GPencil: New conversion to outline in draw mode

This new option converts the stroke to outline perimeter as soon as is drawn.

If no alternative material is set, the actual material is used.

The algorithm is similar to the new operator in D15664

Reviewed By: pepeland

Differential Revision: https://developer.blender.org/D15738

release/scripts/startup/bl_ui/space_view3d_toolbar.py

@@ -1742,6 +1742,12 @@ class VIEW3D_PT_tools_grease_pencil_brush_post_processing(View3DPanel, Panel):
         col1 = col.column(align=True)
         col1.prop(gp_settings, "use_trim")
 
+        row = col.row(heading="Outline", align=True)
+        row.prop(gp_settings, "use_settings_outline", text="")
+        row2 = row.row(align=True)
+        row2.enabled = gp_settings.use_settings_outline
+        row2.prop(gp_settings, "material_alt", text="")
+
 
 class VIEW3D_PT_tools_grease_pencil_brush_random(View3DPanel, Panel):
     bl_context = ".greasepencil_paint"