##// END OF EJS Templates
Backport PR #2294: inputhook_qt4: Use QEventLoop instead of starting up the QCoreApplication...
Backport PR #2294: inputhook_qt4: Use QEventLoop instead of starting up the QCoreApplication I referenced this branch in #2080 and was letting it sit for a little while, but I have decided to make it a full pull request to get some additional visibility. Essentially our Qt event loop mechanism repeatedly starts and quits a `QCoreApplication` object. Unfortunately the `QCoreApplication::quit` slot has a lot of unintended side effects (like emitting an `aboutToQuit` signal which closes all open file dialogs). For our input hook, we _might_ be able to get by with just using a `QEventLoop` whose quit slot is much simpler and less destructive. For a little bit of background on why one might want to just use `QEventLoop::exec`, let's examine what `QCoreApplication::exec` does: ```c++ int QCoreApplication::exec() { if (!QCoreApplicationPrivate::checkInstance("exec")) return -1; // ... [some assertions] threadData->quitNow = false; QEventLoop eventLoop; self->d_func()->in_exec = true; self->d_func()->aboutToQuitEmitted = false; int returnCode = eventLoop.exec(); threadData->quitNow = false; if (self) { self->d_func()->in_exec = false; if (!self->d_func()->aboutToQuitEmitted) emit self->aboutToQuit(); self->d_func()->aboutToQuitEmitted = true; sendPostedEvents(0, QEvent::DeferredDelete); } return returnCode; } ``` As far as I can tell, it's a small wrapper around `QEventLoop::exec` which also: * Sets some variables regarding the current status * Emits an `aboutToQuit` signal right before the function returns (which is the root cause of @denisri's problem in #2080). Historically, our Qt event loop is a python implementation of the (win 32) input hook supplied with the PyQt4 source (see qtcore_input_hook` in `python-qt4/sip/QtCore/qcoreapplication.sip`), which more or less dates to a [mailing list post](http://www.riverbankcomputing.com/pipermail/pyqt/2007-July/016512.html) from July 2007.

File last commit:

r3920:35fb6d87
r9834:71196839
Show More
svg.py
89 lines | 2.3 KiB | text/x-python | PythonLexer
""" Defines utility functions for working with SVG documents in Qt.
"""
# System library imports.
from IPython.external.qt import QtCore, QtGui, QtSvg
def save_svg(string, parent=None):
""" Prompts the user to save an SVG document to disk.
Parameters:
-----------
string : basestring
A Python string containing a SVG document.
parent : QWidget, optional
The parent to use for the file dialog.
Returns:
--------
The name of the file to which the document was saved, or None if the save
was cancelled.
"""
if isinstance(string, unicode):
string = string.encode('utf-8')
dialog = QtGui.QFileDialog(parent, 'Save SVG Document')
dialog.setAcceptMode(QtGui.QFileDialog.AcceptSave)
dialog.setDefaultSuffix('svg')
dialog.setNameFilter('SVG document (*.svg)')
if dialog.exec_():
filename = dialog.selectedFiles()[0]
f = open(filename, 'w')
try:
f.write(string)
finally:
f.close()
return filename
return None
def svg_to_clipboard(string):
""" Copy a SVG document to the clipboard.
Parameters:
-----------
string : basestring
A Python string containing a SVG document.
"""
if isinstance(string, unicode):
string = string.encode('utf-8')
mime_data = QtCore.QMimeData()
mime_data.setData('image/svg+xml', string)
QtGui.QApplication.clipboard().setMimeData(mime_data)
def svg_to_image(string, size=None):
""" Convert a SVG document to a QImage.
Parameters:
-----------
string : basestring
A Python string containing a SVG document.
size : QSize, optional
The size of the image that is produced. If not specified, the SVG
document's default size is used.
Raises:
-------
ValueError
If an invalid SVG string is provided.
Returns:
--------
A QImage of format QImage.Format_ARGB32.
"""
if isinstance(string, unicode):
string = string.encode('utf-8')
renderer = QtSvg.QSvgRenderer(QtCore.QByteArray(string))
if not renderer.isValid():
raise ValueError('Invalid SVG data.')
if size is None:
size = renderer.defaultSize()
image = QtGui.QImage(size, QtGui.QImage.Format_ARGB32)
painter = QtGui.QPainter(image)
renderer.render(painter)
return image