jdatasrc.rar_Called

/* this is not a core library module, so it doesn't define JPEG_INTERNALS */ #include "jinclude.h" #include "jpeglib.h" #include "jerror.h" /* Expanded data source object for stdio input */ typedef struct { struct jpeg_source_mgr pub; /* public fields */ FILE * infile; /* source stream */ JOCTET * buffer; /* start of buffer */ boolean start_of_file; /* have we gotten any data yet? */ } my_source_mgr; typedef my_source_mgr * my_src_ptr; #define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */ /* * Initialize source --- called by jpeg_read_header * before any data is actually read. */ METHODDEF(void) init_source (j_decompress_ptr cinfo) { my_src_ptr src = (my_src_ptr) cinfo->src; /* We reset the empty-input-file flag for each image, * but we don't clear the input buffer. * This is correct behavior for reading a series of images from one source. */ src->start_of_file = TRUE; } METHODDEF(void) init_mem_source (j_decompress_ptr cinfo) { /* no work necessary here */ } /* * Fill the input buffer --- called whenever buffer is emptied. * * In typical applications, this should read fresh data into the buffer * (ignoring the current state of next_input_byte & bytes_in_buffer), * reset the pointer & count to the start of the buffer, and return TRUE * indicating that the buffer has been reloaded. It is not necessary to * fill the buffer entirely, only to obtain at least one more byte. * * There is no such thing as an EOF return. If the end of the file has been * reached, the routine has a choice of ERREXIT() or inserting fake data into * the buffer. In most cases, generating a warning message and inserting a * fake EOI marker is the best course of action --- this will allow the * decompressor to output however much of the image is there. However, * the resulting error message is misleading if the real problem is an empty * input file, so we handle that case specially. * * In applications that need to be able to suspend compression due to input * not being available yet, a FALSE return indicates that no more data can be * obtained right now, but more may be forthcoming later. In this situation, * the decompressor will return to its caller (with an indication of the * number of scanlines it has read, if any). The application should resume * decompression after it has loaded more data into the input buffer. Note * that there are substantial restrictions on the use of suspension --- see * the documentation. * * When suspending, the decompressor will back up to a convenient restart point * (typically the start of the current MCU). next_input_byte & bytes_in_buffer * indicate where the restart point will be if the current call returns FALSE. * Data beyond this point must be rescanned after resumption, so move it to * the front of the buffer rather than discarding it. */ METHODDEF(boolean) fill_input_buffer (j_decompress_ptr cinfo) { my_src_ptr src = (my_src_ptr) cinfo->src; size_t nbytes; nbytes = JFREAD(src->infile, src->buffer, INPUT_BUF_SIZE); if (nbytes <= 0) { if (src->start_of_file) /* Treat empty input file as fatal error */ ERREXIT(cinfo, JERR_INPUT_EMPTY); WARNMS(cinfo, JWRN_JPEG_EOF); /* Insert a fake EOI marker */ src->buffer[0] = (JOCTET) 0xFF; src->buffer[1] = (JOCTET) JPEG_EOI; nbytes = 2; } src->pub.next_input_byte = src->buffer; src->pub.bytes_in_buffer = nbytes; src->start_of_file = FALSE; return TRUE; } METHODDEF(boolean) fill_mem_input_buffer (j_decompress_ptr cinfo) { static JOCTET mybuffer[4]; /* The whole JPEG data is expected to reside in the supplied memory * buffer, so any request for more data beyond the given buffer size * is treated as an error. */ WARNMS(cinfo, JWRN_JPEG_EOF); /* Insert a fake EOI marker */ mybuffer[0] = (JOCTET) 0xFF; mybuffer[1] = (JOCTET) JPEG_EOI; cinfo->src->next_input_byte = mybuffer; cinfo->src->bytes_in_buffer = 2; return TRUE; } /* * Skip data --- used to skip over a potentially large amount of * uninteresting data (such as an APPn marker). * * Writers of suspendable-input applications must note that skip_input_data * is not granted the right to give a suspension return. If the skip extends * beyond the data currently in the buffer, the buffer can be marked empty so * that the next read will cause a fill_input_buffer call that can suspend. * Arranging for additional bytes to be discarded before reloading the input * buffer is the application writer's problem. */ METHODDEF(void) skip_input_data (j_decompress_ptr cinfo, long num_bytes) { struct jpeg_source_mgr * src = cinfo->src; /* Just a dumb implementation for now. Could use fseek() except * it doesn't work on pipes. Not clear that being smart is worth * any trouble anyway --- large skips are infrequent. */ if (num_bytes > 0) { while (num_bytes > (long) src->bytes_in_buffer) { num_bytes -= (long) src->bytes_in_buffer; (void) fill_input_buffer(cinfo); /* note we assume that fill_input_buffer will never return FALSE, * so suspension need not be handled. */ } src->next_input_byte += (size_t) num_bytes; src->bytes_in_buffer -= (size_t) num_bytes; } } /* * An additional method that can be provided by data source modules is the * resync_to_restart method for error recovery in the presence of RST markers. * For the moment, this source module just uses the default resync method * provided by the JPEG library. That method assumes that no backtracking * is possible. */ /* * Terminate source --- called by jpeg_finish_decompress * after all data has been read. Often a no-op. * * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding * application must deal with any cleanup that should happen even * for error exit. */ METHODDEF(void) term_source (j_decompress_ptr cinfo) { /* no work necessary here */ } /* * Prepare for input from a stdio stream. * The caller must have already opened the stream, and is responsible * for closing it after finishing decompression. */ GLOBAL(void) jpeg_stdio_src (j_decompress_ptr cinfo, FILE * infile) { my_src_ptr src; /* The source object and input buffer are made permanent so that a series * of JPEG images can be read from the same file by calling jpeg_stdio_src * only before the first one. (If we discarded the buffer at the end of * one image, we'd likely lose the start of the next one.) * This makes it unsafe to use this manager and a different source * manager serially with the same JPEG object. Caveat programmer. */ if (cinfo->src == NULL) { /* first time for this JPEG object? */ cinfo->src = (struct jpeg_source_mgr *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, SIZEOF(my_source_mgr)); src = (my_src_ptr) cinfo->src; src->buffer = (JOCTET *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, INPUT_BUF_SIZE * SIZEOF(JOCTET)); } src = (my_src_ptr) cinfo->src; src->pub.init_source = init_source; src->pub.fill_input_buffer = fill_input_buffer; src->pub.skip_input_data = skip_input_data; src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */ src->pub.term_source = term_source; src->infile = infile; src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */ src->pub.next_input_byte = NULL; /* until buffer loaded */ } /* * Prepare for input from a supplied memory buffer. * The buffer must contain the whole JPEG data. */ GLOBAL(void) jpeg_mem_src (j_decompress_ptr cinfo, unsigned char * inbuffer, unsigned long insize) { struct jpeg_source_mgr * src; if (inbuffer == NULL || insize == 0) /* Treat empty input as fatal error */ ERREXIT(cinfo, JERR_INPUT_EMPTY); /* The source object is made permanent so that a series of JPEG images * can be read from the same buffer by callin