PyQT4: Drag and drop files into QListWidget

Question

I've been coding a OCR book scanning thing (it renames pages by reading the page number), and have switched to a GUI from my basic CLI Python script.

I'm using PyQT4 and looked at a ton of documents on drag and drop, but no luck. It just refuses to take those files! I was using these to articles for my UI design:

1. http://tech.xster.net/tips/pyqt-drag-images-into-list-widget-for-thumbnail-list/

2. http://zetcode.com/tutorials/pyqt4/dragdrop/

I noticed that there are a TON of ways to setup a PyQT4 GUI. Which one works the best?

Oops, here's the source code for the project.

The main script:

import sys
from PyQt4 import QtCore
from PyQt4 import QtGui
from PyQt4.QtGui import QListWidget
from layout import Ui_window

class StartQT4(QtGui.QMainWindow):
  def __init__(self, parent = None):
    QtGui.QWidget.__init__(self, parent)

    self.ui = Ui_window()
    self.ui.setupUi(self)

    QtCore.QObject.connect(self.ui.listWidget, QtCore.SIGNAL("dropped"), self.picture_dropped)

  def picture_dropped(self, l):
    for url in l:
     if os.path.exists(url):
      picture = Image.open(url)
      picture.thumbnail((72, 72), Image.ANTIALIAS)
      icon = QIcon(QPixmap.fromImage(ImageQt.ImageQt(picture)))
      item = QListWidgetItem(os.path.basename(url)[:20] + "...", self.pictureListWidget)
      item.setStatusTip(url)
      item.setIcon(icon)

class DragDropListWidget(QListWidget):
 def __init__(self, type, parent = None):
  super(DragDropListWidget, self).__init__(parent)
  self.setAcceptDrops(True)
  self.setIconSize(QSize(72, 72))

 def dragEnterEvent(self, event):
  if event.mimeData().hasUrls:
   event.accept()
  else:
   event.ignore()

 def dragMoveEvent(self, event):
  if event.mimeData().hasUrls:
   event.setDropAction(Qt.CopyAction)
   event.accept()
  else:
   event.ignore()

 def dropEvent(self, event):
  if event.mimeData().hasUrls:
   event.setDropAction(Qt.CopyAction)
   event.accept()
   l = []
   for url in event.mimeData().urls():
    l.append(str(url.toLocalFile()))
   self.emit(SIGNAL("dropped"), l)
  else:
   event.ignore()

if __name__ == "__main__":
  app = QtGui.QApplication(sys.argv)
  myapp = StartQT4()
  myapp.show()
  sys.exit(app.exec_())

And the UI file...

# Form implementation generated from reading ui file 'layout.ui'
#
# Created: Thu Nov 11 00:22:52 2010
#      by: PyQt4 UI code generator 4.8.1
#
# WARNING! All changes made in this file will be lost!

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    _fromUtf8 = lambda s: s

class Ui_window(object):
    def setupUi(self, window):
        window.setObjectName(_fromUtf8("window"))
        window.resize(543, 402)
        window.setAcceptDrops(True)
        self.centralwidget = QtGui.QWidget(window)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.verticalLayout = QtGui.QVBoxLayout(self.centralwidget)
        self.verticalLayout.setObjectName(_fromUtf8("verticalLayout"))
        self.listWidget = QtGui.QListWidget(self.centralwidget)
        self.listWidget.setProperty(_fromUtf8("cursor"), QtCore.Qt.SizeHorCursor)
        self.listWidget.setAcceptDrops(True)
        self.listWidget.setObjectName(_fromUtf8("listWidget"))
        self.verticalLayout.addWidget(self.listWidget)
        window.setCentralWidget(self.centralwidget)

        self.retranslateUi(window)
        QtCore.QMetaObject.connectSlotsByName(window)

    def retranslateUi(self, window):
        window.setWindowTitle(QtGui.QApplication.translate("window", "PyNamer OCR", None, QtGui.QApplication.UnicodeUTF8))

Thanks to anybody who can help!

Carnegie

Just to be sure, does "if event.mimeData().hasUrls" in dropEvent evaluates to True when you're dragging files into it? – Crossjack

I added a print() statement inside of every function, and it doesn't even seem to initialize the control! sobs – Carnegie

Answer 1

The code you're using as an example seem to work fine and looks quite clean. According to your comment your list widget is not getting initialized; this should be the root cause of your issue. I've simplified your code a bit a tried it on my Ubuntu 10.04LTS and it worked fine. My code is listed below, see if it would for you also. You should be able to drag and drop a file into the list widget; once it's dropped a new item is added showing the image and image's file name.

import sys
import os
from PyQt4 import QtGui, QtCore

class TestListView(QtGui.QListWidget):
    def __init__(self, type, parent=None):
        super(TestListView, self).__init__(parent)
        self.setAcceptDrops(True)
        self.setIconSize(QtCore.QSize(72, 72))

    def dragEnterEvent(self, event):
        if event.mimeData().hasUrls:
            event.accept()
        else:
            event.ignore()

    def dragMoveEvent(self, event):
        if event.mimeData().hasUrls:
            event.setDropAction(QtCore.Qt.CopyAction)
            event.accept()
        else:
            event.ignore()

    def dropEvent(self, event):
        if event.mimeData().hasUrls:
            event.setDropAction(QtCore.Qt.CopyAction)
            event.accept()
            links = []
            for url in event.mimeData().urls():
                links.append(str(url.toLocalFile()))
            self.emit(QtCore.SIGNAL("dropped"), links)
        else:
            event.ignore()

class MainForm(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainForm, self).__init__(parent)

        self.view = TestListView(self)
        self.connect(self.view, QtCore.SIGNAL("dropped"), self.pictureDropped)
        self.setCentralWidget(self.view)

    def pictureDropped(self, l):
        for url in l:
            if os.path.exists(url):
                print(url)                
                icon = QtGui.QIcon(url)
                pixmap = icon.pixmap(72, 72)                
                icon = QtGui.QIcon(pixmap)
                item = QtGui.QListWidgetItem(url, self.view)
                item.setIcon(icon)        
                item.setStatusTip(url)        

def main():
    app = QtGui.QApplication(sys.argv)
    form = MainForm()
    form.show()
    app.exec_()

if __name__ == '__main__':
    main()

hope this helps, regards

Sob

Wow, this will definitely help. I've already got my program running, and this will make it even better! Would it be possible to override the QListWidget class entirely? I wanted to add some new functions to it. – Carnegie

answer on your question depends on what exactly you're trying to achieve. I would probably start from using QListView and one of QAbstractModel descendants (or wrote my own one). There are plenty of examples around for you to start playing with. – Sob

You should edit all event.mimeData().hasUrls to event.mimeData().hasUrls() (at least for PyQt 4.8) – Nunnally