Fix #133453: Canvas button cannot be enabled

This fixes an issue where the Canvas button is always disabled when
trying to use the experimental feature, Sculpt Texture Paint.

This bug was caused by the new Asset System since it changed how paint
tools work. Before, the UI would check the current tool being used and
determine if the Canvas button should be activated. With the new Asset
System, painting is done with modular brushes instead of tools, so
previous methods of checking tool properties have stopped working.

This is fixed by activating the Canvas button based on the properties
of the current brush. If the brush's type is either Paint or Smear,
then the Canvas button is activated.

Co-authored-by: T0MIS0N <50230774+T0MIS0N@users.noreply.github.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/133566

scripts/startup/bl_ui/space_view3d.py

@@ -983,6 +983,9 @@ class VIEW3D_HT_header(Header):
                 canvas_source = tool_settings.paint_mode.canvas_source
                 icon = 'GROUP_VCOL' if canvas_source == 'COLOR_ATTRIBUTE' else canvas_source
                 row.popover(panel="VIEW3D_PT_slots_paint_canvas", icon=icon)
+                # TODO: Update this boolean condition so that the Canvas button is only active when
+                # the appropriate color types are selected in Solid mode, I.E. 'TEXTURE'
+                row.active = is_paint_tool
             else:
                 row.popover(panel="VIEW3D_PT_slots_color_attributes", icon='GROUP_VCOL')
 

scripts/startup/bl_ui/space_view3d_toolbar.py

@@ -607,7 +607,20 @@ class VIEW3D_PT_slots_paint_canvas(SelectPaintSlotHelper, View3DPanel, Panel):
         tool = ToolSelectPanelHelper.tool_active_from_context(context)
         if tool is None:
             return False
-        return tool.use_paint_canvas
+
+        is_paint_tool = False
+        if tool.use_brushes:
+            brush = context.tool_settings.sculpt.brush
+            if brush:
+                is_paint_tool = brush.sculpt_tool in {'PAINT', 'SMEAR'}
+        else:
+            # TODO: The property use_paint_canvas doesn't work anymore since its associated
+            # C++ function 'rna_WorkSpaceTool_use_paint_canvas_get' passes in a nullptr for
+            # the bContext. This property should be fixed in the future, but will require
+            # some extensive refactoring. For now, use the workaround above.
+            is_paint_tool = tool.use_paint_canvas
+
+        return is_paint_tool
 
     def get_mode_settings(self, context):
         return context.tool_settings.paint_mode