/*
 * wGraph.c
 *
 * Low-level graphics handling
 *
 * © 1994-1998 Straylight
 */

/*----- Licensing note ----------------------------------------------------*
 *
 * This file is part of Straylight's Glass.
 *
 * Glass is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * Glass 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Glass.  If not, write to the Free Software Foundation,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

/*
 * ANSI standard headers
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * Steel headers
 */

#define _STDAPP
#define _LOWLVL
#include "steel/Steel.h"

#include "steel/bbc.h"
#include "steel/colourtran.h"

/*
 * Glass headers
 */

#include "gStruct.h"
#include "gMenus.h"
#include "gIcons.h"

#include "glass.h"
#include "gPrefs.h"
#include "window.h"
#include "_window.h"

/*----- Private variables -------------------------------------------------*/

static int window__dashPos;      /* Current rotating dash position         */

/*----- Main code ---------------------------------------------------------*/

/*
 * void window__colourChange(int col1,int col2)
 *
 * Use
 *  Sets up the current foreground colour so that when plotted over colour
 *  col1 it looks like col2 and vice-versa.  The effects of plotting over
 *  other colours is defined to be psychedelically interesting, but not
 *  pretty.
 *
 *  Basically, all it does is suss out what the colours really mean and XOR
 *  them together.
 *
 * Parameters
 *  int col1,int col2 == the Wimp colour numbers to swap between
 */

void window__colourChange(int col1,int col2)
{
  wimp_palettestr pal;
  int x,y;
  wimpt_noerr(wimp_readpalette(&pal));
  wimpt_noerr(colourtran_return_colournumber(pal.c[col1],&x));
  wimpt_noerr(colourtran_return_colournumber(pal.c[col2],&y));
  if (os_swiv(XOS_SetColour,3,x^y))
  {
    if (wimpt_bpp()==8)
    {
      wimpt_noerr(colourtran_colournumbertoGCOL(x^y,&x));
      bbc_vduq(18,3,x>>2);
      bbc_vduq(23,17,2,(x & 3)<<6,0,0,0,0,0,0);
    }
    else
      bbc_vduq(18,3,x^y);
  }
}

/*
 * void window__setXORColour(glass_windPointer *w,int col)
 *
 * Use
 *  Sets up the current foreground colour so that it appears to be WIMP
 *  colour col on the specified window background.  Lots of tedious
 *  ColourTransing to do on this, with no real reward, but at least it will
 *  look vaguely right in 256 colour modes.
 *
 * Parameters
 *  glass_windPointer *w == the window in which to set the colour
 *  int col == the colour to set
 */

void window__setXORColour(glass_windPointer *w,int col)
{
  int old=w->def->desc.w.colours[3];

  /* --- Make sure the background isn't transparent --- */

  if (old==255)
    old=1;

  window__colourChange(old,col);
}

/*
 * void window__makeDashPattern(int ptn)
 *
 * Use
 *  Sets the OS dash pattern to the given pattern (only the lowest byte
 *  is considered).
 *
 * Parameters
 *  int ptn == the LSB of this word contains the dash pattern as a bit
 *   pattern
 */

void window__makeDashPattern(int ptn)
{
  int byte1,byte2;
  byte1=242;
  byte2=8;
  wimpt_noerr(os_byte(163,&byte1,&byte2)); /* Dot-dash length              */
  bbc_vduq(23,6,ptn,ptn,ptn,ptn,ptn,ptn,ptn,ptn);
}

/*
 * void window__setDash(void)
 *
 * Use
 *  Sets the dashed pattern so that it looks as if a 'rotating' box is being
 *  dragged, like the WIMP's, only better...  The box is set up so that a
 *  SINGLE exclusive-or plot will move the dash round.
 */

#define SECTION(x,i) ((((x)<<(i)) & 0xff00) >> 8)

void window__setDash(void)
{
  int dash=SECTION(0xFCFCFC,window__dashPos);
  int newDash;
  window__dashPos+=2;
  if (window__dashPos>7)
    window__dashPos=0;
  newDash=SECTION(0xFCFCFC,window__dashPos);
  dash^=newDash;
  window__makeDashPattern(dash);
  window__setXORColour(window__dragWind(),window__DRAGCOL);
}

/*
 * void window__rotate(int by)
 *
 * Use
 *  Rotates the current rotating-dash pattern by a given amount.  This is
 *  used to rotate the dash box while the box is moving.
 *
 * Parameters
 *  int by == the number of steps to rotate the dash pattern.
 */

void window__rotate(int by)
{
  window__dashPos+=by;
  if (window__dashPos<0)
    window__dashPos=6;
  else if (window__dashPos>7)
    window__dashPos=0;
  window__makeDashPattern(SECTION(0xFCFCFC,window__dashPos));
  window__setXORColour(window__dragWind(),window__DRAGCOL);
}

/*
 * void window__rectangle(int x,int y,int w,int h)
 *
 * Use
 *  Draws a rectangle, using the current dotted line pattern
 *
 * Parameters
 *  int x == the left side of the rectangle
 *  int y == the right side of the rectangle
 *  int w == the width of the rectangle (may be <0)
 *  int h == the height of the rectangle (may be <0)
 */

void window__rectangle(int x,int y,int w,int h)
{
  bbc_plot(bbc_DottedBoth+bbc_MoveCursorAbs,x,y);
  bbc_plot(bbc_DottedBoth+bbc_DrawRelFore,0,h);
  bbc_plot(bbc_DottedExInit+bbc_DrawRelFore,w,0);
  bbc_plot(bbc_DottedExInit+bbc_DrawRelFore,0,-h);
  bbc_plot(bbc_DottedExBoth+bbc_DrawRelFore,-w,0);
}