Message Sent when Resizing Widgets: Workaround

[Bob Sneidar]

I have a kind of custom group composed of a segmented widget and a transparent button the exact size of the widget, the purpose of which is to be able to handle messages that are otherwise not sent to the widget. In fact almost NO messages are sent to a widget, a source of some consternation from users of this list. 

There are three issues with this, the first being that if there is a button on top of a widget, then no messages get sent directly from the engine to the widget at all! The second is that if I add more segments or resize the widget, the width of the overlay button also needs to match. The third issue is that if I click on the overlay button, I need to know, as in the case of a mouse click which segment was clicked on. 

To this end I wrote some handlers for the widget and the overlay button which allow you to handle any messages a button might receive and then process them for the widget. This is of course just a basic framework. The important handlers are resizeControl and the getProp clickedTab. 

Unfortunately, and although changing the size of the widget will send the resizeContol message to t he widget, editing the width in the widget’s properties palette does NOT send the message. The upshot is that if you make changes to a widget, you can simply run the resizeControl handler to clean things up. 

In my case I always want the widget segments to be the same size, and I always want the widget to be centered on the card. YMMV. You could get even fancier if you wanted and calculate the formattedWidth of the segment names, add a little air around them, then set the width of the widget to the sum of those, and then the minimum segment widths to those formattedWidths. But manipulating the minimum segment widths to get the correct width for each segment is something I have not fathomed. I wish they had given us a property for the *actual* segment widths. 

For the widget itself I have these handlers: 

on hiliteChanged
   put the hilitedItemNames of me into tTabName
   put the itemNames of me into tTabList
   tabChanged tTabName, tTabList
end hiliteChanged

on tabChanged pTab, pTabList
   -- your code here  
end tabChanged

on resizeControl
   wait until the mouse is up with messages
   put the long id of me into tMyID
   put wordOffset("card", tMyID) +1 into tPos
   put word tPos to -1 of tMyID into tParentCard
   put the width of widget "TabBar" into tWidth
   put tWidth / the itemCount of widget "TabBar" into tSegmentWidth
   
   repeat with i = 1 to the itemCount of widget "TabBar"
      put tSegmentWidth into item i of tSegmentWidths
   end repeat
   
   set the itemMinExtents of widget "TabBar" to tSegmentWidths
   
   -- center the widget left to right
   put the loc of widget "TabBar" into tTabLoc
   put the loc of tParentCard into tCardLoc
   put item 1 of tCardLoc into item 1 of tTabLoc
   set the loc of widget "TabBar" to tTabLoc
   
   -- set the rect of the overlay button to match
   set the rect of button "btnTabOverlay" to the rect of widget "TabBar"
end resizeControl


Then for the overlay button: 

on mouseUp
   put the clickedTab of me into tTab
   set the hilitedItemNames of widget "TabBar" to tTab
end mouseUp

on mouseDoubleUp
   put the clickedTab of me into tTab
   
   -- your code here
end mouseDoubleUp

getProp clickedTab
   put the clickLoc into tClickLoc
   put the itemNames of widget "TabBar" into tTabNames
   put the rect of widget "TabBar" into tTabRect
   put item 3 of tTabRect - item 1 of tTabRect into tTabWidth
   put the itemCount of widget "TabBar" into tTabCount
   put tTabWidth / tTabCount into tSegmentWidth
   
   repeat with i = 1 to tTabCount
      put round(item 1 of tTabRect + (tSegmentWidth * i)) into tSegmentBounds
      
      if item 1 of tClickLoc <= tSegmentBounds then
         put item i of tTabNames into tTab
         exit repeat
      end if
   end repeat
   
   put the itemMinExtents of widget "TabBar" into tExtents
   return tTab
end clickedTab