1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
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():
self.undoStack.push(deleteCommand(item, 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)
|
