Re: Catalina scroll view issues
Re: Catalina scroll view issues
- Subject: Re: Catalina scroll view issues
- From: Rob Petrovec via Cocoa-dev <email@hidden>
- Date: Tue, 31 Dec 2019 12:46:30 -0700
> On Dec 31, 2019, at 1:34 AM, Eyal Redler <email@hidden> wrote:
> Nothing old fashioned or unorthodox in what I'm doing.
drawRect is not deprecated. Correct. However, it is technically old
fashioned. It is much more efficient to use layers. Layers can take better
advantage of the video card especially during animations, and don’t require
unnecessary redraws if (part of) your view is covered up and then uncovered
(e.g. during scrolling or windows moving around etc).
> turning it on did not cause the issue to show up on Mohave
> ...
> I, for one, wasn't able to reproduce it on the 5 machines I was able to put
> my hands on.
Curious, how were you able to verify that turning on copyOnScroll in
your app and running it on Mojave did not reproduce the problem if you couldn’t
reproduce the problem on Catalina on the machines you had access to? Just
curious.
—Rob
> On Dec 31, 2019, at 1:34 AM, Eyal Redler <email@hidden> wrote:
>
>>
>> On 30 Dec 2019, at 2:09, Rob Petrovec via Cocoa-dev
>> <email@hidden <mailto:email@hidden>> wrote:
>>
>> I honestly think this is fall out from copiesOnScroll being deprecated and
>> the clip view always behaving as if it was set to true. My guess is you
>> will see the same problems in your apps if you ran them on Mojave with
>> copiesOnScroll set to true. In which case you need to update your app to
>> work with copiesOnScroll set to true. E.g. use layers instead of drawRect.
>
> I agree that this is probably connected to the changes that led to
> copiesOnScroll to be deprecated but turning it on did not cause the issue to
> show up on Mohave nor did it fix the issue on Catalina. AFAIK drawRect is not
> deprecated (yet?) and so my drawing the views, on a mac, using drawRect is
> compatible Apple's current guidelines. Nothing old fashioned or unorthodox in
> what I'm doing.
>
> My understanding (and hopefully those in the know will correct me if I'm
> wrong), with responsive scrolling, copiesOnScroll is not relevant, drawRect
> is not called to paint the newly exposed area as you scroll but rather is
> called ahead of time for the visible area plus some extra content above and
> below. When the user scrolls, the system just copies the bits to the screen
> from some offscreen buffer. I believe that since responsive scrolling was
> introduced, copiesOnScroll was ignored anyway and was relevant only when
> responsive scrolling was turned off.
>
> Last thing to point out, the problem is exclusive to Catalina but it doesn't
> effect all users, I don't have any statistics but gathering from the
> relatively few reports I've received, it seems to effect only a minority of
> users (thank God, this bug really makes me look really bad and I'm completely
> helpless against it). I, for one, wasn't able to reproduce it on the 5
> machines I was able to put my hands on.
>
> Eyal
>
>
>
>>
>> —Rob
>>
>>
>>> On Dec 29, 2019, at 4:08 PM, Jerome Krinock via Cocoa-dev
>>> <email@hidden> wrote:
>>>
>>> Since installing macOS 10.15, I see blocks of empty text view lines or
>>> table view rows often when scrolling through many apps, including file
>>> browser windows in Path Finder (cocoatech.com) and, for heaven’s sake, even
>>> in BBEdit.
>>>
>>> Conclusion: This is not “our” faults. Thank you, Eyal for submitting this
>>> issue to Apple as FB7509033. Maybe someday… [rant omitted].
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