/* sprite.c       moving pieces */

/*
 * xcheckers:     a point and click checkerboard
 * (C):           1999, 2000 Peter Chiocchetti <girbal@tacheles.de>
 */


#include <X11/X.h>
#include <X11/Xlib.h>
#include "xcheckers.h"
#include "board.h"
#include "sprite.h"


#define TGCMASK (GCBackground | GCForeground | GCGraphicsExposures)


int             sx, sy;		/* drag start position, nodes */
int             cx, cy;		/* current position, pixels */
int             picked;		/* 1 while moving a sprite */


/*
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 *                                                             Animated Pieces
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 */


/* prepare GC and pixmap for moving sprites across the board */
void
initSprite(void)
{
  bpix = XCreatePixmap(dpy, win, width, height, DefaultDepth(dpy, screen));

  tgc = XCreateGC(dpy, win, 0, NULL);
  XCopyGC(dpy, gc, TGCMASK, tgc);

  XSetClipMask(dpy, tgc, clip);
}


/* draw a stone, while it flies over the board, no flicker */
void
drawSprite(XMotionEvent * e)
{
  int             dx, dy;	/* delta, pixels */
  int             px = cx;	/* previous position, pixels */
  int             py = cy;

  if (!picked)
    return;

  cx = e->x - width / 2;
  cy = e->y - height / 2;

  dx = cx - px;
  dy = cy - py;

  /* this paints the same thing twice , i. e. the region where the
     new position of the stone overlaps the rectangle around the old
     position - probably use a third gc with clip inverted */

  /* restore board */
  XCopyArea(dpy, fpix, bpix, gc, px, py, width, height, 0, 0);
  XSetClipOrigin(dpy, tgc, dx - width * saved[sx][sy].colour, dy);
  XCopyArea(dpy, scene, bpix, tgc, width * saved[sx][sy].colour, 0,
	    width, height, dx, dy);
  XCopyArea(dpy, bpix, win, gc, 0, 0, width, height, px, py);

  /* paint stone */
  XSetClipOrigin(dpy, tgc, cx - width * saved[sx][sy].colour, cy);
  XCopyArea(dpy, scene, win, tgc, saved[sx][sy].colour * width, 0,
	    width, height, cx, cy);
}


/* pick a stone from the board */
void
pickSprite(XButtonEvent * e)
{
  sx = e->x / width;
  sy = e->y / height;
  board[sx][sy].colour = n;
  drawCell(sx, sy);

  picked = 1;

  cx = e->x - width / 2;
  cy = e->y - height / 2;
  drawSprite((XMotionEvent *) e);
}


/* drop a stone to the board */
void
dropSprite(XButtonEvent * e)
{
  int tx, ty;   /* current position, nodes */

  if (!picked)
    return;

  XCopyArea(dpy, fpix, win, gc, cx, cy, width, height, cx, cy);
  tx = e->x / width;
  ty = e->y / height;
  board[tx][ty].colour = saved[sx][sy].colour;
  saveBoard();
  drawCell(tx, ty);
  XFlush(dpy);
  picked = 0;
}


/* put a stone back to its previous place while its moved */
void
cancelSprite(void)
{
  if (!picked)
    return;

  XCopyArea(dpy, fpix, win, gc, cx, cy, width, height, cx, cy);
  board[sx][sy].colour = saved[sx][sy].colour;
  saveBoard();
  drawCell(sx, sy);
  picked = 0;
}