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  • PyQt4 and QTableView with spinbox and checkbox

    - by ekapek
    Hi, I have a QTableView with QSqlTableModel and with 3 columns, now I need to have: - second column: spinbox after clicked to edit - third column: checkbox (displayed center) My code: class SpinBoxDelegate(QtGui.QItemDelegate): def createEditor(self, parent, option, index): editor = QtGui.QSpinBox(parent) editor.setMinimum(0) editor.setMaximum(100) print 'spinbox' return editor def setEditorData(self, spinBox, index): value = index.model().data(index, QtCore.Qt.EditRole).toInt()[0] spinBox.setValue(value) def setModelData(self, spinBox, model, index): spinBox.interpretText() value = spinBox.value() model.setData(index, value, QtCore.Qt.EditRole) def updateEditorGeometry(self, editor, option, index): editor.setGeometry(option.rect) class myQSqlTableModel(QtSql.QSqlTableModel): def flags(self,index): result = QtSql.QSqlTableModel.flags(self,index); if index.column() == 2: result |= QtCore.Qt.ItemIsUserCheckable return result def data(self,index,role): if not index.isValid: return QtCore.QVariant() value = QtSql.QSqlTableModel.data(self, index, role) if index.column() == 2: if role == QtCore.Qt.CheckStateRole: return QtCore.Qt.Unchecked if QtSql.QSqlTableModel.data(self, index).toInt()[0] else QtCore.Qt.Checked elif role == QtCore.Qt.DisplayRole: return QtCore.QVariant() return value and self.model = myQSqlTableModel(self) self.model.setTable("person") self.model.setEditStrategy(QtSql.QSqlTableModel.OnManualSubmit) self.model.select(): self.model.setHeaderData(0, QtCore.Qt.Horizontal, self.tr("ID")) self.model.setHeaderData(1, QtCore.Qt.Horizontal, self.tr("A")) self.model.setHeaderData(2, QtCore.Qt.Horizontal, self.tr("B")) self.view = QtGui.QTableView() self.view.setModel(self.model) self.view.setSortingEnabled(True) spinDelegate = SpinBoxDelegate() self.view.setItemDelegateForColumn(1,spinDelegate) but it does't work: spinbox don't show after click and checkbox can't be clicked and is aligned to left Any help?

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  • video player with qt phonon (using python)

    - by cppb
    hi, I am working on Windows xp and am trying to get a simple video player running. I am trying to use Phonon::VideoPlayer module for this. I am connecting the signal as connect(self.player,SIGNAL("finished()"),self.player.deleteLater) and then , when the Play button is pressed, it makes the following call: self.player.play(Phonon.MediaSource("C:\vid.mp4")) But, this doesn't display the video in the video player widget. Neither can I hear audio. Can anyone help?? I tried using different video file formats but no luck.

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  • resizing row's height in QTreeWidget/QTreeView

    - by serge
    Hi everyone, I have some problems with sizing row's height in QTreeWidget. I use QStyledItemDelegate with QPlainTextEdit. During editing text in QPlainTextEdit i check for changes with a help of: rect = self.blockBoundingRect(self.firstVisibleBlock()) and if text's height changes i resize editor size and need row in QTreeWidget also resizing. But i don't know how to inform TreeWidget or a Delegate about changes. I tried to initialize editor with index, that i could use in a future, but Delegate creates new editor every time and i failed to use signals. Also I used following function to catch resize event, but it' doesn't: bool QAbstractItemDelegate::editorEvent ( QEvent * event, QAbstractItemModel * model, const QStyleOptionViewItem & option, const QModelIndex & index ) How can i bound editor's size changes with TreeWidget? And one more thing, by default all items (cells) in TreeWidget have -1 or some big value as default width. I need whole text in cell to be visible, so how can i limit cells width only by visible range and make it expand in height? I want for it the same behavior as in instance a table in MSWord. Thank you in advance, Serge

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  • dinamically resizing row height in QTreeWidget/QTreeView during edinitg items

    - by serge
    Hi everyone, I have some problems with sizing row's height in QTreeWidget. I use QStyledItemDelegate with QPlainTextEdit. During editing text in QPlainTextEdit i check for changes with a help of: rect = self.blockBoundingRect(self.firstVisibleBlock()) and if text it's height changes i need row in QTreeWidget also resizing. But i don't know how to inform TreeWidget or a Delegate about changes, i even tried to initialize editor with index, that i could use in a future, but it suddenly changes: class MyEditor(QPlainTextEdit): def __init__(self, index = None, parent=None): super(MyEditor, self).__init__(parent) self.index = index self.connect(self, SIGNAL("textChanged()"), self.setHeight) def setHeight(self): if self.index: rect = self.blockBoundingRect(self.firstVisibleBlock()) self.resize(rect.width(), rect.height()) self.emit(SIGNAL("set_height"), QSize(rect.width(), rect.height()), self.index) How can i bound editor's size changes with TreeWidget? And one more thing, by default all items (cells) in TreeWidget have -1 or some big value as default width. I need whole text in cell to be visible, so how can i limit it only by visible range and expand it in height? Thank you in advance, Serge

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  • QTreeWidget expand sign

    - by serge
    Hi everyone, How to make expandable sign in QTreeWidget always visible even when item doest have any subitems? And how to draw something else instead of default sign? Thanks in advance, Serge

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  • QTreeWidget insertTopLevelItem - index given not accurately displayed in Tree?

    - by mleep
    I am unable to properly insert a QTreeWidgetItem at a specific index, in this case I am removing all QTreeWidgetItems from the tree, doing a custom sort on their Date Objects and then inserting them back into the QTreeWidget. However, upon inserting (even one at a time) the QTreeWidgetItem is not inserted into the correct place. The code below prints out: index 0: 0 index 0: 1 index 1: 0 index 0: 2 index 1: 1 index 2: 0 index 0: 3 index 1: 2 index 2: 0 index 3: 1 index 0: 4 index 1: 2 index 2: 0 index 3: 1 index 4: 3 print 'index 0: ', self.indexOfTopLevelItem(childrenList[0]) self.insertTopLevelItem(0, childrenList[1]) print 'index 0: ', self.indexOfTopLevelItem(childrenList[0]), ' index 1: ',\ self.indexOfTopLevelItem(childrenList[1]) self.insertTopLevelItem(0, childrenList[2]) print 'index 0: ', self.indexOfTopLevelItem(childrenList[0]), ' index 1: ',\ self.indexOfTopLevelItem(childrenList[1]), ' index 2: ', \ self.indexOfTopLevelItem(childrenList[2]) self.insertTopLevelItem(0, childrenList[3]) print 'index 0: ', self.indexOfTopLevelItem(childrenList[0]), ' index 1: ',\ self.indexOfTopLevelItem(childrenList[1]), ' index 2: ',\ self.indexOfTopLevelItem(childrenList[2]), 'index 3: ',\ self.indexOfTopLevelItem(childrenList[3]) self.insertTopLevelItem(0, childrenList[4]) print 'index 0: ', self.indexOfTopLevelItem(childrenList[0]),\ ' index 1: ', self.indexOfTopLevelItem(childrenList[1]),\ ' index 2: ', self.indexOfTopLevelItem(childrenList[2]),\ 'index 3: ', self.indexOfTopLevelItem(childrenList[3]),\ 'index 4: ', self.indexOfTopLevelItem(childrenList[4])

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  • How to display a QGraphicsScene?

    - by Chris
    I've got the following code and I'm not sure how to add the QGraphicsScene to my layout.. class MainForm(QDialog): def __init__(self, parent=None): super(MainForm, self).__init__(parent) self.scene = QGraphicsScene(self) self.scene.setSceneRect(0, 0, 500, 500) self.view = QGraphicsView() self.view.setRenderHint(QPainter.Antialiasing) self.view.setScene(self.scene) self.view.setFocusPolicy(Qt.NoFocus) zoomSlider = QSlider(Qt.Horizontal) zoomSlider.setRange(5, 200) zoomSlider.setValue(100) self.pauseButton = QPushButton("Pause") quitButton = QPushButton("Quit") layout = QVBoxLayout() layout.addWidget(zoomSlider) self.setLayout(layout) self.startTimer(10) How can I get my QGraphicsScene running? I'm new to Qt. Am I even supposed to be adding a QGraphicsScene to a layout/

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  • QTreeWidget set height of each row depending on content

    - by serge
    Hi everyone, I want to make editable cells with multi-lines content in QTreeWidget and I use for this purpose QPlainTextEdit as a delegate. I need to set proper size to all rows that switching between editing and displaying went smooth, without any visible changes. rect = textEdit.blockBoundingRect(textEdit.firstVisibleBlock()) with this I can find out the height I need to set for the row, but I missing the place where I can do it. How can i set proper height to QTreeWidget's rows on initialization stage? Thank you in advance, Serge

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  • Segmentation fault when creating a Phonon MediaObject

    - by Luke Hansford
    I have music playing program made using PySide which uses Phonon to playback audio. I updated to MacOS X Mavericks a few days ago, which meant I needed to reinstall PySide. I'm not sure which of these actions has caused this, but now whenever I try to create a Phonon MediaObject I get a Segmentation Fault: 11 from Python. It's not just in my program, it happens when trying to create a MediaObject in Python without any other actions. I'm getting the following error message from my Mac whenever it crashes: Process: Python [13711] Path: /usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python Identifier: org.python.python Version: 2.7.5 (2.7.5) Code Type: X86-64 (Native) Parent Process: bash [13707] Responsible: Terminal [13704] User ID: 501 Date/Time: 2013-11-01 19:47:53.164 +1000 OS Version: Mac OS X 10.9 (13A603) Report Version: 11 Anonymous UUID: C2686854-18CA-9D37-26E9-60050E3C4DA6 Sleep/Wake UUID: BB983BF6-CCE2-44D1-82A0-1C73382DFFE4 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000008 VM Regions Near 0x8: --> __TEXT 00000001082e8000-00000001082e9000 [ 4K] r-x/rwx SM=COW /usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 QtCore 0x000000010a1b34cb QObject::moveToThread(QThread*) + 17 1 QtDBus 0x000000010d55f98b QDBusDefaultConnection::QDBusDefaultConnection(QDBusConnection::BusType, char const*) + 171 2 QtDBus 0x000000010d55ebdf QDBusConnection::sessionBus() + 71 3 phonon 0x000000010d50228d Phonon::FactoryPrivate::FactoryPrivate() + 189 4 phonon 0x000000010d5024d5 Phonon::$_249::operator->() + 99 5 phonon 0x000000010d502991 Phonon::Factory::registerFrontendObject(Phonon::MediaNodePrivate*) + 17 6 phonon 0x000000010d50b27e Phonon::MediaNodePrivate::MediaNodePrivate(Phonon::MediaNodePrivate::CastId) + 80 7 phonon 0x000000010d50f570 Phonon::MediaObjectPrivate::MediaObjectPrivate() + 24 8 phonon 0x000000010d50be9d Phonon::MediaObject::MediaObject(QObject*) + 45 9 phonon.so 0x000000010d42f24a Sbk_Phonon_MediaObject_Init + 458 10 org.python.python 0x0000000108338707 type_call + 189 11 org.python.python 0x00000001082f74fd PyObject_Call + 101 12 org.python.python 0x00000001083714f0 PyEval_EvalFrameEx + 15525 13 org.python.python 0x0000000108373aaf fast_function + 182 14 org.python.python 0x0000000108370919 PyEval_EvalFrameEx + 12494 15 org.python.python 0x000000010836d721 PyEval_EvalCodeEx + 1638 16 org.python.python 0x000000010836d0b5 PyEval_EvalCode + 54 17 org.python.python 0x000000010838beb8 run_mod + 53 18 org.python.python 0x000000010838bf5f PyRun_FileExFlags + 137 19 org.python.python 0x000000010838baad PyRun_SimpleFileExFlags + 718 20 org.python.python 0x000000010839c58b Py_Main + 3039 21 libdyld.dylib 0x00007fff8e4fb5fd start + 1 Thread 1:: Dispatch queue: com.apple.libdispatch-manager 0 libsystem_kernel.dylib 0x00007fff8c938662 kevent64 + 10 1 libdispatch.dylib 0x00007fff923e743d _dispatch_mgr_invoke + 239 2 libdispatch.dylib 0x00007fff923e7152 _dispatch_mgr_thread + 52 Thread 2: 0 libsystem_kernel.dylib 0x00007fff8c937e6a __workq_kernreturn + 10 1 libsystem_pthread.dylib 0x00007fff90bd8f08 _pthread_wqthread + 330 2 libsystem_pthread.dylib 0x00007fff90bdbfb9 start_wqthread + 13 Thread 3: 0 libsystem_kernel.dylib 0x00007fff8c937e6a __workq_kernreturn + 10 1 libsystem_pthread.dylib 0x00007fff90bd8f08 _pthread_wqthread + 330 2 libsystem_pthread.dylib 0x00007fff90bdbfb9 start_wqthread + 13 Thread 4: 0 libsystem_kernel.dylib 0x00007fff8c937e6a __workq_kernreturn + 10 1 libsystem_pthread.dylib 0x00007fff90bd8f08 _pthread_wqthread + 330 2 libsystem_pthread.dylib 0x00007fff90bdbfb9 start_wqthread + 13 Thread 0 crashed with X86 Thread State (64-bit): rax: 0x00007feba0d19700 rbx: 0x000000010d5b7098 rcx: 0x00000000002f4180 rdx: 0x000000000012c040 rdi: 0x0000000000000000 rsi: 0x00007feba0d19700 rbp: 0x00007fff57917210 rsp: 0x00007fff579171d0 r8: 0x00007feba0fd5d10 r9: 0x00007feba0ff5310 r10: 0x0000000019c04cbe r11: 0x0000000070769b38 r12: 0x00007fff57917220 r13: 0x00007feba0c07190 r14: 0x0000000000000000 r15: 0x00007feba0fe1430 rip: 0x000000010a1b34cb rfl: 0x0000000000010202 cr2: 0x0000000000000008 Logical CPU: 0 Error Code: 0x00000004 Trap Number: 14 Anyone have any ideas about what is happening?

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  • how to set a pop up menu on a particular table view item

    - by Moayyad Yaghi
    hello i have a QTableView , and i need to show a popup menu that shows the item properties . i need to set the context menu to apear only when you right click over a particular items in that tableview. but coudln't find a way to do it . i can set the context menu to appear when your over the table . i cant have it for each item . so how do i set the context menu over items in the tableview ? please tell me if the idea was not clear enough thanks in advance

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  • PySide using Style Sheets to change QtoolBox

    - by efi_ex
    I'm Wondering if somebody knows a better reference than the QT one for style sheets. I try to change the background of the content from a QToolBox but background-color only changes the header of the toolbox and the background of the content it reveals is left in a standard color. I then tried to change the bg of QWidget which worked but left me with problems now at Radiobuttons and Checkboxes, i also think changing QWidget isn't a good solution. The first picture is with Qt standard colors (this is a maya tool) the second when i change QWidget http://i.imgur.com/MNlSedx.png?1 http://i.imgur.com/wuplpmw.png?1

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  • QFileDialog and german umlaute within a path

    - by MB
    Hey Everybody, i am working on a project, which i am developing with Python and PyQT4. I have stumbled upon a somewhat odd behaviour of the QFileDialog, that is not occuring when running the project within in my IDE (Eclipse). The problem is that QFileDialog in ExistingFiles-mode does fail to return the list of selected files, when one of the file paths is containing a german umlaut (ä,ü,ö, etc.) The QFileDialog is not offering options or parameters to make it sensible regarding this scenario. Does anyone have any ideas of how to tackle this issue?

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  • Right clicking on QHeaderView inside of QTreeView

    - by taynaron
    I've written a descendant of QTreeView with multiple columns. I want to create a popup menu that appears whe nthe user right-clicks over the column headers. I have tried catching signals from QTreeView for this, but QTreeView doesn't seem to emit signals on the headers. QTreeView.header() does. I therefore believe I must either: 1: connect one of QHeaderView's signals to a popup function - I have been unable to find a signal that is triggered on a single right click - I have tried sectionClicked, sectionHandleDoubleClicked, sectionDoubleClicked, sectionPressed (not surprised the double click functions didn't catch a single right click - but they do catch a double right click) self.header().sectionClicked.connect(self.headerMenu) self.header().sectionHandleDoubleClicked.connect(self.headerMenu) self.header().sectionDoubleClicked.connect(self.headerMenu) self.header().sectionPressed.connect(self.headerMenu) or, 2: write a descendant of QHeaderView with my own MousePressEvent function, and use that for my headers. I have so far been unsuccessful in connecting the new header class to the QTreeView descendant. I keep getting a Segmentation Fault on runtime, with no more explanation. #in DiceView's init, where DiceHeaders is the QHeaderView descendant self.setHeader(DiceHeaders()) Any ideas?

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  • Calling activateWindow on QDialog sends window to background

    - by Stan
    I am debugging certain application written with C++/Qt4. On Linux it has problems that with certain window managers (gnome-wm/metacity), the main window (based on QDialog) is created in the background (it's not raised). I managed to re-create the scenario using PyQt4 and following code: from PyQt4.QtCore import * from PyQt4.QtGui import * import sys class PinDialog(QDialog): def showEvent(self, event): QDialog.showEvent(self, event) self.raise_() self.activateWindow() if __name__ == "__main__": app = QApplication(sys.argv) widget = PinDialog() app.setActiveWindow(widget) widget.exec_() sys.exit(0) If I remove self.activateWindow() the application works as expected. This seems wrong, since documentation for activateWindow does not specify any conditions under which something like this could happen. My question is: Is there any reason to have activateWindow in showEvent in the first place? If there is some reason, what would be good workaround for focusing issues?

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  • How to update QStandartItemModel without freezing the main UI

    - by user1044002
    I'm starting to learn PyQt4 and have been stuck on something for a long time now and can't figure it out myself: Here is the concept: There is a TreeView with custom QStandartItemModel, which gets rebuild every couple of seconds, and can have a lot (hundreds at least) of entries, there also will be additional delegates for the different columns etc. It's fairly complex and the building time for even plain model, without delegates, goes up to .3 sec, which makes the TreeView to freeze. Please advice me for the best approach on solving this. I was thing of somehow building the model in different thread, and eventually sending it to the TreeView, where it would just perform setModel() with the new one, but couldn't make that work. here is some code that may illustrate the problem a bit: from PyQt4.QtCore import * from PyQt4.QtGui import * import sys, os, re, time app = QApplication(sys.argv) REFRESH = 1 class Reloader_Thread(QThread): def __init__(self, parent = None): QThread.__init__(self, parent) self.loaders = ['\\', '--', '|', '/', '--'] self.emit(SIGNAL('refresh')) def run(self): format = '|%d/%b/%Y %H:%M:%S| ' while True: self.emit(SIGNAL('refresh')) self.sleep(REFRESH) class Model(QStandardItemModel): def __init__(self, viewer=None): QStandardItemModel.__init__(self,None) self.build() def build(self): stTime = time.clock() newRows = [] for r in range(1000): row = [] for c in range(12): item = QStandardItem('%s %02d%02d' % (time.strftime('%H"%M\'%S'), r,c)) row.append(item) newRows.append(row) eTime = time.clock() - stTime outStr = 'Build %03f' % eTime format = '|%d/%b/%Y %H:%M:%S| ' stTime = time.clock() self.beginRemoveRows(QModelIndex(), 0, self.rowCount()) self.removeRows(0, self.rowCount()) self.endRemoveRows() eTime = time.clock() - stTime outStr += ', Remove %03f' % eTime stTime = time.clock() numNew = len(newRows) for r in range(numNew): self.appendRow(newRows[r]) eTime = time.clock() - stTime outStr += ', Set %03f' % eTime self.emit(SIGNAL('status'), outStr) self.reset() w = QWidget() w.setGeometry(200,200,800,600) hb = QVBoxLayout(w) tv = QTreeView() tvm = Model(tv) tv.setModel(tvm) sb = QStatusBar() reloader = Reloader_Thread() tvm.connect(tvm, SIGNAL('status'), sb.showMessage) reloader.connect(reloader, SIGNAL('refresh'), tvm.build) reloader.start() hb.addWidget(tv) hb.addWidget(sb) w.show() app.setStyle('plastique') app.processEvents(QEventLoop.AllEvents) app.aboutToQuit.connect(reloader.quit) app.exec_()

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  • QTreeWidget activate item signals

    - by serge
    Hi everyone, I need to do some actions when item in QTreeWidget activates, but following code doestn't gives me expected result: class MyWidget(QTreeWidget): def __init__(self, parent=None): super(MyWidget, self).__init__(parent) self.connect(self, SIGNAL("activated(QModelIndex)"), self.editCell) def editCell(self, index): print index or class MyWidget(QTreeWidget): def __init__(self, parent=None): super(MyWidget, self).__init__(parent) self.connect(self, SIGNAL("itemActivated(QTreeWidgetItem, int)"), self.editCell) def editCell(self, item, column=0): print item What am i doing wrong or how to hadnle item activation in the right way? Thanks in advance, Serge

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  • how to word wrap a QTreeWidgetItem

    - by japs
    hello all, i have to populate a QTreeWidget with items (or children of items) that may happen to be too long to fit in a single line, so i'm looking for a way to word wrap them. i thought myQTreeWidget.setWordWrap(True) (done via QtDesigner4) would have done the job, but that doesn't seem to be the case. i don't konw if it is relevant, but the tree is enveloped in a splitter frame, so the wrapping should be somehow dynamic to allow resizing of the splitter. Any ideas? I use PyQt4, but hints in any language/binding would be much appreciated. have a good day all.

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  • Editable QTreeView with expandable cells

    - by serge
    Hi everyone, I tried to write an editable table based on QTreeView with wordwraped content in cells which in turn should expand in height (that whole text was visible) like usual cells in tables like in MSWord, but have met insuperable obstacles: first - i can't set fixed cell size. second - i can't make text display in cells wordwraped. For this i used void QTreeWidget::setItemWidget ( QTreeWidgetItem * item, int column, QWidget * widget ), but it works only for readonly solutions. And i haven't come up with any other idea. Can such behavior of QTreeView be realized? And how to solve those problems of mine? Thanks in advance Serge

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  • PyQt4, QThread and opening big files without freezing the GUI

    - by jmrbcu
    Hi, I would like to ask how to read a big file from disk and maintain the PyQt4 UI responsive (not blocked). I had moved the load of the file to a QThread subclass but my GUI thread get freezed. Any suggestions? I think it must be something with the GIL but I don't know how to sort it? EDIT: I am using vtkGDCMImageReader from the GDCM project to read a multiframe DICOM image and display it with vtk and pyqt4. I do this load in a different thread (QThread) but my app freeze until the image is loaded. here is an example code: class ReadThread(QThread): def __init__(self, file_name): super(ReadThread, self).__init__(self) self.file_name = file_name self.reader.vtkgdcm.vtkGDCMImageReader() def run(self): self.reader.SetFileName(self.file_name) self.reader.Update() self.emit(QtCore.SIGNAL('image_loaded'), self.reader.GetOutput())

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  • PyQt4 Move QTableWidget row with widgets

    - by Guard
    I have the following method in my PyQt4 app. r2 is the number of row to move, and r1 is the position where it should be moved. To clarify: the table is filled with cellWidgets, not widgetItems. def move_row(self, r1, r2): tt = self.tableWidget tt.insertRow(r1) for c in range(tt.columnCount()): tt.setCellWidget(r1, c, tt.cellWidget(r2 + 1, c)) tt.removeRow(r2 + 1) # <--- ??? If I comment out the last line, it behaves as expected: the new row is inserted at position r1, it is filled with widgets from r2 (now it's r2+1), and the r2+1 row is empty. If I even hide this row, it behaves well, though it is not what I want (I have the rows numbered, and I don't want this hidden row to occupy the number). But if I remove the row, the widgets initially owned by it disappear. Looks like their ownership is taken on first placement, and is not changed after the move. Any ideas?

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  • Dealing with external processes

    - by Jesse Aldridge
    I've been working on a gui app that needs to manage external processes. Working with external processes leads to a lot of issues that can make a programmer's life difficult. I feel like maintenence on this app is taking an unacceptably long time. I've been trying to list the things that make working with external processes difficult so that I can come up with ways of mitigating the pain. This kind of turned into a rant which I thought I'd post here in order to get some feedback and to provide some guidance to anybody thinking about sailing into these very murky waters. Here's what I've got so far: Output from the child can get mixed up with output from the parent. This can make both outputs misleading and hard to read. It can be hard to tell what came from where. It becomes harder to figure out what's going on when things are asynchronous. Here's a contrived example: import textwrap, os, time from subprocess import Popen test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) proc = Popen('python -B "%s"' % test_path) for i in range(3): print 'Hello %i' % i time.sleep(1) os.remove(test_path) I guess I could have the child process write its output to a file. But it can be annoying to have to open up a file every time I want to see the result of a print statement. If I have code for the child process I could add a label, something like print 'child: Hello %i', but it can be annoying to do that for every print. And it adds some noise to the output. And of course I can't do it if I don't have access to the code. I could manually manage the process output. But then you open up a huge can of worms with threads and polling and stuff like that. A simple solution is to treat processes like synchronous functions, that is, no further code executes until the process completes. In other words, make the process block. But that doesn't work if you're building a gui app. Which brings me to the next problem... Blocking processes cause the gui to become unresponsive. import textwrap, sys, os from subprocess import Popen from PyQt4.QtGui import * from PyQt4.QtCore import * test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) app = QApplication(sys.argv) button = QPushButton('Launch process') def launch_proc(): # Can't move the window until process completes proc = Popen('python -B "%s"' % test_path) proc.communicate() button.connect(button, SIGNAL('clicked()'), launch_proc) button.show() app.exec_() os.remove(test_path) Qt provides a process wrapper of its own called QProcess which can help with this. You can connect functions to signals to capture output relatively easily. This is what I'm currently using. But I'm finding that all these signals behave suspiciously like goto statements and can lead to spaghetti code. I think I want to get sort-of blocking behavior by having the 'finished' signal from QProcess call a function containing all the code that comes after the process call. I think that should work but I'm still a bit fuzzy on the details... Stack traces get interrupted when you go from the child process back to the parent process. If a normal function screws up, you get a nice complete stack trace with filenames and line numbers. If a subprocess screws up, you'll be lucky if you get any output at all. You end up having to do a lot more detective work everytime something goes wrong. Speaking of which, output has a way of disappearing when dealing external processes. Like if you run something via the windows 'cmd' command, the console will pop up, execute the code, and then disappear before you have a chance to see the output. You have to pass the /k flag to make it stick around. Similar issues seem to crop up all the time. I suppose both problems 3 and 4 have the same root cause: no exception handling. Exception handling is meant to be used with functions, it doesn't work with processes. Maybe there's some way to get something like exception handling for processes? I guess that's what stderr is for? But dealing with two different streams can be annoying in itself. Maybe I should look into this more... Processes can hang and stick around in the background without you realizing it. So you end up yelling at your computer cuz it's going so slow until you finally bring up your task manager and see 30 instances of the same process hanging out in the background. Also, hanging background processes can interefere with other instances of the process in various fun ways, such as causing permissions errors by holding a handle to a file or someting like that. It seems like an easy solution to this would be to have the parent process kill the child process on exit if the child process didn't close itself. But if the parent process crashes, cleanup code might not get called and the child can be left hanging. Also, if the parent waits for the child to complete, and the child is in an infinite loop or something, you can end up with two hanging processes. This problem can tie in to problem 2 for extra fun, causing your gui to stop responding entirely and force you to kill everything with the task manager. F***ing quotes Parameters often need to be passed to processes. This is a headache in itself. Especially if you're dealing with file paths. Say... 'C:/My Documents/whatever/'. If you don't have quotes, the string will often be split at the space and interpreted as two arguments. If you need nested quotes you can use ' and ". But if you need to use more than two layers of quotes, you have to do some nasty escaping, for example: "cmd /k 'python \'path 1\' \'path 2\''". A good solution to this problem is passing parameters as a list rather than as a single string. Subprocess allows you to do this. Can't easily return data from a subprocess. You can use stdout of course. But what if you want to throw a print in there for debugging purposes? That's gonna screw up the parent if it's expecting output formatted a certain way. In functions you can print one string and return another and everything works just fine. Obscure command-line flags and a crappy terminal based help system. These are problems I often run into when using os level apps. Like the /k flag I mentioned, for holding a cmd window open, who's idea was that? Unix apps don't tend to be much friendlier in this regard. Hopefully you can use google or StackOverflow to find the answer you need. But if not, you've got a lot of boring reading and frusterating trial and error to do. External factors. This one's kind of fuzzy. But when you leave the relatively sheltered harbor of your own scripts to deal with external processes you find yourself having to deal with the "outside world" to a much greater extent. And that's a scary place. All sorts of things can go wrong. Just to give a random example: the cwd in which a process is run can modify it's behavior. There are probably other issues, but those are the ones I've written down so far. Any other snags you'd like to add? Any suggestions for dealing with these problems?

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  • QAbstractTableModel as a model for one QTableView and few QListViews

    - by ??????
    community. Briefly. I wrote usual model over QAbstractTableModel and using it in usual way for QTableView. But I think I need to use some columns of this model for the few QListViews in QWizard to fill main table in the right way (for user). For example: use the column2 as the QListView's model on the page1 of the wizard; column3 for page2 for its QListView etc. Please, help me to understand just two things: Am I on the right way? If yes then how can I make it simply and explicitly?

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  • Python PyQT4 - Adding an unknown number of QComboBox widgets to QGridLayout

    - by ZZ
    Hi all, I want to retrieve a list of people's names from a queue and, for each person, place a checkbox with their name to a QGridLayout using the addWidget() function. I can successfully place the items in a QListView, but they just write over the top of each other rather than creating a new row. Does anyone have any thoughts on how I could fix this? self.chk_People = QtGui.QListView() items = self.jobQueue.getPeopleOffQueue() for item in items: QtGui.QCheckBox('%s' % item, self.chk_People) self.jobQueue.getPeopleOffQueue() would return something like ['Bob', 'Sally', 'Jimmy'] if that helps.

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  • Why doesn't my QsciLexerCustom subclass work in PyQt4 using QsciScintilla?

    - by Jon Watte
    My end goal is to get Erlang syntax highlighting in QsciScintilla using PyQt4 and Python 2.6. I'm running on Windows 7, but will also need Ubuntu support. PyQt4 is missing the necessary wrapper code for the Erlang lexer/highlighter that "base" scintilla has, so I figured I'd write a lightweight one on top of QsciLexerCustom. It's a little bit problematic, because the Qsci wrapper seems to really want to talk about line+index rather than offset-from-start when getting/setting subranges of text. Meanwhile, the lexer gets arguments as offset-from-start. For now, I get a copy of the entire text, and split that up as appropriate. I have the following lexer, and I apply it with setLexer(). It gets all the appropriate calls when I open a new file and sets this as the lexer, and prints a bunch of appropriate lines based on what it's doing... but there is no styling in the document. I tried making all the defined styles red, and the document is still stubbornly black-on-white, so apparently the styles don't really "take effect" What am I doing wrong? If nobody here knows, what's the appropriate discussion forum where people might actually know these things? (It's an interesting intersection between Python, Qt and Scintilla, so I imagine the set of people who would know is small) Let's assume prefs.declare() just sets up a dict that returns the value for the given key (I've verified this -- it's not the problem). Let's assume scintilla is reasonably properly constructed into its host window QWidget. Specifically, if I apply a bundled lexer (such as QsciLexerPython), it takes effect and does show styled text. prefs.declare('font.name.margin', "MS Dlg") prefs.declare('font.size.margin', 8) prefs.declare('font.name.code', "Courier New") prefs.declare('font.size.code', 10) prefs.declare('color.editline', "#d0e0ff") class LexerErlang(Qsci.QsciLexerCustom): def __init__(self, obj = None): Qsci.QsciLexerCustom.__init__(self, obj) self.sci = None self.plainFont = QtGui.QFont() self.plainFont.setPointSize(int(prefs.get('font.size.code'))) self.plainFont.setFamily(prefs.get('font.name.code')) self.marginFont = QtGui.QFont() self.marginFont.setPointSize(int(prefs.get('font.size.code'))) self.marginFont.setFamily(prefs.get('font.name.margin')) self.boldFont = QtGui.QFont() self.boldFont.setPointSize(int(prefs.get('font.size.code'))) self.boldFont.setFamily(prefs.get('font.name.code')) self.boldFont.setBold(True) self.styles = [ Qsci.QsciStyle(0, QtCore.QString("base"), QtGui.QColor("#000000"), QtGui.QColor("#ffffff"), self.plainFont, True), Qsci.QsciStyle(1, QtCore.QString("comment"), QtGui.QColor("#008000"), QtGui.QColor("#eeffee"), self.marginFont, True), Qsci.QsciStyle(2, QtCore.QString("keyword"), QtGui.QColor("#000080"), QtGui.QColor("#ffffff"), self.boldFont, True), Qsci.QsciStyle(3, QtCore.QString("string"), QtGui.QColor("#800000"), QtGui.QColor("#ffffff"), self.marginFont, True), Qsci.QsciStyle(4, QtCore.QString("atom"), QtGui.QColor("#008080"), QtGui.QColor("#ffffff"), self.plainFont, True), Qsci.QsciStyle(5, QtCore.QString("macro"), QtGui.QColor("#808000"), QtGui.QColor("#ffffff"), self.boldFont, True), Qsci.QsciStyle(6, QtCore.QString("error"), QtGui.QColor("#000000"), QtGui.QColor("#ffd0d0"), self.plainFont, True), ] print("LexerErlang created") def description(self, ix): for i in self.styles: if i.style() == ix: return QtCore.QString(i.description()) return QtCore.QString("") def setEditor(self, sci): self.sci = sci Qsci.QsciLexerCustom.setEditor(self, sci) print("LexerErlang.setEditor()") def styleText(self, start, end): print("LexerErlang.styleText(%d,%d)" % (start, end)) lines = self.getText(start, end) offset = start self.startStyling(offset, 0) print("startStyling()") for i in lines: if i == "": self.setStyling(1, self.styles[0]) print("setStyling(1)") offset += 1 continue if i[0] == '%': self.setStyling(len(i)+1, self.styles[1]) print("setStyling(%)") offset += len(i)+1 continue self.setStyling(len(i)+1, self.styles[0]) print("setStyling(n)") offset += len(i)+1 def getText(self, start, end): data = self.sci.text() print("LexerErlang.getText(): " + str(len(data)) + " chars") return data[start:end].split('\n') Applied to the QsciScintilla widget as follows: _lexers = { 'erl': (Q.SCLEX_ERLANG, LexerErlang), 'hrl': (Q.SCLEX_ERLANG, LexerErlang), 'html': (Q.SCLEX_HTML, Qsci.QsciLexerHTML), 'css': (Q.SCLEX_CSS, Qsci.QsciLexerCSS), 'py': (Q.SCLEX_PYTHON, Qsci.QsciLexerPython), 'php': (Q.SCLEX_PHP, Qsci.QsciLexerHTML), 'inc': (Q.SCLEX_PHP, Qsci.QsciLexerHTML), 'js': (Q.SCLEX_CPP, Qsci.QsciLexerJavaScript), 'cpp': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'h': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'cxx': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'hpp': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'c': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'hxx': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'tpl': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'xml': (Q.SCLEX_XML, Qsci.QsciLexerXML), } ... inside my document window class ... def addContentsDocument(self, contents, title): handler = self.makeScintilla() handler.title = title sci = handler.sci sci.append(contents) self.tabWidget.addTab(sci, title) self.tabWidget.setCurrentWidget(sci) self.applyLexer(sci, title) EventBus.bus.broadcast('command.done', {'text': 'Opened ' + title}) return handler def applyLexer(self, sci, title): (language, lexer) = language_and_lexer_from_title(title) if lexer: l = lexer() print("making lexer: " + str(l)) sci.setLexer(l) else: print("setting lexer by id: " + str(language)) sci.SendScintilla(Qsci.QsciScintillaBase.SCI_SETLEXER, language) linst = sci.lexer() print("lexer: " + str(linst)) def makeScintilla(self): sci = Qsci.QsciScintilla() sci.setUtf8(True) sci.setTabIndents(True) sci.setIndentationsUseTabs(False) sci.setIndentationWidth(4) sci.setMarginsFont(self.smallFont) sci.setMarginWidth(0, self.smallFontMetrics.width('00000')) sci.setFont(self.monoFont) sci.setAutoIndent(True) sci.setBraceMatching(Qsci.QsciScintilla.StrictBraceMatch) handler = SciHandler(sci) self.handlers[sci] = handler sci.setMarginLineNumbers(0, True) sci.setCaretLineVisible(True) sci.setCaretLineBackgroundColor(QtGui.QColor(prefs.get('color.editline'))) return handler Let's assume the rest of the application works, too (because it does :-)

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