I've got an NSCollectionView which houses three columns of NSCollectionViewItems. In each of the NSCollectionViewItem prototype views, I have a single NSImageView. As far as I'm aware, this is a fairly standard setup. I think the problem stems from my use of a popover to present the collection view, but I'm honestly not sure. Basically, the problem I'm having is that when I click on one of the aforementioned NSCollectionViewItems to mark it as "selected," every once in awhile it flickers/flashes. It's not a total deal-breaker, but it's annoying enough to make me post this question.
Coming from the HTML/CSS/JS game, I started to think of all the ways I would prevent the flicker when building stuff with web technologies. My first thought was to make certain parts of the NSCollectionView (and subviews) layer-backed. I figured that by doing the drawing via layers or just setting the collection view to be layer-backed period, it would render better, kind of like GPU-enhanced animations in CSS (e.g. no sub-pixel antialiasing, enables z-depth, etc.).
So, I subclassed NSCollectionView and added a [self setWantsLayer:YES] in the
-(id)initWithCoder:aDecoder method. I was right! It removed the flickering altogether. Also, the scrolling became much smoother. However, in the process of making the flicker go away, everything else started messing up. The popover would take about 10s to load (vs. ~500ms originally), items would do weird overlapping things, etc.
My question to you all is this: what should I do? If anyone could help a brother out, I'd really appreciate it.
Related
It seems that my view-based OutlineView try to re-render text every time user scrolling. I think that was because it tried to save memory by re-using rows that fall outside of visible rectangle, then re-render new data to those old views. How can I disable this? I'm willing to sacrifice memory to archive this so that I can get better scrolling performance. (I have tried with various optimize like layer or so, but no luck).
EDIT: There is another question with same purpose as mine here How to make NSTableView not reuse TableCellViews, but no answer yet :(
I think you are confused -- it doesn't re-render the text. The table only shows views for the visible area (caveat below), and pulls in new views as you scroll -- potentially re-using old views.
You provide the view. Use the delegate method viewForTableColumn:row: and return your own cached view for a given row.
But that isn't going to prevent drawing; the view will likely still get marked dirty and draw.
I don't think you are asking the right question. It sounds like you have a performance problem. To help you with that, we'd have to see samples or instrument traces.
Caveat: Responsive Scrolling will pull in views that are in the non visible area. See the AppKit release notes about this.
corbin
I have a horrible problem that is worthy of a separate stackoverflow question. Perhaps I can save time by asking a different question:
What are the downsides to recreating the whole UICollectionView layout on every device rotation rather than invalidating the UICollectionView layout with invalidateLayout?
Bare in mind that its a small view with a maximum of 6 text based cells - not a lot of data.
This question is a follow on from this one. I implemented the UICollection view and everything is working except the first two buttons inside the cells aren’t changing width on a orientation change, its a mess. Its almost like the method to update the cells is definitely being called but with the data from the last orientation view. Even after lots of debugging I'm still unsure exactly what the problem is.
Update
I managed to solve my nightmare with the information from this answer and the actual code from this answer. But if someone can still answer this question it would be helpful and interesting, I still want to know the answer!
I've been banging my head against the wall (Cocoa) for about a week with this problem and wanted to get some advice if possible.
I'm trying to provide a list of NSTextFields to the user representing a list of features – letting them add additional textfields using an 'Add' button. This is part of a bigger form and the user should just be able to tab through the whole form (including the list)
I implemented the above using an NSCollectionView which pretty much worked except tabbing seemed to intermittently stop working in the NSCollectionView for reasons I can not figure out. You'll be hitting tab, cycling through normally when all of a sudden the collection view is skipped altogether, or sometimes if you're in a specific text field in the collection view hitting tab will just highlight the text but will never jump to the next field without mouse clicking outside the collection view. I was wondering if anyone had experienced this before... or has any advice for debugging something like this? I've attempted logging what the nextResponder is every time a control becomes the responder and there doesn't seem to be any pattern explaining why tabbing just stops working suddenly and then begins again.
There are 3 TabViews with a collection view in each. I have been wondering if that may be causing an issue?
Thanks for any help anyone can provide.
OK, after all this time I may have solved this (Tentatively anyway... I haven't seen any problems on numerous run-throughs and it usually occurs at least once every time before)
Turning on Auto Recalculates View Loop on the Main Window seems to have resolved whatever was happening. I have to admit I don't completely understand why, except that maybe because of the tab views and collections views the key loop needs to be recalculated to keep everything in sync. I'm thinking I need to do more research into exactly how the key loops work...
My problem is that I am using nested scrollviews. One for the horizontal paging and second to show the content with vertical scrolling (cuz content, which is text, is more than the available space). Actually there are multiple copies of this vertical scrollview like:
MainScrollView (Horizontal)
VerticalScrollView1
VerticalScrollView2
VerticalScrollView3
Besides these the vertical scrollviews contains label that are draggable, I implemented dragging using touchesBegan: and moved: events. I developed the whole thing using only one vertical scrollview and it's working just fine and I thought, to my dismay, that it'll work exactly the same for the rest but when I added more vertical scrollviews, only the last one is allowing dragging of the labels. The first two ain't allowing dragging, besides, they are also not responding to the vertical scrolling event, which was perfect earlier. I tried it with two vertical scrollviews and even then only the last one was allowing dragging. Ain't sure about the vertical scrolling cuz right now only the first one has enough content to be scrolled rest need not to. I can try that out too but it's kinda late here, so, if someone can guide me with the provided info. would be much helpful. Else I can try that out tomorrow and post you with the result.
Thanks for your time.
I had similar issues with nesting UIScrollviews. I found this video from WWDC 2010 to be really helpful in showing how to work with scrollviews inside a paging scrollview, and I managed to fix the bugs I had by following the steps in this video and looking at the sample code.
Designing Apps with Scroll Views
Sample code
Anyone have any ideas on how I could go about replicating the scrolling stocks ticker in Notification Center on iOS 5?
What I'm thinking is using a UIScrollView, and use a UIView subclass for the items in the ticker. Would using an NSTimer be the best way to have it scroll automatically? How would I handle manual scrolling acceleration and deceleration like the Apple stocks widget does?
Also, how do I handle infinite scrolling?
Thanks for any suggestions.
Try AutoScrollLabel. It's a relatively old class, but the code design and animation behind it may be useful. If I understand correctly, it's a UIScrollView that holds two labels, each saying the same thing, resulting in "scrolling" as it animates between them. I'm sure you could take that concept and the drawRect: method in the code to create your own subclass of the UIScrollView and animate whatever content you want, complete with infinite scrolling. There may very well be an easier way, but I've used AutoScrollLabel in a few apps and it's easy to use and works without a problem. Let me know if you need more info/a usage example. Hope this helps!