ppmfile.c

本文档包括了几何矫正的主体内容

/*
 * functions for ppm image file format 
 *
 * 
 * Open an old file or new file
 */
#include <imgfile.h>
#define PGM_MAGIC1          'P'
#define RPGM_MAGIC2         '5'
FILE *imgPPMOpen(filename,xflen,yflen,type)
	char *filename;         /* open filename */
	long *xflen,*yflen;      /* file size */
	long type;              /* if exsit: type=0 exist,type=1,new file */
{
	char magic1,magic2;
	int gray_size;
	int width,height;
	int iw,jh;
	char *zero_space;
	FILE *fPtr;
	if(type) {
		printf("new file name: %s\nsize width x height: %d x %d\n",
				filename,*xflen,*yflen);
		width = *xflen;
		height= *yflen;
		if ( (fPtr = fopen(filename,"w+")) == NULL) {
				printf("Error: Open New File \n");
				exit(1);
		}
		fprintf(fPtr,"%c%c\n%d %d\n%d\n",PGM_MAGIC1,RPGM_MAGIC2,
				width,height,255);
		/* init image file ,and allocate enough space */
		zero_space = (char *)malloc(width);
		memset(zero_space,0,width);
		for (jh = 0;jh < height;jh++) {
                       fwrite(zero_space,1,width,fPtr);
		}
		free(zero_space);
		return fPtr;
	} else {
		
                printf("old file name: %s\n",filename);
		if( (fPtr = fopen(filename,"r+")) == NULL) {
			printf("Error: Open Old File \n");
			exit(1);
		}
		fscanf(fPtr,"%c%c\n%d %d\n%d\n",
				&magic1,&magic2,&width,&height,&gray_size);
		printf("size width x height: %d x %d\n",width,height);
		printf("magic : %c%c\ngray_size: %d\n",magic1,magic2,gray_size);
		*xflen = width;
		*yflen  = height;
		return fPtr;
	}
        return 0;	
}
/*
 *  Close  a file
 */
void
imgPPMClose(fPtr)
	FILE *fPtr;
{
	fclose(fPtr);
}
/*
 *  read a ppm file
 */
long
imgPPMRead(fPtr,xBegin,yBegin,xLen,yLen,stenArray)
	FILE *fPtr;
	long xBegin,yBegin;
	long xLen,yLen;
	char *stenArray;
{
	char magic1,magic2;
	int gray_size;
	int width,height;
	int ty,tx;
	fseek(fPtr,0L,SEEK_SET);
	fscanf(fPtr,"%c%c\n%d %d\n%d\n",&magic1,&magic2,&width,&height,&gray_size);
#if 0
	printf("imgRead: %c%c %d %d %d\n",magic1,magic2,width,height,gray_size);
#endif 
	fseek(fPtr,(long)(yBegin*width+xBegin),SEEK_CUR);
	for(ty = 0; ty <yLen-1 ;ty++) {
	    fread(stenArray,1,xLen,fPtr);
	    stenArray += xLen;
	    fseek(fPtr,(long)(width - xLen),SEEK_CUR);
	}
	fread(stenArray,1,xLen,fPtr);
	return 0;
}
/*
 * imgGet
 * get image data from memory
 */
long
imgPPMGet(sImage,xBegin,yBegin,xLen,yLen,sWidth,sHeight,stenArray)
	char *sImage;
	long xBegin,yBegin;
	long xLen,yLen;
	long sWidth,sHeight;
	char *stenArray;
{
	int tx,ty;
	int locBegin;
	yBegin = sHeight - yBegin - 1;
	locBegin = yBegin*sWidth+xBegin;
	sImage += locBegin;
        for(ty = 0;ty <yLen;ty++) {
		for(tx = 0;tx <xLen;tx++) {
			*stenArray = *sImage;
			stenArray++;
			sImage++;
		}
		sImage -= sWidth+xLen;
	}
	/*
	for(tx = 0;tx < xLen;tx++ ) {
		*stenArray = *sImage;
		stenArray++;
		sImage++;
	}*/
	return 0;
}

/*
 * write ppm file
 */
long
imgPPMWrite(fPtr,xBegin,yBegin,xLen,yLen,stenArray)
	FILE *fPtr;
	long xBegin,yBegin;
	long xLen,yLen;
	char *stenArray;
{
	char magic1,magic2;
	int gray_size;
	int width,height;
	int ty;
	fseek(fPtr,0L,SEEK_SET);
        fscanf(fPtr,"%c%c\n%d %d\n%d\n",&magic1,&magic2,&width,&height,&gray_size);
#if 0
	printf("imgWrite: %c%c %d %d %d\n",magic1,magic2,width,height,gray_size);
#endif
        fseek(fPtr,(long)(yBegin*width+xBegin),SEEK_CUR);
	for(ty = 0; ty <yLen ;ty++) {
		fwrite(stenArray,1,xLen,fPtr);
		stenArray += xLen;
		fseek(fPtr,(long)(width - xLen),SEEK_CUR);
	}
        return 0;
}
	
/*
 * imgPut
 * just for ppm file format
 */
long
imgPPMPut(tImage,xBegin,yBegin,xLen,yLen,tWidth,tHeight,stenArray)
	char *tImage;		     
     	long xBegin,yBegin;	
	long xLen,yLen;			
	long tWidth,tHeight;
	char *stenArray;
{
	int tx,ty;
	int locBegin;		
	yBegin = tHeight - yBegin - 1;
	locBegin = yBegin*tWidth+xBegin;
	tImage += locBegin;
	for(ty = 0;ty <yLen;ty++) {					
		for(tx = 0;tx <xLen;tx++) {				
			*tImage = *stenArray;					
			stenArray++;					
			tImage++;				
		}		
		tImage -= tWidth + xLen;
	}				
	return 0;	
}