1#!/usr/bin/env python
2
3
4#############################################################################
5##
6## Copyright (C) 2013 Riverbank Computing Limited
7## Copyright (C) 2010 Darryl Wallace <wallacdj@gmail.com>.
8## Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
9## All rights reserved.
10##
11## This file is part of the examples of PyQt.
12##
13## $QT_BEGIN_LICENSE:BSD$
14## You may use this file under the terms of the BSD license as follows:
15##
16## "Redistribution and use in source and binary forms, with or without
17## modification, are permitted provided that the following conditions are
18## met:
19##   * Redistributions of source code must retain the above copyright
20##     notice, this list of conditions and the following disclaimer.
21##   * Redistributions in binary form must reproduce the above copyright
22##     notice, this list of conditions and the following disclaimer in
23##     the documentation and/or other materials provided with the
24##     distribution.
25##   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
26##     the names of its contributors may be used to endorse or promote
27##     products derived from this software without specific prior written
28##     permission.
29##
30## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
31## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
32## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
33## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
34## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
36## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
37## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
38## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
39## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
40## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
41## $QT_END_LICENSE$
42##
43#############################################################################
44
45
46from PyQt5.QtCore import (pyqtSignal, QAbstractListModel, QDir, QLibraryInfo,
47        QModelIndex, Qt)
48from PyQt5.QtWidgets import (QApplication, QGridLayout, QLabel, QLineEdit,
49        QListView, QSizePolicy, QTextBrowser, QWidget)
50
51
52class FileListModel(QAbstractListModel):
53    numberPopulated = pyqtSignal(int)
54
55    def __init__(self, parent=None):
56        super(FileListModel, self).__init__(parent)
57
58        self.fileCount = 0
59        self.fileList = []
60
61    def rowCount(self, parent=QModelIndex()):
62        return self.fileCount
63
64    def data(self, index, role=Qt.DisplayRole):
65        if not index.isValid():
66            return None
67
68        if index.row() >= len(self.fileList) or index.row() < 0:
69            return None
70
71        if role == Qt.DisplayRole:
72            return self.fileList[index.row()]
73
74        if role == Qt.BackgroundRole:
75            batch = (index.row() // 100) % 2
76            if batch == 0:
77                return QApplication.palette().base()
78
79            return QApplication.palette().alternateBase()
80
81        return None
82
83    def canFetchMore(self, index):
84        return self.fileCount < len(self.fileList)
85
86    def fetchMore(self, index):
87        remainder = len(self.fileList) - self.fileCount
88        itemsToFetch = min(100, remainder)
89
90        self.beginInsertRows(QModelIndex(), self.fileCount,
91                self.fileCount + itemsToFetch)
92
93        self.fileCount += itemsToFetch
94
95        self.endInsertRows()
96
97        self.numberPopulated.emit(itemsToFetch)
98
99    def setDirPath(self, path):
100        dir = QDir(path)
101
102        self.beginResetModel()
103        self.fileList = dir.entryList()
104        self.fileCount = 0
105        self.endResetModel()
106
107
108class Window(QWidget):
109    def __init__(self, parent=None):
110        super(Window, self).__init__(parent)
111
112        model = FileListModel(self)
113        model.setDirPath(QLibraryInfo.location(QLibraryInfo.PrefixPath))
114
115        label = QLabel("Directory")
116        lineEdit = QLineEdit()
117        label.setBuddy(lineEdit)
118
119        view = QListView()
120        view.setModel(model)
121
122        self.logViewer = QTextBrowser()
123        self.logViewer.setSizePolicy(QSizePolicy(QSizePolicy.Preferred, QSizePolicy.Preferred))
124
125        lineEdit.textChanged.connect(model.setDirPath)
126        lineEdit.textChanged.connect(self.logViewer.clear)
127        model.numberPopulated.connect(self.updateLog)
128
129        layout = QGridLayout()
130        layout.addWidget(label, 0, 0)
131        layout.addWidget(lineEdit, 0, 1)
132        layout.addWidget(view, 1, 0, 1, 2)
133        layout.addWidget(self.logViewer, 2, 0, 1, 2)
134
135        self.setLayout(layout)
136        self.setWindowTitle("Fetch More Example")
137
138    def updateLog(self, number):
139        self.logViewer.append("%d items added." % number)
140
141
142if __name__ == '__main__':
143
144    import sys
145
146    app = QApplication(sys.argv)
147
148    window = Window()
149    window.show()
150
151    sys.exit(app.exec_())
152