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
|
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPen
from PyQt5.QtWidgets import QGraphicsView, QGraphicsScene, QGraphicsProxyWidget, QGraphicsItem
from PyQt5 import QtWidgets
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
graphic = getattr(QtWidgets, 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().addItem(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
"""
pass
|
