Hello good people of stack overflow, I have run into a bit of a wall in creating an application. I am using custom wxPanels to display a few similar things.
What I'm having trouble doing is updating a master count when a counter in the panel is updated (the counters are wxSpinCtrl's) I can not, for the life of me, find a way to access the master spinctrl from any of the wxPanels.
I've tried passing a pointer to the master spinctrl, but when I try to access it from there I get a seg fault. I've tried setting up a custom event, but I don't know how to access the children of a wxPanel from the main panel. Does anyone have any suggestions?
You can do this several ways, but the usual way is to use an event that is triggered when the user changes the spin control value.
You do not need a custom event, the provided wxSpinEvent is fine.
You do not need to access the spinctontrol, you can get the new value from the event
void OnSpin( wxSpinEvent& event )
{
count = event.GetPosition();
}
Related
I have bunch of data that has to be displayed continuously on the GUI. I can actually achieve it by setting timer and assigning the new values to the displayed values but I do not want to do in that way. Is there any solution or practical way to do that?
I think you have two options to achieve that:
All your data have a Q_PROPERTY. That means create a get function and a signal
If you want to show them under a list or a treeview, I suggest you gather all the data up, under a QAbstractListModel.
https://doc.qt.io/qt-5/qabstractlistmodel.html
Then implementing the function data, index, ecc., you will have everything already done for the UI
Have you tried using Q_Property? Notify Signal may work for your situation.
You can find the documentation from here.
First, I defined the property and added the notifier called payloadChanged to the signals of my class.
Q_PROPERTY(QList<qreal> PayloadList READ getPayloadList NOTIFY payloadChanged)
Secondly,
qmlRegisterType<<YOUR_CLASS_NAME>>("sample1.sample2", 1, 0, "<QML_ITEM_NAME>");
Finally
QML_ITEM_NAME{
console.log("PROPERTY")
}
When I applied these steps my data is automatically updated without any timer stuff.
I have some widgets that receives a lot of user inputs in a very short period of time.
eg. a selectInput with multiple selection on which the user are clicking a lot very quickly
This causes unnecessary calls to the server side of the Shiny application.
Is there a way to set a delay before the widget sends its new data to the server? either application wise or on a per-widget basis.
I guess that would ask for some 'setTimeout' and 'clearTimeout' in the javascript.
If that's not available natively what are my options?
I have written a few custom widgets using http://www.htmlwidgets.org/ but I don't want to reinvent the wheel and I don't want to make a clone of the native widget because that would force me to track new versions of the the widget and update the clone correspondingly.
Is there a way to extend an existing widget and override only some part of it (the part sending the new input to the server side), and keep getting the updates of this existing widget?
Another option would be to let the widget send its updated input every time there is a change on the widget BUT to tell the server to wait before handling it, in case a new input comes in. That would work for me as well.
NOTE: I don't want to use observeEvent/eventReactive
If you are able to use JavaScript then I would recommend using a setInterval loops stored in variables. I find them really handy for running functions in intervals and you can run multiple loops at the same time and tweak the timing for best performance as you can also close off and start up new ones. Hope this helps.
I have a CListCtrl in my MFC application. The list needs to be updated when I get some notification from the server. Updating list works quite good when there are less notification as operations on the list are less. But in case of heavy load, list control and in turn the application gets freeze.
I am aware of updating UI items in the separate thread in case of bulk updates, but in this case I have the notifications that can come in any order and in any volume, I need to handle in such way that my main thread is not getting blocked.
If anyone faced the issue before please suggest the approach for this case.
You could put all the updates into a queue. Then do a limited number of updates from the queue to the control in the OnIdle function. OnIdle is called when your GUI message queue is empty. It could do up to, say, 20 updates and then return. The main thread would than process any GUI input and when finished with that it would call OnIdle again. In this way you delay and spread out the updates while keeping the GUI alive.
I had a similar situation and resolved it using a Timer. Only when the Timer ticked the ListCtrl could got updated.
Side note: You should do
SetRedraw(FALSE);
before a bulk update
and
SetRedraw(TRUE);
after.
You should not have the control drawing itself at a one-by-one item level, when doing a bulk operation.
Use Thread.I had the same problem and I solved it by just having the loop of adding elements into the clistctrl in thread function. That is,is the POSTMESSAGE() function in the thread should be called as much time as we want to add elements .
MFC Application getting stuck when adding list control elements
Also refer the above link to get some idea
how to refresh List View dynamic data content in android?
I tried loading dynamic data for the List View in android application but no luck .Any advice how to accomplish this?
Call notifyDataSetChanged() on your Adapter object once you've modified the data in that adapter.
Some additional specifics on how/when to call notifyDataSetChanged() can be viewed in this Google I/O video.
Or else Look at this link.it may helpful.
Dynamic ListView in Android app
Or else
The right thing to do is to call notifyDataSetChanged() on your Adapter.
Troubleshooting
If calling notifyDataSetChanged() doesn't work all the layout methods won't help either. Believe me the list view was properly updated. If you fail to find the difference you need to check where the data in your adapter comes from.
If this is just a collection you're keeping in memory check that you actually deleted the item from the collection before calling the notifyDataSetChanged().
If you're working with a database or service backend you'll have to call the method to retrieve the information again (or manipulate the in memory data) before calling the notifyDataSetChanged().
The thing is this notifyDataSetChanged only works if the dataset has changed. So that is the place to look if you don't find changes coming through. Debug if needed.
UI Thread
It is true that this has to be called from the UI thread. Other answers have examples on how to achieve this. However this is only required if you're working on this information from outside the UI thread. That is from a service or a non UI thread. In simple cases you'll be updating your data from a button click or another activity/fragment. So still within the UI thread. No need to always pop that runOnUiTrhead in.
More Information
Another nice post about the power of list Views is found here:http://www.vogella.com/articles/AndroidListView/article.html
I am currently writing a wizard-style application using Qt4. I am not using the wizard class however, since going next/back does not make sense from every step in the process.
The user starts off at a "hub"-window with five buttons, each of which take him to another window at a different stage of the process. At the beginning all but the first button of the hub are disabled. After clearing each stage, the user will be directed back to the hub and one new button/stage will get enabled.
Since every stage has significantly differing objectives, I coded every single stage as a single QWidget that gets instantiated in the main() function. To switch between the widgets, I simply hide() the one I am leaving and show() the one I am going to.
However, this leads to problems if the user resized or moved one widget, since the next widget will always show up at its default position instead of the new one.
Is there a way to synchronize the widgets' sizes and positions?
Or, better yet, is there a more elegant way to deal with those different windows than switching between several hidden widgets?
Thank you in advance!
Create one top-level widget that holds the others.
I suggest that you either use QStackedWidget, or, if you want more control, create your own widget and use QStackedLayout directly.
Why not just have one main QWidget as a container for your pages? That way if the user moves the main QWidget and then goes to the next page, it will still open in the new position inside the main widget.
Generally, I've never had occasion to create multiple widgets inside my main method. Don't quite see the point.
I'm beginning on something similar - with different views (perspectives) for different tasks along the way. Using toolbar icons and file menu, not buttons, to move between views. Similar to how MS Outlook allows you to have the window display email, or a calendar, or contacts, etc.
My intent (haven't started yet) is to have one QMainWindow as the application window, containing my various QWidgets that offer the various views. Depending on what task the user is doing, one composite widget will be visible, and the others hidden.