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On Sun, 6 Oct 2019 21:59:48 +0200
Maurizio Berti <maurizio.berti at gmail.com> wrote:
> After some tests, I found that the problem is not about modal
> windows at all. <snip> A simple solution is to convert the pixmap to
> a QImage and use its save() function, which seems to be thread safe
> and doesn't block the GUI:
> WIN.pixmap.toImage().save('/tmp/nonmodal_test.png')
That didn't change things for me.
... which is good. For my test, I require a long-running task that
locks the GUI. Both QPixmap *save* and QImage *save* seem to fill the
bill.
I changed QMessageBox to *exec_* from *show* and fired it from the
*started* signal of the thread per your example, which seems to be a
straightforward approach, but that couldn't manage to display anything
unless the thread paused with a *sleep* first.
Returning to your kind reply....
> - You don't need to return every function if the returned value is
> not required, as Python implicitly returns None if no explicit
> return exists
Hah! You're not the first to be bugged by this habit of mine. I am
more comfortable making the exit from the function explicit AND
TRAILING although doing so is rundundant. I mightily resist returning
from the middle. I'm sure this has to do with my tenure as a COBOL
'68 programmer where many (of those who were influential) considered
it best practice, although it was (usually) redundant, to insert empty
exit-paragraph labels explicitly to delimit the trailing edge of
*perform*ed code. In Python, where everything is a function with a
return value (which is usually None), I try to consider what to return
and make the choice explicit -- even when IT IS nothing. When I'm
writing my own classes, I'll usually make the *set* methods return
*self*, for example.
> - Avoid using object names that already are existing properties or
> methods (like self.thread)
Oh, heck!
I remember, writing Pascal, where it was fairly common to prefix
labels to indicate their type: x-strings, i-integers, f-functions, and
xxx-methods, where xxx was the abbreviated name of the class. This
had the virtue of avoiding tracking-over implementor's names during
subclassing and having your own tracked-over in turn. In Python, it's
much more chic to rely on implicit typing, and best practice is to
avoid such prefixing, and I get into trouble.
> - You can connect the finished signal directly to the close (or,
> better, accept) slot of the popup and delete the thread itelf:
<snip>
> class WinMain(QMainWindow):
> def test_part_1(self):
> popup = WaitMessage(self)
> worker = ThdWorker(self)
> worker.started.connect(popup.exec_)
> worker.finished.connect(worker.deleteLater)
> worker.finished.connect(popup.deleteLater)
> worker.start()
That's cool! Didn't think of that. The modal dialog can be harnessed
for non-modal duty.
I dithered about whether to *del* the thread and popup structures. In
my extended test suite, they are replaced by new ones for each
scenario, and presumably the old ones are garbage-collected soon
thereafter. Not bothering about garbage collection is one of the
principal virtues of coding in Python, and I shouldn't have worried
about trying to show their destruction explicitly. Aren't explicit
deletes like *del* or *deleteLater* truely rundundant?
Anyway here's a revised example. First is a module containing a
"wOrker" object:
> #!/usr/bin/python
> # -*- coding: utf-8 -*-
> # uidgets.py
> # 2019 Oct 07 . ccr
> """Local extensions to Qt widgets.
>> """
> from __future__ import division
> from PyQt5.QtWidgets import (
> QMessageBox,
> )
> from PyQt5.QtCore import(
> QThread,
> )
> from PyQt5.QtCore import(
> Qt,
> )
> ZERO = 0
> SPACE = ' '
> NULL = ''
> NUL = '\x00'
> NA = -1
> class UiOrker(object):
> """Fork a long-running task into its own thread after displaying a wait
> box.
>> *title* is the window title of the wait box.
>> *text* is the text in the wait box.
>> *parent* is the window that owns the wait box and the forked thread.
>> *process* is the long-running task.
>> *kill* is the epilog performed after the wait box is canceled or the
> forked thread finishes, if any.
>> *run()* starts the process.
>> """
> def __init__(
> self,
> icon=QMessageBox.Information,
> title=None,
> text='Please wait.',
> parent=None,
> process=None,
> kill=None,
> ):
> self.icon = icon
> self.title = title
> self.text = text
> self.parent = parent
> self.process = process
> self.kill = kill
> self.parms = None
> return
> def get_popup(self):
> result = QMessageBox(self.icon, self.title, self.text, parent=self.parent)
> result.setStandardButtons(QMessageBox.Cancel)
> result.setWindowFlags(Qt.Dialog)
> result.finished.connect(self.epilog)
> return result
> def get_fork(self, popup):
> result = QThread(self.parent)
> result.run = self.run_threaded
> result.started.connect(popup.exec_)
> result.finished.connect(popup.close)
> return result
> def run(self, *parms):
> self.parms = parms
> popup = self.get_popup()
> self.fork = self.get_fork(popup)
> self.fork.start()
> return self
> def run_threaded(self):
> QThread.msleep(100)
> self.process(*self.parms)
> return
> def epilog(self):
> self.fork.exit(NA)
> if self.kill:
> self.kill(*self.parms)
> return
> # Fin
And here is the UI:
> #!/usr/bin/python
> # -*- coding: utf-8 -*-
> # nonmodal_example_2.py
> # 2019 Oct 07 . ccr
> """Demonstrate a class showing a non-modal dialog box while starting a
> long-running task.
>> """
> from __future__ import division
> import sys
> from PyQt5.QtWidgets import (
> QApplication,
> QMainWindow,
> QWidget,
> QGridLayout,
> QPushButton,
> )
> from PyQt5.QtGui import (
> QPixmap,
> QTransform,
> )
> import uidgets
> ZERO = 0
> SPACE = ' '
> NULL = ''
> NUL = '\x00'
> NA = -1
> class WinMain(QMainWindow):
> """The (trivial) main window of the graphical user interface.
>> """
> def __init__(self):
> super(WinMain, self).__init__()
> self.resize(800, 600)
> self.central_widget = QWidget(self)
> self.setCentralWidget(self.central_widget)
> self.layout = QGridLayout()
> self.central_widget.setLayout(self.layout)
> self.btn_run = QPushButton('Run Test Scenario', self.central_widget)
> self.btn_run.setMaximumSize(200, 30)
> self.btn_run.clicked.connect(self.test)
> self.layout.addWidget(self.btn_run)
> figure = QPixmap()
> result = figure.load('/usr/share/qt5/doc/qtdesigner/images/designer-screenshot.png')
> if result:
> pass
> else:
> raise NotImplementedError
> transformation = QTransform()
> transformation.scale(5.0, 5.0)
> self.pixmap = figure.transformed(transformation)
> return
> def test(self):
> """Fork a thread.
>> """
> def long_running_task(*parms):
> print 'process', parms
> self.pixmap.toImage().save('/tmp/nonmodal_test.png')
> return
> def kill(*parms):
> print 'kill', parms
> return
> uidgets.UiOrker(parent=self, process=long_running_task, kill=kill).run('Ui', ZERO)
> return
> if __name__ == "__main__":
> APP = QApplication(sys.argv)
> WIN = WinMain()
> WIN.show()
> result = APP.exec_()
> sys.exit(result)
> # Fin
Still, it'd be nice not to have that niggling *sleep* at the beginning
of the thread, you know.
- --
.. Be Seeing You,
.. Chuck Rhode, Sheboygan, WI, USA
.. Weather: http://LacusVeris.com/WX
.. 53掳 鈥� Wind W 8 mph
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‘She has never mentioned her father to me. Was he—well, the sort of man whom the County Club would not have blackballed?’ "We walked by the side of our teams or behind the wagons, we slept on the ground at night, we did our own cooking, we washed our knives by sticking them into the ground rapidly a few times, and we washed our plates with sand and wisps of grass. When we stopped, we arranged our wagons in a circle, and thus formed a 'corral,' or yard, where we drove our oxen to yoke them up. And the corral was often very useful as a fort, or camp, for defending ourselves against the Indians. Do you see that little hollow down there?" he asked, pointing to a depression in the ground a short distance to the right of the train. "Well, in that hollow our wagon-train was kept three days and nights by the Indians. Three days and nights they stayed around, and made several attacks. Two of our men were killed and three were wounded by their arrows, and others had narrow escapes. One arrow hit me on the throat, but I was saved by the knot of my neckerchief, and the point only tore the skin a little. Since that time I have always had a fondness for large neckties. I don't know how many of the Indians we killed, as they carried off their dead and wounded, to save them from being scalped. Next to getting the scalps of their enemies, the most important thing with the Indians is to save their own. We had several fights during our journey, but that one was the worst. Once a little party of us were surrounded in a small 'wallow,' and had a tough time to defend ourselves successfully. Luckily for us, the Indians had no fire-arms then, and their bows and arrows were no match for our rifles. Nowadays they are well armed, but there are[Pg 41] not so many of them, and they are not inclined to trouble the railway trains. They used to do a great deal of mischief in the old times, and many a poor fellow has been killed by them." As dusk came on nearly the whole population of Maastricht, with all their temporary guests, formed an endless procession and went to invoke God's mercy by the Virgin Mary's intercession. They went to Our Lady's Church, in which stands the miraculous statue of Sancta Maria Stella Maris. The procession filled all the principal streets and squares of the town. I took my stand at the corner of the Vrijthof, where all marched past me, men, women, and children, all praying aloud, with loud voices beseeching: "Our Lady, Star of the Sea, pray for us ... pray for us ... pray for us ...!" It had not occurred to her for some hours after Mrs. Campbell had told her of Landor's death that she was free now to give herself to Cairness. She had gasped, indeed, when she did remember it, and had put the thought away, angrily and self-reproachfully. But it returned now, and she felt that she might cling to it. She had been grateful, and she had been faithful, too.[Pg 286] She remembered only that Landor had been kind to her, and forgot that for the last two years she had borne with much harsh coldness, and with a sort of contempt which she felt in her unanalyzing mind to have been entirely unmerited. Gradually she raised herself until she sat quite erect by the side of the mound, the old exultation of her half-wild girlhood shining in her face as she planned the future, which only a few minutes before had seemed so hopeless. After he had gloated over Sergeant Ramsey, Shorty got his men into the road ready to start. Si placed himself in front of the squad and deliberately loaded his musket in their sight. Shorty took his place in the rear, and gave out: The groups about each gun thinned out, as the shrieking fragments of shell mowed down man after man, but the rapidity of the fire did not slacken in the least. One of the Lieutenants turned and motioned with his saber to the riders seated on their horses in the line of limbers under the cover of the slope. One rider sprang from each team and ran up to take the place of men who had fallen. "As long as there's men and women in the world, the men 'ull be top and the women bottom." Then, in the house, the little girls were useful. Mrs. Backfield was not so energetic as she used to be. She had never been a robust woman, and though her husband's care had kept her well and strong, her frame was not equal to Reuben's demands; after fourteen years' hard labour, she suffered from rheumatism, which though seldom acute, was inclined to make her stiff and slow. It was here that Caro and Tilly came in, and Reuben began to appreciate his girls. After all, girls were needed in a house—and as for young men and marriage, their father could easily see that such follies did not spoil their usefulness or take them from him. Caro and Tilly helped their grandmother in all sorts of ways—they dusted, they watched pots, they shelled peas and peeled potatoes, they darned house-linen, they could even make a bed between them. HoME一级毛片视频免费公开
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