source/blender/blenkernel/BKE_grease_pencil.hh

@@ -25,6 +25,12 @@ namespace gpencil {
 class LayerGroup;
 class Layer;
 
+/**
+ * A TreeNode represents one node in the layer tree.
+ * It can either be a layer or a group. The node has zero children if it is a layer or zero or more
+ * children if it is a group.
+ * This class is mainly used for iteration over the layer tree.
+ */
 class TreeNode : public ::GreasePencilLayerTreeNode {
   using TreeNodeIterFn = FunctionRef<void(TreeNode &)>;
   using LayerIterFn = FunctionRef<void(Layer &)>;
@@ -210,6 +216,10 @@ class TreeNode : public ::GreasePencilLayerTreeNode {
   }
 };
 
+/**
+ * A layer maps drawings to scene frames. It can be thought of as one independent channel in the
+ * timeline.
+ */
 class Layer : public TreeNode, ::GreasePencilLayer {
  private:
   /**
@@ -268,6 +278,7 @@ class Layer : public TreeNode, ::GreasePencilLayer {
 
   Map<int, int> &frames_for_write()
   {
+    sorted_keys_cache_.tag_dirty();
     return frames_;
   }
 
@@ -325,6 +336,9 @@ class Layer : public TreeNode, ::GreasePencilLayer {
   }
 };
 
+/**
+ * A LayerGroup is a grouping of zero or more Layers.
+ */
 class LayerGroup : public TreeNode {
  public:
   LayerGroup() : TreeNode(GREASE_PENCIL_LAYER_TREE_GROUP) {}
@@ -389,7 +403,7 @@ class LayerGroup : public TreeNode {
     return children_[index].get()->as_layer();
   }
 
-  int num_children()
+  int num_children() const
   {
     return children_.size();
   }

source/blender/blenkernel/intern/grease_pencil.cc

@@ -41,7 +41,7 @@ static void grease_pencil_init_data(ID *id)
 {
   using namespace blender::bke;
 
-  printf("grease_pencil_init_data\n");
+  // printf("grease_pencil_init_data\n");
   GreasePencil *grease_pencil = (GreasePencil *)id;
   grease_pencil->runtime = MEM_new<GreasePencilRuntime>(__func__);
 }
@@ -53,7 +53,7 @@ static void grease_pencil_copy_data(Main * /*bmain*/,
 {
   using namespace blender;
 
-  printf("grease_pencil_copy_data\n");
+  // printf("grease_pencil_copy_data\n");
   GreasePencil *grease_pencil_dst = (GreasePencil *)id_dst;
   const GreasePencil *grease_pencil_src = (GreasePencil *)id_src;
 
@@ -107,7 +107,7 @@ static void grease_pencil_copy_data(Main * /*bmain*/,
 
 static void grease_pencil_free_data(ID *id)
 {
-  printf("grease_pencil_free_data\n");
+  // printf("grease_pencil_free_data\n");
   GreasePencil *grease_pencil = (GreasePencil *)id;
   BKE_animdata_free(&grease_pencil->id, false);
 
@@ -773,8 +773,8 @@ static void read_layer_node_recursive(blender::bke::gpencil::LayerGroup &current
       GreasePencilLayerTreeLeaf *node_leaf = reinterpret_cast<GreasePencilLayerTreeLeaf *>(node);
       Layer new_layer(node_leaf->base.name);
       for (int i = 0; i < node_leaf->layer.frames_storage.size; i++) {
-        new_layer.frames_for_write().add(node_leaf->layer.frames_storage.keys[i],
-                                         node_leaf->layer.frames_storage.values[i]);
+        new_layer.insert_frame(node_leaf->layer.frames_storage.keys[i],
+                               node_leaf->layer.frames_storage.values[i]);
       }
       current_group.add_layer(std::move(new_layer));
       break;

source/blender/blenkernel/intern/grease_pencil_test.cc

@@ -63,11 +63,11 @@ TEST(gpencil, remove_drawing)
   Layer layer1("Layer1");
   Layer layer2("Layer2");
 
-  layer1.frames_for_write().add(0, 0);
-  layer1.frames_for_write().add(10, 1);
-  layer1.frames_for_write().add(20, 2);
+  layer1.insert_frame(0, 0);
+  layer1.insert_frame(10, 1);
+  layer1.insert_frame(20, 2);
 
-  layer2.frames_for_write().add(0, 1);
+  layer2.insert_frame(0, 1);
 
   grease_pencil.root_group().add_layer(std::move(layer1));
   grease_pencil.root_group().add_layer(std::move(layer2));

source/blender/makesdna/DNA_grease_pencil_types.h

@@ -162,8 +162,6 @@ typedef struct GreasePencilLayerTreeStorage {
 
 /**
  * The grease pencil data-block.
- * It holds a set of grease pencil drawings, a tree of layer groups, and a set of layers whithin
- * each layer group.
  */
 typedef struct GreasePencil {
   ID id;
@@ -171,7 +169,9 @@ typedef struct GreasePencil {
   struct AnimData *adt;
 
   /**
-   * An array of GreasePencilDrawing's.
+   * An array of pointers to drawings. The drawing can own it's data or reference it from another
+   * data-block. Note that the order of this array is arbitrary. The mapping of drawings to frames
+   * is done by the layers. See the `Layer` class in `BKE_grease_pencil.hh`.
    */
   GreasePencilDrawingOrReference **drawing_array;
   int drawing_array_size;