GPencil: Fill tool refactor and Multiframe in Draw mode

This commit is a refactor of the fill tool to solve several problems we had since the first version of the tool.

Changes:

* The filling speed has been improved for each step of the process with the optimization of each algorithm/function.
* New `AutoFit` option to fill areas outside of the viewport. When enable, the total size of the frame is calculated to fit the filling area.
* New support multiframe filling. Now it is possible to fill multiple similar frames in one go.
* New `Stroke Extension` option to create temporary closing strokes. These strokes can be displayed and adjusted dynamically using wheel mouse or PageUp/Down keys.
* Parameter `Resolution` now is named `Precision` and has been moved to topbar.
* `Resolution` now has decimals and can be lower than 1 to allow quick filling in storyboarding workflows. Maximum value has been set as 5.
* Parameter `Simplify` has been moved to Advanced panel.
* Improved fill outline detection. In some cases, the outline penetrated the area to be filled with unexpected results.
* Fixes some corner case bugs with infinite loops.

As a result of this refactor, also these new functionalities has been added.

* New support for multiframe in `Draw` mode. Any drawing in active frame is duplicated to all selected frame.
* New multiframe display mode. Keyframes before or after of the active frame are displayed using onion colors. This can be disable using Onion overlay options.

1 files changed, 7 insertions, 7 deletions

diff --git a/source/blender/editors/gpencil/gpencil_utils.c b/source/blender/editors/gpencil/gpencil_utils.c
index 42e3055ef65..9b12772bc9b 100644
--- a/source/blender/editors/gpencil/gpencil_utils.c
+++ b/source/blender/editors/gpencil/gpencil_utils.c
@@ -3032,12 +3032,12 @@ void ED_gpencil_sbuffer_vertex_color_set(Depsgraph *depsgraph,
   }
 }
 
-/* Helper to get the bigger 2D bound box points. */
-static void gpencil_projected_2d_bound_box(GP_SpaceConversion *gsc,
-                                           bGPDstroke *gps,
-                                           const float diff_mat[4][4],
-                                           float r_min[2],
-                                           float r_max[2])
+/* Get the bigger 2D bound box points. */
+void ED_gpencil_projected_2d_bound_box(GP_SpaceConversion *gsc,
+                                       bGPDstroke *gps,
+                                       const float diff_mat[4][4],
+                                       float r_min[2],
+                                       float r_max[2])
 {
   float bounds[8][2];
   BoundBox bb;
@@ -3082,7 +3082,7 @@ bool ED_gpencil_stroke_check_collision(GP_SpaceConversion *gsc,
     BKE_gpencil_stroke_boundingbox_calc(gps);
   }
 
-  gpencil_projected_2d_bound_box(gsc, gps, diff_mat, boundbox_min, boundbox_max);
+  ED_gpencil_projected_2d_bound_box(gsc, gps, diff_mat, boundbox_min, boundbox_max);
 
   rcti rect_stroke = {boundbox_min[0], boundbox_max[0], boundbox_min[1], boundbox_max[1]};