[wxPython-users] Re: BitmapButton shows focus erroneously

[Robin Dunn]

Jeffrey Barish wrote:
> Robin Dunn wrote:
>> The only thing I can think of is to decouple the code that decides when 
>> to set the bg color out of the controls and move it into some sort of 
>> highlight manager class.  When a control that is supposed to set its bg 
>> color receives the focus then it asks the highlight manager if it can do 
>> it.  The highlight manager keeps track of which control currently has 
>> the highlight and notifies it if a new control requests it so the 
>> current one can reset its bg to the default.  Since the buttons would 
>> not request the highlight then the current highlighted control would not 
>> lose it.
> 
> I implemented something close to this proposal and it works nicely, but
> there was still one small problem.  If I covered my application and then
> exposed it, the shading would disappear. 

Since you are using SetBackgroundColour then that shouldn't happen. 
When the controls refresh themselves after they are damaged they should 
still use that background color.  Are you doing anything that would get 
the setting of the bg color out of sync with where it should be?


> I solved the problem, but I am
> not confident that my solution is optimal.  First I catch the paint event
> directed to the main panel:
> 
>     def doMainPanelPaint(self, event):
>         wx.PaintDC(self) # online doc says must create PaintDC object
>                          # even if not used
>         self.backgroundManager.resetFocus()
>         event.Skip()

Since you are calling Skip then you shouldn't need to create the 
wx.PaintDC since the default handler will do it.

> 
> Then the BackgroundManager restores the background:
> 
>     def resetFocus(self):
>         win = self.restoreFocusWin
>         if win.GetBackgroundColour != self.shadedCol:
>             win.SetBackgroundColour(self.shadedCol)
>             win.Refresh(True)
> 
> I am worried about this solution because doMainPanelPaint gets called
> frequently for events that have nothing to do with restoring the background
> shading.  Is there another event that relates more closely to the problem I
> am solving?  Is the overhead for my handler small?  I suppose that
> something like the wx.PaintDC call happens regardless, so if the call to
> resetFocus is the extent of the overhead then perhaps it is negligible.
> 
> I just noticed that when I minimize and restore my application, the shading
> is right but the application no longer responds to keyboard commands to
> move the focus, so probably I still have something wrong.

Perhaps not calling Skip from a focus handler?  Also, when the window is 
restored the control that last had the focus will get another focus 
event as the focus is restored, so be sure that there isn't anything 
that could go wonky if the control that it thinks already has the focus 
gets it again.


-- 
Robin Dunn
Software Craftsman
http://wxPython.org  Java give you jitters?  Relax with wxPython!