On 08/01/2010, at 3:58 PM, David Blanton wrote: > If a scroll view's content view is larger than the scroll view then the > scroll view generates scrollers - correct? > > Let me try to get to some of the REALLY > > 1. I want to always make the content view some factor larger than the scroll > view to keep the scroller knobs a uniform size.
For this I'd perhaps consider subclassing NSScroller and override -setKnobProportion: to call super with some constant value regardless of what is passed in. That will keep the knob a constant size. If the content view is some fixed proportion of the visible view, this will just happen anyway, but I'm unsure just how sensible this would be. > > 2. If the user scrolls I want to tell my model how much was scrolled so it > can regenerate a bitmap for display. Sounds very hacky. What would probably be better is wait until the view needs to draw something, then figure out if that part has been cached as a bitmap yet. If so, you can just draw it. If not, you can generate the bitmap there and then and then just draw it. This way your document/data model needs to know nothing about the view, in keeping with good MVC design. Instead, it waits for the view to ask it for data for some portion, and then it has the information about what part of the view is being drawn. This approach automatically takes care of scrolling, zooming, sizing and so forth without any hacks. The view just makes its dirty rects available to the data model when it is requesting data. If it slows down drawing too much initially, you could use the "no cache data available" state to trigger creation of that data, maybe in a background thread, then redraw it when it is available. In the meantime you'd have to draw something else, such as a blank background or a pattern denoting "no data yet" perhaps. > 3. If the window size changes apply a factor to the content view to achieve 1 > above. OK, if that makes sense for the app. Sounds a bit weird, but what do I know? What happens if the user does some work in the corner of the content area then makes the window smaller? Wouldn't that lose that work? --Graham _______________________________________________ Cocoa-dev mailing list ([email protected]) 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
