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from PyQt5.QtCore import Qt, QPointF, pyqtSignal
from PyQt5.QtGui import QPen, QKeySequence
from PyQt5.QtWidgets import QGraphicsView, QGraphicsScene, QGraphicsProxyWidget, QGraphicsItem, QUndoStack, QAction, QUndoView
from .undo import *
from .dialogs import showUndoDialog
import shapes
class CustomView(QGraphicsView):
"""
Defines custom QGraphicsView with zoom features and drag-drop accept event, overriding wheel event
"""
def __init__(self, scene = None, parent=None):
if scene is not None: #overloaded constructor
super(CustomView, self).__init__(scene, parent)
else:
super(CustomView, self).__init__(parent)
self._zoom = 1
self.setDragMode(True) #sets pannable using mouse
self.setAcceptDrops(True) #sets ability to accept drops
#following four functions are required to be overridden for drag-drop functionality
def dragEnterEvent(self, QDragEnterEvent):
#defines acceptable drop items
if QDragEnterEvent.mimeData().hasText():
QDragEnterEvent.acceptProposedAction()
def dragMoveEvent(self, QDragMoveEvent):
#defines acceptable drop items
if QDragMoveEvent.mimeData().hasText():
QDragMoveEvent.acceptProposedAction()
def dragLeaveEvent(self, QDragLeaveEvent):
#accept any drag leave event, avoid unnecessary logging
QDragLeaveEvent.accept()
def dropEvent(self, QDropEvent):
#defines item drop, fetches text, creates corresponding QGraphicItem and adds it to scene
if QDropEvent.mimeData().hasText():
#QDropEvent.mimeData().text() defines intended drop item, the pos values define position
obj = QDropEvent.mimeData().text().split('/')
graphic = getattr(shapes, obj[0])(*map(lambda x: int(x) if x.isdigit() else x, obj[1:]))
graphic.setPos(QDropEvent.pos().x(), QDropEvent.pos().y())
self.scene().addItemPlus(graphic)
QDropEvent.acceptProposedAction()
def wheelEvent(self, QWheelEvent):
#overload wheelevent, to zoom if control is pressed, else scroll normally
if QWheelEvent.modifiers() & Qt.ControlModifier: #check if control is pressed
if QWheelEvent.source() == Qt.MouseEventNotSynthesized: #check if precision mouse(mac)
# angle delta is 1/8th of a degree per scroll unit
if self.zoom + QWheelEvent.angleDelta().y()/2880 > 0.1: # hit and trial value (2880)
self.zoom += QWheelEvent.angleDelta().y()/2880
else:
# precision delta is exactly equal to amount to scroll
if self.zoom + QWheelEvent.pixelDelta().y() > 0.1:
self.zoom += QWheelEvent.angleDelta().y()
QWheelEvent.accept() # accept event so that scrolling doesnt happen simultaneously
else:
return super(CustomView, self).wheelEvent(QWheelEvent) # scroll if ctrl not pressed
@property
def zoom(self):
# property for zoom
return self._zoom
@zoom.setter
def zoom(self, value):
# set scale according to zoom value being set
temp = self.zoom
self._zoom = value
self.scale(self.zoom / temp, self.zoom / temp)
class CustomScene(QGraphicsScene):
"""
Extends QGraphicsScene with undo-redo functionality
"""
labelAdded = pyqtSignal(shapes.QGraphicsItem)
def __init__(self, *args, parent=None):
super(CustomScene, self).__init__(*args, parent=parent)
self.undoStack = QUndoStack(self) #Used to store undo-redo moves
self.createActions() #creates necessary actions that need to be called for undo-redo
def createActions(self):
# helper function to create delete, undo and redo shortcuts
self.deleteAction = QAction("Delete Item", self)
self.deleteAction.setShortcut(Qt.Key_Delete)
self.deleteAction.triggered.connect(self.deleteItem)
self.undoAction = self.undoStack.createUndoAction(self, "Undo")
self.undoAction.setShortcut(QKeySequence.Undo)
self.redoAction = self.undoStack.createRedoAction(self, "Redo")
self.redoAction.setShortcut(QKeySequence.Redo)
def createUndoView(self, parent):
# creates an undo stack view for current QGraphicsScene
undoView = QUndoView(self.undoStack, parent)
showUndoDialog(undoView, parent)
def deleteItem(self):
# (slot) used to delete all selected items, and add undo action for each of them
if self.selectedItems():
for item in self.selectedItems():
if(issubclass(item.__class__,shapes.LineGripItem) or issubclass(item.__class__,shapes.SizeGripItem) ):
itemToDelete = item.parentItem()
else:
itemToDelete = item
self.count = 0
if(issubclass(itemToDelete.__class__,shapes.NodeItem)):
for i in itemToDelete.lineGripItems:
for j in i.lines:
self.count+=1
self.undoStack.push(deleteCommand(j, self))
self.undoStack.push(deleteCommand(itemToDelete, self))
def itemMoved(self, movedItem, lastPos):
#item move event, checks if item is moved
self.undoStack.push(moveCommand(movedItem, lastPos))
self.advance()
def addItemPlus(self, item):
# extended add item method, so that a corresponding undo action is also pushed
self.undoStack.push(addCommand(item, self))
def mousePressEvent(self, event):
# overloaded mouse press event to check if an item was moved
bdsp = event.buttonDownScenePos(Qt.LeftButton) #get click pos
point = QPointF(bdsp.x(), bdsp.y()) #create a Qpoint from click pos
itemList = self.items(point) #get items at said point
self.movingItem = itemList[0] if itemList else None #set first item in list as moving item
if self.movingItem and event.button() == Qt.LeftButton:
self.oldPos = self.movingItem.pos() #if left click is held, then store old pos
self.clearSelection() #clears selected items
return super(CustomScene, self).mousePressEvent(event)
def mouseReleaseEvent(self, event):
# overloaded mouse release event to check if an item was moved
if self.movingItem and event.button() == Qt.LeftButton:
if self.oldPos != self.movingItem.pos():
#if item pos had changed, when mouse was realeased, emit itemMoved signal
self.itemMoved(self.movingItem, self.oldPos)
self.movingItem = None #clear movingitem reference
return super(CustomScene, self).mouseReleaseEvent(event)
def reInsertLines(self):
currentIndex = self.undoStack.index()
i = 2
while i != self.count+2:
currentLine = self.undoStack.command(currentIndex-i).diagramItem
startGrip = self.undoStack.command(currentIndex-i).startGrip
endGrip = self.undoStack.command(currentIndex-i).endGrip
index_LineGripStart = self.undoStack.command(currentIndex-i).indexLGS
index_LineGripEnd = self.undoStack.command(currentIndex-i).indexLGE
startGrip.lineGripItems[index_LineGripStart].lines.append(currentLine)
endGrip.lineGripItems[index_LineGripEnd].lines.append(currentLine)
self.undoStack.setIndex(currentIndex-i)
i+=1
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