+
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+/* Demonstration of user chunk support of the sTER and vpAg chunks */
+
+/* (sTER is a public chunk not yet known by libpng. vpAg is a private
+chunk used in ImageMagick to store "virtual page" size). */
+
+static struct user_chunk_data
+{
+ png_const_infop info_ptr;
+ png_uint_32 vpAg_width, vpAg_height;
+ png_byte vpAg_units;
+ png_byte sTER_mode;
+ int location[2];
+}
+user_chunk_data;
+
+/* Used for location and order; zero means nothing. */
+#define have_sTER 0x01
+#define have_vpAg 0x02
+#define before_PLTE 0x10
+#define before_IDAT 0x20
+#define after_IDAT 0x40
+
+static void
+init_callback_info(png_const_infop info_ptr)
+{
+ MEMZERO(user_chunk_data);
+ user_chunk_data.info_ptr = info_ptr;
+}
+
+static int
+set_location(png_structp png_ptr, struct user_chunk_data *data, int what)
+{
+ int location;
+
+ if ((data->location[0] & what) || (data->location[1] & what))
+ return 0; /* already have one of these */
+
+ /* Find where we are (the code below zeros info_ptr to indicate that the
+ * chunks before the first IDAT have been read.)
+ */
+ if (data->info_ptr == NULL) /* after IDAT */
+ location = what | after_IDAT;
+
+ else if (png_get_valid(png_ptr, data->info_ptr, PNG_INFO_PLTE))
+ location = what | before_IDAT;
+
+ else
+ location = what | before_PLTE;
+
+ if (data->location[0] == 0)
+ data->location[0] = location;
+
+ else
+ data->location[1] = location;
+
+ return 1; /* handled */
+}
+
+static int PNGCBAPI read_user_chunk_callback(png_struct *png_ptr,
+ png_unknown_chunkp chunk)
+{
+ struct user_chunk_data *my_user_chunk_data =
+ (struct user_chunk_data*)png_get_user_chunk_ptr(png_ptr);
+
+ if (my_user_chunk_data == NULL)
+ png_error(png_ptr, "lost user chunk pointer");
+
+ /* Return one of the following:
+ * return (-n); chunk had an error
+ * return (0); did not recognize
+ * return (n); success
+ *
+ * The unknown chunk structure contains the chunk data:
+ * png_byte name[5];
+ * png_byte *data;
+ * png_size_t size;
+ *
+ * Note that libpng has already taken care of the CRC handling.
+ */
+
+ if (chunk->name[0] == 115 && chunk->name[1] == 84 && /* s T */
+ chunk->name[2] == 69 && chunk->name[3] == 82) /* E R */
+ {
+ /* Found sTER chunk */
+ if (chunk->size != 1)
+ return (-1); /* Error return */
+
+ if (chunk->data[0] != 0 && chunk->data[0] != 1)
+ return (-1); /* Invalid mode */
+
+ if (set_location(png_ptr, my_user_chunk_data, have_sTER))
+ {
+ my_user_chunk_data->sTER_mode=chunk->data[0];
+ return (1);
+ }
+
+ else
+ return (0); /* duplicate sTER - give it to libpng */
+ }
+
+ if (chunk->name[0] != 118 || chunk->name[1] != 112 || /* v p */
+ chunk->name[2] != 65 || chunk->name[3] != 103) /* A g */
+ return (0); /* Did not recognize */
+
+ /* Found ImageMagick vpAg chunk */
+
+ if (chunk->size != 9)
+ return (-1); /* Error return */
+
+ if (!set_location(png_ptr, my_user_chunk_data, have_vpAg))
+ return (0); /* duplicate vpAg */
+
+ my_user_chunk_data->vpAg_width = png_get_uint_31(png_ptr, chunk->data);
+ my_user_chunk_data->vpAg_height = png_get_uint_31(png_ptr, chunk->data + 4);
+ my_user_chunk_data->vpAg_units = chunk->data[8];
+
+ return (1);
+}
+
+#ifdef PNG_WRITE_SUPPORTED
+static void
+write_sTER_chunk(png_structp write_ptr)
+{
+ png_byte png_sTER[5] = {115, 84, 69, 82, '\0'};
+
+ if (verbose)
+ fprintf(STDERR, "\n stereo mode = %d\n", user_chunk_data.sTER_mode);
+
+ png_write_chunk(write_ptr, png_sTER, &user_chunk_data.sTER_mode, 1);
+}
+
+static void
+write_vpAg_chunk(png_structp write_ptr)
+{
+ png_byte png_vpAg[5] = {118, 112, 65, 103, '\0'};
+
+ png_byte vpag_chunk_data[9];
+
+ if (verbose)
+ fprintf(STDERR, " vpAg = %lu x %lu, units = %d\n",
+ (unsigned long)user_chunk_data.vpAg_width,
+ (unsigned long)user_chunk_data.vpAg_height,
+ user_chunk_data.vpAg_units);
+
+ png_save_uint_32(vpag_chunk_data, user_chunk_data.vpAg_width);
+ png_save_uint_32(vpag_chunk_data + 4, user_chunk_data.vpAg_height);
+ vpag_chunk_data[8] = user_chunk_data.vpAg_units;
+ png_write_chunk(write_ptr, png_vpAg, vpag_chunk_data, 9);
+}
+
+static void
+write_chunks(png_structp write_ptr, int location)
+{
+ int i;
+
+ /* Notice that this preserves the original chunk order, however chunks
+ * intercepted by the callback will be written *after* chunks passed to
+ * libpng. This will actually reverse a pair of sTER chunks or a pair of
+ * vpAg chunks, resulting in an error later. This is not worth worrying
+ * about - the chunks should not be duplicated!
+ */
+ for (i=0; i<2; ++i)
+ {
+ if (user_chunk_data.location[i] == (location | have_sTER))
+ write_sTER_chunk(write_ptr);
+
+ else if (user_chunk_data.location[i] == (location | have_vpAg))
+ write_vpAg_chunk(write_ptr);
+ }
+}
+#endif /* PNG_WRITE_SUPPORTED */
+#else /* !PNG_READ_USER_CHUNKS_SUPPORTED */
+# define write_chunks(pp,loc) ((void)0)
+#endif
+/* END of code to demonstrate user chunk support */
+
+/* START of code to check that libpng has the required text support; this only
+ * checks for the write support because if read support is missing the chunk
+ * will simply not be reported back to pngtest.
+ */
+#ifdef PNG_TEXT_SUPPORTED
+static void
+pngtest_check_text_support(png_const_structp png_ptr, png_textp text_ptr,
+ int num_text)
+{
+ while (num_text > 0)
+ {
+ switch (text_ptr[--num_text].compression)
+ {
+ case PNG_TEXT_COMPRESSION_NONE:
+ break;
+
+ case PNG_TEXT_COMPRESSION_zTXt:
+# ifndef PNG_WRITE_zTXt_SUPPORTED
+ ++unsupported_chunks;
+# endif
+ break;
+
+ case PNG_ITXT_COMPRESSION_NONE:
+ case PNG_ITXT_COMPRESSION_zTXt:
+# ifndef PNG_WRITE_iTXt_SUPPORTED
+ ++unsupported_chunks;
+# endif
+ break;
+
+ default:
+ /* This is an error */
+ png_error(png_ptr, "invalid text chunk compression field");
+ break;
+ }
+ }
+}
+#endif
+/* END of code to check that libpng has the required text support */
+
projects / wxWidgets.git / blobdiff