ppm_image.c

此程序需要Brew sdk2.1版本以上,是关于OpenGL的手机编程.

/*=================================================================================
FILE:			ppm_image.c
  
DESCRIPTION:	This file is provide as a standard sample Brew source file. 
				Please refer to this OpenGL(R)ES brew sample application as a 
				reference on how to use the standard OpenGL-ES and EGL APIs.
                          
ABSTRACT:		PPM format image loader

AUTHOR:			QUALCOMM
                        
				Copyright (c) 2004 QUALCOMM Incorporated.
					   All Rights Reserved.
					QUALCOMM Proprietary/GTDR
=================================================================================*/

/*-------------------------------------------------------------------------------*
 *                      I N C L U D E   F I L E S                                *
 *-------------------------------------------------------------------------------*/
#include "ppm_image.h"

/*-------------------------------------------------------------------------------*
 *                 F U N C T I O N   P R O T O T Y P E S                         *
 *-------------------------------------------------------------------------------*/
int             ReadPPMLine( IFile*, char * );

/*-------------------------------------------------------------------------------*
 *							S T R U C T											 *
 *-------------------------------------------------------------------------------*/
/* format of each 24-bit texel in a raw ppm file:								 */
struct rgb
{
	unsigned char r, g, b;
};

/*-------------------------------------------------------------------------------*
 *                          B E G I N   P R O G R A M                            *
 *-------------------------------------------------------------------------------*/

/*===========================================================================
FUNCTION: PPMToTexture
  
DESCRIPTION:
	This function will read the ppm file as texture
  
PROTOTYPE:
	unsigned char * PPMToTexture(IShell *shell, char *filename, int *widthp, int *heightp )
      
PARAMETERS:
	shell	: A pointer pointing to the IShell Interface object
	filename : A pointer pointing to a file
	widthp	: A pointer pointing to the width of the texture
	heightp	: A pointer pointing to the height of the texture
            
DEPENDENCIES
	none
              
RETURN VALUE
	none
                
===========================================================================*/
unsigned char *
PPMToTexture(IShell *shell, const char *filename, int *widthp, int *heightp )
{
	IFileMgr *m_pIFileMgr;
    IFile* pFile;
  
	int n;			/* # items read				*/
	int width, height;	/* image size				*/
	unsigned char *texture;	/* texture array			*/
	int range;		/* color range, should be 256		*/
	char line[256];		/* hold the ascii lines			*/


	/* open the filename and read width and height:			*/
	if (ISHELL_CreateInstance(shell, AEECLSID_FILEMGR, (void **)&m_pIFileMgr) != SUCCESS) 
		return NULL;

	pFile = IFILEMGR_OpenFile(m_pIFileMgr, filename, _OFM_READ);
	if(pFile == NULL) return NULL;

	n = ReadPPMLine( pFile, line );

	n = ReadPPMLine( pFile, line );

	sscanf( line, "%d %d", &width, &height );

	n = ReadPPMLine( pFile, line );

	sscanf( line, "%d", &range );


	/* allocate the texture array:					*/

	texture = ( unsigned char *) MALLOC( 3 * width * height * 1 );

	if (!texture)
	{
		DBGPRINTF("texture allocation failed");
		return NULL;
	}

	/* read the entire file:					*/

	n = IFILE_Read(pFile, texture, width*height*3);

	/* close the file and return:					*/
    if (pFile) IFILE_Release(pFile);
    if (m_pIFileMgr) IFILEMGR_Release(m_pIFileMgr);
	*widthp = width;
	*heightp = height;
	return texture;
}


/*===========================================================================
FUNCTION: ReadPPMLine
  
DESCRIPTION:
	This function will read one line of the input file
  
PROTOTYPE:
	int ReadPPMLine( IFile* pFile, char *line )
      
PARAMETERS:
	pFile : pointer to a file
	line  : pointer to line[] char array
            
DEPENDENCIES
	none
              
RETURN VALUE
	1 : finish reading the line
   
===========================================================================*/
int
ReadPPMLine( IFile* pFile, char *line )
{
	char *p;		/* pointer into line[] array		*/
	char c;			/* character read			*/


	/* keep reading until we get a non-comment:			*/

	for( ; ; )
	{
		p = line;
		IFILE_Read(pFile, &c, 1);
		while(c != '\n')
		{
			*p++ = c;
			IFILE_Read(pFile, &c, 1);
		}


		/* terminate with a null:				*/

		*p = '\0';


		/* get out if not a comment:				*/

		if( line[0] != '#' )
			break;
	}

	return 1;
}