I'm trying to understand a strange (to my understanding) behavior when trying to insert a column in a treeview at index 0.
While I understand that this is not a suggested course of action, the result still puzzles me.
If I add a child to an item that is not in the first column, it is obviously not shown, since only children of the root index in first column are expanded; but it seems that when the new column is inserted, the existing children of the previous first column are "inherited" by the new item.
class TreeTest(QtWidgets.QWidget):
def __init__(self):
super().__init__()
layout = QtWidgets.QVBoxLayout(self)
insertColBtn = QtWidgets.QPushButton('insert column')
layout.addWidget(insertColBtn)
insertColBtn.clicked.connect(self.insertColumn)
insertColAfterBtn = QtWidgets.QPushButton('insert child and insert column')
layout.addWidget(insertColAfterBtn)
insertColAfterBtn.clicked.connect(self.insertColumnAfter)
removeColBtn = QtWidgets.QPushButton('remove column')
layout.addWidget(removeColBtn)
removeColBtn.clicked.connect(self.removeColumn)
self.tree = QtWidgets.QTreeView()
layout.addWidget(self.tree)
self.model = QtGui.QStandardItemModel()
self.tree.setModel(self.model)
self.parent1 = QtGui.QStandardItem('parent 1')
self.parent2 = QtGui.QStandardItem('parent 2')
self.model.appendRow([self.parent1, self.parent2])
self.child = QtGui.QStandardItem('child of parent 1')
self.parent1.appendRow(self.child)
self.parent2.appendRow(QtGui.QStandardItem('child of parent 2'))
self.tree.expandAll()
self.tree.header().setSectionResizeMode(QtWidgets.QHeaderView.ResizeToContents)
def insertColumn(self):
newParent = QtGui.QStandardItem('new parent')
self.model.insertColumn(0, [newParent])
newChild = QtGui.QStandardItem('new column child')
self.parent1.appendRow(newChild)
def insertColumnAfter(self):
newParent = QtGui.QStandardItem('new parent')
newChild = QtGui.QStandardItem('new column child')
self.parent1.appendRow(newChild)
self.model.insertColumn(0, [newParent])
def removeColumn(self):
self.model.removeColumn(0)
This is the what appears at the beginning (the "child of parent 2" is obviously hidden):
Then I insert a new first column, then I add a child to the previous parent (which is now on the second column); as you can see, the previous child is now apparently become a child of the new item, while the new child item is not visible:
Finally, I try to remove the first column, and the previously added child is now visible:
Strangely enough, if a new child item of the previous first column is added before inserting the new column (insertColumnAfter()), it works "as expected", probably due to the delay item views usually have before laying out the items after a model change:
Again, I realize this is not the "standard" way to deal with a tree model.
Still, I'd like to understand what's going on here, whether it's an expected behavior (probably by design, even if not perfect) or some kind of bug.
I've been able to reproduce this behavior with PyQt up to 5.12.4, I can't test with newer versions.
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
In a QVBoxLayout added two QTableViews. The first one has constant number of rows (2), the second one has many. The goal is to make the second table begin just after last row in the first table.
I tried change QSizePolicy, setMinimumSize() - nothing helps. Here is sample of code:
layout = QVBoxLayout()
first_table = QTableView()
second_table = QTableVew()
first_table.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)
second_table.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
layout.addWidget(first_table)
layout.addWidget(second_table)
It looks like it uses sizeHint() no matter of setMinimumSize(h, v) values. How to make the first table do not show space without rows?
You might want to do the following:
layout = QVBoxLayout()
first_table = QTableView()
second_table = QTableVew()
layout.addWidget(first_table)
layout.addWidget(second_table)
layout.addStretch(1); // <--- to keep both tables together.
I have a QTreeView in which I have implemented drag and drop to allow the re-ordering of items.
GIven the following example of a tree:
Food <--fixed
|--Vegetables <--fixed
| |--carrots <-- draggable/parentable
| |--lettuce <-- draggable/parentable
| | |--icebergLettuce <-- draggable but NOT parentable
|--Fruit <-- fixed
| |--apple <-- draggable/parentable
| |--orange <-- draggable/parentable
| |--bloodOrange <-- draggable/parentable
etc...
Anything marked as draggable may be dragged. Anything marked as parentable may have a draggable item as a child. Anything marked fixed is, well, fixed.
My question is, how would I go about limiting the dropping of an item to stay within a particular parent? For example, I could drag 'bloodOrange' and make it a child of 'apple' or 'orange' (or even just change its ordinal position inside of 'Fruit'), but I should not be able to make it a child of carrots or lettuce etc.
I've managed to correctly code the flags for everything except the part that limits a drop operation to stay within a particular parent. I just don't know how to capture the currently dragged QModelIndex (from which I can determine parent, grandparent, etc.)
Thanks!
Here is my code for the flags method in case it helps: Note: I refer to the top level children as Nodes (i.e. 'Food'), the next level as Groups (i.e. 'Fruit'), and the final two levels (i.e. lettuce and icebergLettuce) are both Params.
#---------------------------------------------------------------------------
def flags(self, index):
"""
Returns whether or not the current item is editable/selectable/etc.
"""
if not index.isValid():
return QtCore.Qt.ItemIsEnabled
#by default, you can't do anything
enabled = QtCore.Qt.NoItemFlags
selectable = QtCore.Qt.NoItemFlags
editable = QtCore.Qt.NoItemFlags
draggable = QtCore.Qt.NoItemFlags
droppable = QtCore.Qt.NoItemFlags
#get a pointer to the referenced object
item = index.internalPointer()
#only 'valid' cells may be manipulated ('valid' is defined by the obj)
if item.column_is_valid(index.column()):
#all valid cells are selectable and enabled
selectable = QtCore.Qt.ItemIsSelectable
enabled = QtCore.Qt.ItemIsEnabled
#column 0 cells may occasionally be dragged and dropped
if index.column() == 0:
#drag/drop is only possible if it is a param...
if item.get_obj_type() == 'param':
#...and then only child-less params may be dragged...
if item.get_child_count() == 0:
draggable = QtCore.Qt.ItemIsDragEnabled
#...and only params with a group as parent may be dropped on
if item.get_parent().get_obj_type() == "group":
droppable = QtCore.Qt.ItemIsDropEnabled
#all other valid columns > 0 may be edited (no drag or drop)
else:
editable = QtCore.Qt.ItemIsEditable
#return our flags.
return enabled | selectable| editable| draggable| droppable
If you want the drag to display the "not allowed" icon when hovering over certain rows, I believe you can't do it from the model. You'd have to intercept the dragEnter/Move events on the View wiedget.
However, dropMimeData() can return False to indicate that the drop is rejected.
Note that (in my Qt version) there is a bug in qdnd_win regarding drops that are rejected by the model. Here is my workaround based on some source diving; this is a method defined on my QTreeView subclass:
def dropEvent(self, evt):
QTreeView.dropEvent(self, evt)
if not evt.isAccepted():
# qdnd_win.cpp has weird behavior -- even if the event isn't accepted
# by target widget, it sets accept() to true, which causes the executed
# action to be reported as "move", which causes the view to remove the
# source rows even though the target widget didn't like the drop.
# Maybe it's better for the model to check drop-okay-ness during the
# drag rather than only on drop; but the check involves not-insignificant work.
evt.setDropAction(Qt.IgnoreAction)
(note that by "not-insignificant work" I really mean "I don't want to bother intercepting the events" :-)
I am little bit confuse.
I am working with QTreeView as model I assigned QSortFilterProxyModel.
http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qsortfilterproxymodel.html
//treeview
self.ProxyView = QtGui.QTreeView(self.centralwidget)
//model
self.ProxyModel = QtGui.QSortFilterProxyModel(self)
self.ProxyModel.setSourceModel(QtGui.QStandardItemModel(0, 3, self))
//assign model to tree
self.ProxyView.setModel(self.ProxyModel)
On button click I want to add row to this tree.
Here is my slot
def pushButton_addRow(self):
self.ProxyModel.insertRow(0)
self.ProxyModel.setData(self.ProxyModel.index(0,0), "hi")
It doesnt work, it works only for first row, then I added empty rows. But wenn I fill second cell it works.
self.ProxyModel.setData(self.ProxyModel.index(0,1), "hi")
Any Idea?
Maybe your new QModelIndex has wrong parent()?
I want to be able to expand or collapse all children of a particular branch in a QTreeView. I am using PyQt4.
I know that QTreeView's have an expand all children feature that is bound to *, but I need two things: It needs to be bound to a different key combination (shift-space) and I also need to be able to collapse all children as well.
Here is what I have tried so far:
I have a subclass of a QTreeView wherein I am checking for the shift-space key combo. I know that QModelIndex will let me pick a specific child with the "child" function, but that requires knowing the number of children. I am able to get a count of the children by looking at the internalPointer, but that only gives me info for the first level of the hierarchy. If I try to use recursion, I can get a bunch of child counts, but then I am lost as to how to get these converted back into a valid QModelIndex.
Here is some code:
def keyPressEvent(self, event):
"""
Capture key press events to handle:
- enable/disable
"""
#shift - space means toggle expanded/collapsed for all children
if (event.key() == QtCore.Qt.Key_Space and
event.modifiers() & QtCore.Qt.ShiftModifier):
expanded = self.isExpanded(self.selectedIndexes()[0])
for cellIndex in self.selectedIndexes():
if cellIndex.column() == 0: #only need to call it once per row
#I can get the actual object represented here
item = cellIndex.internalPointer()
#and I can get the number of children from that
numChildren = item.get_child_count()
#but now what? How do I convert this number into valid
#QModelIndex objects? I know I could use:
# cellIndex.child(row, 0)
#to get the immediate children's QModelIndex's, but how
#would I deal with grandchildren, great grandchildren, etc...
self.setExpanded(cellIndex, not(expanded))
return
Here is the beginning of the recursion method I was investigating, but I get stuck when actually trying to set the expanded state because once inside the recursion, I lose "contact" with any valid QModelIndex...
def toggle_expanded(self, item, expand):
"""
Toggles the children of item (recursively)
"""
for row in range(0,item.get_child_count()):
newItem = item.get_child_at_row(row)
self.toggle_expanded(newItem, expand)
#well... I'm stuck here because I'd like to toggle the expanded
#setting of the "current" item, but I don't know how to convert
#my pointer to the object represented in the tree view back into
#a valid QModelIndex
#self.setExpanded(?????, expand) #<- What I'd like to run
print "Setting", item.get_name(), "to", str(expand) #<- simple debug statement that indicates that the concept is valid
Thanks to all for taking the time to look at this!
Ok... siblings did not actually get me to where I wanted to go. I managed to get the code working as follows (and it seems like a decent implementation). Kudos still to Prof.Ebral who got me going on the right track with the idea of siblings (turns out I needed to use QModelIndex.child(row, column) and iterate recursively from there).
Note that there is the following assumption in the code: It assumes that your underlying data store objects have the ability to report how many children they have (get_child_count() in my code). If that is not the case, you will somehow have to get a child count differently... perhaps by just arbitrarily trying to get child indexes - using QModelIndex.child(row, col) - with an ever increasing row count till you get back an invalid index? - this is what Prof.Ebral suggested and I might still try that (It is just that I already have an easy way to get the child count by requesting it from my data store).
Also note that I actually expand/collpase each node at a different point in the recursion based on whether I am expanding or collapsing. This is because, through trial and error, I discovered that animated tree views would stutter and pop if I just did it at one place in the code. Now, by reversing the order in which I do it based on whether I am at the top level (i.e. the root of the branch I am affecting - not the root of the entire treeview) I get a nice smooth animation. This is documented below.
The following code is in a QTreeView subclass.
#---------------------------------------------------------------------------
def keyPressEvent(self, event):
if (event.key() == QtCore.Qt.Key_Space and self.currentIndex().column() == 0):
shift = event.modifiers() & QtCore.Qt.ShiftModifier
if shift:
self.expand_all(self.currentIndex())
else:
expand = not(self.isExpanded(self.currentIndex()))
self.setExpanded(self.currentIndex(), expand)
#---------------------------------------------------------------------------
def expand_all(self, index):
"""
Expands/collapses all the children and grandchildren etc. of index.
"""
expand = not(self.isExpanded(index))
if not expand: #if collapsing, do that first (wonky animation otherwise)
self.setExpanded(index, expand)
childCount = index.internalPointer().get_child_count()
self.recursive_expand(index, childCount, expand)
if expand: #if expanding, do that last (wonky animation otherwise)
self.setExpanded(index, expand)
#---------------------------------------------------------------------------
def recursive_expand(self, index, childCount, expand):
"""
Recursively expands/collpases all the children of index.
"""
for childNo in range(0, childCount):
childIndex = index.child(childNo, 0)
if expand: #if expanding, do that first (wonky animation otherwise)
self.setExpanded(childIndex, expand)
subChildCount = childIndex.internalPointer().get_child_count()
if subChildCount > 0:
self.recursive_expand(childIndex, subChildCount, expand)
if not expand: #if collapsing, do it last (wonky animation otherwise)
self.setExpanded(childIndex, expand)
model.rowCount(index) is the method you want.
model = index.model() # or some other way of getting it
for i in xrange(model.rowCount(index)):
child = model.index(i,0, index)
# do something with child
model.index(row,col, parent) is essentially the same as calling index.child(row,col); just with fewer indirections.
I would recommend using a QTreeWidget which inherits QTreeView. You can then grab the children as a QTreeWidgetItem.
Since you do not want to use the QTreeWidget but want to stick to your current model .. you can iterate through the 'possible' children using, .isValid(). You should not use the internalPointer() though. Instead use the cellItem you have, as it is the original ModalIndex .. then attempt to find it's siblings. Something like
x = 0; y =0
while cellIndex.sibling(x, y).isValid():
child = cellIndex.sibling(x, y)
x += 1
I make a evnetFilter Class for that.
My particular use case is shift click the drop indicator then expand all or collapse all the child nodes like software maya outliner.
class MTreeExpandHook(QtCore.QObject):
"""
MTreeExpandHook( QTreeView )
"""
def __init__(self, tree):
super(MTreeExpandHook, self).__init__()
tree.viewport().installEventFilter(self)
self.tree = tree
def eventFilter(self, receiver, event):
if (
event.type() == QtCore.QEvent.Type.MouseButtonPress
and event.modifiers() & QtCore.Qt.ShiftModifier
):
pos = self.tree.mapFromGlobal(QtGui.QCursor.pos())
index = self.tree.indexAt(pos)
if not self.tree.isExpanded(index):
self.tree.expandRecursively(index)
return True
return super(MTreeExpandHook, self).eventFilter(self.tree, event)
Usage Example below
import sys
from PySide2 import QtCore,QtGui,QtWidgets
class MTreeExpandHook(QtCore.QObject):
"""
MTreeExpandHook( QTreeView )
"""
def __init__(self, tree):
super(MTreeExpandHook, self).__init__()
self.setParent(tree)
# NOTE viewport for click event listen
tree.viewport().installEventFilter(self)
self.tree = tree
def eventFilter(self, receiver, event):
if (
# NOTE mouse left click
event.type() == QtCore.QEvent.Type.MouseButtonPress
# NOTE keyboard shift press
and event.modifiers() & QtCore.Qt.ShiftModifier
):
# NOTE get mouse local position
pos = self.tree.mapFromGlobal(QtGui.QCursor.pos())
index = self.tree.indexAt(pos)
if not self.tree.isExpanded(index):
# NOTE expand all child
self.tree.expandRecursively(index)
return True
return super(MTreeExpandHook, self).eventFilter(self.tree, event)
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
model = QtGui.QStandardItemModel()
# NOTE create nested data
for i in range(3):
parent = QtGui.QStandardItem('Family {}'.format(i))
for j in range(3):
child = QtGui.QStandardItem('Child {}'.format(i*3+j))
for k in range(3):
sub_child = QtGui.QStandardItem("Sub Child")
child.appendRow([sub_child])
for x in range(2):
sub_child_2 = QtGui.QStandardItem("Sub Child 2")
sub_child.appendRow([sub_child_2])
parent.appendRow([child])
model.appendRow(parent)
treeView = QtWidgets.QTreeView()
treeView.setHeaderHidden(True)
MTreeExpandHook(treeView)
treeView.setModel(model)
treeView.show()
sys.exit(app.exec_())
example gif