+ if (png_ptr->zowner != png_IDAT)
+ {
+ /* First time. Ensure we have a temporary buffer for compression and
+ * trim the buffer list if it has more than one entry to free memory.
+ * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
+ * created at this point, but the check here is quick and safe.
+ */
+ if (png_ptr->zbuffer_list == NULL)
+ {
+ png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
+ png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
+ png_ptr->zbuffer_list->next = NULL;
+ }
+
+ else
+ png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
+
+ /* It is a terminal error if we can't claim the zstream. */
+ if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
+ png_error(png_ptr, png_ptr->zstream.msg);
+
+ /* The output state is maintained in png_ptr->zstream, so it must be
+ * initialized here after the claim.
+ */
+ png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
+ png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
+ }
+
+ /* Now loop reading and writing until all the input is consumed or an error
+ * terminates the operation. The _out values are maintained across calls to
+ * this function, but the input must be reset each time.
+ */
+ png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
+ png_ptr->zstream.avail_in = 0; /* set below */
+ for (;;)
+ {
+ int ret;
+
+ /* INPUT: from the row data */
+ uInt avail = ZLIB_IO_MAX;
+
+ if (avail > input_len)
+ avail = (uInt)input_len; /* safe because of the check */
+
+ png_ptr->zstream.avail_in = avail;
+ input_len -= avail;
+
+ ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
+
+ /* Include as-yet unconsumed input */
+ input_len += png_ptr->zstream.avail_in;
+ png_ptr->zstream.avail_in = 0;
+
+ /* OUTPUT: write complete IDAT chunks when avail_out drops to zero, note
+ * that these two zstream fields are preserved across the calls, therefore
+ * there is no need to set these up on entry to the loop.
+ */
+ if (png_ptr->zstream.avail_out == 0)
+ {
+ png_bytep data = png_ptr->zbuffer_list->output;
+ uInt size = png_ptr->zbuffer_size;
+
+ /* Write an IDAT containing the data then reset the buffer. The
+ * first IDAT may need deflate header optimization.
+ */
+# ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+ if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
+ png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+ optimize_cmf(data, png_image_size(png_ptr));
+# endif
+
+ png_write_complete_chunk(png_ptr, png_IDAT, data, size);
+ png_ptr->mode |= PNG_HAVE_IDAT;
+
+ png_ptr->zstream.next_out = data;
+ png_ptr->zstream.avail_out = size;
+
+ /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with
+ * the same flush parameter until it has finished output, for NO_FLUSH
+ * it doesn't matter.
+ */
+ if (ret == Z_OK && flush != Z_NO_FLUSH)
+ continue;
+ }
+
+ /* The order of these checks doesn't matter much; it just effect which
+ * possible error might be detected if multiple things go wrong at once.
+ */
+ if (ret == Z_OK) /* most likely return code! */
+ {
+ /* If all the input has been consumed then just return. If Z_FINISH
+ * was used as the flush parameter something has gone wrong if we get
+ * here.
+ */
+ if (input_len == 0)
+ {
+ if (flush == Z_FINISH)
+ png_error(png_ptr, "Z_OK on Z_FINISH with output space");
+
+ return;
+ }
+ }
+
+ else if (ret == Z_STREAM_END && flush == Z_FINISH)
+ {
+ /* This is the end of the IDAT data; any pending output must be
+ * flushed. For small PNG files we may still be at the beginning.
+ */
+ png_bytep data = png_ptr->zbuffer_list->output;
+ uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;
+
+# ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+ if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
+ png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+ optimize_cmf(data, png_image_size(png_ptr));
+# endif
+
+ png_write_complete_chunk(png_ptr, png_IDAT, data, size);
+ png_ptr->zstream.avail_out = 0;
+ png_ptr->zstream.next_out = NULL;
+ png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
+
+ png_ptr->zowner = 0; /* Release the stream */
+ return;
+ }
+
+ else
+ {
+ /* This is an error condition. */
+ png_zstream_error(png_ptr, ret);
+ png_error(png_ptr, png_ptr->zstream.msg);
+ }
+ }
projects / wxWidgets.git / blobdiff