gd_gd2.c

下载来的一个看图软件的源代码

/*
   * gd_gd2.c
   *
   * Implements the I/O and support for the GD2 format.
   *
   * Changing the definition of GD2_DBG (below) will cause copious messages
   * to be displayed while it processes requests.
   *
   * Designed, Written & Copyright 1999, Philip Warner.
   *
 */

#include <stdio.h>
#include <errno.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <zlib.h>
#include "gd.h"
#include "gdhelpers.h"

#define TRUE 1
#define FALSE 0

/* Use this for commenting out debug-print statements. */
/* Just use the first '#define' to allow all the prints... */
/*#define GD2_DBG(s) (s) */
#define GD2_DBG(s)

typedef struct
  {
    int offset;
    int size;
  }
t_chunk_info;

extern int _gdGetColors (gdIOCtx * in, gdImagePtr im, int gd2xFlag);
extern void _gdPutColors (gdImagePtr im, gdIOCtx * out);

/* */
/* Read the extra info in the gd2 header. */
/* */
static
int
_gd2GetHeader (gdIOCtxPtr in, int *sx, int *sy,
 int *cs, int *vers, int *fmt, int *ncx, int *ncy, t_chunk_info ** chunkIdx)
{
  int i;
  int ch;
  char id[5];
  t_chunk_info *cidx;
  int sidx;
  int nc;

  GD2_DBG (printf ("Reading gd2 header info\n"));

  for (i = 0; i < 4; i++)
    {
      ch = gdGetC (in);
      if (ch == EOF)
	{
	  goto fail1;
	};
      id[i] = ch;
    };
  id[4] = 0;

  GD2_DBG (printf ("Got file code: %s\n", id));

  /* Equiv. of 'magick'.  */
  if (strcmp (id, GD2_ID) != 0)
    {
      GD2_DBG (printf ("Not a valid gd2 file\n"));
      goto fail1;
    };

  /* Version */
  if (gdGetWord (vers, in) != 1)
    {
      goto fail1;
    };
  GD2_DBG (printf ("Version: %d\n", *vers));

  if ((*vers != 1) && (*vers != 2))
    {
      GD2_DBG (printf ("Bad version: %d\n", *vers));
      goto fail1;
    };

  /* Image Size */
  if (!gdGetWord (sx, in))
    {
      GD2_DBG (printf ("Could not get x-size\n"));
      goto fail1;
    }
  if (!gdGetWord (sy, in))
    {
      GD2_DBG (printf ("Could not get y-size\n"));
      goto fail1;
    }
  GD2_DBG (printf ("Image is %dx%d\n", *sx, *sy));

  /* Chunk Size (pixels, not bytes!) */
  if (gdGetWord (cs, in) != 1)
    {
      goto fail1;
    };
  GD2_DBG (printf ("ChunkSize: %d\n", *cs));

  if ((*cs < GD2_CHUNKSIZE_MIN) || (*cs > GD2_CHUNKSIZE_MAX))
    {
      GD2_DBG (printf ("Bad chunk size: %d\n", *cs));
      goto fail1;
    };

  /* Data Format */
  if (gdGetWord (fmt, in) != 1)
    {
      goto fail1;
    };
  GD2_DBG (printf ("Format: %d\n", *fmt));

  if ((*fmt != GD2_FMT_RAW) && (*fmt != GD2_FMT_COMPRESSED))
    {
      GD2_DBG (printf ("Bad data format: %d\n", *fmt));
      goto fail1;
    };


  /* # of chunks wide */
  if (gdGetWord (ncx, in) != 1)
    {
      goto fail1;
    };
  GD2_DBG (printf ("%d Chunks Wide\n", *ncx));

  /* # of chunks high */
  if (gdGetWord (ncy, in) != 1)
    {
      goto fail1;
    };
  GD2_DBG (printf ("%d Chunks vertically\n", *ncy));

  if ((*fmt) == GD2_FMT_COMPRESSED)
    {
      nc = (*ncx) * (*ncy);
      GD2_DBG (printf ("Reading %d chunk index entries\n", nc));
      sidx = sizeof (t_chunk_info) * nc;
      cidx = gdCalloc (sidx, 1);
      for (i = 0; i < nc; i++)
	{
	  if (gdGetInt (&cidx[i].offset, in) != 1)
	    {
	      goto fail1;
	    };
	  if (gdGetInt (&cidx[i].size, in) != 1)
	    {
	      goto fail1;
	    };
	};
      *chunkIdx = cidx;
    };

  GD2_DBG (printf ("gd2 header complete\n"));

  return 1;

fail1:
  return 0;
}

static
  gdImagePtr
_gd2CreateFromFile (gdIOCtxPtr in, int *sx, int *sy,
		    int *cs, int *vers, int *fmt,
		    int *ncx, int *ncy, t_chunk_info ** cidx)
{
  gdImagePtr im;

  if (_gd2GetHeader (in, sx, sy, cs, vers, fmt, ncx, ncy, cidx) != 1)
    {
      GD2_DBG (printf ("Bad GD2 header\n"));
      goto fail1;
    }

  im = gdImageCreate (*sx, *sy);
  if (im == NULL)
    {
      GD2_DBG (printf ("Could not create gdImage\n"));
      goto fail1;
    };

  if (!_gdGetColors (in, im, (*vers) == 2))
    {
      GD2_DBG (printf ("Could not read color palette\n"));
      goto fail2;
    }
  GD2_DBG (printf ("Image palette completed: %d colours\n", im->colorsTotal));

  return im;

fail2:
  gdImageDestroy (im);
  return 0;

fail1:
  return 0;

}

static
int
_gd2ReadChunk (int offset, char *compBuf, int compSize, char *chunkBuf, uLongf * chunkLen, gdIOCtx * in)
{
  int zerr;

  if (gdTell (in) != offset)
    {
      GD2_DBG (printf ("Positioning in file to %d\n", offset));
      gdSeek (in, offset);
    }
  else
    {
      GD2_DBG (printf ("Already Positioned in file to %d\n", offset));
    };

  /* Read and uncompress an entire chunk. */
  GD2_DBG (printf ("Reading file\n"));
  if (gdGetBuf (compBuf, compSize, in) != compSize)
    {
      return FALSE;
    };
  GD2_DBG (printf ("Got %d bytes. Uncompressing into buffer of %d bytes\n", compSize, *chunkLen));
  zerr = uncompress ((unsigned char *) chunkBuf, chunkLen,
		     (unsigned char *) compBuf, compSize);
  if (zerr != Z_OK)
    {
      GD2_DBG (printf ("Error %d from uncompress\n", zerr));
      return FALSE;
    };
  GD2_DBG (printf ("Got chunk\n"));
  return TRUE;
}

gdImagePtr
gdImageCreateFromGd2 (FILE * inFile)
{
  gdIOCtx *in = gdNewFileCtx (inFile);
  gdImagePtr im;

  im = gdImageCreateFromGd2Ctx (in);

  in->free (in);

  return im;
}

gdImagePtr
gdImageCreateFromGd2Ctx (gdIOCtxPtr in)
{
  int sx, sy;
  int i;
  int ncx, ncy, nc, cs, cx, cy;
  int x, y, ylo, yhi, xlo, xhi;
  int ch, vers, fmt;
  t_chunk_info *chunkIdx = NULL;	/* So we can gdFree it with impunity. */
  unsigned char *chunkBuf = NULL;	/* So we can gdFree it with impunity. */
  int chunkNum = 0;
  int chunkMax;
  uLongf chunkLen;
  int chunkPos;
  int compMax;
  int bytesPerPixel;
  char *compBuf = NULL;		/* So we can gdFree it with impunity. */

  gdImagePtr im;

  /* Get the header */
  im = _gd2CreateFromFile (in, &sx, &sy, &cs, &vers, &fmt, &ncx, &ncy, &chunkIdx);

  if (im == NULL)
    {
      return 0;
    };
  bytesPerPixel = im->trueColor ? 4 : 1;
  nc = ncx * ncy;

  if (fmt == GD2_FMT_COMPRESSED)
    {
      /* Find the maximum compressed chunk size. */
      compMax = 0;
      for (i = 0; (i < nc); i++)
	{
	  if (chunkIdx[i].size > compMax)
	    {
	      compMax = chunkIdx[i].size;
	    };
	};
      compMax++;

      /* Allocate buffers */
      chunkMax = cs * bytesPerPixel * cs;
      chunkBuf = gdCalloc (chunkMax, 1);
      compBuf = gdCalloc (compMax, 1);
      GD2_DBG (printf ("Largest compressed chunk is %d bytes\n", compMax));
    };

/*      if ( (ncx != sx / cs) || (ncy != sy / cs)) { */
/*              goto fail2; */
/*      }; */

  /* Read the data... */
  for (cy = 0; (cy < ncy); cy++)
    {
      for (cx = 0; (cx < ncx); cx++)
	{

	  ylo = cy * cs;
	  yhi = ylo + cs;
	  if (yhi > im->sy)
	    {
	      yhi = im->sy;
	    };

	  GD2_DBG (printf ("Processing Chunk %d (%d, %d), y from %d to %d\n", chunkNum, cx, cy, ylo, yhi));

	  if (fmt == GD2_FMT_COMPRESSED)
	    {

	      chunkLen = chunkMax;

	      if (!_gd2ReadChunk (chunkIdx[chunkNum].offset,
				  compBuf,
				  chunkIdx[chunkNum].size,
				  chunkBuf, &chunkLen, in))
		{
		  GD2_DBG (printf ("Error reading comproessed chunk\n"));
		  goto fail2;
		};

	      chunkPos = 0;
	    };

	  for (y = ylo; (y < yhi); y++)
	    {

	      xlo = cx * cs;
	      xhi = xlo + cs;
	      if (xhi > im->sx)
		{
		  xhi = im->sx;
		};
	      /*GD2_DBG(printf("y=%d: ",y)); */
	      if (fmt == GD2_FMT_RAW)
		{
		  for (x = xlo; x < xhi; x++)
		    {

		      if (im->trueColor)
			{
			  if (!gdGetInt (&im->tpixels[y][x], in))
			    {
			      /*printf("EOF while reading\n"); */
			      /*gdImageDestroy(im); */
			      /*return 0; */
			      im->tpixels[y][x] = 0;
			    }
			}
		      else
			{
			  int ch;
			  if (!gdGetByte (&ch, in))
			    {
			      /*printf("EOF while reading\n"); */
			      /*gdImageDestroy(im); */
			      /*return 0; */
			      ch = 0;
			    }
			  im->pixels[y][x] = ch;
			}
		    }
		}
	      else
		{
		  for (x = xlo; x < xhi; x++)
		    {
		      if (im->trueColor)
			{
			  /* 2.0.1: work around a gcc bug by being verbose.
			     TBB */
			  int a = chunkBuf[chunkPos++] << 24;
			  int r = chunkBuf[chunkPos++] << 16;
			  int g = chunkBuf[chunkPos++] << 8;
			  int b = chunkBuf[chunkPos++];
			  im->pixels[y][x] = a + r + g + b;
			}
		      else
			{
			  im->pixels[y][x] = chunkBuf[chunkPos++];
			}
		    };
		};
	      /*GD2_DBG(printf("\n")); */
	    };
	  chunkNum++;
	};
    };

  GD2_DBG (printf ("Freeing memory\n"));

  gdFree (chunkBuf);
  gdFree (compBuf);
  gdFree (chunkIdx);

  GD2_DBG (printf ("Done\n"));

  return im;

fail2:
  gdImageDestroy (im);
  gdFree (chunkBuf);
  gdFree (compBuf);
  gdFree (chunkIdx);
  return 0;

}

gdImagePtr
gdImageCreateFromGd2Part (FILE * inFile, int srcx, int srcy, int w, int h)
{
  gdImagePtr im;
  gdIOCtx *in = gdNewFileCtx (inFile);

  im = gdImageCreateFromGd2PartCtx (in, srcx, srcy, w, h);

  in->free (in);

  return im;
}

gdImagePtr
gdImageCreateFromGd2PartCtx (gdIOCtx * in, int srcx, int srcy, int w, int h)
{
  int scx, scy, ecx, ecy, fsx, fsy;
  int nc, ncx, ncy, cs, cx, cy;
  int x, y, ylo, yhi, xlo, xhi;
  int dstart, dpos;
  int i;
  int ch, vers, fmt;
  t_chunk_info *chunkIdx = NULL;
  char *chunkBuf = NULL;
  int chunkNum;
  int chunkMax;
  uLongf chunkLen;
  int chunkPos;
  int compMax;
  char *compBuf = NULL;

  gdImagePtr im;

  /* */
  /* The next few lines are basically copied from gd2CreateFromFile */