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from PyQt5.QtCore import Qt, QPointF
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
if scene:
self.addAction(scene.undoAction)
self.addAction(scene.redoAction)
self.addAction(scene.deleteAction)
#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
graphic = getattr(shapes, QDropEvent.mimeData().text())(QDropEvent.pos().x()-150, QDropEvent.pos().y()-150, 300, 300)
graphic.setPen(QPen(Qt.black, 2))
graphic.setFlags(QGraphicsItem.ItemIsSelectable | QGraphicsItem.ItemIsMovable)
self.scene().addItemPlus(graphic)
QDropEvent.acceptProposedAction()
def wheelEvent(self, QWheelEvent):
#overload wheelevent, to zoom if control is pressed, else scroll normally
if 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().wheelEvent(self, 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):
"""
re-implement QGraphicsScene for future functionality
hint: QUndoFramework
"""
def __init__(self, *args, parent=None):
super(customScene, self).__init__(*args, parent=parent)
self.undoStack = QUndoStack(self)
self.createActions()
def createActions(self):
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):
undoView = QUndoView(self.undoStack, parent)
# undoView.resize(400, 400)
# undoView.show()
# undoView.setAttribute(Qt.WA_QuitOnClose, False)
showUndoDialog(undoView, parent)
def deleteItem(self):
if self.selectedItems():
for item in self.selectedItems():
self.undoStack.push(deleteCommand(item, self))
def itemMoved(self, movedItem, lastPos):
self.undoStack.push(moveCommand(movedItem, lastPos))
def addItemPlus(self, item):
# returnVal = self.addItem(item)
self.undoStack.push(addCommand(item, self))
# return returnVal
def mousePressEvent(self, event):
bdsp = event.buttonDownScenePos(Qt.LeftButton)
point = QPointF(bdsp.x(), bdsp.y())
itemList = self.items(point)
self.movingItem = itemList[0] if itemList else None
if self.movingItem and event.button() == Qt.LeftButton:
self.oldPos = self.movingItem.pos()
self.clearSelection()
return super(customScene, self).mousePressEvent(event)
def mouseReleaseEvent(self, event):
if self.movingItem and event.button() == Qt.LeftButton:
if self.oldPos != self.movingItem.pos():
self.itemMoved(self.movingItem, self.oldPos)
self.movingItem = None
return super(customScene, self).mouseReleaseEvent(event)
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