Imported from libpng-1.0.6.tar
diff --git a/example.c b/example.c
index 4635bc8..ed2619c 100644
--- a/example.c
+++ b/example.c
@@ -6,17 +6,28 @@
/* This is an example of how to use libpng to read and write PNG files.
* The file libpng.txt is much more verbose then this. If you have not
* read it, do so first. This was designed to be a starting point of an
- * implementation. This is not officially part of libpng, and therefore
- * does not require a copyright notice.
+ * implementation. This is not officially part of libpng, is hereby placed
+ * in the public domain, and therefore does not require a copyright notice.
*
* This file does not currently compile, because it is missing certain
* parts, like allocating memory to hold an image. You will have to
* supply these parts to get it to compile. For an example of a minimal
- * working PNG reader/writer, see pngtest.c, included in this distribution.
+ * working PNG reader/writer, see pngtest.c, included in this distribution;
+ * see also the programs in the contrib directory.
*/
#include "png.h"
+ /* The png_jmpbuf() macro, used in error handling, became available in
+ * libpng version 1.0.6. If you want to be able to run your code with older
+ * versions of libpng, you must define the macro yourself (but only if it
+ * is not already defined by libpng!).
+ */
+
+#ifndef png_jmpbuf
+# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#endif
+
/* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp()
* returns zero if the image is a PNG and nonzero if it isn't a PNG.
*
@@ -111,7 +122,8 @@
* the normal method of doing things with libpng). REQUIRED unless you
* set up your own error handlers in the png_create_read_struct() earlier.
*/
- if (setjmp(png_jmp_env(png_ptr)))
+
+ if (setjmp(png_jmpbuf(png_ptr)))
{
/* Free all of the memory associated with the png_ptr and info_ptr */
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
@@ -231,7 +243,7 @@
screen_gamma = 1.7 or 1.0; /* A good guess for Mac systems */
}
- /* Tell libpng to handle the gamma conversion for you. The second call
+ /* Tell libpng to handle the gamma conversion for you. The final call
* is a good guess for PC generated images, but it should be configurable
* by the user at run time by the user. It is strongly suggested that
* your application support gamma correction.
@@ -240,7 +252,7 @@
int intent;
if (png_get_sRGB(png_ptr, info_ptr, &intent))
- png_set_sRGB(png_ptr, info_ptr, intent);
+ png_set_gamma(png_ptr, screen_gamma, 0.45455);
else
{
double image_gamma;
@@ -405,7 +417,7 @@
return ERROR;
}
- if (setjmp(png_jmp_env((*png_ptr))))
+ if (setjmp(png_jmpbuf((*png_ptr))))
{
png_destroy_read_struct(png_ptr, info_ptr, (png_infopp)NULL);
return ERROR;
@@ -433,7 +445,7 @@
process_data(png_structp *png_ptr, png_infop *info_ptr,
png_bytep buffer, png_uint_32 length)
{
- if (setjmp(png_jmp_env((*png_ptr))))
+ if (setjmp(png_jmpbuf((*png_ptr))))
{
/* Free the png_ptr and info_ptr memory on error */
png_destroy_read_struct(png_ptr, info_ptr, (png_infopp)NULL);
@@ -549,7 +561,7 @@
/* Set error handling. REQUIRED if you aren't supplying your own
* error handling functions in the png_create_write_struct() call.
*/
- if (setjmp(png_ptr->jmpbuf))
+ if (setjmp(png_jmpbuf(png_ptr)))
{
/* If we get here, we had a problem reading the file */
fclose(fp);
@@ -632,7 +644,7 @@
png_set_text(png_ptr, info_ptr, text_ptr, 3);
/* other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs, */
- /* note that if sRGB is present the cHRM chunk must be ignored
+ /* note that if sRGB is present the gAMA and cHRM chunks must be ignored
* on read and must be written in accordance with the sRGB profile */
/* Write the file header information. REQUIRED */
