I'm working in a legacy application using MFC.
We have a mechanism to enable/disable controls depending on some business logic.
This mechanism is implemented in the CView-derived class. The way it works is all the views in the application derived from a common CView-derived class (CBaseView) and on the PreTranslateMessage all controls of the view are enabled/disabled.
This worked fine so far because all controls send at least WM_PAINT message when they need to be painted. So the system worked without the user having to move the mouse or anything. I recently added some drawing features and I had to use WS_EX_COMPOSITE to get ride of some flickering. With this flag activated my CView-derived class is not getting any called to PreTranslateMessage when creating the view....so the controls are not disabled until the user moves the mouse over the control.
I understand there is no way to send WM_PAINT using WS_EX_COMPOSITE but is there other message I can use to get the same behaviour???
Edited:
I am currently using the OnIdle approach but it has a big drawback, the windows doesn't become idle until after drawing all the controls...so when you enter the screen al controls are enabled and inmediately they are disabled...this makes a quite ugly effect!
More solutions???
Thanks in advance...
The logical place to enable/disable controls would be CView::OnUpdate, it is called by the framework after the view's document has been modified and from OnInitialUpdate(); you can also call this function if there is some change that would trigger re-evaluation of your business logic.
EDIT
After reading the question a bit more closely, what you could also do is to post a private message at the end of OnInitialUpdate and "catch" it in your PreTranslateMessage:
PostMessage(WM_APP, 0, 0);
Calling InvalidateRect followed by UpdateWindow against the window in question will mark the entire client area as dirty and force an immediate repaint. Remember that WM_PAINT is not really a message, in the queue in the usual sense, it is pushed out after all other messages have been processed for that window, which would include any invalidations of the area being drawn. No message is generated at all if there are no invalid segments of the active window display.
Related
I am a newbie to xaml and windows app dev so sorry if this question might seem silly.
I created a textbox and in the designer I right clicked it and selected edit template=>edit a copy and put it into my custom dictionary.
In the control template for this textbox I saw visual states like disabled,focused and so on. And I modified them and run the mobile app and observed that my changes work like changing border color when textbox is focused.
But in order for this to work somebody has to call
VisualStateManager.GoToState("Focused")
when the textbox is focused so who is calling this because I don't see any visual transitions in the control template so how is this happening?
The code in the control itself is calling VisualStateManager.GoToState(...) .
When you start implementing your own custom controls, you might subscribe to events you have available and transition states based on your own logic. Here is an example of a custom control with its own two custom states.
https://github.com/xyzzer/WinRTXamlToolkit/blob/master/WinRTXamlToolkit/Controls/WatermarkTextBox/WatermarkTextBox.cs
XAML is a compiled language, and if you've looked extra close, what happens under the hood, is that the class behind your xaml has the same namespace as your xaml code.
This means (for no practical purpose) that compiling your program turns all of that XAML into C# code before then going over to MSIL and eventually execute as a binary program.
Much of the state changes that happen are event based, and TextBox, like all other user controls, will transmit a message and listen to messages. The Page that contains the TextBox will probably be the one that transmits a state change whenever one of it's children gets focus, and as a good control, the TextBox listens for this event and reacts to it.
In my application there are a lots of dialogs being opened and closed all the time. The dialogs are non-modal.
In order to save some performace, we are "recycling" some of the more complicated controls. When one dialog is closed, the controls are not destroyed, but their pointers are stored in an array so that they can be reused when another dialog is opened.
The problem is that after the control is positioned in the new dialog, it does not receive all the messages. For instance the message WM_DRAWITEM (the control is derived from CListCtrl) is not being sent anymore. The WM_LBUTTONDOWN on the other hand is still arriving. It is as if the control does not know its class anymore. The NC area (border and list header) is being painted correctly.
Did anyone have similar problems? What could be wrong? Can the controls be "detached" and "reattached" in this way at all?
For CListCtrl to respond to WM_DRAWITEM image it is needed it has the LVS_OWNERDRAWFIXED style. Are you sure you have it set?
And from http://msdn.microsoft.com/en-us/library/windows/desktop/bb774739(v=vs.85).aspx , it seems it only occurs if it is in Report view (Seems strange to me!).
I want to minimize my app and after the timer end get it back.
I use code below.
To minimize application use following line of code:
Display.getDisplay (MIDLET_CLASS_NAME).setCurrent (null);
To get the screen back use the following:
Display.getDisplay (MIDLET_CLASS_NAME).setCurrent (myCanvas);
But when phone display is dismissed and going to clock mode my midlet display isn't shown until press any button.
any idea?
From your question it sounds that you expect setCurrent to somehow "force" device to immediately display your screen or maybe return only after screen gets visible.
This is not so, as clearly explained in the API documentation for Display.setCurrent:
Requests that a different Displayable object be made visible on the display. The change will typically not take effect immediately. It may be delayed so that it occurs between event delivery method calls, although it is not guaranteed to occur before the next event delivery method is called. The setCurrent method returns immediately, without waiting for the change to take place...
...if the application is in the background, passing a non-null reference to setCurrent may be interpreted by the application management software as a request that the application is requesting to be brought to the foreground... These are only requests, and there is no requirement that the application management software comply with these requests in a timely fashion if at all...
Consider redesigning your MIDlet to adjust to specified behavior.
If myCanvas is an instance of Canvas, one can use showNotify() events.
For a generic Displayable screen isShown() method checks if the it is actually visible on the display.
Sometimes it could even make sense to let user explicitly confirm return from background, like
display.setCurrent(new Alert("back to foreground", "dismiss to continue...",
null, AlertType.INFO), myCanvas);
Does MvvmCross support a cross platform solution for displaying alerts or popups?
Searching the code I found MvxDialogActivityView but it has been commented out. Will this remain the case for now?
If there is no direct support how would you suggest this is best done? (Perhaps the ViewModel would change a property and call FirePropertyChanged so that the View would be aware of it and show an alert.)
Edit 16:04 16th June 2012
What I am trying to do for this specific case is as follows:
On the page a button is clicked, which causes a method to run in the ViewModel which does an evaluation to determine which of two messages should be shown to the customer. The message would be shown as an alert or popup (either native, or preferably totally styled by me). The message would fade after (the click of the OK button, or preferably 3 seconds).
After the message has been dismissed a new page will be navigated too (depending on which of the two messages was shown).
How to handle this definitely depends on what the situation is - there's no single best rule (IMHO)
For a general error display pattern, there's one proposal at http://slodge.blogspot.co.uk/2012/05/one-pattern-for-error-handling-in.html
I've used similar patterns for showing application level notifications - e.g. for when a long running operation completes or when a chat message arrives or...
One interesting post about how to display message boxes was: http://awkwardcoder.blogspot.co.uk/2012/03/showing-message-box-from-viewmodel-in.html - I'm not sure I'd completely follow the end solution, but there are definitely some good points there about what not to do.
For your updated scenario, I would consider using a messenger (like TinyMessenger) or using normal C# events exposed by the ViewModel and consumed by its View
On the page a button is clicked, which causes a method to run in the ViewModel
I would implement this using an ICommand bound to the button Click/Tap/TouchDown
which does an evaluation to determine which of two messages should be shown to the customer.
I would definitely implement the logic within a Service
This would be called from the ViewModel - and the result/decision would probably cause some property or private field state change.
How does the View then decide to show a message? I can think of 3 options:
The View could just respond to a Property change (normal Mvvm INPC) - this would be my preference
The ViewModel could expose a normal C# event which it triggers...
The ViewModel could send a Message
This last option (Messenging) is probably the most flexible solution here - it decouples the View and ViewModel in case you later decide to change responsibilities. To implement messenging, either:
implement your own hub (like I do for errors in http://slodge.blogspot.co.uk/2012/05/one-pattern-for-error-handling-in.html)
or use a generic solution like TinyMessenger
The message would be shown as an alert or popup (either native, or preferably totally styled by me).
This is a View concern - so would be entirely controlled by the View project. I'd use controls like: UIAlert, Toast, ToastPrompt, etc - all of which can be styled
The message would fade after (the click of the OK button, or preferably 3 seconds). After the message has been dismissed...
I'd use some form of Code Behind (or maybe a Behaviour in WP7) in the View. This would detect the click/fade/disappear and would then invoke either an ICommand (my preference) or public method on the ViewModel
a new page will be navigated too
This navigation would be requested from the ViewModel
(depending on which of the two messages was shown).
This would be easy to track through the above flow... presumably the ViewModel already knows what to show.
So that's what I'd do...
it keeps the application flow logic inside the ViewModels (and lower)
it keeps the presentation inside the Views
...but I'm sure there are other options :)
One final note... the fade out and then navigate logic can really get "messed up" by Switching/Tombstoning on WP7 and Android - this may or may not matter for your particular scenario.
I have a bunch of control objects (TextBoxes, to be precise) that get injected into my code using the #FXML annotation during the FXML load.
I would like to save the states of these controls, specifically the text values, when the user closes the Scene by clicking the close box on the title bar.
However, when I trap the CloseRequest event in an OnCloseRequest handler I find that the values of the control variables are null (the original injection works, so this is something that happens in between the loading of the FXML and the calling of OnCloseRequest).
Can anyone explain this behavior and/or suggest how I can get the functionality that I want?
TIA
onCloseRequest is
Called when there is an external request to close this Window. ...
(from Javadoc). One of the meanings of "external request" is when you close the window through OS native window close button. The closeRequest event is not triggered through the programmatic stage.close() or stage.hide() calls. So consider to handle onHiding or onHidden events.
Otherwise post your OnCloseRequest handler code.