> On Dec 6, 2015, at 4:51 AM, Roland King <r...@rols.org> wrote: > >> >> 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.
UIView will not dirty its layer if your subclass does not implement -drawRect:. > > 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/david.duncan%40apple.com > > This email sent to david.dun...@apple.com -- David Duncan _______________________________________________ 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
