My goal
I would like to add a vibrancy effect to a collection view.
The setup
I have the following view hierarchy:
When I use this layout, the background has the vibrancy effect as expected, but the performance is not quite there.
NSCollectionView is optimized to work with layer-backed views, so I enable the CALayer on the collection view's enclosing scroll view.
The problem
If I do this, the visual effect view is no longer visible, and the collection view has a white background.
My question
Is there any way to make a layer-backed view work together with NSVisualEffectView?
So if anyone's wondering, here's the trick:
adding the NSVisualEffectView: correct
making the enclosing scroll view layer-backed: correct
enabling the scroll view to draw a background: wrong
Make sure to either set drawsBackground to false, or disable it in Interface Builder, and your collection view will have the vibrant background, and fast scrolling as well 👍
Related
I'm working on an app made by a NSWindow which own a lot of custom subviews, that could be opaque or not.
Whenever I call SetNeedsDisplay: or SetNeedsDisplayInRect: on a subview, the system calls the drawRect of each single subview starting from the content view of the parent NSWindows.
How can it be avoided? How can I redraw just the dirty subview (it should be the default behaviour)? Is there something that I'm missing maybe in subclassing the NSView? Or in setting the properties or the syle of the parent NSWindow?
Thanks
The that could be opaque or not is the trouble-some bit. Any non-opaque view triggers a redraw of the entire view hierarchy, because the window must restore that views background to a pristine state. Only views set to opaque may not require anything else below them to be redrawn. They might still trigger redraws "above" though, if the opaque view itself is partially covered by other views.
Ok, I think I’ve figured it out. It seems that turning all the subviews into layer-backed views did the trick.
And this is reasonable giving the way the layers are managed by the gpu and how the layer compositing is performed.
But I still don't understand why, using the "classic" NSViews, no matter if they are opaque or not, siblings or children, overlapped or not , I cannot invalidate a single view without the system calls the re-drawing of the entire view hierarchy of the window
I have a view with several subviews (NSButton, NSTextField, NSPopUpButton) and a NSImageView with a spinner icon which should be displayed on top of the other views while data is retrieved from the web.
To display the NSImageView on top I have set
imageViewSpinner.wantsLayer = true
imageViewSpinner.layer?.backgroundColor = NSColor.windowBackgroundColor.cgColor
The problem is, that the focus borders and PopUpButtons are still accessible/shining through the NSImageView (see attached video).
To solve this, I could iterate over all the other subviews and set them to "isHidden" or "disabled" but I wonder, if there is a cleaner solution to this problem, for example defining the NSImageView as topmost layer without things getting through?
You could put all of the other views inside of one container view and hide that.
You can also use a tab-less tab view to programmatically switch between view sub-hierarchies. (That basically achieves the same thing. It's better when there are more than 2 views to manage.)
I have a NSView as the documentView for a NSScrollView. I also have a NSImageView as a subview of the NSView. The image dynamically changes size so the scroll bars become active/inactive at various times. Once the image has changed, I'd like to scroll to a certain point on the image. From within the NSView's drawRect: method, I call
[[myScrollView contentView] scrollToPoint: myPoint];
The scroll bars update and the image appears as I'd like, but as soon as the image is scrolled, a double image appears or parts of the image get cut off. Any help would be appreciated. Thank you.
Sounds like you might want to turn off the "Copy On Scroll" behavior option of the NSScrollView either in Interface Builder or programmatically.
From Scroll View Programming Guide for Mac OS X: How Scrolling Works:
The NSClipView class provides low-level scrolling support through the
scrollToPoint: method. This method translates the origin of the
content view’s bounds rectangle and optimizes redisplay by copying as
much of the rendered document view as remains visible, only asking the
document view to draw newly exposed regions. This usually improves
scrolling performance but may not always be appropriate. You can turn
this behavior off using the NSClipView method setCopiesOnScroll:
passing NO as the parameter. If you do leave copy-on-scroll active, be
sure to scroll the document view programmatically using the NSView
method scrollPoint: method rather than translateOriginToPoint:.
I have an application with an NSTableView in a window. I want to use a CALayer as the background for the entire window, and the table view. In all my my experiments so far, the CALayer always draws over the NSTableView, which is not the effect I'm looking for. Is there a way to make this work, or am I simply out of luck due to the nature of layer-hosting views vs NSViews?
My test setup is a window with the usual NSScrollView/NSTableView combo, and a sibling NSView behind it in the view order. The NSView is set to be layer-hosting with my custom layer within it (just a layer with a backgroundColor set). I've experimented with setting the window's content view to be layer-backed, as well as the table view itself, as well as wrapping the NSScrollView in a layer-backed NSView. The result is always the same.
Thanks for any insight you might be able to provide.
It is simple. all overlapping views or layers should be layer backing or layer hosting for correct ordering.
you can set [tableview setWantsLayer:YES]
or simply check it in the layers tab when editing the interface.
I'm having a problem since Lion introduced elastic scrolling (pictured below). When you scroll my table view (cell-based, with alternating row colors) beyond its bounds, the background doesn't draw. I've tried doing my own drawing in -[drawBackgroundInClipRect:], but it seems like you can't exceed the bounds of the table view. How can I extend the background into elastic scrolling territory?
In Answer to Your Question
A view drawing outside its bounds is generally a no-no. When using alternating background colors, the NSTableView draws its background directly. But in a view-based table view, NSTableRowView is used and if it has its own background color, this is poses even more challenge.
The Bad News
The assemblage of NSScrollView (and its various parts), NSTableView, and NSTableHeaderView is complicated on its own. Once you throw view-based functionality into the mix (where each row has a view and each cell has their own view, and each are reused, animated around, etc.), overriding this behavior "is no way to go through life, son!" ;-)
The Good News
The issue of alternating background colors not extending in an elastically-stretched scrolled table view has been resolved (at least on 10.10, that I can tell), so this is no longer an issue unless you have row/cell views with custom backgrounds or just background colors.
A General Solution For Custom Document (Scrolled) Views
For all other scrolled views with ruled backgrounds you wish to extend for elastic scrolling, you'll need a custom NSScrollView subclass that expects a document view (your custom scrolled view) to conform to a protocol you define (like -(NSImage *)backgroundImageForClipViewBounds:). The scroll view would observe its content view (NSClipView) for bounds change notifications and flag itself for display. When the scroll view's -drawRect: is called, it would then ask the scrolled view for its -backgroundImageForClipViewBounds: (via your protocol) and draw it into itself, thereby making the scrolled view's "infinite background" its own.
I haven't tested this theory but I believe it would work. I hope this helps.