I recreated the example of a webkit that displays the content of a textEdit containing HTML: http://qt-project.org/doc/qt-4.8/webkit-previewer.html
I changed it so rather than the webkit HTML being changed upon clicking the button, it's changed upon the text in the textEdit being changed:
// changed when button is click. Works fine.
void Previewer::on_previewButton_clicked()
{
// Update the contents in web viewer
QString text = htmlTextEdit->toPlainText();
webView->setHtml(text);
}
// change when text is changed. Crashes.
void Previewer::on_htmlTextEdit_textChanged()
{
// Update the contents in web viewer
QString text = "<html><body><h1>No crash!</h1></body></html>";
webView->setHtml(text);
}
This causes the program to crash as soon as it starts. I altered the program to run the function only a bit later (I thought maybe something needed to be initialized) but it still crashed once it reached the textChanged function. Why is it crashing? How can I fix this?
Your program is entering an infinite loop because, in the example, there's a connection between the webView's loadFinished(bool) signal and the text/html editor's updateTextEdit() slot.
Basically, editing the HTML causes the page to load again, which causes an update to the editor, which causes the page to load again, so on and so forth.
A quick way I solved this was to add a static bool flag to the updateTextEdit SLOT/function that only allows it to run once.
void MainWindow::updateTextEdit()
{
static bool once = false;
if (once) {
return;
}
once = true;
QWebFrame *mainFrame = centralWidget->webView->page()->mainFrame();
QString frameText = mainFrame->toHtml();
centralWidget->plainTextEdit->setPlainText(frameText);
}
Doing this worked for me, but your version might work differently than mine. I followed the example closely, but added an htmlchanged() slot to the previewer class, and made the connection like so:
connect(centralWidget->plainTextEdit, SIGNAL(textChanged()), centralWidget, SLOT(html_changed()));
Also, I'm no expert, but I'm pretty sure this is not the best way to get around this, and I assume that updateTextEdit() needs to run more than once. It'll work for the time being, though.
Related
I am trying to make a JavaFX application (running in the background to show up (set visible)) by a specific keystroke and to make the window the active window immediately. Therefore I set the primary stage alwaysOnTop-property true, call stage.toFront() and finally call stage.requestFocus(). Afterwards I request focus for a text field. When the window is made visible I would like to instantly start typing into the text field.
However, when I for example have a Ubuntu-terminal selected and make the window visible and start typing, the application is shown on top of everything, however, the typing goes to the terminal. The application window is not active! Nevertheless, the focused property of the stage is true. Is that a bug or am I missing something? Is it OS related?
Edit: I am willed to give my little hack-around for this problem that I am using at the moment, because the internet is suggesting, that a lot of people are facing this problem: Since I am working on a linux maschine I have access to the wonderful tool wmctrl. It is part of most standard repositories. wmctrl -a WINDOWNAME sets the window with the name WINDOWNAME active. For now, I simply call this tool from my source code when I need the window to be active. Since this is more of a dirty hack than any thing else, I sure want to get rid of it.
Not perfect, but it works:
Platform.runLater(() ->
{
//primaryStage.setAlwaysOnTop(true);
//primaryStage.setAlwaysOnTop(false);
primaryStage.setIconified(true);
primaryStage.setIconified(false);
});
If your node is not getting focused, try wrapping requestFocus() in a Runnable and call Platform.runLater():
final TextField text = new TextField();
Platform.runLater(new Runnable() {
#Override
public void run() {
text.requestFocus();
}
});
We're currently using QtWebKit to build an application, part of which displays the product catalogue page of our website. On that webpage we're using the jQuery.history plugin to keep track of sorting and filtering options without users needing to reloading the page.
When jQuery.history's pushState() function is called the URL provided is pushed to the history properly, but QWebView's urlChanged() signal (which we're listening for to update back/forward buttons and the address bar) isn't fired even though the current URL has changed. I can only assume this is because no link was clicked, nor was there a page reload so Qt doesn't think it needs to do anything URL-related.
Is there any way to detect a URL change made via the HTML5 history API in QtWebKit, or am I missing something obvious?
There is QWebPage::saveFrameStateRequested signal:
This signal is emitted shortly before the history of navigated pages in frame is changed, for example when navigating back in the history.
You can use it to track history changes:
void MainWindow::saveFrameStateRequested(QWebFrame *frame, QWebHistoryItem *item) {
// this slot is executed before the history is changed,
// so we need to wait a bit:
QTimer::singleShot(100, this, SLOT(listHistoryItems()));
}
void MainWindow::listHistoryItems() {
for (QWebHistoryItem historyItem: view->page()->history()->items()) {
qDebug() << "item" << historyItem.url() << historyItem.title();
}
}
void MainWindow::finishLoading(bool) {
// (re)connect the signal to track history change,
// maybe there is a better place to connect this signal
// where disconnect won't be needed
disconnect(view->page(), SIGNAL(saveFrameStateRequested(QWebFrame*,QWebHistoryItem*)),
this, SLOT(saveFrameStateRequested(QWebFrame*,QWebHistoryItem*)));
connect(view->page(), SIGNAL(saveFrameStateRequested(QWebFrame*,QWebHistoryItem*)),
this, SLOT(saveFrameStateRequested(QWebFrame*,QWebHistoryItem*)));
}
The modified Fancy Browser example screenshot.
I have a timer in my application. For every 30 min, it will hit the web services and fetch the data and updates the UI. The application was working fine till yesterday. Suddenly, because of some issue, the web services were not available for some time. During that period, Application displayed the RPC Error multiple times(More than 100 alert boxes) in alert window. Because of this alert boxes, my application was hanged and i was not able to do anything.
I have tried several approaches, but nothing worked.Finally, I have tried to use a flag. In all the approaches, this looked promising. so i have implemented it.Basically, in this approach whenever we open an alert we will set a flag.While opening and closing alert we will reset this flag. But it didn't work as expected. Is there any approach, which can help us in avoiding multiple alert windows.
Please help me, to fix this issue.
I would write wrapper for opening alerts, and use only this wrapper, not Alert.show in the code:
public class AlertWrapper {
private static var lastAlert:Alert;
public static function showAlert(text:String, title:String):void {
if (lastAlert) {
PopUpManager.removePopUp(lastAlert);
//or
//return; //ignore last alert
}
lastAlert = Alert.show(text, title, null, 4, onAlertClose);
}
private static function onAlertClose(event:CloseEvent):void {
lastAlert = null;
}
}
Imports are missing, but I hope the idea is clear.
My application consists of a WebView widget. A mouse click on the widget is not handled by the mousePressEvent() of my application, but by the WebView widget. So, I installed an event filter to receive the events. Now, I get notified of all events, except the mouseReleaseEvent for the right click (Everything works fine for left clicks and mousePressEvent for the right click is also getting registered). I guess it has got something to do with context events getting generated by right clicks (a pop-up menu gets generated). But since I am using a filter, the event should first be sent to me. The following is the code for the event filter
in Jambi, but I hope I can modify an answer given in Qt for Jambi.
public boolean eventFilter(QObject o,QEvent event)
{
if (event.type()==QEvent.Type.MouseButtonPress) // One can call the mousePressEvent() functions from here,which can do this work but speed
{
if (((QMouseEvent)event).button()==Qt.MouseButton.LeftButton)
{
mousebuttontype=1;
clickedorpressed=1;
}
else
if (((QMouseEvent)event).button()==Qt.MouseButton.RightButton)
{
mousebuttontype=2;
System.out.println("right");
}
t1=QTime.currentTime();
t1.start();
}
else
if (event.type()==QEvent.Type.MouseButtonRelease)
{
if (t1.elapsed()>900)
{
switch(mousebuttontype)
{
case 1: browser.back();
break;
case 2: browser.forward();
break;
}
}System.out.println("choda");
}
return false;
}
MY BASIC AIM IS GETTING THE TIME INTERVAL FOR WHICH THE RIGHT CLICK WAS PRESSED. ANY WORKAROUND ?
Some digging around certainly seems to suggest that there may be no right-mouse release event being generated if that is the trigger for a context menu on your particular system. These are conveyed as a QContextMenuEvent.
This Qt Labs post hints about this too.
A work around may be tricky if it is system dependent. Have you tried overriding event() in the QApplication class to see if the event comes through there? Some events don't necessarily get to the children but everything goes through QApplication::event().
Another option for you is, subclass Qwebview and override mouseReleaseEvent event
I've found a fix for this that I dont think will be system dependent.
My particular case was using mouseReleaseEvent in order to catch the events, and use them myself. I didn't get these events.
On all child widgets of the widget that I want to handle the event, I added to the class definition:
protected:
void mouseReleaseEvent(QMouseEvent *event) {event->ignore();}
This overrides the default implementation for context menu's, and sends the mouseReleaseEvent back up the parent chain like it would for other mousebuttons.
http://doc.qt.io/qt-5/qevent.html#ignore
This shows that it will probably propagate to the parent widget. As the link indicates, this fixed it for me at Qt 5.9, but I think it should work for virtually all version.
(I am aware this question is literally 7 years old, but it doesn't contain the fix that I think would be the best fix, and shows up as result 2 on google(qt not getting mouse release event on rightclick). So I think it deserves an up to date answer.)
Without going in to broader implementation explanations, the core problem I needed to solve related to this issue was that I needed to know if a context menu swallowed the right-click so I could ensure some custom state was handled properly. The simplest workaround I was able to find was to implement contextMenuEvent, which gets called after mousePressEvent, to detect if the event was accepted (a context menu was opened somewhere in my QGraphicsScene/Items). Here is a minimal example in Python to demonstrate how the event state might be used:
def contextMenuEvent(self, event):
event.setAccepted(False)
super(MyGraphicsView, self).contextMenuEvent(event)
self.__context_menu_used = event.isAccepted()
Note you can also skip running the the base class contextMenuEvent entirely to block the scene/items from opening a context menu. This is handy if you want to do 3D-DCC-like alt-RMB-zooming without accidentally opening a context menu, e.g.:
def contextMenuEvent(self, event):
# Block context menus if alt is held down
if event.modifiers() & QtCore.Qt.AltModifier:
return
event.setAccepted(False)
super(MyGraphicsView, self).contextMenuEvent(event)
self.__context_menu_used = event.isAccepted()
Can I add a ProgressEvent listener to the stage?
I don't see it in any of the auto-complete options when I am typing in Flex.
What do people normally do to get a progress readout of the entire main runner's loading progress?
I try the following, which is where I would expect to see the ProgressEvent options pop up:
stage.addEventListener(
Thanks...
Try adding it to loaderInfo.
something like:
this.loaderInfo.addEventListener(ProgressEvent.PROGRESS, progressHandler);
Also , if you're using the framework, you should probably extend the DownloadProgressBar.
I remember this old tutorial, but surely there must be plenty online.
I have a new problem:
I use the following code to show the progress of the download of my site content:
public function mainProgress(e:ProgressEvent):void
{
var w:Number = e.bytesLoaded / e.bytesTotal;
_mainprog.graphics.clear();
_mainprog.graphics.beginFill(0x000000);
_mainprog.graphics.drawRect(0, 0, w * stage.stageWidth, 50);
_mainprog.graphics.endFill();
}
But it doesn't seem to work.
What happens is that the loaderInfo object thinks that the site has loaded before I am actually ready to display anything. So what ends up happening (I think) is the site loads, the loader progress disappears before the initial page's graphics have fully loaded, and then there is a delay between when the completion of the loaderInfo object happens and the actual graphics appearing.
Has anyone else had this problem before?
Thanks...