Re: autoresizing in the case of negative flexible space (was Re: Pixel-aligned autoresizing)

[Tim Schmielau]

Thanks!

On 23 Jul 2011, at 14:44, Fred Kiefer wrote:

> 
> Thank you, I committed your change.
> 
> On 22.07.2011 21:27, Tim Schmielau wrote:
>> 
>> Hi Eric and Fred,
>> 
>> thanks for the great work you are doing! I'd like to suggest a little change 
>> though to fix a recently introduced incompatibility:
>> 
>> I have an app where at the bottom of a window there is a GUI element whose 
>> visibility can change. When the visibility changes, the height of the window 
>> is adjusted for the additional space needed. As the GUI element is supposed 
>> to appear at a fixed position from the top left corner of the window, only 
>> NSViewMinYMargin is set in the _autoresizingMask of the GUI element.
>> 
>> I believe this to be a common pattern under Cocoa, and the code worked well 
>> both on Mac OS and on GNUstep before the recent changes.
>> 
>> Since SVN revision 33482 however, the GUI element permanently disappears 
>> below the lower window border on the first time it is made invisible. This 
>> is because the window size adjustment makes the (now invisible) GUI element 
>> move to a negative Y position. Once the Y position is negative, the total 
>> flexibleSpace is negative, and the GUI element will not be moved back up 
>> again when the window becomes larger again.
>> 
>> This is a deviation from the behavior on Cocoa.  While I haven't 
>> investigated Cocoa's behavior more closely, it can be fixed by falling back 
>> to the old autoresizing behavior instead of just giving up when negative 
>> flexible space is encountered. The simple patch below achieves that.
>> 
>> Thanks,
>> Tim
>> 
>> Index: Source/NSView.m
>> ===================================================================
>> --- Source/NSView.m  (revision 33608)
>> +++ Source/NSView.m  (working copy)
>> @@ -1970,7 +1970,7 @@
>>      flexibleSpace += oldContainerSize - oldContentPosition - oldContentSize;
>> 
>> 
>> -  if (flexibleSpace == 0.0)
>> +  if (flexibleSpace<= 0.0)
>>      {
>>        /**
>>         * In this code path there is no flexible space so we divide
>> @@ -1994,7 +1994,7 @@
>>          }
>>      }
>>      }
>> -  else if (flexibleSpace>  0.0)
>> +  else
>>      {
>>        /**
>>         * In this code path we distribute the change proportionately
>