Layer blending mode editor

import os
import substance_painter as sp

# Qt5 vs Qt6 check
IsQt5 = sp.application.version_info() < (10,1,0)

if IsQt5 :
    from PySide2 import QtGui
    from PySide2 import QtWidgets
else :
    from PySide6 import QtGui
    from PySide6 import QtWidgets

SCRIPT_FOLDER = os.path.dirname(os.path.realpath(__file__))

WIDGETS = []
WIDGET_NODE_NAME = None
WIDGET_NODE_TYPE = None
WIDGET_NODE_ID = None
WIDGET_BLEND_LAYOUT = None
VALID_TYPES = [
    sp.layerstack.NodeType.PaintLayer,
    sp.layerstack.NodeType.FillLayer
]
FRAME_STYLE = """
.QFrame
{
    border: 1px solid #252525;
    border-radius: 4px;
    background-color: #303030;
}
"""
BLEND_MODES = []

def ChangeBlendMode( Layer, ChannelType, Dropdown ) :
    # Retrieve blending mode
    Index = Dropdown.currentIndex()
    BlendMode = sp.layerstack.BlendingMode( Index )

    # Change blending mode
    Layer.set_blending_mode( BlendMode, ChannelType )

def BuildChannelUI( Layer, ChannelType, ChannelInfo ) :
    Parent = QtWidgets.QFrame()
    Parent.setFrameStyle( QtWidgets.QFrame.Panel )
    Parent.setFrameShadow( QtWidgets.QFrame.Raised )
    Parent.setStyleSheet( FRAME_STYLE )

    Layout = QtWidgets.QVBoxLayout()
    Parent.setLayout( Layout )

    Label = QtWidgets.QLabel( ChannelType.name )
    Layout.addWidget( Label )

    Dropdown = QtWidgets.QComboBox()
    Dropdown.addItems( BLEND_MODES )
    Layout.addWidget( Dropdown )

    # Retrieve layer current blending mode
    # and update dropdown to show it
    BlendModeName = Layer.get_blending_mode( ChannelType ).name
    BlendModeIndex = BLEND_MODES.index( BlendModeName )
    Dropdown.setCurrentIndex( BlendModeIndex )

    # Connect a function to be able to change the
    # blending mode from our own UI
    Dropdown.currentIndexChanged.connect(
        lambda: ChangeBlendMode( Layer, ChannelType, Dropdown )
    )

    WIDGET_BLEND_LAYOUT.addWidget(Parent)

def Update( Arg ) :
    global WIDGET_NODE_ID

    Stack = sp.textureset.get_active_stack()
    Layers = sp.layerstack.get_selected_nodes( Stack )

    if not len(Layers) == 1 :
        WIDGET_NODE_NAME.setText( "(Too many selected)" )
        WIDGET_NODE_TYPE.setText( "(none)" )
        WIDGET_BLEND_LAYOUT.setEnabled( False )
        ResetUI()
        return

    if not any( Layers[0].get_type() == Type for Type in VALID_TYPES ) :
        WIDGET_NODE_NAME.setText( "(Unsupported layer/effect)" )
        WIDGET_NODE_TYPE.setText( "(none)" )
        WIDGET_BLEND_LAYOUT.setEnabled( False )
        ResetUI()
        return

    WIDGET_NODE_NAME.setText( Layers[0].get_name() )
    WIDGET_NODE_TYPE.setText( "(" + str(Layers[0].get_type()) + ")" )
    WIDGET_BLEND_LAYOUT.setEnabled( True )

    ResetUI()

    Channels = Stack.all_channels()

    for ChannelType in Channels :
        BuildChannelUI( Layers[0], ChannelType, Channels[ChannelType] )

def ResetUI() :
    if WIDGET_BLEND_LAYOUT :
        while WIDGET_BLEND_LAYOUT.count():
            child = WIDGET_BLEND_LAYOUT.takeAt(0)
            if child.widget():
                child.widget().deleteLater()

def Separator() :
    Separator = QtWidgets.QFrame()
    Separator.setFrameShape( QtWidgets.QFrame.HLine )
    Separator.setFrameShadow( QtWidgets.QFrame.Raised )
    Separator.setStyleSheet( "QFrame { border-bottom: 1px solid #252525; }" )
    return Separator

def BuildUI() :
    global WIDGET_NODE_NAME
    global WIDGET_NODE_TYPE
    global WIDGET_BLEND_LAYOUT

    Parent = QtWidgets.QFrame()
    Parent.setWindowTitle("Blend Modes")
    Parent.setWindowIcon( QtGui.QIcon(SCRIPT_FOLDER + "/" + "icon.svg") )

    ParentLayout = QtWidgets.QVBoxLayout()
    Parent.setLayout( ParentLayout )

    Margin = 10
    ParentLayout.setContentsMargins( Margin, Margin, Margin, Margin )

    # Build top UI
    TitleLabel = QtWidgets.QLabel( "<b>INFO</b>" )
    NodeLabel = QtWidgets.QLabel( "(No layer selected)" )
    NodeType = QtWidgets.QLabel( "(none)" )

    ParentLayout.addWidget( TitleLabel )
    ParentLayout.addWidget( NodeLabel )
    ParentLayout.addWidget( NodeType )

    EmptyLabel = QtWidgets.QLabel( "" )
    ParentLayout.addWidget( EmptyLabel )

    ParentLayout.addWidget( Separator() )

    # Build scrollable layout for blend modes
    BlendLabel = QtWidgets.QLabel( "<b>BLEND MODES</b>" )
    ParentLayout.addWidget( BlendLabel )

    Widget = QtWidgets.QWidget()
    VerticalLayout = QtWidgets.QVBoxLayout( Widget )

    BlendLayout = QtWidgets.QVBoxLayout()
    VerticalLayout.addLayout( BlendLayout )
    VerticalLayout.addStretch()
    VerticalLayout.setContentsMargins( 0, 0, 8, 0 )

    ScrollArea = QtWidgets.QScrollArea()
    ScrollArea.setWidget( Widget )
    ScrollArea.setWidgetResizable( True )

    ParentLayout.addWidget( ScrollArea )

    # Finish
    WIDGET_NODE_NAME = NodeLabel
    WIDGET_NODE_TYPE = NodeType
    WIDGET_BLEND_LAYOUT = BlendLayout

    return Parent

def start_plugin():
    global BLEND_MODES

    # Add event for getting layer stack selection updates
    sp.event.DISPATCHER.connect( sp.event.LayerStacksModelDataChanged, Update )

    # Build dock UI
    Parent = BuildUI()
    sp.ui.add_dock_widget( Parent, sp.ui.UIMode.Edition )
    ResetUI()
    WIDGETS.append(Parent)

    # Some enums at not iteratable currently,
    # so we rely on the members attribute to build a list
    BLEND_MODES = [ Value for Value in sp.layerstack.BlendingMode.__members__ ]

def close_plugin():
    sp.event.DISPATCHER.disconnect( sp.event.LayerStacksModelDataChanged, Update )

    for Widget in WIDGETS :
        sp.ui.delete_ui_element( Widget )

    WIDGETS.clear()

if __name__ == "__main__":
    start_plugin()