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More fixes and tidying after reading through libpng example.c

master
Ian Jones 2021-10-13 14:13:22 +07:00 committed by Robert Clausecker
parent 3566a6a42b
commit 2989d8e6ea
1 changed files with 22 additions and 39 deletions
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61
src/readPNG.c
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@ -78,6 +78,7 @@
#include <setjmp.h> #include <setjmp.h>
#define MAX(x,y) (((x) > (y)) ? (x) : (y)) #define MAX(x,y) (((x) > (y)) ? (x) : (y))
#define PNG_BYTES_TO_CHECK 4
#ifndef DISABLE_TRACE #ifndef DISABLE_TRACE
extern int srcTrace; extern int srcTrace;
@ -96,48 +97,39 @@ ReadPNG(FILE *infile,int *width, int *height, XColor *colrs)
double screen_gamma; double screen_gamma;
png_byte *png_pixels=NULL, **row_pointers=NULL; png_byte *png_pixels=NULL, **row_pointers[*height];
int i, j, bit_depth, color_type, num_palette, interlace_type; int i, j, bit_depth, color_type, num_palette, interlace_type;
png_color std_color_cube[216]; png_color std_color_cube[216];
png_colorp palette; png_colorp palette;
/* first check to see if its a valid PNG file. If not, return. */ /* first check to see if its a valid PNG file. If not, return. */
/* we assume that infile is a valid filepointer */ /* we assume that infile is a valid filepointer */
{ {
int ret; png_byte buf[PNG_BYTES_TO_CHECK];
png_byte buf[8];
ret = fread(buf, 1, 8, infile); if (fread(buf, 1, PNG_BYTES_TO_CHECK, infile) != PNG_BYTES_TO_CHECK)
if(ret != 8)
return 0; return 0;
ret = png_sig_cmp(buf, 0, 8); return(!png_sig_cmp(buf, 0, PNG_BYTES_TO_CHECK));
if(ret)
return(0);
} }
/* OK, it is a valid PNG file, so let's rewind it, and start /* allocate the structures */
decoding it */
rewind(infile);
/* allocate the structures */
/*png_ptr = (png_struct *)malloc(sizeof(png_struct));*/
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if(!png_ptr) if(!png_ptr)
fclose(infile);
return 0; return 0;
/* initialize the structures */ /* initialize the structures */
info_ptr = png_create_info_struct(png_ptr); info_ptr = png_create_info_struct(png_ptr);
if(!info_ptr) { if(!info_ptr) {
/*free(png_ptr);*/ fclose(infile);
png_destroy_read_struct(png_ptr, NULL, NULL);
return 0; return 0;
} }
/* Establish the setjmp return context for png_error to use. */ /* Establish the setjmp return context for png_error to use. */
if (setjmp(png_jmpbuf(png_ptr))) { if (setjmp(png_jmpbuf(png_ptr))) {
#ifndef DISABLE_TRACE #ifndef DISABLE_TRACE
@ -146,17 +138,15 @@ ReadPNG(FILE *infile,int *width, int *height, XColor *colrs)
} }
#endif #endif
/*png_read_destroy(png_ptr, info_ptr, (png_info *)0); */ png_destroy_read_struct(png_ptr, info_ptr, NULL);
png_destroy_read_struct(&png_ptr, &info_ptr, NULL); fclose(infile);
if(png_pixels != NULL) if(png_pixels != NULL)
free((char *)png_pixels); free((char *)png_pixels);
if(row_pointers != NULL) if(row_pointers != NULL)
free((png_byte **)row_pointers); free((png_byte **)row_pointers);
/*free((char *)png_ptr);*/
free((char *)info_ptr);
return 0; return 0;
} }
@ -292,10 +282,10 @@ ReadPNG(FILE *infile,int *width, int *height, XColor *colrs)
else { else {
#ifndef DISABLE_TRACE #ifndef DISABLE_TRACE
if (srcTrace) { if (srcTrace) {
fprintf(stderr,"setting gamma=%f\n",0.45); fprintf(stderr,"setting gamma=%f\n",0.45455);
} }
#endif #endif
png_set_gamma(png_ptr, screen_gamma, 0.45); png_set_gamma(png_ptr, screen_gamma, 0.45455);
} }
} }
} }
@ -328,9 +318,8 @@ ReadPNG(FILE *infile,int *width, int *height, XColor *colrs)
(*height) * sizeof(png_byte)); (*height) * sizeof(png_byte));
row_pointers = (png_byte **) malloc((*height) * sizeof(png_byte *));
for (i=0; i < *height; i++) for (i=0; i < *height; i++)
row_pointers[i]=png_pixels+(rowbytes*i); row_pointers[i]=png_malloc(png_ptr, rowbytes);
/* FINALLY - read the darn thing. */ /* FINALLY - read the darn thing. */
@ -418,14 +407,8 @@ ReadPNG(FILE *infile,int *width, int *height, XColor *colrs)
free((png_byte **)row_pointers); free((png_byte **)row_pointers);
/* clean up after the read, and free any memory allocated */ /* clean up after the read, and free any memory allocated */
/*png_read_destroy(png_ptr, info_ptr, (png_info *)0);*/ png_destroy_read_struct(png_ptr, info_ptr, NULL);
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
/* free the structures */
/*free((char *)png_ptr);*/
free((char *)info_ptr);
return pixmap; return pixmap;
} }