[PyQt] FetchMore Example

[Darryl Wallace]

Hello Everyone,

Since I was interested in the FetchMore example (included in Qt4.5) and 
extending it for myself, I just decided to port the FetchMore example to 
PyQt4 since I noticed it was not included in the ItemViews examples in 
the latest snapshot. 

Feel free to use it as you wish.

Phil feel free to included it in your list of examples should it be 
deemed acceptable.  The only thing that I have done differently is that 
I force the QStringList to be a Python list.  I wrote it using PyQt4.4.2 
in Linux (Ubuntu).

See the attached file.

Regards,
Darryl
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# Fetch More Example
# Ported to PyQt4 by Darryl Wallace, 2009 - wallacdj at gmail.com

import sys
from PyQt4 import QtGui, QtCore

class FileListModel(QtCore.QAbstractListModel):
    
    def __init__(self, parent=None):
        QtCore.QAbstractListModel.__init__(self, parent)
        self.fileCount=0    
        self.fileList=[]    #initialize the file list as a Python list.
    #__init__
    
    def rowCount(self, parent):
        """
        parent=QModelIndex
        """
        return self.fileCount
    #rowCount
    
    def data(self, index, role=QtCore.Qt.DisplayRole):
        """
        index=QModelIndex
        """
        if not index.isValid():
            return QtCore.QVariant()
        
        if index.row()>=len(self.fileList) or index.row()<0:
            return QtCore.QVariant()
        
        if role==QtCore.Qt.DisplayRole:
            return QtCore.QVariant(self.fileList[index.row()])
        elif role==QtCore.Qt.BackgroundRole:
            batch=(index.row()/100)%2
            if batch==0:
                return QtCore.QVariant(QtGui.qApp.palette().base())
            else:
                return QtCore.QVariant(QtGui.qApp.palette().alternateBase())
        return QtCore.QVariant()
    #data
    
    def canFetchMore(self, index):
        """
        index=QModelIndex
        """
        if self.fileCount<len(self.fileList):
            return True
        else:
            return False
    #canFetchMore
    
    def fetchMore(self, index):
        """
        Index=QModelIndex
        """
        
        remainder=len(self.fileList)-self.fileCount
        itemsToFetch=min(100, remainder)
        
        self.beginInsertRows(QtCore.QModelIndex(), self.fileCount, self.fileCount+itemsToFetch)
        
        self.fileCount+=itemsToFetch
        
        self.endInsertRows()
        
        self.emit(QtCore.SIGNAL("numberPopulated"), itemsToFetch)
    #fetchMore
    
    def setDirPath(self, path):
        dir=QtCore.QDir(path)
        
        self.fileList=list(dir.entryList()) # force Python list.
        self.fileCount=0
        self.reset()
    #setDirPath
#FileListModel

class Window(QtGui.QWidget):
    
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        
        self.model = FileListModel(self)
        self.model.setDirPath(QtCore.QLibraryInfo.location(QtCore.QLibraryInfo.PrefixPath))
        
        label = QtGui.QLabel(self.tr("Directory"))
        lineEdit=QtGui.QLineEdit()
        label.setBuddy(lineEdit)
        
        view=QtGui.QListView()
        view.setModel(self.model)
        
        self.logViewer=QtGui.QTextBrowser()
        self.logViewer.setSizePolicy(QtGui.QSizePolicy(QtGui.QSizePolicy.Preferred, QtGui.QSizePolicy.Preferred))
        
        self.connect(lineEdit, QtCore.SIGNAL("textChanged(const QString &)"), self.model.setDirPath)
        self.connect(lineEdit, QtCore.SIGNAL("textChanged(const QString &)"), 
                     self.logViewer, QtCore.SLOT("clear()"))
        self.connect(self.model, QtCore.SIGNAL("numberPopulated"), self.updateLog)
        
        layout=QtGui.QGridLayout()
        layout.addWidget(label, 0, 0)
        layout.addWidget(lineEdit, 0, 1)
        layout.addWidget(view, 1, 0, 1, 2)
        layout.addWidget(self.logViewer, 2, 0, 1, 2)
        
        self.setLayout(layout)
        
        self.setWindowTitle(self.tr("Fetch More Example"))
    #__init__
    
    def updateLog(self, number):
        self.logViewer.append(self.tr("%1 items added.").arg(number))
    #updateLog
#Window

if __name__=='__main__':
    qApp=QtGui.QApplication(sys.argv)
    
    fetchMoreWindow=Window()
    fetchMoreWindow.show()
    sys.exit(qApp.exec_())