I'm writing a mozilla plugin on the mac. I'm trying to capture events like button clicks, etc. I've done the normal thing of creating my views in inteface builder, and linking the sentActions to methods in my program. This works in stand-alone programs.
However, in my NPAPI plugin, those methods never get called. The button reacts, depresses, whatever, but it doesn't do its action.
Instead, the NPP_HandleEvent method gets called, but I never get the MouseDown or MouseUp event, only the UpdateEvt.
I set up the buttons to accept clicks via: (superview is the Mozilla view, topview is the top of my view hierarchy.)
[superView setNextResponder: topView];
[topView setNextResponder: nil];
[browserWindow makeFirstResponder: topView];
NEVER MIND: I'm an idiot. It IS calling the button sent actions. I was looking at the wrong method. That'll teach me to leave around a zoom: method when I'm actually using a doZoom: method... D'oh,.
So, the problem was that I wasn't able to get buttons to work. The buttons were supposed to (for example) zoom an image in an IKImageView. (or rather, zoom the view). It didn't appear that it was working. The screen was flashing a lot, but nothing was happening... I put a printf in my zoom method, and it was NEVER GETTING CALLED! and so I asked the question.
Later, I noticed that I wasn't TRYING to call zoom, I was calling doZoom! doZoom WAS being called. And the reason that it wasn't zooming was an unrelated problem.
The problem ended up being that I was sending setImage to my IKImageView on every event, which re-set the view to 1-1, rightside up mode. Once I took out the extra setImage call, things started to work.
In the unlikely event that anyone else every experiences this, the answer is my cunning plan for world domination:
step 1: Don't be an idiot.
step 2: ???????
step 3: Dominate the world.
(If I could master step 1, I might just be able to figure out what step 2 was B-)
Related
G'day!
Note: Minimal example linked below. I'll refrain from longish code excerpts and rather explain the problem concisely.
I am in the process of updating an old (but small) Cocoa application to current APIs.
One of the places that looked easy enough at first: When the user tries to close the application window with unsaved changes, the app first displays an NSAlert asking "Save your stuff?". If that is confirmed a modal NSSavePanel is shown. In the original code they were opened via, respectively:
beginSheetModalForWindow:modalDelegate:didEndSelector:contextInfo:
beginSheetForDirectory:file:modalForWindow:modalDelegate:didEndSelector:contextInfo:
Current Cocoa API uses completion blocks and thus the alert prefers to be shown via beginSheetModalForWindow:completionHandler:. So I moved the code from the didEndSelector into the completionHandler.
Unfortunately the modal NSSavePanel does animate in but disappears immediately together with the application main window if it is shown from the NSAlert's completion block. If I switch the alert back to the didEndSelector I can show the NSSavePanel either selector-basedly or completion block-ly just fine.
Here's the NSAlert's completion block that forwards to the disappearing save panel.
I have thought about threading issues. All of this is happening on the main thread. Maybe there's something subtle going on with run loop modes that I'm missing?
The minimal example is available over on GitHub. You can switch between selectors and blocks with defines in AppDelegate.h. All the interesting code is in AppDelegate.m. (Unless the problem is somewhere else...)
As #Willeke pointed out this wasn't an overly mysterious issue with threading and whatnot. No. It was just me having looked at the code way too often over the course of days.
The solution is simple:
The breaks in the switch statement in confirmUnsavedChanges are missing.
I have a Cocoa app that draws a lot data to the main screen(31000 samples by about 315 channels) so we are being very studious about profiling and getting everything as efficient as possible. I have a window controller that when opened updates it's view every 2 seconds based on the data. I am using an NSTimer and specifying the view update method.
The problem I am having is every time the timer fires the method, the main display hiccups slightly. I thought it would just be a matter of optimizing the drawRect method in the view subclass, but when I could not find any specific area in the draw rect method where the performance was bad, I decided to try commenting out the contents of the drawRect method.
results:
If I comment out the contents of the drawRect method, I will still get a hiccup.
If I comment out the call to [view setNeedsDisply: YES] in the calling method, it resolves the hiccup.
What Ive Tried:
1) I modified the method calls so that when the timer fired I was using performSelectorOnMainThread to call the view
2) I then tried to use the main dispatch queue with async.
neither of these things worked.
There is some kind of lag happening here even when there is no drawing work to do.
Any help is appreciated.
NOTE: Updated below...
I have a cocoa desktop application which consists of a series of controls around a custom NSView. I am using displayLink to drive the updates.
When a user clicks on an NSControl (a slider, a button, a checkbox, a radio button) the application appears to freeze until the mouse is released. I can confirm in fact that the displayLink callback (getFrameForTime) is NOT firing during the time. If I create a timer, that also does not fire, both remain paused until the user releases the mouse, at which point the application resumes updating.
The control is bound, and if I update that value from another thread (for example, via a callback from a MIDI interface) the slider behaves as expected: it moves, the value updates and the application does not pause.
I feel like this should be a fairly obvious fix, but I'm stumped.
Checking "continuous" in IB does as advertised: sends the values continuously, but still exhibits this behavior (preventing the UI update) until the mouse is released.
This seems to be related specifically to mouseDown on NSControl? Why would this block, and do I really need to subclass all my UI elements to change this behavior (seems extreme)
DisplayLink is in its own thread, so why mouseDown on the main thread block it? If this is the case, given the injunction on updating the Cocoa UI from other than the main thread, how do I deal with it?
Any help much appreciated.
Update
Per #Nikolai's comments below, I can confirm that using an NSTimer and adding it to NSEventTrackingRunLoopMode does NOT block. However, I would really like to use CVDisplayLink which (according to the documentation) runs in it's own thread and should not be blocked in this way. Unlike CADisplayLink, I cannot find a way to explicitly assign a runloop to CVDisplayLink (it seems it doesn't work that way), so perhaps the new question should be:
Why does CVDisplayLink block on NSEventTrackingRunLoopMode?
When clicking on an NSControl the runloop mode goes from NSDefaultRunLoopMode to NSEventTrackingRunLoopMode, as long as the mouse is down. That means that only run loop sources (display link) and timers fire that have been added to this mode.
You can add timers to any mode by using -[NSRunLoop addTimer:forMode:]. For a display link the equivalent method is -[CADisplayLink addToRunLoop:forMode:].
To make your animation continue during event tracking you would do something like:
[myDisplayLink addToRunLoop:[NSRunLoop currentRunLoop]
forMode:NSEventTrackingRunLoopMode];
Your test project shows that you are calling a view's display method from within the display link's callback.
When commenting the display message out, the display link is called continuously even while moving the slider.
So what goes wrong is that when the runloop goes into event tracking mode, the call to display on the display link's thread blocks until the mouse is released and the run loop goes back to default mode. You can easily confirm this by putting a log statement before the call and one after it.
Why exactly that happens is not clear to me. What is clear is that it's illegal to call a view's methods from a background thread. You have to trigger the view's display by dispatching a setNeedsDisplay: on the main thread:
static CVReturn MyDisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp* now, const CVTimeStamp* outputTime, CVOptionFlags flagsIn, CVOptionFlags* flagsOut, void* displayLinkContext)
{
dispatch_async(dispatch_get_main_queue(), ^{
[(__bridge MyCustomView*)displayLinkContext setNeedsDisplay:YES];
});
return kCVReturnSuccess;
}
I want to make a windowless application. The problem is that I'm using a framework that shows some alert boxes sometimes, and I'm not able to suppress them (at least not without a crash).
I've set LSBackgroundOnly to 1 (in the info.plist app file), but this doesn't seem to work. Any chance I'm missing something here (maybe some other settings that I need to set)?
I've also tried creating a category for NSWindow:
Overwritten alloc and allocWithZone: so that no window gets created. This works on some situations, but starting a modal session throws exception (because sending a nil parameter to beginModalSessionForWindow:).
Tried overwriting NSApplication's beginModalSessionForWindow: and returned nil everytime, but this leads to EXC_BADACCESS somewhere in the framework (runModalSession: and endModalSession: were also overwritten, but the crash is before any of them being called).
Any other ideas will be welcome.
In case it helps, the framework that I'm using is Twain.Framework, so if instead anyone knows a way to block all UI from twain (this includes error alerts shown when a device is not connected) it would be great if you share.
It's not clear what you're hoping for. Are you hoping for an app that doesn't normally display windows but does allow the third-party framework to show its alerts? Or are you hoping to find a way to prevent the framework from showing its alerts so your app absolutely never has any windows?
If it's the former, you're probably looking for LSUIElement. That's an app which can have some UI elements, but doesn't show in the Dock or the Command-Tab application switcher and doesn't have a menu bar.
I managed to make it 'windowless' (some windows are still shown, but at least they're not visible, and they're automatically closed). I only handled modal windows, since these where shown in my situation.
I made a category for NSWindow, so that all windows are invisible, and can't become key or main windows:
-(BOOL)canBecomeKeyWindow{
[self setOpaque:NO];
self.alphaValue = 0;
return NO;
}
-(BOOL)canBecomeMainWindow{
[self setOpaque:NO];
self.alphaValue = 0;
return NO;
}
Subclassed NSApplication:
-(NSInteger)runModalForWindow:(NSWindow *)aWindow{
return NSCancelButton;
}
-(NSModalSession)beginModalSessionForWindow:(NSWindow *)aWindow{
NSModalSession session = [super beginModalSessionForWindow:aWindow];
[aWindow performSelector:#selector(close) withObject:nil afterDelay:1];
return session;
}
However, this didn't help much. In case of runModalForWindow: everything was good, since the owner of the window received a response. In case of beginModalSessionForWindow: the application got stuck, most probably because the window's owner was waiting for a specific event (e.g. button click) which it never received.
UPDATE: With the blush of shame I discovered that the order had nothing to do with the speed of tapping. I was calling the visual code before the super touchesEnded:withEvent call, which was why if you tapped really fast, the display never got a chance to draw the highlighted state before being dismissed again. Because the code that was actually causing the main thread to block just a few milliseconds, the highlighted state would stay visible until the main thread unblocked again, where as if you tapped really fast, it looked like nothing happened at all. Moving the super call up to the top of the overridden method fixed it all. Sorry, if any moderator sees this post it can be deleted. shame
This problem must have been asked a 1000 times at SO, yet I can't find the explanation to match my specific issue.
I have a UIButton subclass with a custom design. Of course the design is custom enough that I can't just use the regular setSomething:forControlState: methods. I need a different backgroundcolor on touch, for one, and some icons that need to flash.
To implement these view changes, I (counter-intuitively) put the display code in (A) touchesBegan:withEvent and (Z) touchesEnded:withEvent:, before calling their respective super methods. Feels weird, but it works as intended, or so it seemed at first.
After implementing addTarget:action:forControlEvents was used to bind the UIControlEventTouchUpInside to the method (X) itemTapped:, I would expect these methods to always fire in the order (A)(X)(Z). However, if you tap the screen real fast (or the mouse in simulator), they fire in the order (A)(Z)(X). Where (A) and (Z) follow each other in such rapid succession, that the whole visual feedback for tapping is invisible. This is unwanted behavior. This also can't be the way to go, for so many apps need similar behavior, right?
So my question to you is: What am I doing wrong? One thing I'm guessing is that the visual appearance of the buttons shouldn't be manipulated in the touchesBegan:withEvent and touchesEnded:withEvent, but then where? Or am I missing some other well known fact?
Thanks for the nudge,
Eric-Paul.
I don't know why the order is different, but here's 2 suggestions to help deal with it.
What visual changes are you making to the button? If it's things like changing title/image/background image, you can do all this by modifying the highlighted state of the button. You can set a few properties like title and background image per-state. When the user's finger is down on the button, the highlighted state is turned on, so any changes you make to this state will be visible at this time. Do note that if you're making use of the selected state on the button, then you'll need to also set up the visual appearance for UIControlStateHighlighted|UIControlStateSelected, otherwise it will default back to inheriting from Normal when both highlighted & selected are on.
The other suggestion is to ditch touchesBegan:withEvent: and touchesEnded:withEvent: and switch over to using the methods inherited from UIControl, namely beginTrackingWithTouch:withEvent: and endTrackingWithTouch:withEvent:. You may also want to implement continueTrackingWithTouch:withEvent: and use the touchInside property to turn off your visual tweaks if the touch leaves the control.