> On 6 Dec 2015, at 20:18, Roland King <r...@rols.org> wrote: > > >> >> CALayer has a mechanism built in for the sort of thing you want to do. Read >> up on -[CALayer display]. You should be able to override that, or implement >> the corresponding delegate method in your UIView and perform management of >> your custom bitmap there. I myself do this in one app to share one bitmap >> between multiple layers for example. >> >> The other thing worth investigating perhaps is whether CATiledLayer would >> better suit your drawing needs, or if you could split your custom view up >> into a series of sub-views, so you only need invalidate slices of one or two >> of them. >> >> Mike. > > That’s what I was just trying. I made a subclass of CALayer() and overrode > just display() to do absolutely nothing at all, except print ‘display()’. I > then made a UIView subclass which overrides layerClass() to return the type > and stuck one such view randomly in my NIB. The view is made, the layer is > created .. and absolutely nothing else happens. I expected to get at least > ONE call to display() as the view/layer starts dirty, but I don’t get even > that. I even hooked up a button to call setNeedsDisplay on the view but that > didn’t prompt it either. I overrode a bunch of other methods too to print but > the only one which currently gets called is init(). > > I expected the UIView would drive at least an initial setNeedsDisplay on the > layer, and a setNeedsDisplay on the view would end up being passed-through, > but it doesn’t. Calling setNeedsDisplay on the actual layer object itself > seems to work, but I did sort of expect the UIView to do some things with the > layer automatically. Guess I was wrong and I will need to hook all those bits > up for myself.
ok I begin to see how it all works now. So if the layer is the view’s layer, instead of a separate totally custom layer you add to the layer, then the view sets some things on it but not everything. It turns off needsDisplayOnBoundsChange (which I had set on init in the layer) unless the view’s contentMode is redraw, which somewhat confused me. That causes the layer to call display() on itself on bounds change. However it doesn’t pass setNeedsDisplay() and setNeedsDisplayInRect() through to the underlying layer which I’d have expected. I assume it only calls those that if the layer is a normal UIView layer and not a custom one. I think as long as that’s the extent of its meddling with ‘its layer’, just setting a few properties when it starts up and adjusting the bounds for me, I can live with it. I’ll try out a few more things on the view to see if there are other things I need to be prepared to deal with, just having it manage the layer bounds automatically is helpful if that’s about all it does. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
