gp_toolbox/OP_brushes.py

import bpy
from bpy_extras.io_utils import ImportHelper
from pathlib import Path
from .utils import get_addon_prefs


def get_brushes(blend_fp):
    '''Get all brush from passed blend that aren't already in there (can take Path object)'''
    cur_brushes = [b.name for b in bpy.data.brushes]
    with bpy.data.libraries.load(str(blend_fp), link=False) as (data_from, data_to):
        # load brushes if not already there
        data_to.brushes = [b for b in data_from.brushes if not b in cur_brushes]

    ## force fake user for appended the brushes
    for b in data_to.brushes:
        print(f'Append Brush: {b.name}')
        b.use_fake_user = True

    return len(data_to.brushes)


class GPTB_OT_load_brushes(bpy.types.Operator, ImportHelper):
    bl_idname = "gp.load_brushes"
    bl_label = "Load Brushes"
    bl_description = "Load all brushes from chosen blend file in current if brushes aren't already there\nIf a replacement is needed, delete the previous brush before"
    #bl_options = {"REGISTER", "INTERNAL"}

    # @classmethod
    # def poll(cls, context):
    #     return context.object and context.object.type == 'GPENCIL'

    filename_ext = '.blend'

    filter_glob: bpy.props.StringProperty(default='*.blend', options={'HIDDEN'} )
    
    filepath : bpy.props.StringProperty(
        name="File Path", 
        description="File path used for import", 
        maxlen= 1024)

    def execute(self, context):
        print(f'Appending brushes from file : {self.filepath}')
        bct = get_brushes(self.filepath)
        if bct:
            self.report({'INFO'}, f'{bct} brushes appended')
        else:
            self.report({'WARNING'}, 'Brushes are already there (if need to re-import, delete first)')
        return {"FINISHED"}


class GPTB_OT_brush_set(bpy.types.Operator):
    bl_idname = "gp.brush_set"
    bl_label = "Set Brush"
    bl_description = "Set Gpencil brush"
    bl_options = {"REGISTER", "UNDO"}

    brush_name : bpy.props.StringProperty(name='Brush', description='Name of the brush to use')

    @classmethod
    def poll(cls, context):
        return context.object and context.mode == 'PAINT_GPENCIL'

    def execute(self, context):
        brush = bpy.data.brushes.get(self.brush_name)
        if not brush:
            self.report({'ERROR'}, f'Brush "{self.brush_name}" not found')
            return {"CANCELLED"}
        context.scene.tool_settings.gpencil_paint.brush = brush
        return {"FINISHED"}

### -- MENU ENTRY --

def load_brush_ui(self, context):
    prefs = get_addon_prefs()
    if context.mode == 'PAINT_GPENCIL':
        self.layout.operator('gp.load_brushes', icon='KEYTYPE_JITTER_VEC').filepath = prefs.brush_path

def load_brush_top_bar_ui(self, context):
    prefs = get_addon_prefs()
    if context.mode == 'PAINT_GPENCIL':
        self.layout.operator('gp.load_brushes').filepath = prefs.brush_path

classes = (
GPTB_OT_load_brushes,
GPTB_OT_brush_set,
)

def register():
    for cl in classes:
        bpy.utils.register_class(cl)

    bpy.types.VIEW3D_MT_brush_gpencil_context_menu.append(load_brush_ui)
    bpy.types.VIEW3D_HT_tool_header.append(load_brush_top_bar_ui)

def unregister():
    bpy.types.VIEW3D_HT_tool_header.remove(load_brush_top_bar_ui)
    bpy.types.VIEW3D_MT_brush_gpencil_context_menu.remove(load_brush_ui)
    
    for cl in reversed(classes):
        bpy.utils.unregister_class(cl)