NSScrollView/NSClipView resizing.

[Pascal Bourguignon]

Hi!

There is a difference of behavior  between the resizing of a couple of
NSScrollView/NSClipView  on GNUstep  and  on OPENSTEP  4.2, where  the
behavior on GNUstep is not good.

Namely this  can be seen  when using ScalingScrollView, a  subclass of
NSScrollView which override or implements these methods:

Overrides:
    -(id)initWithFrame:(NSRect)rect;
        // [super initWithFrame:rect]; and proper attributes initialization.
    -(void)tile;
        // [super tile]; and reposition the pop-up and horizontal scroll.

    -(void)setHasHorizontalScroller:(BOOL)flag;
        // only remove the zoom pop-up when no horizontal scroll.
          
New methods:                                     
    -(void)_makeScalePopUpButton;
    -(void)scalePopUpAction:(id)sender;
    -(float)scaleFactor;
    -(void)setScaleFactor:(float)newScaleFactor;
        // set the clipView bounds according the the scale factor.

(Source of ScalingScrollView is to  be found in the AppKit Examples of
OPENSTEP 4.2).


Now, when the  window is resized and then the  scroll view is resized,
on OPENSTEP 4.2, the relative  size of the clipView is conserved, that
is, the scale factor is conserved.

But on GNUstep,  the clipView is entirely reset,  reverting to a scale
factor  of  100%,  and  invaliding  the  invariants  of  the  subclass
ScalingScrollView.

Resizing a  NSScrollView should be done  in a way  that conserve ratio
between the bounds dans the frame of the clipView.


ScalingScrollView subclass of NSScrollView, contains NSClipView, which
contains MTVTree view.
    
On GNUstep:

Before resizing, with zoom factor 50%:
G: ----------------------------------------------------
G: (MTVTree*)(0x0850f1b0): 
G:       bounds = {{   845100.00,  2501032.00},{    56787.00,    81520.00}}
G:       frame  = {{        0.00,        0.00},{    56787.00,    81520.00}}
G: (NSClipView*)(0x084c7c78): 
G:       bounds = {{       22.96,     7120.00},{     1612.00,     1338.00}}
G:       frame  = {{       20.00,        1.00},{      806.00,      669.00}}
G: (ScalingScrollView*)(0x084cefa0): 
G:       bounds = {{        0.00,        0.00},{      827.00,      690.00}}
G:       frame  = {{        8.00,       82.00},{      827.00,      690.00}}

After resizing:
G: ----------------------------------------------------
G: (MTVTree*)(0x0850f1b0): 
G:       bounds = {{   845100.00,  2501032.00},{    56787.00,    81520.00}}
G:       frame  = {{        0.00,        0.00},{    56787.00,    81520.00}}
G: (NSClipView*)(0x084c7c78): 
G:       bounds = {{       22.96,     7120.00},{      653.00,      581.00}} BAD
G:       frame  = {{       20.00,        1.00},{      653.00,      581.00}}
G: (ScalingScrollView*)(0x084cefa0): 
G:       bounds = {{        0.00,        0.00},{      674.00,      602.00}}
G:       frame  = {{        8.00,       82.00},{      674.00,      602.00}}


On OPENSTEP 4.2:

Before resizing, with zoom factor 50%:
O: ----------------------------------------------------
O: (MTVTree*)(0x0010b0e8): 
O:       bounds = {{   845100.00,  2501032.00},{    56787.00,    81520.00}}
O:       frame  = {{        0.00,        0.00},{    56787.00,    81520.00}}
O: (NSClipView*)(0x0010b234): 
O:       bounds = {{     8810.75,     6659.75},{     1382.00,     1194.00}}
O:       frame  = {{       20.00,        1.00},{      691.00,      597.00}}
O: (ScalingScrollView*)(0x0010b168): 
O:       bounds = {{        0.00,        0.00},{      712.00,      618.00}}
O:       frame  = {{        8.00,       82.00},{      712.00,      618.00}}

After resizing:
O: ----------------------------------------------------
O: (MTVTree*)(0x0010b0e8): 
O:       bounds = {{   845100.00,  2501032.00},{    56787.00,    81520.00}}
O:       frame  = {{        0.00,        0.00},{    56787.00,    81520.00}}
O: (NSClipView*)(0x0010b234): 
O:       bounds = {{     8810.75,     6659.75},{     1230.00,     1084.00}} GOOD
O:       frame  = {{       20.00,        1.00},{      615.00,      542.00}}
O: (ScalingScrollView*)(0x0010b168): 
O:       bounds = {{        0.00,        0.00},{      636.00,      563.00}}
O:       frame  = {{        8.00,       82.00},{      636.00,      563.00}}


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