original editor compliance and some fixes

src/anm2/item.cpp

@@ -295,4 +295,18 @@ namespace anm2ed::anm2
       if (frame.atFrame == atFrame) return i;
     return -1;
   }
+
+  float Item::frame_time_from_index_get(int index)
+  {
+    if (!vector::in_bounds(frames, index)) return 0.0f;
+
+    float time{};
+    for (auto [i, frame] : std::views::enumerate(frames))
+    {
+      if (i == index) return time;
+      time += frame.duration;
+    }
+
+    return time;
+  }
 }

src/anm2/item.h

@@ -26,5 +26,6 @@ namespace anm2ed::anm2
     void frames_generate_from_grid(glm::ivec2, glm::ivec2, glm::ivec2, int, int, int);
     void frames_sort_by_at_frame();
     int frame_index_from_at_frame_get(int);
+    float frame_time_from_index_get(int);
   };
 }