graphics_graph_event.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""B-ASIC Scheduler-gui Graphics Graph Event Module.

Contains event filters and handlers for GraphicsGraphItem objects."""

import os
import sys
from typing     import Any, Optional
from pprint     import pprint
from typing     import Any, AnyStr, Generic, Protocol, TypeVar, Union, Optional, overload, Final, final
# from typing_extensions import Self, Final, Literal, LiteralString, TypeAlias, final
import numpy    as np
from copy       import deepcopy
from itertools  import combinations

import qtpy
from qtpy import QtCore
from qtpy import QtGui
from qtpy import QtWidgets

# QGraphics and QPainter imports
from qtpy.QtCore    import (
    Qt, QObject, QRect, QRectF, QPoint, QSize, QSizeF, QByteArray, Slot, QEvent)
from qtpy.QtGui     import (
    QPaintEvent, QPainter, QPainterPath, QColor, QBrush, QPen, QFont, QPolygon, QIcon, QPixmap,
    QLinearGradient, QTransform, QCursor, QFocusEvent)
from qtpy.QtWidgets import (
    QGraphicsView, QGraphicsScene, QGraphicsWidget,
    QGraphicsLayout, QGraphicsLinearLayout, QGraphicsGridLayout, QGraphicsLayoutItem, QGraphicsAnchorLayout,
    QGraphicsItem, QGraphicsItemGroup, QGraphicsPathItem, QGraphicsLineItem, QGraphicsRectItem,
    QStyleOptionGraphicsItem, QWidget,
    QGraphicsObject, QGraphicsSceneMouseEvent, QGraphicsSceneHoverEvent, QGraphicsSceneContextMenuEvent,
    QGraphicsSceneDragDropEvent, QGraphicsSceneWheelEvent)
from qtpy.QtCore    import (
    QPoint, QPointF)

from abc import ABC
from graphics_component_item import GraphicsComponentItem




# class GraphicsGraphEvent(ABC):
class GraphicsGraphEvent(QGraphicsItem):
    """Event filter and handlers for GraphicsGraphItem"""
    # _components:   list[GraphicsComponentItem]
    _current_pos: QPointF

    # def __init__(self, parent: QGraphicsItem = None):
    #     super().__init__(parent)
        # self._current_pos: QPointF()
        # self.setAcceptedMouseButtons(Qt.LeftButton)
        # self.setFlag(QGraphicsItem.ItemIsMovable)
        # self.setFlag(QGraphicsItem.ItemIsSelectable)
        # self.setAcceptHoverEvents(True)
        # self.setFlag(QGraphicsItem.ItemSendsGeometryChanges)
        
        # self.setFlag(QGraphicsItem.ItemIsMovable)
        # self.setFlag(QGraphicsItem.ItemIsSelectable)
        # self.setAcceptHoverEvents(True)
        # print(f'GraphicsGraphItem.handlesChildEvents(): {self.handlesChildEvents()}')
        # self.setHandlesChildEvents(True)   # PySide2 QGraphicsItemGroup default: true. PyQt5 not an option
        # self.setAcceptedMouseButtons(Qt.NoButton)



    #################
    #### Filters ####
    #################
    def installSceneEventFilters(self) -> None:
        """Installs an event filter for 'item' on 'self', causing
        all events for 'item' to first pass through 'self's
        sceneEventFilter() function."""
        for item in self._components:
            item.installSceneEventFilter(self)
        # self.setFiltersChildEvents(True)    # default false
        
    def removeSceneEventFilters(self) -> None:
        """Removes an event filter on 'item' from 'self'."""
        for item in self._components:
            item.removeSceneEventFilter(self)
        # self.setFiltersChildEvents(False)
        
    
    def sceneEventFilter(self, item: QGraphicsItem, event: QEvent) -> bool:
        """Returns true if the event was filtered (i.e. stopped), otherwise false.
        If false is returned, the event is forwarded to the appropriate child in
        the event chain."""
        handler = None

        if isinstance(item, GraphicsComponentItem):
            switch = {
                QEvent.FocusIn:                         self.comp_focusInEvent,
                QEvent.GraphicsSceneContextMenu:        self.comp_contextMenuEvent,
                QEvent.GraphicsSceneDragEnter:          self.comp_dragEnterEvent,
                QEvent.GraphicsSceneDragMove:           self.comp_dragMoveEvent,
                QEvent.GraphicsSceneDragLeave:          self.comp_dragLeaveEvent,
                QEvent.GraphicsSceneDrop:               self.comp_dropEvent,
                QEvent.GraphicsSceneHoverEnter:         self.comp_hoverEnterEvent,
                QEvent.GraphicsSceneHoverMove:          self.comp_hoverMoveEvent,
                QEvent.GraphicsSceneHoverLeave:         self.comp_hoverLeaveEvent,
                QEvent.GraphicsSceneMouseMove:          self.comp_mouseMoveEvent,
                QEvent.GraphicsSceneMousePress:         self.comp_mousePressEvent,
                QEvent.GraphicsSceneMouseRelease:       self.comp_mouseReleaseEvent,
                QEvent.GraphicsSceneMouseDoubleClick:   self.comp_mouseDoubleClickEvent,
                QEvent.GraphicsSceneWheel:              self.comp_wheelEvent
            }

            handler = switch.get(event.type())
        else:
            raise TypeError
        
        if handler:
            handler(event)
            return True
        return False    # returns False if event is ignored and pass through event to its child

    # def sceneEvent(self, event: QEvent) -> bool:
    #     print(f'sceneEvent() --> {event.type()}')
    #     # event.accept()
    #     # QApplication.sendEvent(self.scene(), event)
    #     return False


    ###############################################
    #### Event Handlers: GraphicsComponentItem ####
    ###############################################
    def comp_focusInEvent(self, event: QFocusEvent) -> None: ...
    def comp_contextMenuEvent(self, event: QGraphicsSceneContextMenuEvent) -> None: ...
    def comp_dragEnterEvent(self, event: QGraphicsSceneDragDropEvent) -> None: ...
    def comp_dragMoveEvent(self, event: QGraphicsSceneDragDropEvent) -> None: ...
    def comp_dragLeaveEvent(self, event: QGraphicsSceneDragDropEvent) -> None: ...
    def comp_dropEvent(self, event: QGraphicsSceneDragDropEvent) -> None: ...
    
    def comp_hoverEnterEvent(self, event: QGraphicsSceneHoverEvent) -> None:
        """Changes the cursor to OpenHandCursor when hovering an object."""
        self.setCursor(QCursor(Qt.OpenHandCursor))
    
    def comp_hoverMoveEvent(self, event: QGraphicsSceneHoverEvent) -> None: ...
    
    def comp_hoverLeaveEvent(self, event: QGraphicsSceneHoverEvent) -> None:
        """Changes the cursor to ArrowCursor when leaving an object."""
        self.setCursor(QCursor(Qt.ArrowCursor))

    def comp_mouseMoveEvent(self, event: QGraphicsSceneMouseEvent) -> None:
        """Set the position of the graphical element in the graphic scene, 
        translate coordinates of the cursor within the graphic element 
        in the coordinate system of the parent object."""
        # Qt.DragMoveCursor
        # button = event.button()
        item = self.scene().mouseGrabberItem()
        dx = (item.mapToParent(event.pos()) - self._current_pos).x()
        if dx > 0.505:
            pos = item.x() + 1.0
            if self.is_valid_pos(pos):
                self.prepareGeometryChange()
                item.setX(pos)
                self._current_pos.setX(self._current_pos.x() + 1.0)
        elif dx < -0.505:
            pos = item.x() - 1.0
            if self.is_valid_pos(pos):
                self.prepareGeometryChange()
                item.setX(pos)
                self._current_pos.setX(self._current_pos.x() - 1.0)
    
    def comp_mousePressEvent(self, event: QGraphicsSceneMouseEvent) -> None:
        """Changes the cursor to ClosedHandCursor when grabbing an object."""
        item = self.scene().mouseGrabberItem()
        self._current_pos = item.mapToParent(event.pos())
        self.setCursor(QCursor(Qt.ClosedHandCursor))
        event.accept()
    
    def comp_mouseReleaseEvent(self, event: QGraphicsSceneMouseEvent) -> None:
        """Changes the cursor to OpenHandCursor when releasing an object."""
        self.setCursor(QCursor(Qt.OpenHandCursor))
        event.accept()

    def comp_mouseDoubleClickEvent(self, event: QGraphicsSceneMouseEvent) -> None: ...
    def comp_wheelEvent(self, event: QGraphicsSceneWheelEvent) -> None: ...
    
    ###############################################
    #### Event Handlers: GraphicsComponentItem ####
    ###############################################