blender/release/scripts/startup/bl_ui/properties_grease_pencil_common.py

# ##### BEGIN GPL LICENSE BLOCK #####
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
# ##### END GPL LICENSE BLOCK #####

# <pep8 compliant>

import bpy
from bpy.types import Menu, UIList
from bpy.app.translations import pgettext_iface as iface_


def gpencil_stroke_placement_settings(context, layout):
    if context.space_data.type == 'VIEW_3D':
        propname = "annotation_stroke_placement_view3d"
    elif context.space_data.type == 'SEQUENCE_EDITOR':
        propname = "annotation_stroke_placement_sequencer_preview"
    elif context.space_data.type == 'IMAGE_EDITOR':
        propname = "annotation_stroke_placement_image_editor"
    else:
        propname = "annotation_stroke_placement_view2d"

    tool_settings = context.tool_settings

    col = layout.column(align=True)

    if context.space_data.type != 'VIEW_3D':
        col.label(text="Stroke Placement:")
        row = col.row(align=True)
        row.prop_enum(tool_settings, propname, 'VIEW')
        row.prop_enum(tool_settings, propname, 'CURSOR', text="Cursor")


def gpencil_active_brush_settings_simple(context, layout):
    tool_settings = context.tool_settings
    brush = tool_settings.gpencil_paint.brush
    if brush is None:
        layout.label(text="No Active Brush")
        return

    col = layout.column()
    col.label(text="Active Brush:      ")

    row = col.row(align=True)
    row.operator_context = 'EXEC_REGION_WIN'
    row.operator_menu_enum("gpencil.brush_change", "brush", text="", icon='BRUSH_DATA')
    row.prop(brush, "name", text="")

    col.prop(brush, "size", slider=True)
    row = col.row(align=True)
    row.prop(brush, "use_random_pressure", text="", icon='RNDCURVE')
    row.prop(brush, "pen_sensitivity_factor", slider=True)
    row.prop(brush, "use_pressure", text="", icon='STYLUS_PRESSURE')
    row = col.row(align=True)
    row.prop(brush, "use_random_strength", text="", icon='RNDCURVE')
    row.prop(brush, "strength", slider=True)
    row.prop(brush, "use_strength_pressure", text="", icon='STYLUS_PRESSURE')
    row = col.row(align=True)
    row.prop(brush, "jitter", slider=True)
    row.prop(brush, "use_jitter_pressure", text="", icon='STYLUS_PRESSURE')
    row = col.row()
    row.prop(brush, "angle", slider=True)
    row.prop(brush, "angle_factor", text="Factor", slider=True)


# XXX: To be replaced with active tools
class AnnotationDrawingToolsPanel:
    # subclass must set
    # bl_space_type = 'IMAGE_EDITOR'
    bl_label = "Annotation"
    bl_category = "Annotation"
    bl_region_type = 'TOOLS'

    def draw(self, context):
        layout = self.layout

        is_3d_view = context.space_data.type == 'VIEW_3D'
        is_clip_editor = context.space_data.type == 'CLIP_EDITOR'

        col = layout.column(align=True)

        col.label(text="Draw:")
        row = col.row(align=True)
        row.operator("gpencil.annotate", icon='GREASEPENCIL', text="Draw").mode = 'DRAW'
        # XXX: Needs a dedicated icon
        row.operator("gpencil.annotate", icon='FORCE_CURVE', text="Erase").mode = 'ERASER'

        row = col.row(align=True)
        row.operator("gpencil.annotate", icon='LINE_DATA', text="Line").mode = 'DRAW_STRAIGHT'
        row.operator("gpencil.annotate", icon='MESH_DATA', text="Poly").mode = 'DRAW_POLY'

        col.separator()

        sub = col.column(align=True)
        sub.operator("gpencil.blank_frame_add", icon='FILE_NEW')
        sub.operator("gpencil.active_frames_delete_all", icon='X', text="Delete Frame(s)")

        #sub = col.column(align=True)
        #sub.prop(context.tool_settings, "use_gpencil_draw_additive", text="Additive Drawing")
        #sub.prop(context.tool_settings, "use_gpencil_continuous_drawing", text="Continuous Drawing")
        #sub.prop(context.tool_settings, "use_gpencil_draw_onback", text="Draw on Back")

        col.separator()
        col.separator()

        if context.space_data.type == 'CLIP_EDITOR':
            col.separator()
            col.label(text="Data Source:")
            row = col.row(align=True)
            if is_3d_view:
                row.prop(context.tool_settings, "grease_pencil_source", expand=True)
            elif is_clip_editor:
                row.prop(context.space_data, "grease_pencil_source", expand=True)

        # col.separator()
        # col.separator()

        gpencil_stroke_placement_settings(context, col)


class GreasePencilStrokeEditPanel:
    # subclass must set
    # bl_space_type = 'IMAGE_EDITOR'
    bl_label = "Edit Strokes"
    bl_category = "Tools"
    bl_region_type = 'TOOLS'

    @classmethod
    def poll(cls, context):
        if context.gpencil_data is None:
            return False

        gpd = context.gpencil_data
        return bool(context.editable_gpencil_strokes) and bool(gpd.use_stroke_edit_mode)

    def draw(self, context):
        layout = self.layout

        is_3d_view = context.space_data.type == 'VIEW_3D'

        if not is_3d_view:
            layout.label(text="Select:")
            col = layout.column(align=True)
            col.operator("gpencil.select_all", text="Select All")
            col.operator("gpencil.select_box")
            col.operator("gpencil.select_circle")

            layout.separator()

            col = layout.column(align=True)
            col.operator("gpencil.select_linked")
            col.operator("gpencil.select_more")
            col.operator("gpencil.select_less")
            col.operator("gpencil.select_alternate")

        layout.label(text="Edit:")
        row = layout.row(align=True)
        row.operator("gpencil.copy", text="Copy")
        row.operator("gpencil.paste", text="Paste").type = 'ACTIVE'
        row.operator("gpencil.paste", text="Paste by Layer").type = 'LAYER'

        col = layout.column(align=True)
        col.operator("gpencil.delete")
        col.operator("gpencil.duplicate_move", text="Duplicate")
        if is_3d_view:
            col.operator("gpencil.stroke_cyclical_set", text="Toggle Cyclic").type = 'TOGGLE'
            col.operator_menu_enum("gpencil.stroke_caps_set", text="Toggle Caps...", property="type")

        layout.separator()

        if not is_3d_view:
            col = layout.column(align=True)
            col.operator("transform.translate")                # icon='MAN_TRANS'
            col.operator("transform.rotate")                   # icon='MAN_ROT'
            col.operator("transform.resize", text="Scale")     # icon='MAN_SCALE'

            layout.separator()

        layout.separator()
        col = layout.column(align=True)
        col.operator_menu_enum("gpencil.stroke_arrange", text="Arrange Strokes...", property="direction")
        col.operator("gpencil.stroke_change_color", text="Assign Material")

        layout.separator()
        col = layout.column(align=True)
        col.operator("gpencil.stroke_subdivide", text="Subdivide")
        row = col.row(align=True)
        row.operator("gpencil.stroke_simplify_fixed", text="Simplify")
        row.operator("gpencil.stroke_simplify", text="Adaptive")
        row.operator("gpencil.stroke_trim", text="Trim")

        col.separator()

        row = col.row(align=True)
        row.operator("gpencil.stroke_merge", text="Merge")
        row.operator("gpencil.stroke_join", text="Join").type = 'JOIN'
        row.operator("gpencil.stroke_join", text="& Copy").type = 'JOINCOPY'

        col.operator("gpencil.stroke_flip", text="Flip Direction")

        if is_3d_view:
            layout.separator()

            col = layout.column(align=True)
            col.operator_menu_enum("gpencil.stroke_separate", text="Separate...", property="mode")
            col.operator("gpencil.stroke_split", text="Split")

            col = layout.column(align=True)
            col.label(text="Cleanup:")
            col.operator_menu_enum("gpencil.reproject", text="Reproject Strokes...", property="type")
            col.operator_menu_enum("gpencil.frame_clean_fill", text="Clean Boundary Strokes...", property="mode")


class GreasePencilStrokeSculptPanel:
    # subclass must set
    # bl_space_type = 'IMAGE_EDITOR'
    bl_label = "Sculpt Strokes"
    bl_category = "Tools"

    def draw(self, context):
        layout = self.layout
        layout.use_property_split = True
        layout.use_property_decorate = False

        settings = context.tool_settings.gpencil_sculpt
        brush = settings.brush

        layout.template_icon_view(settings, "sculpt_tool", show_labels=True)

        if not self.is_popover:
            from bl_ui.properties_paint_common import (
                brush_basic_gpencil_sculpt_settings,
            )
            brush_basic_gpencil_sculpt_settings(layout, context, brush)


class GreasePencilSculptOptionsPanel:
    bl_label = "Sculpt Strokes"

    @classmethod
    def poll(cls, context):
        settings = context.tool_settings.gpencil_sculpt
        tool = settings.sculpt_tool

        return bool(tool in {'SMOOTH', 'RANDOMIZE', 'SMOOTH'})

    def draw(self, context):
        layout = self.layout
        layout.use_property_split = True
        layout.use_property_decorate = False

        settings = context.tool_settings.gpencil_sculpt
        tool = settings.sculpt_tool
        brush = settings.brush

        if tool in {'SMOOTH', 'RANDOMIZE'}:
            layout.prop(settings, "use_edit_position", text="Affect Position")
            layout.prop(settings, "use_edit_strength", text="Affect Strength")
            layout.prop(settings, "use_edit_thickness", text="Affect Thickness")

            if tool == 'SMOOTH':
                layout.prop(brush, "use_edit_pressure")

            layout.prop(settings, "use_edit_uv", text="Affect UV")


# GP Object Tool Settings
class GreasePencilAppearancePanel:
    bl_label = "Brush Appearance"
    bl_options = {'DEFAULT_CLOSED'}

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

    def draw(self, context):
        layout = self.layout
        layout.use_property_split = True
        layout.use_property_decorate = False

        tool_settings = context.tool_settings
        ob = context.active_object

        if ob.mode == 'PAINT_GPENCIL':
            brush = tool_settings.gpencil_paint.brush
            gp_settings = brush.gpencil_settings

            sub = layout.column(align=True)
            sub.enabled = not brush.use_custom_icon
            sub.prop(gp_settings, "gp_icon", text="Icon")

            layout.prop(brush, "use_custom_icon")
            sub = layout.column()
            sub.active = brush.use_custom_icon
            sub.prop(brush, "icon_filepath", text="")

            layout.prop(gp_settings, "use_cursor", text="Show Brush")

            if brush.gpencil_tool == 'DRAW':
                layout.prop(gp_settings, "show_lasso", text="Show fill color while drawing")

            if brush.gpencil_tool == 'FILL':
                layout.prop(brush, "cursor_color_add", text="Color")

        elif ob.mode in {'SCULPT_GPENCIL', 'WEIGHT_GPENCIL'}:
            settings = tool_settings.gpencil_sculpt
            brush = settings.brush
            tool = settings.sculpt_tool

            col = layout.column(align=True)
            col.prop(brush, "use_cursor", text="Show Brush")

            if tool in {'THICKNESS', 'STRENGTH'}:
                col.prop(brush, "cursor_color_add", text="Add")
                col.prop(brush, "cursor_color_sub", text="Subtract")
            elif tool == 'PINCH':
                col.prop(brush, "cursor_color_add", text="Pinch")
                col.prop(brush, "cursor_color_sub", text="Inflate")
            elif tool == 'TWIST':
                col.prop(brush, "cursor_color_add", text="CCW")
                col.prop(brush, "cursor_color_sub", text="CW")
            else:
                col.prop(brush, "cursor_color_add", text="")


class GPENCIL_MT_pie_tool_palette(Menu):
    """A pie menu for quick access to Grease Pencil tools"""
    bl_label = "Grease Pencil Tools"

    def draw(self, context):
        layout = self.layout

        pie = layout.menu_pie()
        gpd = context.gpencil_data

        # W - Drawing Types
        col = pie.column()
        col.operator("gpencil.draw", text="Draw", icon='GREASEPENCIL').mode = 'DRAW'
        col.operator("gpencil.draw", text="Straight Lines", icon='LINE_DATA').mode = 'DRAW_STRAIGHT'
        col.operator("gpencil.draw", text="Poly", icon='MESH_DATA').mode = 'DRAW_POLY'

        # E - Eraser
        # XXX: needs a dedicated icon...
        col = pie.column()
        col.operator("gpencil.draw", text="Eraser", icon='FORCE_CURVE').mode = 'ERASER'

        # E - "Settings" Palette is included here too, since it needs to be in a stable position...
        if gpd and gpd.layers.active:
            col.separator()
            col.operator(
                "wm.call_menu_pie",
                text="Settings...",
                icon='SCRIPTWIN').name = "GPENCIL_MT_pie_settings_palette"

        # Editing tools
        if gpd:
            if gpd.use_stroke_edit_mode and context.editable_gpencil_strokes:
                # S - Exit Edit Mode
                pie.operator("gpencil.editmode_toggle", text="Exit Edit Mode", icon='EDIT')

                # N - Transforms
                col = pie.column()
                row = col.row(align=True)
                row.operator("transform.translate", icon='MAN_TRANS')
                row.operator("transform.rotate", icon='MAN_ROT')
                row.operator("transform.resize", text="Scale", icon='MAN_SCALE')
                row = col.row(align=True)
                row.label(text="Proportional Edit:")
                row.prop(context.tool_settings, "use_proportional_edit", text="", icon_only=True)
                row.prop(context.tool_settings, "proportional_edit_falloff", text="", icon_only=True)

                # NW - Select (Non-Modal)
                col = pie.column()
                col.operator("gpencil.select_all", text="Select All", icon='PARTICLE_POINT')
                col.operator("gpencil.select_all", text="Select Inverse", icon='BLANK1')
                col.operator("gpencil.select_linked", text="Select Linked", icon='LINKED')
                col.operator("gpencil.palettecolor_select", text="Select Color", icon='COLOR')

                # NE - Select (Modal)
                col = pie.column()
                col.operator("gpencil.select_box", text="Box Select", icon='BORDER_RECT')
                col.operator("gpencil.select_circle", text="Circle Select", icon='META_EMPTY')
                col.operator("gpencil.select_lasso", text="Lasso Select", icon='BORDER_LASSO')
                col.operator("gpencil.select_alternate", text="Alternate Select", icon='BORDER_LASSO')

                # SW - Edit Tools
                col = pie.column()
                col.operator("gpencil.duplicate_move", icon='PARTICLE_PATH', text="Duplicate")
                col.operator("gpencil.delete", icon='X', text="Delete...")

                # SE - More Tools
                pie.operator("wm.call_menu_pie", text="More...").name = "GPENCIL_MT_pie_tools_more"
            else:
                # Toggle Edit Mode
                pie.operator("gpencil.editmode_toggle", text="Enable Stroke Editing", icon='EDIT')


class GPENCIL_MT_pie_settings_palette(Menu):
    """A pie menu for quick access to Grease Pencil settings"""
    bl_label = "Grease Pencil Settings"

    @classmethod
    def poll(cls, context):
        return bool(context.gpencil_data and context.active_gpencil_layer)

    def draw(self, context):
        layout = self.layout

        pie = layout.menu_pie()
        gpd = context.gpencil_data
        gpl = context.active_gpencil_layer
        palcolor = None  # context.active_gpencil_palettecolor

        is_editmode = bool(gpd and gpd.use_stroke_edit_mode and context.editable_gpencil_strokes)

        # W - Stroke draw settings
        col = pie.column(align=True)
        if palcolor is not None:
            col.enabled = not palcolor.lock
            col.label(text="Stroke")
            col.prop(palcolor, "color", text="")
            col.prop(palcolor, "alpha", text="", slider=True)

        # E - Fill draw settings
        col = pie.column(align=True)
        if palcolor is not None:
            col.enabled = not palcolor.lock
            col.label(text="Fill")
            col.prop(palcolor, "fill_color", text="")
            col.prop(palcolor, "fill_alpha", text="", slider=True)

        # S Brush settings
        gpencil_active_brush_settings_simple(context, pie)

        # N - Active Layer
        col = pie.column()
        col.label(text="Active Layer:      ")

        row = col.row()
        row.operator_context = 'EXEC_REGION_WIN'
        row.operator_menu_enum("gpencil.layer_change", "layer", text="", icon='GREASEPENCIL')
        row.prop(gpl, "info", text="")
        row.operator("gpencil.layer_remove", text="", icon='X')

        row = col.row()
        row.prop(gpl, "lock")
        row.prop(gpl, "hide")
        col.prop(gpl, "use_onion_skinning")

        # NW/NE/SW/SE - These operators are only available in editmode
        # as they require strokes to be selected to work
        if is_editmode:
            # NW - Move stroke Down
            col = pie.column(align=True)
            col.label(text="Arrange Strokes")
            col.operator("gpencil.stroke_arrange", text="Send to Back").direction = 'BOTTOM'
            col.operator("gpencil.stroke_arrange", text="Send Backward").direction = 'DOWN'

            # NE - Move stroke Up
            col = pie.column(align=True)
            col.label(text="Arrange Strokes")
            col.operator("gpencil.stroke_arrange", text="Bring to Front").direction = 'TOP'
            col.operator("gpencil.stroke_arrange", text="Bring Forward").direction = 'UP'

            # SW - Move stroke to color
            col = pie.column(align=True)
            col.operator("gpencil.stroke_change_color", text="Move to Color")

            # SE - Join strokes
            col = pie.column(align=True)
            col.label(text="Join Strokes")
            row = col.row()
            row.operator("gpencil.stroke_join", text="Join").type = 'JOIN'
            row.operator("gpencil.stroke_join", text="Join & Copy").type = 'JOINCOPY'
            col.operator("gpencil.stroke_flip", text="Flip Direction")

            col.prop(gpd, "show_stroke_direction", text="Show Drawing Direction")


class GPENCIL_MT_pie_tools_more(Menu):
    """A pie menu for accessing more Grease Pencil tools"""
    bl_label = "More Grease Pencil Tools"

    @classmethod
    def poll(cls, context):
        gpd = context.gpencil_data
        return bool(gpd and gpd.use_stroke_edit_mode and context.editable_gpencil_strokes)

    def draw(self, _context):
        layout = self.layout

        pie = layout.menu_pie()
        # gpd = context.gpencil_data

        col = pie.column(align=True)
        col.operator("gpencil.copy", text="Copy", icon='COPYDOWN')
        col.operator("gpencil.paste", text="Paste", icon='PASTEDOWN').type = 'ACTIVE'
        col.operator("gpencil.paste", text="Paste by Layer").type = 'LAYER'

        col = pie.column(align=True)
        col.operator("gpencil.select_more", icon='ADD')
        col.operator("gpencil.select_less", icon='REMOVE')

        pie.operator("transform.mirror", icon='MOD_MIRROR')
        pie.operator("transform.bend", icon='MOD_SIMPLEDEFORM')
        pie.operator("transform.shear", icon='MOD_TRIANGULATE')
        pie.operator("transform.tosphere", icon='MOD_MULTIRES')

        pie.operator("gpencil.convert", icon='OUTLINER_OB_CURVE', text="Convert...")
        pie.operator("wm.call_menu_pie", text="Back to Main Palette...").name = "GPENCIL_MT_pie_tool_palette"


class GPENCIL_MT_pie_sculpt(Menu):
    """A pie menu for accessing Grease Pencil stroke sculpt settings"""
    bl_label = "Grease Pencil Sculpt"

    @classmethod
    def poll(cls, context):
        gpd = context.gpencil_data
        return bool(gpd and gpd.use_stroke_edit_mode and context.editable_gpencil_strokes)

    def draw(self, context):
        layout = self.layout

        pie = layout.menu_pie()

        settings = context.tool_settings.gpencil_sculpt
        brush = settings.brush

        # W - Launch Sculpt Mode
        col = pie.column()
        # col.label(text="Tool:")
        col.prop(settings, "sculpt_tool", text="")
        col.operator("gpencil.sculpt_paint", text="Sculpt", icon='SCULPTMODE_HLT')

        # E - Common Settings
        col = pie.column(align=True)
        col.prop(brush, "size", slider=True)
        row = col.row(align=True)
        row.prop(brush, "strength", slider=True)
        # row.prop(brush, "use_pressure_strength", text="", icon_only=True)
        col.prop(brush, "use_falloff")
        if settings.sculpt_tool in {'SMOOTH', 'RANDOMIZE'}:
            row = col.row(align=True)
            row.prop(settings, "use_edit_position", text="Position", icon='MESH_DATA', toggle=True)
            row.prop(settings, "use_edit_strength", text="Strength", icon='COLOR', toggle=True)
            row.prop(settings, "use_edit_thickness", text="Thickness", icon='LINE_DATA', toggle=True)

        # S - Change Brush Type Shortcuts
        row = pie.row()
        row.prop_enum(settings, "tool", value='GRAB')
        row.prop_enum(settings, "tool", value='PUSH')
        row.prop_enum(settings, "tool", value='CLONE')

        # N - Change Brush Type Shortcuts
        row = pie.row()
        row.prop_enum(settings, "tool", value='SMOOTH')
        row.prop_enum(settings, "tool", value='THICKNESS')
        row.prop_enum(settings, "tool", value='STRENGTH')
        row.prop_enum(settings, "tool", value='RANDOMIZE')


class GPENCIL_MT_snap(Menu):
    bl_label = "Snap"

    def draw(self, _context):
        layout = self.layout

        layout.operator("gpencil.snap_to_grid", text="Selection to Grid")
        layout.operator("gpencil.snap_to_cursor", text="Selection to Cursor").use_offset = False
        layout.operator("gpencil.snap_to_cursor", text="Selection to Cursor (Keep Offset)").use_offset = True

        layout.separator()

        layout.operator("gpencil.snap_cursor_to_selected", text="Cursor to Selected")
        layout.operator("view3d.snap_cursor_to_center", text="Cursor to World Origin")
        layout.operator("view3d.snap_cursor_to_grid", text="Cursor to Grid")


class GPENCIL_MT_gpencil_draw_delete(Menu):
    bl_label = "Delete"

    def draw(self, _context):
        layout = self.layout

        layout.operator_context = 'INVOKE_REGION_WIN'

        layout.operator("gpencil.delete", text="Delete Active Keyframe (Active Layer)").type = 'FRAME'
        layout.operator("gpencil.active_frames_delete_all", text="Delete Active Keyframes (All Layers)")


class GPENCIL_MT_cleanup(Menu):
    bl_label = "Clean Up"

    def draw(self, _context):

        ob = _context.active_object

        layout = self.layout

        layout.operator("gpencil.frame_clean_loose", text="Delete Loose Points")

        if ob.mode != 'PAINT_GPENCIL':
            layout.operator("gpencil.stroke_merge_by_distance", text="Merge by Distance")
        
        layout.separator()

        layout.operator("gpencil.frame_clean_fill", text="Boundary Strokes").mode = 'ACTIVE'
        layout.operator("gpencil.frame_clean_fill", text="Boundary Strokes all Frames").mode = 'ALL'

        if ob.mode != 'PAINT_GPENCIL':
            layout.separator()

            layout.operator("gpencil.reproject")


class GPENCIL_UL_annotation_layer(UIList):
    def draw_item(self, _context, layout, _data, item, icon, _active_data, _active_propname, _index):
        # assert(isinstance(item, bpy.types.GPencilLayer)
        gpl = item

        if self.layout_type in {'DEFAULT', 'COMPACT'}:
            if gpl.lock:
                layout.active = False

            split = layout.split(factor=0.2)
            split.prop(gpl, "color", text="", emboss=True)
            split.prop(gpl, "info", text="", emboss=False)

            row = layout.row(align=True)
            row.prop(gpl, "annotation_hide", text="", emboss=False)
        elif self.layout_type == 'GRID':
            layout.alignment = 'CENTER'
            layout.label(text="", icon_value=icon)


class AnnotationDataPanel:
    bl_label = "Annotations"
    bl_region_type = 'UI'
    bl_options = {'DEFAULT_CLOSED'}

    @classmethod
    def poll(cls, context):
        # Show this panel as long as someone that might own this exists
        # AND the owner isn't an object (e.g. GP Object)
        if context.gpencil_data_owner is None:
            return False
        elif type(context.gpencil_data_owner) is bpy.types.Object:
            return False
        else:
            return True

    def draw_header(self, context):
        if context.space_data.type not in {'VIEW_3D', 'TOPBAR'}:
            self.layout.prop(context.space_data, "show_annotation", text="")

    def draw(self, context):
        layout = self.layout
        layout.use_property_decorate = False

        # Grease Pencil owner.
        gpd_owner = context.gpencil_data_owner
        gpd = context.gpencil_data

        # Owner selector.
        if context.space_data.type == 'CLIP_EDITOR':
            layout.row().prop(context.space_data, "grease_pencil_source", expand=True)

        layout.template_ID(gpd_owner, "grease_pencil", new="gpencil.data_add", unlink="gpencil.data_unlink")

        # List of layers/notes.
        if gpd and gpd.layers:
            self.draw_layers(context, layout, gpd)

    def draw_layers(self, context, layout, gpd):
        row = layout.row()

        col = row.column()
        if len(gpd.layers) >= 2:
            layer_rows = 5
        else:
            layer_rows = 3
        col.template_list("GPENCIL_UL_annotation_layer", "", gpd, "layers", gpd.layers, "active_index",
                          rows=layer_rows, sort_reverse=True, sort_lock=True)

        col = row.column()

        sub = col.column(align=True)
        sub.operator("gpencil.layer_add", icon='ADD', text="")
        sub.operator("gpencil.layer_remove", icon='REMOVE', text="")

        gpl = context.active_gpencil_layer
        if gpl:
            if len(gpd.layers) > 1:
                col.separator()

                sub = col.column(align=True)
                sub.operator("gpencil.layer_move", icon='TRIA_UP', text="").type = 'UP'
                sub.operator("gpencil.layer_move", icon='TRIA_DOWN', text="").type = 'DOWN'

        tool_settings = context.tool_settings
        if gpd and gpl:
            layout.prop(gpl, "thickness")
        else:
            layout.prop(tool_settings, "annotation_thickness", text="Thickness")

        if gpl:
            # Full-Row - Frame Locking (and Delete Frame)
            row = layout.row(align=True)
            row.active = not gpl.lock

            if gpl.active_frame:
                lock_status = iface_("Locked") if gpl.lock_frame else iface_("Unlocked")
                lock_label = iface_("Frame: %d (%s)") % (gpl.active_frame.frame_number, lock_status)
            else:
                lock_label = iface_("Lock Frame")
            row.prop(gpl, "lock_frame", text=lock_label, icon='UNLOCKED')
            row.operator("gpencil.active_frame_delete", text="", icon='X')


class AnnotationOnionSkin:
    bl_label = "Onion Skin"
    bl_region_type = 'UI'
    bl_options = {'DEFAULT_CLOSED'}

    @classmethod
    def poll(cls, context):
        # Show this panel as long as someone that might own this exists
        # AND the owner isn't an object (e.g. GP Object)
        if context.gpencil_data_owner is None:
            return False
        elif type(context.gpencil_data_owner) is bpy.types.Object:
            return False
        else:
            gpl = context.active_gpencil_layer
            if gpl is None:
                return False

            return True

    def draw_header(self, context):
        gpl = context.active_gpencil_layer
        self.layout.prop(gpl, "use_annotation_onion_skinning", text="")

    def draw(self, context):
        layout = self.layout
        layout.use_property_decorate = False

        gpl = context.active_gpencil_layer
        col = layout.column()
        split = col.split(factor=0.5)
        split.active = gpl.use_annotation_onion_skinning

        # - Before Frames
        sub = split.column(align=True)
        row = sub.row(align=True)
        row.prop(gpl, "annotation_onion_before_color", text="")
        sub.prop(gpl, "annotation_onion_before_range", text="Before")

        # - After Frames
        sub = split.column(align=True)
        row = sub.row(align=True)
        row.prop(gpl, "annotation_onion_after_color", text="")
        sub.prop(gpl, "annotation_onion_after_range", text="After")


class GreasePencilToolsPanel:
    # For use in "2D" Editors without their own toolbar
    # subclass must set
    # bl_space_type = 'IMAGE_EDITOR'
    bl_label = "Grease Pencil Settings"
    bl_region_type = 'UI'
    bl_options = {'DEFAULT_CLOSED'}

    @classmethod
    def poll(cls, context):
        # XXX - disabled in 2.8 branch.
        return False

        return (context.gpencil_data is not None)

    def draw(self, context):
        layout = self.layout

        gpencil_active_brush_settings_simple(context, layout)

        layout.separator()

        gpencil_stroke_placement_settings(context, layout)


class GreasePencilMaterialsPanel:
    # Mix-in, use for properties editor and top-bar.
    def draw(self, context):
        layout = self.layout
        show_full_ui = (self.bl_space_type == 'PROPERTIES')

        is_view3d = (self.bl_space_type == 'VIEW_3D')
        tool_settings = context.scene.tool_settings
        gpencil_paint = tool_settings.gpencil_paint
        brush = gpencil_paint.brush

        ob = context.object
        row = layout.row()

        if ob:
            is_sortable = len(ob.material_slots) > 1
            rows = 7

            row.template_list("GPENCIL_UL_matslots", "", ob, "material_slots", ob, "active_material_index", rows=rows)

            # if topbar popover and brush pinned, disable
            if is_view3d and brush is not None:
                gp_settings = brush.gpencil_settings
                if gp_settings.use_material_pin:
                    row.enabled = False

            col = row.column(align=True)
            if show_full_ui:
                col.operator("object.material_slot_add", icon='ADD', text="")
                col.operator("object.material_slot_remove", icon='REMOVE', text="")

            col.menu("GPENCIL_MT_color_context_menu", icon='DOWNARROW_HLT', text="")

            if is_sortable:
                col.separator()

                col.operator("object.material_slot_move", icon='TRIA_UP', text="").direction = 'UP'
                col.operator("object.material_slot_move", icon='TRIA_DOWN', text="").direction = 'DOWN'

                col.separator()

                sub = col.column(align=True)
                sub.operator("gpencil.color_isolate", icon='LOCKED', text="").affect_visibility = False
                sub.operator("gpencil.color_isolate", icon='RESTRICT_VIEW_ON', text="").affect_visibility = True

            if show_full_ui:
                row = layout.row()

                row.template_ID(ob, "active_material", new="material.new", live_icon=True)

                slot = context.material_slot
                if slot:
                    icon_link = 'MESH_DATA' if slot.link == 'DATA' else 'OBJECT_DATA'
                    row.prop(slot, "link", icon=icon_link, icon_only=True)

                if ob.data.use_stroke_edit_mode:
                    row = layout.row(align=True)
                    row.operator("gpencil.stroke_change_color", text="Assign")
                    row.operator("gpencil.color_select", text="Select").deselect = False
                    row.operator("gpencil.color_select", text="Deselect").deselect = True
        # stroke color
            ma = None
            if is_view3d and brush is not None:
                gp_settings = brush.gpencil_settings
                if gp_settings.use_material_pin is False:
                    ma = ob.material_slots[ob.active_material_index].material
                else:
                    ma = gp_settings.material

            if ma is not None and ma.grease_pencil is not None:
                gpcolor = ma.grease_pencil
                if (
                        gpcolor.stroke_style == 'SOLID' or
                        gpcolor.use_stroke_pattern or
                        gpcolor.use_stroke_texture_mix
                ):
                    row = layout.row()
                    row.prop(gpcolor, "color", text="Stroke Color")

        else:
            space = context.space_data
            row.template_ID(space, "pin_id")


class GPENCIL_UL_layer(UIList):
    def draw_item(self, _context, layout, _data, item, icon, _active_data, _active_propname, _index):
        # assert(isinstance(item, bpy.types.GPencilLayer)
        gpl = item

        if self.layout_type in {'DEFAULT', 'COMPACT'}:
            if gpl.lock:
                layout.active = False

            row = layout.row(align=True)
            row.label(
                text="",
                icon='BONE_DATA' if gpl.is_parented else 'BLANK1',
            )
            row.prop(gpl, "info", text="", emboss=False)

            row = layout.row(align=True)
            row.prop(gpl, "mask_layer", text="",
                     icon='MOD_MASK' if gpl.mask_layer else 'LAYER_ACTIVE',
                     emboss=False)

            row.prop(gpl, "lock", text="", emboss=False)
            row.prop(gpl, "hide", text="", emboss=False)
            subrow = row.row(align=True)
            subrow.prop(
                gpl,
                "use_onion_skinning",
                text="",
                icon='ONIONSKIN_ON' if gpl.use_onion_skinning else 'ONIONSKIN_OFF',
                emboss=False,
            )
        elif self.layout_type == 'GRID':
            layout.alignment = 'CENTER'
            layout.label(
                text="",
                icon_value=icon,
            )


classes = (
    GPENCIL_MT_pie_tool_palette,
    GPENCIL_MT_pie_settings_palette,
    GPENCIL_MT_pie_tools_more,
    GPENCIL_MT_pie_sculpt,

    GPENCIL_MT_snap,
    GPENCIL_MT_cleanup,

    GPENCIL_MT_gpencil_draw_delete,

    GPENCIL_UL_annotation_layer,
    GPENCIL_UL_layer,
)

if __name__ == "__main__":  # only for live edit.
    from bpy.utils import register_class
    for cls in classes:
        register_class(cls)