jload.c File Reference

#include "../game/q_shared.h"
#include "../qcommon/qcommon.h"
#include "jpeglib.h"

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Functions
int	LoadJPG (const char *filename, unsigned char **pic, int *width, int *height)

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Function Documentation

int LoadJPG (  const char *  filename, unsigned char **  pic, int *  width, int *  height )

Definition at line 16 of file jload.c. References buffer, fileHandle_t, FS_FCloseFile(), FS_FOpenFileRead(), height, jpeg_create_decompress(), jpeg_destroy_decompress(), jpeg_finish_decompress(), jpeg_read_header(), jpeg_read_scanlines(), jpeg_start_decompress(), jpeg_std_error(), jpeg_stdio_src(), JSAMPARRAY, jpeg_decompress_struct::output_components, jpeg_decompress_struct::output_height, jpeg_decompress_struct::output_scanline, jpeg_decompress_struct::output_width, qfalse, TRUE, width, and Z_Malloc(). { /* This struct contains the JPEG decompression parameters and pointers to * working space (which is allocated as needed by the JPEG library). */ struct jpeg_decompress_struct cinfo; /* We use our private extension JPEG error handler. * Note that this struct must live as long as the main JPEG parameter * struct, to avoid dangling-pointer problems. */ /* This struct represents a JPEG error handler. It is declared separately * because applications often want to supply a specialized error handler * (see the second half of this file for an example). But here we just * take the easy way out and use the standard error handler, which will * print a message on stderr and call exit() if compression fails. * Note that this struct must live as long as the main JPEG parameter * struct, to avoid dangling-pointer problems. */ struct jpeg_error_mgr jerr; /* More stuff */ fileHandle_t infile; /* source file */ JSAMPARRAY buffer; /* Output row buffer */ int row_stride; /* physical row width in output buffer */ unsigned char *out; /* In this example we want to open the input file before doing anything else, * so that the setjmp() error recovery below can assume the file is open. * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that * requires it in order to read binary files. */ FS_FOpenFileRead( filename, &infile, qfalse ); if (infile == 0) { return 0; } /* Step 1: allocate and initialize JPEG decompression object */ /* We have to set up the error handler first, in case the initialization * step fails. (Unlikely, but it could happen if you are out of memory.) * This routine fills in the contents of struct jerr, and returns jerr's * address which we place into the link field in cinfo. */ cinfo.err = jpeg_std_error(&jerr); /* Now we can initialize the JPEG decompression object. */ jpeg_create_decompress(&cinfo); /* Step 2: specify data source (eg, a file) */ jpeg_stdio_src(&cinfo, infile); /* Step 3: read file parameters with jpeg_read_header() */ (void) jpeg_read_header(&cinfo, TRUE); /* We can ignore the return value from jpeg_read_header since * (a) suspension is not possible with the stdio data source, and * (b) we passed TRUE to reject a tables-only JPEG file as an error. * See libjpeg.doc for more info. */ /* Step 4: set parameters for decompression */ /* In this example, we don't need to change any of the defaults set by * jpeg_read_header(), so we do nothing here. */ /* Step 5: Start decompressor */ (void) jpeg_start_decompress(&cinfo); /* We can ignore the return value since suspension is not possible * with the stdio data source. */ /* We may need to do some setup of our own at this point before reading * the data. After jpeg_start_decompress() we have the correct scaled * output image dimensions available, as well as the output colormap * if we asked for color quantization. * In this example, we need to make an output work buffer of the right size. */ /* JSAMPLEs per row in output buffer */ row_stride = cinfo.output_width * cinfo.output_components; out = Z_Malloc(cinfo.output_width*cinfo.output_height*cinfo.output_components); *pic = out; *width = cinfo.output_width; *height = cinfo.output_height; /* Step 6: while (scan lines remain to be read) */ /* jpeg_read_scanlines(...); */ /* Here we use the library's state variable cinfo.output_scanline as the * loop counter, so that we don't have to keep track ourselves. */ while (cinfo.output_scanline < cinfo.output_height) { /* jpeg_read_scanlines expects an array of pointers to scanlines. * Here the array is only one element long, but you could ask for * more than one scanline at a time if that's more convenient. */ buffer = (JSAMPARRAY)out+(row_stride*cinfo.output_scanline); (void) jpeg_read_scanlines(&cinfo, buffer, 1); } /* Step 7: Finish decompression */ (void) jpeg_finish_decompress(&cinfo); /* We can ignore the return value since suspension is not possible * with the stdio data source. */ /* Step 8: Release JPEG decompression object */ /* This is an important step since it will release a good deal of memory. */ jpeg_destroy_decompress(&cinfo); /* After finish_decompress, we can close the input file. * Here we postpone it until after no more JPEG errors are possible, * so as to simplify the setjmp error logic above. (Actually, I don't * think that jpeg_destroy can do an error exit, but why assume anything...) */ FS_FCloseFile(infile); /* At this point you may want to check to see whether any corrupt-data * warnings occurred (test whether jerr.pub.num_warnings is nonzero). */ /* And we're done! */ return 1; }

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