1#!/usr/bin/env python
2
3
4#############################################################################
5##
6## Copyright (C) 2013 Riverbank Computing Limited.
7## All rights reserved.
8##
9## This file is part of the examples of PyQt.
10##
11## You may use this file under the terms of the BSD license as follows:
12##
13## "Redistribution and use in source and binary forms, with or without
14## modification, are permitted provided that the following conditions are
15## met:
16##   * Redistributions of source code must retain the above copyright
17##     notice, this list of conditions and the following disclaimer.
18##   * Redistributions in binary form must reproduce the above copyright
19##     notice, this list of conditions and the following disclaimer in
20##     the documentation and/or other materials provided with the
21##     distribution.
22##   * Neither the name of Riverbank Computing Limited nor the names of
23##     its contributors may be used to endorse or promote products
24##     derived from this software without specific prior written
25##     permission.
26##
27## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
30## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
31## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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33## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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35## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
37## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
38##
39#############################################################################
40
41
42from PyQt5.QtCore import pyqtProperty, pyqtSignal, pyqtSlot
43from PyQt5.QtWidgets import QApplication, QTextEdit
44
45
46# The purpose of this class is to show that Designer's property editor shows
47# all Python classes in the hierarchy that define properties.
48class PyTextViewer(QTextEdit):
49
50    # Initialise the instance.
51    def __init__(self, parent=None):
52        super(PyTextViewer, self).__init__(parent)
53
54        self.setReadOnly(True)
55
56        # Initialise the author property by calling it's reset function.
57        self.resetAuthor()
58
59    # The getter for the author property.  Note that we cannot follow the Qt
60    # naming convention (ie. by using the naming the getter "author") because
61    # it would conflict with the property name.
62    def getAuthor(self):
63        return self._author
64
65    # The setter for the author property.
66    def setAuthor(self, name):
67        self._author = name
68
69    # The resetter for the author property.  Only Qt Designer uses this.  Qt
70    # Designer does not use the deleter function of the property.
71    def resetAuthor(self):
72        self._author = "David Boddie"
73
74    # Define the author property.  This will look like a C++ property to Qt
75    # Designer and a Python property to Python.
76    author = pyqtProperty(str, getAuthor, setAuthor, resetAuthor)
77
78
79# This is the class that implements the custom widget.
80class PyDemo(PyTextViewer):
81
82    # Define the Qt signals as a sequence of C++ function signatures excluding
83    # the return type.  These may be connected to other signals or slots in Qt
84    # Designer.
85    zoomChanged = pyqtSignal(int)
86
87    # Initialise the instance.
88    def __init__(self, parent=None):
89        super(PyDemo, self).__init__(parent)
90
91        self.setWindowTitle("PyQt Demonstration Widget")
92        self.setText(_demo_text)
93
94        # Initialise the zoom property.  We don't just call the resetter
95        # because it assumes that this has already been initialised.
96        self._zoom = 0
97
98    # The getter for the zoom property.
99    def getZoom(self):
100        return self._zoom
101
102    # The setter for the zoom property.  We also make define this as a Qt slot
103    # which can be connected to Qt signals in Qt Designer.
104    @pyqtSlot(int)
105    def setZoom(self, zoom):
106        # Don't do anything if nothing has changed.
107        if self._zoom == zoom:
108            return
109
110        # Zoom in or out according to the relative zoom levels.
111        if self._zoom < zoom:
112            self.zoomIn(zoom - self._zoom)
113        elif self._zoom > zoom:
114            self.zoomOut(self._zoom - zoom)
115
116        # Remember the new zoom level.
117        self._zoom = zoom
118
119        # Emit the Qt signal to say that the zoom level has changed.
120        self.zoomChanged.emit(zoom)
121
122    # The resetter for the zoom property.
123    def resetZoom(self):
124        self.setZoom(0)
125
126    # Define the zoom property.  Changing the value of this in Qt Designer's
127    # property editor causes the zoom level to change dynamically.
128    zoom = pyqtProperty(int, getZoom, setZoom, resetZoom)
129
130
131# The text displayed in the custom widget.
132_demo_text = """<h3>PyQt Demonstration Widget</h3>
133<p>This simple example demonstrates the following features.</p>
134<ul>
135 <li>The definition of properties that behave as C++ properties to Qt and
136     Python properties to Python.</li>
137 <li>The definition of new Qt signals that can be connected to other signals
138     and Qt slots in Designer.</li>
139 <li>The definition of new Qt slots that can be connected to signals in
140     Designer.</li>
141</ul>
142"""
143
144
145# Display the custom widget if the script is being run directly from the
146# command line.
147if __name__ == "__main__":
148
149    import sys
150
151    app = QApplication(sys.argv)
152
153    demo = PyDemo()
154    demo.show()
155
156    sys.exit(app.exec_())
157