Tracking: Make image accessor own what it needs

Previously image accessor was sharing array pointer for tracks access.
Now it is possible to pass a temporary array valid only during the
initialization process.

Should be no functional changes.

2 files changed, 16 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/tracking_util.c b/source/blender/blenkernel/intern/tracking_util.c
index 7146be1d521..eb57c28de09 100644
--- a/source/blender/blenkernel/intern/tracking_util.c
+++ b/source/blender/blenkernel/intern/tracking_util.c
@@ -1021,7 +1021,10 @@ TrackingImageAccessor *tracking_image_accessor_new(MovieClip *clips[MAX_ACCESSOR
 
   memcpy(accessor->clips, clips, num_clips * sizeof(MovieClip *));
   accessor->num_clips = num_clips;
-  accessor->tracks = tracks;
+
+  accessor->tracks = MEM_malloc_arrayN(
+      num_tracks, sizeof(MovieTrackingTrack *), "image accessor tracks");
+  memcpy(accessor->tracks, tracks, num_tracks * sizeof(MovieTrackingTrack *));
   accessor->num_tracks = num_tracks;
 
   accessor->libmv_accessor = libmv_FrameAccessorNew((libmv_FrameAccessorUserData *)accessor,
@@ -1040,5 +1043,6 @@ void tracking_image_accessor_destroy(TrackingImageAccessor *accessor)
   IMB_moviecache_free(accessor->cache);
   libmv_FrameAccessorDestroy(accessor->libmv_accessor);
   BLI_spin_end(&accessor->cache_lock);
+  MEM_freeN(accessor->tracks);
   MEM_freeN(accessor);
 }
diff --git a/source/blender/blenkernel/tracking_private.h b/source/blender/blenkernel/tracking_private.h
index 5bd4baa536d..64db84d5ac3 100644
--- a/source/blender/blenkernel/tracking_private.h
+++ b/source/blender/blenkernel/tracking_private.h
@@ -132,14 +132,25 @@ struct libmv_FrameAccessor;
 #define MAX_ACCESSOR_CLIP 64
 typedef struct TrackingImageAccessor {
   struct MovieCache *cache;
+
   struct MovieClip *clips[MAX_ACCESSOR_CLIP];
   int num_clips;
+
+  /* Array of tracks which are being tracked.
+   * Points to actual track from the `MovieClip` (or multiple of them).
+   * This accessor owns the array, but not the tracks themselves. */
   struct MovieTrackingTrack **tracks;
   int num_tracks;
+
   struct libmv_FrameAccessor *libmv_accessor;
   SpinLock cache_lock;
 } TrackingImageAccessor;
 
+/* Clips are used to access images of an actual footage.
+ * Tracks are used to access masks associated with the tracks.
+ *
+ * NOTE: Both clips and tracks arrays are copied into the image accessor. It means that the caller
+ * is allowed to pass temporary arrays which are only valid during initialization. */
 TrackingImageAccessor *tracking_image_accessor_new(MovieClip *clips[MAX_ACCESSOR_CLIP],
                                                    int num_clips,
                                                    MovieTrackingTrack **tracks,