Circle Layer
============

+------------------+--------------------------------------------------------------------------+
| Property in .sif |                     Path to Property in lottie                           |
+==================+==========================================================================+
|      Z_depth     |           Depends on ordering of layers in lottie format                 |
+------------------+--------------------------------------------------------------------------+
|      Amount      | layers/solid.json -> "ef" -> effects/fill.json -> effects/opacity.json   |
+------------------+--------------------------------------------------------------------------+
|   Blend Method   |         layers/solid.json -> “bm” -> helpers/blendMode.json              |
+------------------+--------------------------------------------------------------------------+
|       Color      |  layers/solid.json -> "ef" -> effects/fill.json -> effects/color.json    |
+------------------+--------------------------------------------------------------------------+
|       Radius     |      Calculation of  layers/solid.json -> helpers/mask.json -> "pt"      |
+------------------+--------------------------------------------------------------------------+
|      Origin      |      Calculation of  layers/solid.json -> helpers/mask.json -> "pt"      |
+------------------+--------------------------------------------------------------------------+
|      Invert      |           layers/solid.json -> helpers/mask.json -> "inv"                |
+------------------+--------------------------------------------------------------------------+
|   Antialiasing   |           This property is always present(true) in lottie                |
+------------------+--------------------------------------------------------------------------+
|      Feather     |                            Not supported                                 |
+------------------+--------------------------------------------------------------------------+

Important points
----------------

- Instead of directly using the shapes layer from Lottie, a solid region layer is used and is masked(using masks) to draw a circle. This is done to support the invert parameter from Synfig.

- The mask is drawn according to: https://github.com/synfig/synfig/blob/678cc3a7b1208fcca18c8b54a29a20576c499927/synfig-core/src/modules/mod_geometry/circle.cpp