IMB_metadata improvements

- Metadata handling is now separate from `ImBuf *`, allowing it to be
  used with a generic `IDProperty *`.
- Merged `IMB_metadata_add_field()` and `IMB_metadata_change_field()`
  into a more robust `IMB_metadata_set_field()`. This new function
  doesn't return any status (it now always succeeds, and the previously
  existing return value was never checked anyway).
- Removed `IMB_metadata_del_field()` as it was never actually used
  anywhere.
- Use `IMB_metadata_ensure()` instead of having
  `IMB_metadata_set_field()` create the containing `IDProperty` for
  you.
- Deduplicated function declarations, moved `intern/IMB_metadata.h` out
  of `intern/`. Note that this does mean that we have some extra
  `#include "IMB_metadata.h"` lines now, as the metadata functions are
  no longer declared in `IMB_imbuf.h`.
- Deduplicated function declarations, all metadata-related declarations
  are now in imbuf/IMB_metadata.h.

Part of: https://developer.blender.org/D2273

Reviewed by: @campbellbarton

1 files changed, 2 insertions, 1 deletions

diff --git a/source/blender/imbuf/intern/png.c b/source/blender/imbuf/intern/png.c
index 857f72e10eb..29fbe79d8db 100644
--- a/source/blender/imbuf/intern/png.c
+++ b/source/blender/imbuf/intern/png.c
@@ -759,8 +759,9 @@ ImBuf *imb_loadpng(const unsigned char *mem, size_t size, int flags, char colors
 		if (flags & IB_metadata) {
 			png_text *text_chunks;
 			int count = png_get_text(png_ptr, info_ptr, &text_chunks, NULL);
+			IMB_metadata_ensure(&ibuf->metadata);
 			for (int i = 0; i < count; i++) {
-				IMB_metadata_add_field(ibuf, text_chunks[i].key, text_chunks[i].text);
+				IMB_metadata_set_field(ibuf->metadata, text_chunks[i].key, text_chunks[i].text);
 				ibuf->flags |= IB_metadata;
 			}
 		}