextRestoreGState(fl_gc);
  } else {
    float r = (w+h)*0.25f;
    CGContextAddArc(fl_gc, cx, cy, r, a1, a2, 1);
    CGContextAddLineToPoint(fl_gc, cx, cy);
    CGContextClosePath(fl_gc);
  }
  CGContextFillPath(fl_gc);
#else
# error unsupported platform
#endif
}

//
// End of "$Id$".
//