Can anybody tell me when this event is fired?
This event handler is bound to the control events for the underlying UIControl implementation for the given control event called...UIControlEventValueChanged
According to the Apple docs this means it is called when: "A touch dragging or otherwise manipulating a control, causing it to emit a series of different values."
This may or may not be what you want to trigger off of, plan accordingly.
For the full list of events: http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIControl_Class/Reference/Reference.html
Related
I'm trying to create a Chrome Extension that deals with selected text. Some website pages' otherwise selectable text content has click/mouse-up/down event handlers that navigate to a new page.
Is there a way from the background or content script to temporarily disable (and restore) the page's arbitrary event handlers without interfering with the native text selection?
Worst case I'm thinking of is to detach, clone the body html, allow the selection, and then restore the bound original. Seems like trouble.
Thanks!
Most HTML DOM events follow the capture-target-bubble event model. This means, for example, that if you click on a button, that the "click" event is first dispatched at the root, all the way down to the button, then back up. Event propagation can be stopped, which prevents the event listener at the next level from being notified of the event.
The earliest possibility of receiving the event is at the root, often window at the capture phase. To bind an event listener to the capture phase, use addEventListener with the third parameter set to true:
// in a content script, at run_at:document_start
window.addEventListener('click', function(event) {
event.stopImmediatePropagation();
}, true);
Many web pages use jQuery to manage DOM events, which binds the event listeners at the bubbling phase, so the previous method will work on most sites. If the page does not use jQuery, then you have to bind your event listener at document_start to make sure that your event listener is triggered before every other event listener.
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.
I've found myself in the following situation: I've got an NSTableView subclass with an active cell. when I click elsewhere on the user interface, the delegate method (i) is fired, this in turn fires (ii) (my own method) cocoa then proceeds to process the click, resulting in the final two calls. I was surprised and disappointed by this sequence, since I had assumed the mouse click would be the first rather than the last event processed. It also causes me a problem because the ideal implementation of manageState is dependent on some of the processing I do in mouseDown:, but of course when manageState is called mouseDown: has not yet been executed.
Is their a way to delay the execution of manageState until mouseDown has returned? For example, in manageState I'd say something like Stop! a mouse down event might be in the events queue. Wait until it's finished, then resume. As the previous sentence implies, it's also possible that this method could be triggered by something other than a mouse down. In this situation, there's no need to look out for a mouse down event and processing can continue as normal.
MOUSE CLICK on NSTextView while NSTableView cell has focus...
+-------------------------+--------------------------------------------------------+
|Event |Triggered because |
+=========================+========================================================+
|controlTextDidEndEditing:|The mouse click ends the editing session |
| |of the active cell in my table view |
+-------------------------+--------------------------------------------------------+
|manageState |This method is a selector that belongs to a notification|
| |that is fired from within controlTextDidEndEditing: |
+-------------------------+--------------------------------------------------------+
|becomeFirstResponder |I clicked on the NSTextView instance |
+-------------------------+--------------------------------------------------------+
|mouseDown: |Finally, the click that started it all is processed |
+-------------------------+--------------------------------------------------------+
I figured this one out for myself. I feared I'd have to cobble together a threads-based solution, but a bit more docs-scouring turned up the NSEvent class method addLocalMonitorForEventsMatchingMask:handler.
When my app starts I call this method, define the associated block, and 'tell' the method what events I want to look out for. Then, whenever one of these events is detected, the block runs. Crucially ,this happens before any of the processing precipitated by the event is set in motion. In the block you have the opportunity to stop the event in its tracks, or let processing continue, you also have access to the event itself . Going back to my question, this means I am effectively inserting an additional row at the top of the table. This was perfect since it allows me to act on the event before any of the subsequent event executes.
[NSEvent addLocalMonitorForEventsMatchingMask:NSLeftMouseDownMask
handler:^NSEvent *(NSEvent *event) {
// whenever an event of type NSLeftMouseDownMask is detected, this code
// will run before any other event processing
// do some processing, then...
return event; // or nil, if you want to block the event
}];
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.