plotutils-graph-patches-lloda/libxmi/drawing.c

/* This is a sample program that uses libxmi to draw on a 60x35 canvas, and
   writes the canvas to standard output.  Actually, since libxmi uses a
   two-stage graphics pipeline, the program first constructs a `painted
   set' (a set of points with integer coordinates, partitioned by pixel
   value), and merges the painted set onto a 60x35 canvas.

   The painted set consists of a filled rectangle, a polyline, and an arc
   that subtends 270 degrees.  The rectangle is filled with color 1.  The
   polyline and the arc are dashed.  Their line type is
   MI_LINE_ON_OFF_DASHED, and the `on' dashes are multicolored: they cycle
   through colors 1,2,3.  (The `off' dashes are not drawn, but if they were
   [which would be the case if MI_LINE_DOUBLE_DASHED were the line type],
   they would all be in color 0.)  The background color of the canvas onto
   which the painted set is merged is 0.

   All these color values are miPixel values, and may be chosen
   arbitrarily.  By default, miPixel is typedef'd to `unsigned int'.  You
   may interpret a miPixel however you choose.  It could be a color index,
   an RGB value,...

   The line width for both the polyline and the arc is set to `0'.  This is
   a special value: it requests that a so-called Bresenham algorithm be
   used.  A Bresenham algorithm often yields better-looking lines than line
   width 1.  If the line width is positive, the polyline and the arc will
   be drawn with a brush of that width, and all pixels touched by the brush
   will be painted.  Dashing may be requested for positive line width, just
   as it is for line width 0. */

#include <stdio.h>
#include <stdlib.h>
#include <xmi.h>		/* public libxmi header file */

int main ()
{
  miRectangle rect;		/* 1 rectangle to be filled */
  miPoint points[4];		/* 3 line segments in polyline to be drawn */
  miArc arc;			/* 1 arc to be drawn */
  miPixel pixels[4];		/* pixel values for drawing and dashing */
  unsigned int dashes[2];	/* length of `on' and `off' dashes */
  miGC *pGC;			/* graphics context */
  miPaintedSet *paintedSet;	/* opaque object to be painted */
  miCanvas *canvas;		/* drawing canvas (including pixmap) */
  miPoint offset;		/* for miPaintedSet -> miCanvas transfer */
  int i, j;
     
  /* Define rectangle: upper left vertex = (40,0), lower right = (55,5). */
  /* But note libxmi's convention: right and bottom edges of filled
     polygons (including rectangles) are never painted, in order that
     adjacent polygons will abut with no overlaps or gaps.  This filled
     rectangle, when merged onto the canvas, will extend only to (54,4). */
  rect.x = 40;		rect.y = 0;
  rect.width = 15;	rect.height = 5;

  /* define polyline: vertices are (25,5) (5,5), (5,25), (35,22) */
  points[0].x = 25;  points[0].y = 5;
  points[1].x = 5;   points[1].y = 5;
  points[2].x = 5;   points[2].y = 25;
  points[3].x = 35;  points[3].y = 22;
     
  /* define elliptic arc */
  arc.x = 20; arc.y = 15;   /* upper left corner of bounding box */
  arc.width = 30;           /* x range of box: 20..50 */
  arc.height = 16;          /* y range of box: 15..31 */
  arc.angle1 = 0 * 64;      /* starting angle (1/64'ths of a degree) */
  arc.angle2 = 270 * 64;    /* angle range (1/64'ths of a degree) */
     
  /* create and modify graphics context */
  pixels[0] = 0;            /* pixel value for `off' dashes, if drawn */
  pixels[1] = 1;            /* default pixel for drawing */
  pixels[2] = 2;            /* another pixel, for multicolored dashes */
  pixels[3] = 3;            /* another pixel, for multicolored dashes */
  dashes[0] = 4;            /* length of `on' dashes */
  dashes[1] = 2;            /* length of `off' dashes */
  pGC = miNewGC (4, pixels);
  miSetGCAttrib (pGC, MI_GC_LINE_STYLE, MI_LINE_ON_OFF_DASH);
  miSetGCDashes (pGC, 2, dashes, 0);
  miSetGCAttrib (pGC, MI_GC_LINE_WIDTH, 0); /* Bresenham algorithm */
     
  /* create empty painted set */
  paintedSet = miNewPaintedSet ();
     
  /* Paint filled rectangle, dashed polyline and dashed arc onto painted
     set.  Rectangle will be filled with the default pixel value for
     drawing, i.e., pixels[1], i.e., 2, and polyline and arc will be drawn
     rather than filled: they will be dashed as specified above. */
  miFillRectangles (paintedSet, pGC, 1, &rect);
  miDrawLines (paintedSet, pGC, MI_COORD_MODE_ORIGIN, 4, points);
  miDrawArcs (paintedSet, pGC, 1, &arc);
     
  /* create 60x35 canvas (initPixel=0); merge painted set onto it */
  canvas = miNewCanvas (60, 35, 0);
  offset.x = 0; offset.y = 0;
  miCopyPaintedSetToCanvas (paintedSet, canvas, offset);
     
  /* write canvas's pixmap (a 60x35 array of miPixels) to stdout */
  for (j = 0; j < canvas->drawable->height; j++)
    {
      for (i = 0; i < canvas->drawable->width; i++)
	/* note: column index precedes row index */
	printf ("%d", canvas->drawable->pixmap[j][i]);
      printf ("\n");
    }
     
  /* clean up */
  miDeleteCanvas (canvas);
  miDeleteGC (pGC);
  miClearPaintedSet (paintedSet); /* not necessary */
  miDeletePaintedSet (paintedSet);
     
  return 0;
}