control the splitter bar

Hi all,

Has anybody tried to control how far you can move the splitter bar?

I've got two containers, one containing a list and a couple of buttons and
fields next to the list, and one containing a multi-line text box. Now I'm
trying to prevent the 1st container to become too small to make sure that
the controls always stay visible.

Anybody any ideas?

Cheers,

Ted
www.tedbracht.co.uk

Ted,

> Has anybody tried to control how far you can move the splitter bar?
>
> I've got two containers, one containing a list and a couple of buttons and
> fields next to the list, and one containing a multi-line text box. Now I'm
> trying to prevent the 1st container to become too small to make sure that
> the controls always stay visible.
>
> Anybody any ideas?

A bad one :(   Worst case, you could wait for the resize and adjust the
arrangements if needed (perhaps in a deferred action) and invalidate the
layout.  Hopefully there's a way to constrain it on the fly though.  Some
browsing starting with #constrainPoint: might turn up something useful.

Have a good one,

Bill

--
Wilhelm K. Schwab, Ph.D.
[hidden email]

Ted,

> Anybody any ideas?

This appears to work - caveats apply.

I created a subclass of Splitter called RestrictedSplitter and overrode one
method (just changing the point's x value from 0 to 150)

constrainPosition: aPoint
    "Private - An attempt may be made to change the position of the receiver
to
    aPoint.
    Answers the actual position that may be achieved."
    | position |
    position := aPoint max: 150 @ 0.
    self isVertical ifTrue: [position x: self x] ifFalse: [position y: self
y].
    ^position

This stops the Splitter being dragged within 150 pixels of the left/top
border.  It gets a bit confused if the shell is max/minimised or resized
though so it's not a complete solution.

NB: The easiest way to use it is to add a normal Splitter and then mutate it
into a RestrictedSplitter.

Regards
    Ian

>
> This stops the Splitter being dragged within 150 pixels of the left/top
> border.  It gets a bit confused if the shell is max/minimised or resized
> though so it's not a complete solution.
>

Cheers Ian (and Bill), got it working ok except like you said when changing
window size. I'll have a look into how to control that as well.

Thanks

Ted

Ted,

> Cheers Ian (and Bill), got it working ok except like you said when
> changing window size. I'll have a look into how to control that as
> well.

If you have only two subviews with a splitter between them then this might
be an alternative.  If you edit ProportionalLayout>>layoutContainer: to read
as below (there's only one change about 2/3 of the way through which I've
marked - sorry about the formatting) then the first subview is always laid
out with to a minimum width of 150 pixels - irrespective of how the resize
is done.

Creating a subclass to override this one method and using that as the layout
manager in your application would obviously be better than modifying the
existing class though :-)

If the layout manager looks after more than two sub views then it doesn't
quite work correctly, the right hand view is resized when the left splitter
is moved, but I think that could be overcome with a more extensive change.

Ian

layoutContainer: aContainerView
"Performs a layout operation on the contents in aContainerView"
| subviews extent majorExtent minorExtent point freeSize totalProportion
fixedSize viewMajorExtent viewExtent insets |
subviews := aContainerView managedSubViews .
insets := aContainerView actualInsets.
extent := (aContainerView clientWidth - (insets left + insets right)) @
(aContainerView clientHeight - (insets top + insets bottom)).
majorExtent := self majorDimensionOf: extent.
minorExtent := self minorDimensionOf: extent.
fixedSize := 0.
(subviews select: [:aView | self hasFixedSize: aView]) do: [:aView |
fixedSize := fixedSize + (self majorDimensionOf: aView layoutExtent)].
freeSize := majorExtent - fixedSize max: 0.
totalProportion := self totalProportionsOf: subviews.
point := insets origin.
subviews keysAndValuesDo: [:index :aView |
viewMajorExtent := (self hasFixedSize: aView)
ifTrue: [self majorDimensionOf: aView layoutExtent]
ifFalse: [index = subviews size
ifTrue: [majorExtent + (self majorDimensionOf: insets origin) - (self
majorDimensionOf: point)]

ifFalse: ["Change this block to read"
| temp |
temp := ((self arrangementOf: aView) / totalProportion * freeSize)
truncated.
index = 1 & (temp < 150) ifTrue: [temp := 150].
temp]].

viewExtent := self pointWithMajor: viewMajorExtent minor: minorExtent.
aView basicInvalidateLayout.
aView rectangle: (point extent: viewExtent).
point := point + (self pointWithMajor: viewMajorExtent minor: 0)].
aContainerView validateLayout.

Hi Ian,

> If you have only two subviews with a splitter between them then this might
> be an alternative.  If you edit ProportionalLayout>>layoutContainer: to
read
> as below (there's only one change about 2/3 of the way through which I've
> marked - sorry about the formatting) then the first subview is always laid
> out with to a minimum width of 150 pixels - irrespective of how the resize
> is done.
>

Nice ;-)

It would be nice if we had some aspect in the ProportionalLayout manager to
control this. I guess the most logical place would actually be the
proportional containers having a minimum size.

I'll see if I can do something with these suggestions to wrap it all up in a
nice little tool.

Ted