+ if(png_ptr->sig_bytes < 3)
+ png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
+}
+
+#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_iCCP_SUPPORTED)
+/*
+ * This pair of functions encapsulates the operation of (a) compressing a
+ * text string, and (b) issuing it later as a series of chunk data writes.
+ * The compression_state structure is shared context for these functions
+ * set up by the caller in order to make the whole mess thread-safe.
+ */
+
+typedef struct
+{
+ char *input; /* the uncompressed input data */
+ int input_len; /* its length */
+ int num_output_ptr; /* number of output pointers used */
+ int max_output_ptr; /* size of output_ptr */
+ png_charpp output_ptr; /* array of pointers to output */
+} compression_state;
+
+/* compress given text into storage in the png_ptr structure */
+static int /* PRIVATE */
+png_text_compress(png_structp png_ptr,
+ png_charp text, png_size_t text_len, int compression,
+ compression_state *comp)
+{
+ int ret;
+
+ comp->num_output_ptr = comp->max_output_ptr = 0;
+ comp->output_ptr = NULL;
+ comp->input = NULL;
+
+ /* we may just want to pass the text right through */
+ if (compression == PNG_TEXT_COMPRESSION_NONE)
+ {
+ comp->input = text;
+ comp->input_len = text_len;
+ return((int)text_len);
+ }
+
+ if (compression >= PNG_TEXT_COMPRESSION_LAST)
+ {
+#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
+ char msg[50];
+ sprintf(msg, "Unknown compression type %d", compression);
+ png_warning(png_ptr, msg);
+#else
+ png_warning(png_ptr, "Unknown compression type");
+#endif
+ }
+
+ /* We can't write the chunk until we find out how much data we have,
+ * which means we need to run the compressor first and save the
+ * output. This shouldn't be a problem, as the vast majority of
+ * comments should be reasonable, but we will set up an array of
+ * malloc'd pointers to be sure.
+ *
+ * If we knew the application was well behaved, we could simplify this
+ * greatly by assuming we can always malloc an output buffer large
+ * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
+ * and malloc this directly. The only time this would be a bad idea is
+ * if we can't malloc more than 64K and we have 64K of random input
+ * data, or if the input string is incredibly large (although this
+ * wouldn't cause a failure, just a slowdown due to swapping).
+ */
+
+ /* set up the compression buffers */
+ png_ptr->zstream.avail_in = (uInt)text_len;
+ png_ptr->zstream.next_in = (Bytef *)text;
+ png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+ png_ptr->zstream.next_out = (Bytef *)png_ptr->zbuf;
+
+ /* this is the same compression loop as in png_write_row() */
+ do
+ {
+ /* compress the data */
+ ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
+ if (ret != Z_OK)
+ {
+ /* error */
+ if (png_ptr->zstream.msg != NULL)
+ png_error(png_ptr, png_ptr->zstream.msg);
+ else
+ png_error(png_ptr, "zlib error");
+ }
+ /* check to see if we need more room */
+ if (!png_ptr->zstream.avail_out && png_ptr->zstream.avail_in)
+ {
+ /* make sure the output array has room */
+ if (comp->num_output_ptr >= comp->max_output_ptr)
+ {
+ int old_max;
+
+ old_max = comp->max_output_ptr;
+ comp->max_output_ptr = comp->num_output_ptr + 4;
+ if (comp->output_ptr != NULL)
+ {
+ png_charpp old_ptr;
+
+ old_ptr = comp->output_ptr;
+ comp->output_ptr = (png_charpp)png_malloc(png_ptr,
+ (png_uint_32)(comp->max_output_ptr * sizeof (png_charpp)));
+ png_memcpy(comp->output_ptr, old_ptr, old_max
+ * sizeof (png_charp));
+ png_free(png_ptr, old_ptr);
+ }
+ else
+ comp->output_ptr = (png_charpp)png_malloc(png_ptr,
+ (png_uint_32)(comp->max_output_ptr * sizeof (png_charp)));
+ }
+
+ /* save the data */
+ comp->output_ptr[comp->num_output_ptr] = (png_charp)png_malloc(png_ptr,
+ (png_uint_32)png_ptr->zbuf_size);
+ png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
+ png_ptr->zbuf_size);
+ comp->num_output_ptr++;
+
+ /* and reset the buffer */
+ png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+ png_ptr->zstream.next_out = png_ptr->zbuf;
+ }
+ /* continue until we don't have any more to compress */
+ } while (png_ptr->zstream.avail_in);
+
+ /* finish the compression */
+ do
+ {
+ /* tell zlib we are finished */
+ ret = deflate(&png_ptr->zstream, Z_FINISH);
+
+ if (ret == Z_OK)
+ {
+ /* check to see if we need more room */
+ if (!(png_ptr->zstream.avail_out))
+ {
+ /* check to make sure our output array has room */
+ if (comp->num_output_ptr >= comp->max_output_ptr)
+ {
+ int old_max;
+
+ old_max = comp->max_output_ptr;
+ comp->max_output_ptr = comp->num_output_ptr + 4;
+ if (comp->output_ptr != NULL)
+ {
+ png_charpp old_ptr;
+
+ old_ptr = comp->output_ptr;
+ /* This could be optimized to realloc() */
+ comp->output_ptr = (png_charpp)png_malloc(png_ptr,
+ (png_uint_32)(comp->max_output_ptr * sizeof (png_charpp)));
+ png_memcpy(comp->output_ptr, old_ptr,
+ old_max * sizeof (png_charp));
+ png_free(png_ptr, old_ptr);
+ }
+ else
+ comp->output_ptr = (png_charpp)png_malloc(png_ptr,
+ (png_uint_32)(comp->max_output_ptr * sizeof (png_charp)));
+ }
+
+ /* save off the data */
+ comp->output_ptr[comp->num_output_ptr] =
+ (png_charp)png_malloc(png_ptr, (png_uint_32)png_ptr->zbuf_size);
+ png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
+ png_ptr->zbuf_size);
+ comp->num_output_ptr++;
+
+ /* and reset the buffer pointers */
+ png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+ png_ptr->zstream.next_out = png_ptr->zbuf;
+ }
+ }
+ else if (ret != Z_STREAM_END)
+ {
+ /* we got an error */
+ if (png_ptr->zstream.msg != NULL)
+ png_error(png_ptr, png_ptr->zstream.msg);
+ else
+ png_error(png_ptr, "zlib error");
+ }
+ } while (ret != Z_STREAM_END);
+
+ /* text length is number of buffers plus last buffer */
+ text_len = png_ptr->zbuf_size * comp->num_output_ptr;
+ if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
+ text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
+
+ return((int)text_len);
+}
+
+/* ship the compressed text out via chunk writes */
+static void /* PRIVATE */
+png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
+{
+ int i;
+
+ /* handle the no-compression case */
+ if (comp->input)
+ {
+ png_write_chunk_data(png_ptr, (png_bytep)comp->input,
+ (png_size_t)comp->input_len);
+ return;
+ }
+
+ /* write saved output buffers, if any */
+ for (i = 0; i < comp->num_output_ptr; i++)
+ {
+ png_write_chunk_data(png_ptr,(png_bytep)comp->output_ptr[i],
+ png_ptr->zbuf_size);
+ png_free(png_ptr, comp->output_ptr[i]);
+ comp->output_ptr[i]=NULL;
+ }
+ if (comp->max_output_ptr != 0)
+ png_free(png_ptr, comp->output_ptr);
+ comp->output_ptr=NULL;
+ /* write anything left in zbuf */
+ if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
+ png_write_chunk_data(png_ptr, png_ptr->zbuf,
+ png_ptr->zbuf_size - png_ptr->zstream.avail_out);
+
+ /* reset zlib for another zTXt/iTXt or the image data */
+ deflateReset(&png_ptr->zstream);
+
projects / wxWidgets.git / blobdiff