[libpng16] Implement eXIf chunk support

pngwutil.c

@@ -1473,6 +1473,37 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
 }
 #endif
 
+#ifdef PNG_WRITE_eXIf_SUPPORTED
+/* Write the Exif data */
+void /* PRIVATE */
+png_write_eXIf(png_structrp png_ptr, png_bytep exif, int num_exif)
+{
+   int i;
+   png_byte buf[3];
+
+   png_debug(1, "in png_write_eXIf");
+
+   if (num_exif > (int)png_ptr->num_exif)
+   {
+      png_debug2(3, "num_exif = %d, png_ptr->num_exif = %d", num_exif,
+          png_ptr->num_exif);
+
+      png_warning(png_ptr, "Invalid number of exif bytes specified");
+      return;
+   }
+
+   png_write_chunk_header(png_ptr, png_eXIf, (png_uint_32)(num_exif));
+
+   for (i = 0; i < num_exif; i++)
+   {
+      buf[i] = exif[i];
+      png_write_chunk_data(png_ptr, buf, (png_size_t)1);
+   }
+
+   png_write_chunk_end(png_ptr);
+}
+#endif
+
 #ifdef PNG_WRITE_hIST_SUPPORTED
 /* Write the histogram */
 void /* PRIVATE */