GPencil: Improve default brush draw mode

Mainly a UI adjustment, no functional changes

To have the default mode in the advanced panel as separated option is not the best solution.

Now, there is a pin option and when it is enabled, the brush keeps this mode.

Differential Revision: https://developer.blender.org/D8974

3 files changed, 52 insertions, 6 deletions

diff --git a/release/scripts/startup/bl_ui/properties_paint_common.py b/release/scripts/startup/bl_ui/properties_paint_common.py
index d5f48876491..135ba802655 100644
--- a/release/scripts/startup/bl_ui/properties_paint_common.py
+++ b/release/scripts/startup/bl_ui/properties_paint_common.py
@@ -1148,11 +1148,19 @@ def brush_basic__draw_color_selector(context, layout, brush, gp_settings, props)
 
     if brush.gpencil_tool in {'DRAW', 'FILL'}:
         row.separator(factor=1.0)
-        row.prop_enum(settings, "color_mode", 'MATERIAL', text="", icon='MATERIAL')
-        row.prop_enum(settings, "color_mode", 'VERTEXCOLOR', text="", icon='VPAINT_HLT')
         sub_row = row.row(align=True)
-        sub_row.enabled = settings.color_mode == 'VERTEXCOLOR'
+        sub_row.enabled = not gp_settings.pin_draw_mode
+        if gp_settings.pin_draw_mode:
+            sub_row.prop_enum(gp_settings, "brush_draw_mode", 'MATERIAL', text="", icon='MATERIAL')
+            sub_row.prop_enum(gp_settings, "brush_draw_mode", 'VERTEXCOLOR', text="", icon='VPAINT_HLT')
+        else:
+            sub_row.prop_enum(settings, "color_mode", 'MATERIAL', text="", icon='MATERIAL')
+            sub_row.prop_enum(settings, "color_mode", 'VERTEXCOLOR', text="", icon='VPAINT_HLT')
+
+        sub_row = row.row(align=True)
+        sub_row.enabled = settings.color_mode == 'VERTEXCOLOR' or gp_settings.brush_draw_mode == 'VERTEXCOLOR'
         sub_row.prop_with_popover(brush, "color", text="", panel="TOPBAR_PT_gpencil_vertexcolor")
+        row.prop(gp_settings, "pin_draw_mode", text="")
 
     if props:
         row = layout.row(align=True)
diff --git a/release/scripts/startup/bl_ui/space_view3d_toolbar.py b/release/scripts/startup/bl_ui/space_view3d_toolbar.py
index 5a7d335ce3a..a8bb032f565 100644
--- a/release/scripts/startup/bl_ui/space_view3d_toolbar.py
+++ b/release/scripts/startup/bl_ui/space_view3d_toolbar.py
@@ -1405,9 +1405,6 @@ class VIEW3D_PT_tools_grease_pencil_brush_advanced(View3DPanel, Panel):
 
         col = layout.column(align=True)
         if brush is not None:
-            col.prop(gp_settings, "brush_draw_mode")
-            col.separator()
-
             if brush.gpencil_tool != 'FILL':
                 col.prop(gp_settings, "input_samples")
                 col.separator()
diff --git a/source/blender/makesrna/intern/rna_brush.c b/source/blender/makesrna/intern/rna_brush.c
index 675a46f48d1..1f5aaabe59f 100644
--- a/source/blender/makesrna/intern/rna_brush.c
+++ b/source/blender/makesrna/intern/rna_brush.c
@@ -971,6 +971,38 @@ static bool rna_BrushGpencilSettings_material_poll(PointerRNA *UNUSED(ptr), Poin
   return (ma->gp_style != NULL);
 }
 
+static bool rna_GPencilBrush_pin_mode_get(PointerRNA *ptr)
+{
+  Brush *brush = (Brush *)ptr->owner_id;
+  if ((brush != NULL) && (brush->gpencil_settings != NULL)) {
+    return (brush->gpencil_settings->brush_draw_mode != GP_BRUSH_MODE_ACTIVE);
+  }
+  return false;
+}
+
+static void rna_GPencilBrush_pin_mode_set(PointerRNA *ptr, bool value)
+{
+  /* All data is set in update. Keep this function only to avoid RNA compilation errors. */
+  return;
+}
+
+static void rna_GPencilBrush_pin_mode_update(bContext *C, PointerRNA *ptr)
+{
+  Brush *brush = (Brush *)ptr->owner_id;
+  if ((brush != NULL) && (brush->gpencil_settings != NULL)) {
+    if (brush->gpencil_settings->brush_draw_mode != GP_BRUSH_MODE_ACTIVE) {
+      /* If not active, means that must be set to off. */
+      brush->gpencil_settings->brush_draw_mode = GP_BRUSH_MODE_ACTIVE;
+    }
+    else {
+      ToolSettings *ts = CTX_data_tool_settings(C);
+      brush->gpencil_settings->brush_draw_mode = GPENCIL_USE_VERTEX_COLOR(ts) ?
+                                                     GP_BRUSH_MODE_VERTEXCOLOR :
+                                                     GP_BRUSH_MODE_MATERIAL;
+    }
+  }
+}
+
 #else
 
 static void rna_def_brush_texture_slot(BlenderRNA *brna)
@@ -1689,6 +1721,15 @@ static void rna_def_gpencil_options(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Direction", "Direction of the fill");
   RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
 
+  prop = RNA_def_property(srna, "pin_draw_mode", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_funcs(
+      prop, "rna_GPencilBrush_pin_mode_get", "rna_GPencilBrush_pin_mode_set");
+  RNA_def_property_ui_icon(prop, ICON_UNPINNED, 1);
+  RNA_def_property_flag(prop, PROP_CONTEXT_UPDATE);
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_update(prop, NC_GPENCIL | ND_DATA, "rna_GPencilBrush_pin_mode_update");
+  RNA_def_property_ui_text(prop, "Pin Mode", "Pin the mode to the brush");
+
   prop = RNA_def_property(srna, "brush_draw_mode", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_sdna(prop, NULL, "brush_draw_mode");
   RNA_def_property_enum_items(prop, rna_enum_gpencil_brush_modes_items);