In E3 we had a couple of handlers that were to be checked, and so the handler had to figure out when to be checked. Back then that was an easy task:
public class MyHandler extends AbstractHandler implements IElementUpdater {
#Override
public void updateElement(UIElement element, Map parameters) {
element.setChecked(calculateCheckState());
}
}
I found this similar question, but it's much broader (updating all commands, while I only want to set the checked state whenever the framework seems it necessary). Since tool and menu items can be check or radio items, this has to be possible somehow.
So how do I set the check state of a handler in E4?
You can set the check (selected) state in the #CanExecute method of the handler using something like:
#CanExecute
public boolean canExecute(MItem item)
{
item.setSelected(... checked state ....);
return true;
}
For a menu item the #CanExecute method is called every time the menu is displayed.
For a tool bar item you may need to use the IEventBroker UIEvents.REQUEST_ENABLEMENT_UPDATE_TOPIC event to force the method to run.
eventBroker.send(UIEvents.REQUEST_ENABLEMENT_UPDATE_TOPIC, argument);
argument can be
UIEvents.ALL_ELEMENT_ID to update all items.
The id of a single item to be updated.
A Selector (org.eclipse.e4.ui.workbench.Selector) to select the items to be updated.
Related
I'm just starting with wxWidgets and I've run into a problem.
I have a mainwindow and another class derived from wxDialog. The main window launches the dialog box in non-modal mode. When the dialog closes, it posts an event but the handler for this event never gets called.
I'm using wxWidgets 3.1.5
The above two classes share a common header file, in which I have this code
wxDECLARE_EVENT(EVT_VISOR, wxCommandEvent);
This is my event table
BEGIN_EVENT_TABLE(VisorFrame, wxFrame)
....
EVT_COMMAND(ID_DlgDisplayLogsTerminated, EVT_VISOR, VisorFrame::OnDlgDisplayLogsTerinated)
....
END_EVENT_TABLE()
In the class derived from wxDialog, I have this at the top of my file
wxDEFINE_EVENT(EVT_VISOR, wxCommandEvent);
This is my event handler
void
VisorFrame::OnDlgDisplayLogsTerinated(wxCommandEvent& event)
{
wxPuts(_("VisorFrame::OnDlgDisplayLogsTerinated ent"));
}
And finally, this is how I post my event
void
DlgDisplayLogs::OnClose(wxCloseEvent& ev)
{
wxPuts(_("send event"));
wxCommandEvent event(EVT_VISOR, ID_DlgDisplayLogsTerminated); // enum value
event.SetEventObject(this);
event.SetString("Hello");
QueueEvent(event.Clone());
ev.Skip();
}
I have followed the documentation but I must be doing something wrong!
I think you're nearly there. I think what you could do is pass the wxFrame as a parent to your modeless dialog and post the event via the parent.
wxCommandEvent event(EVT_VISOR, ID_DlgDisplayLogsTerminated);
event.SetEventObject(this);
event.SetString("Hello");
wxPostEvent(frameParentPtr, event);
And in your wxFrame event table:
EVT_COMMAND(wxID_ANY, EVT_VISOR, VisorFrame::OnDlgDisplayLogsTerinated)
I'm not sure but from my hours of debugging, this should be the best description of my problem I can give.
I'm creating a WinRT app, there are two pages- Main Page and Details Page. Inside Main Page constructor, I have initialized a listbox. On click of any of the element of listbox, user is taken to the Details page.
I'm just learning all this and design may not be best but here is what I did.
I took a static variable in MainPage.cs, and set it to point to the element which is clicked by the user. Now in the constructor of the Details page, I used this static variable to set the datacontext of Details Page itself.
What flow I'm expecting is:-
MainPage is created first. Listbox is setup.
User will click on any of the element of listbox. Itemclick event handler runs. It will set the static variable (of Mainpage.cs) to hold the infomation which item is clicked and navigate user to the Details page.
In Details page constructor, I have set the datacontext to point to some information based on the value of static variable mentioned in the previous step.
It works for most of the times, but once in like every 5 times, The Details page constructor throws an exception stating the static variable is not initialized yet. Why is Details page's constructor running when I'm starting the app? and why only sometimes? Do I need to set DataContext of Details Page in some other method instead of constructor?
The code is somewhat complex and too much in terms of domain of the problem so I'm avoiding posting it. But if I'm failing to explain the problem please tell, I'll post it keeping it as related as I can.
CODE:-
This is the method called when an item in listbox is clicked--will take user to the Details page.
private void overviewlistbox_Tapped_1(object sender, TappedRoutedEventArgs e)
{
MatchOverview selectedmatch = (sender as ListBox).SelectedItem as MatchOverview;
matchFullDetails = new ObservableCollection<Match>();
foreach (Match m in UpdateController.matchList)
{
if (m.matchDescription == selectedmatch.matchDesc)
{
matchFullDetails.Add(m);
break;
}
}
if(!(matchFullDetails.Count == 0))
this.Frame.Navigate(typeof(Details));
}
This is the constructor for Main Page:-
public static ObservableCollection<Match> matchFullDetails;
public MainPage()
{
matchFullDetails = new ObservableCollection<Match>();
this.InitializeComponent();
UpdateController update = new UpdateController(); // Creating new object will update the overview_list of UpdateController(static list).
overviewlistbox.ItemsSource = UpdateController.overview_list;
}
And this is the code for constructor of details page, where the exception occurs:-
public static ObservableCollection<Match> matchdetails = new ObservableCollection<Match>();
DispatcherTimer dtm_detailspage = null;
public Details()
{
this.InitializeComponent();
matchdetails = MainPage.matchFullDetails; // matchdetails.Last<>() is take because we only need item which is added latest to the collection.
if (matchdetails.Last<Match>().type == "TEST") // Exception is thrown here--Initialization
// error. When I check MainPage.matchFullDetails,
// no data is shown which means its not yet
// initialized. Also the exception is thrown either at
// the start of the app, or when details page is visited. That too once in 4-5 times, not always.
{
matchdetails.Add(matchdetails.First<Match>() as TestMatch);
}
if (matchdetails.Last<Match>().type == "ODI")
{
matchdetails.Add(matchdetails.Last<Match>() as ODIMatch);
}
if (matchdetails.Last<Match>().type == "T20")
{
matchdetails.Add(matchdetails.Last<Match>() as T20Match);
}
}
Exception Screenshot:-
Call Stack data on bug encounter:-
[Cricket Expert.exe!Cricket_Expert.Details.Details() Line 33 + 0x5 bytes
[External Code]
Cricket Expert.exe!Cricket_Expert.Common.SuspensionManager.RestoreFrameNavigationState(Windows.UI.Xaml.Controls.Frame frame) Line 236 + 0x5 bytes
Cricket Expert.exe!Cricket_Expert.Common.SuspensionManager.RestoreAsyn() Line 124 0x8 bytes
Cricket Expert.exe!Cricket_Expert.App.OnLaunched(Windows.ApplicationModel.Activation.LaunchActivatedEventArgs args) Line 74 + 0x5 bytes
[External Code]
MAJOR UPDATE:
I finally found the flaw. If the Details page is still active, and the app is restarted, the problem occurs.
Is there a solution to this problem??
You can pass information on what needs to be displayed on the Details page through the Navigate call and set the DataContext in OnNavigatedTo override to avoid using static variables. Pages don't get created unless you do it specifically e.g. by navigating to one. They might not be recreated if a page has NavigationCacheMode changed from the default (Disabled) so instances of the page can be reused during navigation calls. Ultimately it's hard to say what's wrong but it seems like something in your code and we couldn't help you if you don't share a sample that reproduces the problem.
*EDIT
One way to debug Details being created before MainPage would be to add this code at the beginning of the Details constructor:
if (MainPage.matchFullDetails == null)
{
System.Diagnostics.Debugger.Break();
}
Then look at the Call Stack panel in Visual Studio to see how it gets constructed.
One way to see if matchFullDetails is ever set to null is to search for its assignment (put a cursor on matchFullDetails in Visual Studio code editor and hit Shift+F12).
Another way would be to make matchFullDetails into a property and test it like this:
private static ObservableCollection<Match> _matchFullDetails;
public static ObservableCollection<Match> matchFullDetails
{
get
{
return _matchFullDetails;
}
set
{
if (value == null)
{
System.Diagnostics.Debugger.Break();
}
_matchFullDetails = value;
}
}
*EDIT 2
You can initialize your static property in a static constructor like this:
public static ObservableCollection<Match> matchFullDetails;
static MainPage()
{
matchFullDetails = new ObservableCollection<Match>();
}
public MainPage()
{
this.InitializeComponent();
UpdateController update = new UpdateController(); // Creating new object will update the overview_list of UpdateController(static list).
overviewlistbox.ItemsSource = UpdateController.overview_list;
}
this will prevent the null reference exception but won't fix your problem overall. When your app gets suspended and resumed - you have to restore the full state and it seems like your matchFullDetails collection would need to be serialized and saved to disk when your app gets suspended. Alternatively you might simply ignore the suspension manager call in App.xaml.cs and always start on home page, though that's not a very good experience and I am not sure if it satisfies app certification.
The objects passed as arguments are only received an Navigation event. I want to receive them on Click Event,what should I use instead of Parameter??
void App1::MainPage::btuN_Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
Variables^ data = (Variables^)e->OriginalSource;
if (data->sNotf!=nullptr)
Frame->Navigate(TypeName(BlankPage3::typeid), data);
}
I used OriginalSource, but it didn't work. Would any one help me? Thanks in Adv
OriginalSource property contains a reference to the object that raised the event. It has nothing to do with navigation parameters.
I'm not exactly sure which parameters you'd like to access in your button click event. The ones passed to your page in its navigation event? In this case you should handle said navigation event, retrieve the parameters there and store them into a private field of your page. In click event you can then read them back from the private field and pass them forward.
On a related note: passing non-basic types as navigation parameters is discouraged. If you need to do that, it's a better idea to just pass the object ids and read their values inside the page from a common repository.
When you navigate to your page, if the parameters from your navigation event are important, you should store them within your page object so it can be accessed later.
//MainPage needs to have a private Variables^ named Info
void MainPage::OnNavigatedTo(NavigationEventArgs^ e)
{
if(e->Parameter)
this->Info = dynamic_cast<Variables^>(e->Parameter);
}
And then access that variable from within your click handler:
void MainPage::btuN_Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
if(this->Info)
if (this->Info->sNotf!=nullptr)
Frame->Navigate(TypeName(BlankPage3::typeid), Info);
}
I want to write the contents of a per occasion active TextBox back to the bound property of the ViewModel when the user presses the key combination for save (Ctrl-S).
My Problem with it is, that I'm not able to trigger the execution of the binding so that the bound Text-Property reflects the contents of the TextBox.
-There seems to be no GetBinding-method. Therefore I can not get the Binding and execute it manualy.
-There is no Validate-method such as in WinForms which executes the Binding
-Giving focus to another control from within KeyDown seems not to work, the binding does not execute
How can I achieve this?
Take a look at Aaron's discussion about this in his WiredPrarie blog post : http://www.wiredprairie.us/blog/index.php/archives/1701
I think I understand your question better now. One way around this would be to use a sub-classed textbox with a new property like this from here:
public class BindableTextBox : TextBox
{
public string BindableText
{
get { return (string)GetValue(BindableTextProperty); }
set { SetValue(BindableTextProperty, value); }
}
// Using a DependencyProperty as the backing store for BindableText. This enables animation, styling, binding, etc...
public static readonly DependencyProperty BindableTextProperty =
DependencyProperty.Register("BindableText", typeof(string), typeof(BindableTextBox), new PropertyMetadata("", OnBindableTextChanged));
private static void OnBindableTextChanged(DependencyObject sender, DependencyPropertyChangedEventArgs eventArgs)
{
((BindableTextBox)sender).OnBindableTextChanged((string)eventArgs.OldValue, (string)eventArgs.NewValue);
}
public BindableTextBox()
{
TextChanged += BindableTextBox_TextChanged;
}
private void OnBindableTextChanged(string oldValue, string newValue)
{
Text = newValue ? ? string.Empty; // null is not allowed as value!
}
private void BindableTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
BindableText = Text;
}
}
Then bind to the BindableText property.
Solution for command-instances
Here a solution I have found which is relatively leightweight, but also a bit "hackish":
btn.Focus(Windows.UI.Xaml.FocusState.Programmatic);
Dispatcher.ProcessEvent(CoreProcessEventsOption.ProcessAllIfPresent);
btn.Command.Execute(null);
First I give the focus to another control (In my case the button which has the bound command). Then I give the system time to execute the bindings and in the end I raise the command which is bound to the button.
Solution without bound commands
Give the Focus to another control and call the Dispatcher.ProcessEvent(...).
anotherControl.Focus(Windows.UI.Xaml.FocusState.Programmatic);
Dispatcher.ProcessEvent(CoreProcessEventsOption.ProcessAllIfPresent);
// Do your action here, the bound Text-property (or every other bound property) is now ready, binding has been executed
Please see also the solution of BStateham.
It's another way to solve the problem
I've got a contributed command and a handler for it. The handler's execute event has to get the value for the property actually selected in the properties view and act on it, or to be disabled if no property selected.
I've tried:
1) Set the selection provider to something which provides selection from the property view. Something in this case is just PropertySheetViewer for my PropertySheetPage, but i can't set it as the selection provider because the PropertySheetPage's viewer is private and has no getter.
2) Overriding PropertySheetPage's createControl method: This method creates a Tree control for the PropertySheetViewer. A selection listener can be installed for that tree control, so maybe i can make my command handler implement SelectionListener... The solution would be somethin like:
In my editor:
public Object getAdapter(#SuppressWarnings("rawtypes") Class type) {
if (type == IPropertySheetPage.class) {
PropertySheetPage page = new PropertySheetPage() {
#Override
public void createControl(Composite parent) {
super.createControl(parent);
IHandler handler = someWayToGetMyCmdHandler();
((org.eclipse.swt.widgets.Tree) getControl())
.addSelectionListener(handler);
}
};
IPropertySheetEntry entry = new UndoablePropertySheetEntry(
getCommandStack());
page.setRootEntry(entry);
return page;
}
return super.getAdapter(type);
}
And my command handler implementing SelectionListener as i said... The problem with this approach is that i can't find a way to get a reference to my contributed command handler (someWayToGetMyCmdHandler() above).
Has anybody got any clue on this, or any other possible approach to the problem??
There's handleEntrySelection(ISelection selection) method in PropertySheetPage that you could override to be notified about selection changes in the viewer (although PropertySheetPage is #noextend).
The second part (updating the handler) is a bit more tricky than it would normally be. Commands/handlers get updated automatically when workbench selection changes (you just need to implement setEnabled(Object evaluationContext) AbstractHandler). But since PropertySheetPage is designed to change its input on global selection change, then you have to find some custom way to notify/update your handler.
As I understand, it is currently not possible to extend the platform command event handling mechanism with custom variables, so you just need to directly look up your handler using IHandlerService of the workbench.