Please house help. When using tkinter, I find it difficult to call a defined function in a button when the def is below the button. I use python 3.6.9. Example
import tkinter
window = tkinter.Tk
button = tkinter.Button(window, text="hello",command=newpage()).grid(column=0, row=0)
def newpage():
new = tkinter.toplevel()
The button does not work except I use lambda and also the lambda does not work if I define something new under the button. The new definition blocks the lambda from seeing the other def.
NB: I use the lambda like this lambda:newpage()
NB: I use python 3.6.9
Also please how can I make many tkinter buttons to use the same command (as in def)
The newpage function should really be defined before being used, just as a good programming practice if for no other reason.
The variable window is being set to tkinter.Tk instead of the object returned by tkinter.Tk().
The button is calling the function immediately because command expects a function to run, and thinks you want it to run something returned by newpage, instead remove the () command=newpage.
Toplevel is capitalized, tkinter.Toplevel().
A function can be used by any button, just assign the command to use the function:
import tkinter
def newpage():
new = tkinter.Toplevel()
window = tkinter.Tk()
button1 = tkinter.Button(window,
text="hello1",
command=newpage).grid(column=0, row=0)
button2 = tkinter.Button(window,
text="hello2",
command=newpage).grid(column=0, row=1)
button3 = tkinter.Button(window,
text="hello3",
command=newpage).grid(column=0, row=2)
Related
I have two QListWidgets. The user can select multiple items from one list and drag them to the other list. But within each list, some items are draggable and some are not. If the selection contains both draggable and non-draggable items, a problem happens. Only the draggable items appear in the second list, which is correct. But all the items disappear from the first list.
In the animated image above, items 00, 01, and 02 are selected. Only items 00 and 02 are drag enabled. After the drag-and-drop, all three items are gone from the first list. How can I fix this?
Here is some code to reproduce the problem:
import random
import sys
from PySide import QtCore, QtGui
class TestMultiDragDrop(QtGui.QMainWindow):
def __init__(self, parent=None):
super(TestMultiDragDrop, self).__init__(parent)
centralWidget = QtGui.QWidget()
self.setCentralWidget(centralWidget)
layout = QtGui.QHBoxLayout(centralWidget)
self.list1 = QtGui.QListWidget()
self.list1.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
self.list1.setDefaultDropAction(QtCore.Qt.MoveAction)
self.list1.setSelectionMode(QtGui.QListWidget.ExtendedSelection)
self.list2 = QtGui.QListWidget()
self.list2.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
self.list2.setDefaultDropAction(QtCore.Qt.MoveAction)
self.list2.setSelectionMode(QtGui.QListWidget.ExtendedSelection)
layout.addWidget(self.list1)
layout.addWidget(self.list2)
self.fillListWidget(self.list1, 8, 'someItem')
self.fillListWidget(self.list2, 4, 'anotherItem')
def fillListWidget(self, listWidget, numItems, txt):
for i in range(numItems):
item = QtGui.QListWidgetItem()
newTxt = '{0}{1:02d}'.format(txt, i)
if random.randint(0, 1):
item.setFlags(QtCore.Qt.ItemIsSelectable | QtCore.Qt.ItemIsEnabled)
else:
# If the item is draggable, indicate it with a *
newTxt += ' *'
item.setFlags(QtCore.Qt.ItemIsSelectable | QtCore.Qt.ItemIsEnabled | QtCore.Qt.ItemIsDragEnabled)
item.setText(newTxt)
listWidget.addItem(item)
def openMultiDragDrop():
global multiDragDropUI
try:
multiDragDropUI.close()
except:
pass
multiDragDropUI = TestMultiDragDrop()
multiDragDropUI.setAttribute(QtCore.Qt.WA_DeleteOnClose)
multiDragDropUI.show()
return multiDragDropUI
if __name__ == '__main__':
app = QtGui.QApplication([])
openMultiDragDrop()
sys.exit(app.exec_())
Here I have some suspicion on setDefaultDropAction(QtCore.Qt.MoveAction)
Read below para from documentation: Specially the bold line
In the simplest case, the target of a drag and drop action receives a copy of the data being dragged, and the source decides whether to delete the original. This is described by the CopyAction action. The target may also choose to handle other actions, specifically the MoveAction and LinkAction actions. If the source calls QDrag::exec(), and it returns MoveAction, the source is responsible for deleting any original data if it chooses to do so. The QMimeData and QDrag objects created by the source widget should not be deleted - they will be destroyed by Qt.
(http://doc.qt.io/qt-4.8/dnd.html#overriding-proposed-actions)
First give a try with QtCore.Qt.CopyAction
Second, if MoveAction is mandatory, try creating QMimeData and QDrag objects in your source list widget's mouseMoveEvent.
Here in below link, you can find some help for creating QMimeData and QDrag objects in your source list widget's mouseMoveEvent. (code is in C++, My intention is to get conceptual idea).
http://doc.qt.io/qt-4.8/dnd.html#overriding-proposed-actions
I think Kuba Ober is right that this is a Qt bug. In the C++ source code, there is a function void QAbstractItemViewPrivate::clearOrRemove(). It deletes all selected rows, but it does not look at whether each item is drag-enabled or not.
That being the case, I came up with a few workarounds:
Method 1: Make all non-draggable items non-selectable as well
This is the easiest method. Just remove the QtCore.Qt.ItemIsEnabled flag from all non-draggable items. Of course if you want all of your items to be selectable, this won't work.
Method 2: Recreate the "startDrag" function
Since the clearOrRemove function belongs to a private class, I cannot override it. But that function is called by the startDrag function, which can be overridden. So I essentially duplicated the function in Python and replaced the call to clearOrRemove with my own function removeSelectedDraggableItems.
The problem with this method is that startDrag contains calls to a few other functions belonging to a private class. And those functions call other private class functions. Specifically, these functions are responsible for controlling how the items are drawn during the drag event. Since I didn't want to recreate all the functions, I just ignored those. The result is that this method results in the correct functionality, but it loses the graphical indication of which items are being dragged.
class DragListWidget(QtGui.QListWidget):
def __init__(self):
super(DragListWidget, self).__init__()
def startDrag(self, supportedDragActions):
indexes = self.getSelectedDraggableIndexes()
if not indexes:
return
mimeData = self.model().mimeData(indexes)
if not mimeData:
return
drag = QtGui.QDrag(self)
rect = QtCore.QRect()
# "renderToPixmap" is from a private class in the C++ code, so I can't use it.
#pixmap = renderToPixmap(indexes, rect)
#drag.setPixmap(pixmap)
drag.setMimeData(mimeData)
# "pressedPosition" is from a private class in the C++ code, so I can't use it.
#drag.setHotSpot(pressedPostion() - rect.topLeft())
defaultDropAction = self.defaultDropAction()
dropAction = QtCore.Qt.IgnoreAction
if ((defaultDropAction != QtCore.Qt.IgnoreAction) and
(supportedDragActions & defaultDropAction)):
dropAction = defaultDropAction
elif ((supportedDragActions & QtCore.Qt.CopyAction) and
(self.dragDropMode() != self.InternalMove)):
dropAction = QtCore.Qt.CopyAction
dragResult = drag.exec_(supportedDragActions, dropAction)
if dragResult == QtCore.Qt.MoveAction:
self.removeSelectedDraggableItems()
def getSelectedDraggableIndexes(self):
""" Get a list of indexes for selected items that are drag-enabled. """
indexes = []
for index in self.selectedIndexes():
item = self.itemFromIndex(index)
if item.flags() & QtCore.Qt.ItemIsDragEnabled:
indexes.append(index)
return indexes
def removeSelectedDraggableItems(self):
selectedDraggableIndexes = self.getSelectedDraggableIndexes()
# Use persistent indices so we don't lose track of the correct rows as
# we are deleting things.
root = self.rootIndex()
model = self.model()
persistentIndices = [QtCore.QPersistentModelIndex(i) for i in selectedDraggableIndexes]
for pIndex in persistentIndices:
model.removeRows(pIndex.row(), 1, root)
Method 3: Hack "startDrag"
This method changes the drop action from "MoveAction" to "CopyAction" before calling the built-in "startDrag" method. Then it calls a custom function for deleting the selected drag-enabled items. This solves the problem of losing the graphical dragging animation.
This is a pretty easy hack, but it comes with its own problem. Say the user installs an event filter that changes the drop action from "MoveAction" to "IgnoreAction" in certain cases. This hack code doesn't get the updated value. It will still delete the items as though the action is "MoveAction". (Method 2 does not have this problem.) There are workarounds for this problem, but I won't go into them here.
class DragListWidget2(QtGui.QListWidget):
def startDrag(self, supportedDragActions):
dropAction = self.defaultDropAction()
if dropAction == QtCore.Qt.MoveAction:
self.setDefaultDropAction(QtCore.Qt.CopyAction)
super(DragListWidget2, self).startDrag(supportedDragActions)
if dropAction == QtCore.Qt.MoveAction:
self.setDefaultDropAction(dropAction)
self.removeSelectedDraggableItems()
def removeSelectedDraggableItems(self):
# Same code from Method 2. Removed here for brevity.
pass
I'm trying to use the IntSlider widget in IPython.html.widgets, and I want to call a function whenever the slider value changes. Additionally, I want to pass multiple arguments into the function. I was able to use on_trait_change() to call a function but have no idea how to pass arguments:
def somefn(parameter1, parameter2):
print (parameter1, parameter2)
slider = widgets.IntSlider(min=0,max=3,step=1)
slider.on_trait_change(somefn)
I would suggest using a partial.
from IPython.display import display
import ipywidgets as widgets
def somefn(parameter1,my_arg):
print ("parameter1: {}".format(parameter1))
print ("my_arg: {}".format(my_arg))
from functools import partial
somefn_arg_0 = partial(somefn, my_arg=0)
slider = widgets.IntSlider(min=0,max=3,step=1)
slider.observe(somefn_arg_0)
display(slider)
Note I have replaced the deprecated on_trait_change with observe.
I was wondering if I can make an output interactively run a piece of code. So if for example I had a class (parts in pseudo-code):
import numpy as np
class test(object):
def __init__():
self.a = np.random.randn(10)
print ## Interactive Output: Click me to view data array##
def show():
print a
So when I create a class instance it should output some interactive link (maybe in html) or something like that and when I click it, the show() method should be called. However, I have no idea how to achieve that.
You could use the widgets shipped with the notebook (for jupyter they are an independent package).
Something like this could do what you want (Python 3):
from IPython.html import widgets
from IPython.display import display
import numpy as np
class Test(object):
def __init__(self, arraylen):
self.a = np.random.randn(arraylen)
self.button = widgets.Button(description = 'Show')
self.button.on_click(self.show)
display(self.button)
def show(self, ev = None):
display(self.a)
self.button.disabled = True
test = Test(10)
You create a button widget when you initialise the class widgets.Button(description = 'Show')
Attach an event to it button.on_click(self.show)
And display the button display(self.button)
In the show method I included a way to disable the button functionality once the array is showed self.button.disabled = True. You can comment this line if you want to show more times the array.
I pretty new in this whole Python thing and my question is how to make, that a button runs the command, when clicking it and not before.
I searched much in the Internet but i didnt find anything.
I dont understand the classes at all. Is there no other way to do this?
Here is my work, i did on the programm.
Thanks for your help
from tkinter import *
import os
t = ""
def ordner(x):
print ("def")
if os.path.exists(os.path.join("/Kunden/",x)) == True:
pass
else:
os.mkdir(os.path.join("/Kunden/",x))
def E1holen():
x = E1.get()
ordner(x)
#Hauptfenster
main=Tk(className='Kundendatenbank')
main.iconbitmap('icon.ico')
#Inhalt Hauptfenster
L1 = Label(main, text="Kundenname:")
L1.pack(side = LEFT)
E1 = Entry(main, bd =5, textvariable=t)
E1.pack(side = RIGHT)
a = Button (main, text=("erstellen/bearbeiten"), command=E1holen()).pack()
main.mainloop()
It runs immediately ecause you tell it to.
What is the syntax for calling a function in Python? It's foo(), right? So, when you do command=E1holen(), what should python do? It should call E1holen(), and then pass the result to the command attribute.
Put another way, the command attribute takes a reference to a function, but because of the () you were calling the function and giving the command attribute whatever that function returned. The solution? Remove the ():
a = Button(..., command=E1holen)
I'm trying to upload a photo to vk.com using QtWebKit module. The problem I'm facing is inability to properly fill input(type="file")'s value. Here's some related code I use:
def upload():
print 'uploading...'
photoInput = web.page().mainFrame().documentElement().findFirst('input[id="photos_upload_input"]')
assert photoInput, 'No input found'
photoInput.setAttribute('value', '/Users/elmigranto/Downloads/stuff.png')
print photoInput.evaluateJavaScript('return this.value;').toString()
It's reasonable to note, that filling value of file input is impossible from Javascript due to browser security policy. However, it should be possible using Qt API, more specifically, QWebElement::setAttribute() method. And that's what I did… with no effect (well, photoInput.attribute('value') returns expected result, but photoInput.evaluateJavaScript('return this.value;').toString() returns empty string, input's onchange handler is also not triggered).
Setting other attributes is no problem, for example, QWebElement::addClass() works like a charm.
Any help would be super great.Thanks.
The setAttribute method might still not work for security reasons.
But you can redefine the function QWebPage::chooseFile that should normally open the upload dialog and return the filename so that it returns a static file name without opening the dialog, and activate that upload by simulating a "return" key press on the input element.
This seems to work:
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtWebKit import *
import sys
class WebPage(QWebPage):
def __init__(self, parent = None):
super(WebPage, self).__init__(parent)
self.overrideUpload = None
def chooseFile(self, originatingFrame, oldFile):
if self.overrideUpload is None:
return super(WebPage, self).chooseFile(originatingFrame, oldFile)
result = self.overrideUpload
self.overrideUpload = None
return result
def setUploadFile(self, selector, filename):
button = self.mainFrame().documentElement().findFirst(selector)
self.overrideUpload = filename
# set the focus on the input element
button.setFocus();
# and simulate a keypress event to make it call our chooseFile method
webview.event(QKeyEvent(QEvent.KeyPress, Qt.Key_Enter, Qt.NoModifier))
def upload():
print 'uploading...'
page.setUploadFile('input[id="photos_upload_input"]',
'/Users/elmigranto/Downloads/stuff.png')
# The change seems to be asynchronous, at it isn't visible
# just after the previous call
app = QApplication(sys.argv)
webview = QWebView()
page = WebPage(webview)
webview.setPage(page)
source = '''
<form action="#">
Select a file: <input type="file" id="photos_upload_input">
<input type="submit">
</form>
'''
webview.loadFinished.connect(upload)
webview.show()
webview.setHtml(source)
sys.exit(app.exec_())