| how to resize a top level base widget [message #83832] |
Sat, 06 April 2013 12:48 |
markb77
Messages: 217
Registered: July 2006
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Senior Member |
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I've been messing around with resizing top level base widgets under
Windows (IDL 8.0.1). After some experimentation, I've figured out one
or two things that are worth noting for future reference.
As far as I can ascertain, the correct way to resize a TLB is to
resize the widgets contained within it.
Let's say you have a graphics window which you want the user to be
able to resize. You have set the TLB_SIZE_EVENTS keyword for the
base. Now the user resizes the base and your event handler receives a
resize event. What happens next?
If you use WIDGET_INFO to check the geometry of the TLB at this point,
you get back the new size of the TLB.
The first time you use WIDGET_CONTROL to resize one of the child
widgets of the TLB, however, the size of the TLB will "snap back" to
the largest extents of its child widgets.
Therefore, the correct procedure for resizing is, after receiving the
resize event, to use WIDGET_CONTROL to appropriately resize the
widgets within your TLB in order to fill up the new space. This will
result in a TLB that has the same size that the user selected.
Warning: DO NOT use WIDGET_CONTROL to directly resize the top level
base widget. This results in strange behavior and will mess up your
widget layout. If you need to programmatically resize the TLB, simply
adjust the size of the widgets contained within, and the size of the
TLB will change automatically.
I should note that In my case, the TLB specifies the COLUMN keyword,
so the layout of the child widgets is managed by the top level base
widget. I'm not sure if what I've described above applies when this
isn't the case, or on platforms other than Windows.
Some of this is already covered in David's article about resizeable
widget programs, but I got stuck on this a couple of times so I
thought I'd add this to the list.
Mark
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