upiwin/src/devctxt.c

#include <string.h>
#include <stdlib.h>
#include "log.h"
#include "gfxtype.h"
#include "gfxobj.h"
#include "devctxt.h"

inline static BYTE line_clip_outcode(INT32 x, INT32 y, INT32 xmin, INT32 ymin, INT32 xmax, INT32 ymax)
{
  BYTE rc = 0;
  if (y < ymin)
    rc |= 0x8;
  else if (y >= ymax)
    rc |= 0x4;
  if (x < xmin)
    rc |= 0x1;
  else if (x >= xmax)
    rc |= 0x2;
  return rc;
}

#define CPX 4  /* clipping precision in bits */

#define ONE (1 << CPX)  /* constant for mathematics */

/* these macros keep the number of bits straight when doing fixed-point multiply & divide */
#define M(a, b)  ((((a) * (b))) >> CPX)
#define D(a, b)  (((a) << CPX) / (b))

static BOOL line_clip(PINT32 output, INT32 x1, INT32 y1, INT32 x2, INT32 y2, INT32 xmin, INT32 ymin, INT32 xmax, INT32 ymax)
{
  BYTE outcode1, outcode2;
  INT32 tmp;
  int nloop = 0;
  
  Log(LDEBUG, "clipping line from (%d, %d) to (%d, %d) against bounding box (%d, %d, %d, %d)", x1 >> CPX, y1 >> CPX, x2 >> CPX, y2 >> CPX,
      xmin >> CPX, ymin >> CPX, xmax >> CPX, ymax >> CPX);
  
  /* Cohen-Sutherland line-clipping algorithm (see Foley & Van Dam, pp. 145-149) */
  for (;;)
  {
    if (++nloop == 20)
	{
	  Log(LDEBUG, "POSSIBLE INFINITE LOOP DETECTED - REJECTING");
	  return FALSE;
	}
    outcode1 = line_clip_outcode(x1, y1, xmin, ymin, xmax, ymax);
	outcode2 = line_clip_outcode(x2, y2, xmin, ymin, xmax, ymax);
	if ((outcode1 & outcode2) != 0)
	{
	  Log(LDEBUG,"*REJECT*");
	  return FALSE; /* trivial rejection */
	}
	else if ((outcode1 == 0) && (outcode2 == 0))
	{
	  Log(LDEBUG,"*ACCEPT*");
	  break; /* trivial acceptance */
	}
	if (outcode1 == 0)
	{
	  Log(LDEBUG, "exchange points");
	  tmp = x1;
	  x1 = x2;
	  x2 = tmp;
	  tmp = y1;
	  y1 = y2;
	  y2 = tmp;
	  outcode1 = outcode2;  /* we don't reference outcode2 in the rest of the loop */
	}
	if (outcode1 & 0x8)
	{
	  tmp = M(x2 - x1, D(ymin - y1, y2 - y1));
	  x1 += tmp;
	  y1 = ymin;
	  Log(LDEBUG, "clipped against top to point (%d, %d), dx=%d/%d", x1 >> CPX, y1 >> CPX, tmp >> CPX, tmp);
	}
	else if (outcode1 & 0x4)
	{
	  tmp = M(x2 - x1, D(ymax - ONE - y1, y2 - y1));
	  x1 += tmp;
	  y1 = ymax - ONE;
	  Log(LDEBUG, "clipped against bottom to point (%d, %d), dx=%d/%d", x1 >> CPX, y1 >> CPX, tmp >> CPX, tmp);
	}
	else if (outcode1 & 0x2)
	{
	  tmp = M(y2 - y1, D(xmax - ONE - x1, x2 - x1));
	  y1 += tmp;
	  x1 = xmax - ONE;
	  Log(LDEBUG, "clipped against right to point (%d, %d), dy=%d/%d", x1 >> CPX, y1 >> CPX, tmp >> CPX, tmp);
	}
	else if (outcode1 & 0x1)
	{
	  tmp = M(y2 - y1, D(xmin - x1, x2 - x1));
	  y1 += tmp;
	  x1 = xmin;
	  Log(LDEBUG, "clipped against left to point (%d, %d), dy=%d/%d", x1 >> CPX, y1 >> CPX, tmp >> CPX, tmp);
	}
  }
  Log(LDEBUG, "final line is from (%d, %d) to (%d, %d)", x1 >> CPX, y1 >> CPX, x2 >> CPX, y2 >> CPX);
  output[0] = x1;
  output[1] = y1;
  output[2] = x2;
  output[3] = y2;
  return TRUE;
}

static BOOL internal_line(PDCTXT pdctxt, INT32 x1, INT32 y1, INT32 x2, INT32 y2)
{
  INT32 buffer[4];
  if (line_clip(buffer, x1 << CPX, y1 << CPX, x2 << CPX, y2 << CPX, pdctxt->cliprect.left << CPX, pdctxt->cliprect.top << CPX,
				pdctxt->cliprect.right << CPX, pdctxt->cliprect.bottom << CPX))
    return (*pdctxt->funcs->line)(pdctxt->privdata, buffer[0] >> CPX, buffer[1] >> CPX, buffer[2] >> CPX, buffer[3] >> CPX, pdctxt->color, pdctxt->rop2);
  return TRUE;
}

PDCTXT _DC_Allocate(PDCFUNTABLE funcs, PVOID privdata)
{
  PDCTXT rc = (PDCTXT)malloc(sizeof(DCTXT));
  if (!rc)
    return NULL;
  memset(rc, 0, sizeof(DCTXT));
  _Go_init(&(rc->hdr), DCTXT_SIG_WORD, sizeof(DCTXT));
  rc->funcs = funcs;
  rc->privdata = privdata;
  rc->rop2 = R2_COPYPEN;
  return rc;
}

void _DC_FinalizeCommon(PDCTXT pdctxt)
{
  /* nothing here yet */
}

COLORREF DC_SetPixel(PDCTXT pdctxt, INT32 x, INT32 y, COLORREF color)
{
  if (!G_coords_in_rect(&(pdctxt->cliprect), x, y))
	return (COLORREF)(-1);
  return (*(pdctxt->funcs->set_pixel))(pdctxt->privdata, x, y, color, pdctxt->rop2);
}

BOOL DC_LineTo(PDCTXT pdctxt, INT32 x, INT32 y)
{
  BOOL rc = internal_line(pdctxt, pdctxt->pos.x, pdctxt->pos.y, x, y);
  if (rc)
  {
    pdctxt->pos.x = x;
	pdctxt->pos.y = y;
  }
  return rc;
}

BOOL DC_MoveTo(PDCTXT pdctxt, INT32 x, INT32 y, PPOINT oldpt)
{
  if (oldpt)
    memcpy(oldpt, &(pdctxt->pos), sizeof(POINT));
  pdctxt->pos.x = x;
  pdctxt->pos.y = y;
  return TRUE;
}

BOOL DC_Rectangle(PDCTXT pdctxt, INT32 left, INT32 top, INT32 right, INT32 bottom)
{
  internal_line(pdctxt, left, top, right - 1, top);
  internal_line(pdctxt, left, top + 1, left, bottom - 2);
  internal_line(pdctxt, right - 1, top + 1, right - 1, bottom - 2);
  internal_line(pdctxt, left, bottom - 1, right - 1, bottom - 1);
  return TRUE;
}

UINT32 DC_GetROP2(PDCTXT pdctxt)
{
  return pdctxt->rop2;
}

UINT32 DC_SetROP2(PDCTXT pdctxt, UINT32 rop)
{
  UINT32 rc = pdctxt->rop2;
  pdctxt->rop2 = rop;
  return rc;
}

COLORREF DC_GetTextColor(PDCTXT pdctxt)
{
  return pdctxt->color;
}

COLORREF DC_SetTextColor(PDCTXT pdctxt, COLORREF cr)
{
  COLORREF rc = pdctxt->color;
  pdctxt->color = cr;
  return rc;
}

BOOL DC_GetClipRect(PDCTXT pdctxt, PRECT prect)
{
  memcpy(prect, &(pdctxt->cliprect), sizeof(RECT));
  return TRUE;
}

BOOL DC_SetClipRect(PDCTXT pdctxt, PRECT prect)
{
  memcpy(&(pdctxt->cliprect), prect, sizeof(RECT));
  return TRUE;
}