[core] Use optional where SpriteAtlas return values might not exist

Fixes #3162

1 files changed, 6 insertions, 7 deletions

diff --git a/src/mbgl/sprite/sprite_atlas.hpp b/src/mbgl/sprite/sprite_atlas.hpp
index 0e3e8cf225..0d1e52cf81 100644
--- a/src/mbgl/sprite/sprite_atlas.hpp
+++ b/src/mbgl/sprite/sprite_atlas.hpp
@@ -6,6 +6,8 @@
 #include <mbgl/util/noncopyable.hpp>
 #include <mbgl/util/ptr.hpp>
 
+#include <mapbox/optional.hpp>
+
 #include <string>
 #include <map>
 #include <mutex>
@@ -41,15 +43,12 @@ public:
     SpriteAtlas(dimension width, dimension height, float pixelRatio, SpriteStore& store);
     ~SpriteAtlas();
 
-    // Returns the coordinates of an image that is sourced from the sprite image.
-    // This getter attempts to read the image from the sprite if it is already loaded.
-    // In that case, it copies it into the sprite atlas and returns the dimensions.
-    // Otherwise, it returns a 0/0/0/0 rect.
-    // This function is used during bucket creation.
-    SpriteAtlasElement getImage(const std::string& name, const bool wrap);
+    // If the sprite is loaded, copies the requsted image from it into the atlas and returns
+    // the resulting icon measurements. If not, returns an empty optional.
+    mapbox::util::optional<SpriteAtlasElement> getImage(const std::string& name, const bool wrap);
 
     // This function is used for getting the position during render time.
-    SpriteAtlasPosition getPosition(const std::string& name, bool repeating = false);
+    mapbox::util::optional<SpriteAtlasPosition> getPosition(const std::string& name, bool repeating = false);
 
     // Binds the atlas texture to the GPU, and uploads data if it is out of date.
     void bind(bool linear = false);