source/blender/blenkernel/BKE_grease_pencil.hh

@@ -223,10 +223,11 @@ class TreeNode : public ::GreasePencilLayerTreeNode {
 class Layer : public TreeNode, ::GreasePencilLayer {
  private:
   /**
-   * This Map maps a scene frame number (key) to an index into GreasePencil->drawings (value). The
-   * frame number indicates the first frame the drawing is shown. The end time is implicitly
-   * defined by the next greater frame number (key) in the map. If the value mapped to (index) is
-   * -1, no drawing is shown at this frame.
+   * This Map maps a scene frame number (key) to a GreasePencilFrame. This struct holds an index
+   * (drawing_index) to the drawing in the GreasePencil->drawings array. The frame number indicates
+   * the first frame the drawing is shown. The end time is implicitly defined by the next greater
+   * frame number (key) in the map. If the value mapped to (index) is -1, no drawing is shown at
+   * this frame.
    *
    *    \example:
    *
@@ -246,7 +247,7 @@ class Layer : public TreeNode, ::GreasePencilLayer {
    * referenced drawings are discarded. If the frame is longer than the number of referenced
    * drawings, then the last referenced drawing is held for the rest of the duration.
    */
-  Map<int, int> frames_;
+  Map<int, GreasePencilFrame> frames_;
   mutable SharedCache<Vector<int>> sorted_keys_cache_;
 
  public:
@@ -271,27 +272,39 @@ class Layer : public TreeNode, ::GreasePencilLayer {
     return this != &other;
   }
 
-  const Map<int, int> &frames()
+  const Map<int, GreasePencilFrame> &frames()
   {
     return frames_;
   }
 
-  Map<int, int> &frames_for_write()
+  Map<int, GreasePencilFrame> &frames_for_write()
   {
     sorted_keys_cache_.tag_dirty();
     return frames_;
   }
 
-  bool insert_frame(int frame_number, int index)
+  bool insert_frame(int frame_number, GreasePencilFrame &frame)
   {
     sorted_keys_cache_.tag_dirty();
-    return frames_for_write().add(frame_number, index);
+    return frames_for_write().add(frame_number, frame);
   }
 
-  bool overwrite_frame(int frame_number, int index)
+  bool insert_frame(int frame_number, GreasePencilFrame &&frame)
   {
     sorted_keys_cache_.tag_dirty();
-    return frames_for_write().add_overwrite(frame_number, index);
+    return frames_for_write().add(frame_number, frame);
+  }
+
+  bool overwrite_frame(int frame_number, GreasePencilFrame &frame)
+  {
+    sorted_keys_cache_.tag_dirty();
+    return frames_for_write().add_overwrite(frame_number, frame);
+  }
+
+  bool overwrite_frame(int frame_number, GreasePencilFrame &&frame)
+  {
+    sorted_keys_cache_.tag_dirty();
+    return frames_for_write().add_overwrite(frame_number, frame);
   }
 
   Span<int> sorted_keys()
@@ -326,14 +339,14 @@ class Layer : public TreeNode, ::GreasePencilLayer {
     }
     /* After or at the last drawing, return the last drawing. */
     if (frame >= sorted_keys.last()) {
-      return frames().lookup(sorted_keys.last());
+      return frames().lookup(sorted_keys.last()).drawing_index;
     }
     /* Search for the drawing. upper_bound will get the drawing just after. */
     auto it = std::upper_bound(sorted_keys.begin(), sorted_keys.end(), frame);
     if (it == sorted_keys.end() || it == sorted_keys.begin()) {
       return -1;
     }
-    return frames().lookup(*std::prev(it));
+    return frames().lookup(*std::prev(it)).drawing_index;
   }
 };
 

source/blender/blenkernel/intern/grease_pencil.cc

@@ -520,13 +520,13 @@ void GreasePencil::remove_drawing(int index_to_remove)
   if (index_to_remove != last_drawing_index) {
     this->root_group().foreach_layer_pre_order(
         [last_drawing_index, index_to_remove](Layer &layer) {
-          blender::Map<int, int> &frames = layer.frames_for_write();
-          for (auto item : frames.items()) {
-            if (item.value == last_drawing_index) {
-              item.value = index_to_remove;
+          blender::Map<int, GreasePencilFrame> &frames = layer.frames_for_write();
+          for (auto [key, value] : frames.items()) {
+            if (value.drawing_index == last_drawing_index) {
+              value.drawing_index = index_to_remove;
             }
-            else if (item.value == index_to_remove) {
-              item.value = last_drawing_index;
+            else if (value.drawing_index == index_to_remove) {
+              value.drawing_index = last_drawing_index;
             }
           }
         });
@@ -557,8 +557,10 @@ void GreasePencil::remove_drawing(int index_to_remove)
 
   /* Remove any frame that points to the last drawing. */
   this->root_group().foreach_layer_pre_order([last_drawing_index](Layer &layer) {
-    blender::Map<int, int> &frames = layer.frames_for_write();
-    frames.remove_if([last_drawing_index](auto item) { return item.value == last_drawing_index; });
+    blender::Map<int, GreasePencilFrame> &frames = layer.frames_for_write();
+    frames.remove_if([last_drawing_index](auto item) {
+      return item.value.drawing_index == last_drawing_index;
+    });
   });
 
   /* Shrink drawing array. */
@@ -711,10 +713,10 @@ static void save_layer_to_storage(blender::bke::gpencil::Layer &node,
   int frames_size = node.frames().size();
   new_leaf->layer.frames_storage.size = frames_size;
   new_leaf->layer.frames_storage.keys = MEM_cnew_array<int>(frames_size, __func__);
-  new_leaf->layer.frames_storage.values = MEM_cnew_array<int>(frames_size, __func__);
+  new_leaf->layer.frames_storage.values = MEM_cnew_array<GreasePencilFrame>(frames_size, __func__);
 
   MutableSpan<int> keys{new_leaf->layer.frames_storage.keys, frames_size};
-  MutableSpan<int> values{new_leaf->layer.frames_storage.values, frames_size};
+  MutableSpan<GreasePencilFrame> values{new_leaf->layer.frames_storage.values, frames_size};
   keys.copy_from(node.sorted_keys());
   for (int i : keys.index_range()) {
     values[i] = node.frames().lookup(keys[i]);
@@ -820,8 +822,7 @@ void GreasePencil::read_layer_tree_storage(BlendDataReader *reader)
         /* Read layer data. */
         BLO_read_int32_array(
             reader, node_leaf->layer.frames_storage.size, &node_leaf->layer.frames_storage.keys);
-        BLO_read_int32_array(
-            reader, node_leaf->layer.frames_storage.size, &node_leaf->layer.frames_storage.values);
+        BLO_read_data_address(reader, &node_leaf->layer.frames_storage.values);
         break;
       }
       case GREASE_PENCIL_LAYER_TREE_GROUP: {
@@ -847,8 +848,10 @@ void GreasePencil::write_layer_tree_storage(BlendWriter *writer)
         /* Write layer data. */
         BLO_write_int32_array(
             writer, node_leaf->layer.frames_storage.size, node_leaf->layer.frames_storage.keys);
-        BLO_write_int32_array(
-            writer, node_leaf->layer.frames_storage.size, node_leaf->layer.frames_storage.values);
+        BLO_write_struct_array(writer,
+                               GreasePencilFrame,
+                               node_leaf->layer.frames_storage.size,
+                               node_leaf->layer.frames_storage.values);
         break;
       }
       case GREASE_PENCIL_LAYER_TREE_GROUP: {

source/blender/blenkernel/intern/grease_pencil_convert_legacy.cc

@@ -121,7 +121,11 @@ void legacy_gpencil_to_grease_pencil(GreasePencil &grease_pencil, bGPdata &gpd)
 
       /* Convert the frame to a drawing. */
       legacy_gpencil_frame_to_curves_geometry(drawing, *gpf);
-      new_layer.insert_frame(gpf->framenum, i);
+
+      GreasePencilFrame frame;
+      frame.drawing_index = i;
+      frame.type = gpf->key_type;
+      new_layer.insert_frame(gpf->framenum, std::move(frame));
       i++;
     }
   }

source/blender/blenkernel/intern/grease_pencil_test.cc

@@ -63,11 +63,11 @@ TEST(gpencil, remove_drawing)
   Layer layer1("Layer1");
   Layer layer2("Layer2");
 
-  layer1.insert_frame(0, 0);
-  layer1.insert_frame(10, 1);
-  layer1.insert_frame(20, 2);
+  layer1.insert_frame(0, GreasePencilFrame{0});
+  layer1.insert_frame(10, GreasePencilFrame{1});
+  layer1.insert_frame(20, GreasePencilFrame{2});
 
-  layer2.insert_frame(0, 1);
+  layer2.insert_frame(0, GreasePencilFrame{1});
 
   grease_pencil.root_group().add_layer(std::move(layer1));
   grease_pencil.root_group().add_layer(std::move(layer2));
@@ -82,7 +82,7 @@ TEST(gpencil, remove_drawing)
     EXPECT_EQ(layer.frames().size(), expected_frames_size[layer_i]);
     if (layer_i == 0) {
       for (const int i : IndexRange(2)) {
-        EXPECT_EQ(layer.frames().lookup(expected_frames_pairs_layer0[i][0]),
+        EXPECT_EQ(layer.frames().lookup(expected_frames_pairs_layer0[i][0]).drawing_index,
                   expected_frames_pairs_layer0[i][1]);
       }
     }

source/blender/makesdna/DNA_grease_pencil_types.h

@@ -91,6 +91,28 @@ typedef struct GreasePencilDrawingReference {
   struct GreasePencil *id_reference;
 } GreasePencilDrawingReference;
 
+/**
+ * A GreasePencilFrame is a single keyframe in the timeline.
+ * It references a drawing by index into the drawing array.
+ */
+typedef struct GreasePencilFrame {
+  /**
+   * Index into the GreasePencil->drawings array.
+   */
+  int drawing_index;
+
+  /**
+   * Flag. Used to set e.g. the selection.
+   */
+  uint32_t flag;
+
+  /**
+   * Keyframe type.
+   */
+  uint8_t type;
+  char _pad[3];
+} GreasePencilFrame;
+
 /**
  * Storage for the Map in `blender::bke::gpencil::Layer`.
  * See the description there for more detail.
@@ -99,7 +121,7 @@ typedef struct GreasePencilLayerFramesMapStorage {
   /* Array of `frames` keys (sorted in ascending order). */
   int *keys;
   /* Array of `frames` values (order matches the keys array). */
-  int *values;
+  GreasePencilFrame *values;
   /* Size of the map (number of key-value pairs). */
   int size;
   char _pad[4];