Thread View: borland.public.cppbuilder.nativeapi
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4 total messages
Started by Christophe MINETTI
Fri, 12 May 2006 05:51
TTrackBar and Event
Author: Christophe MINETTI
Date: Fri, 12 May 2006 05:51
Date: Fri, 12 May 2006 05:51
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1143 bytes
Hi All, I am using the function PeekMessage() to remove the huge amount of event sent by the OnChange event of a TrackBar component. My question is: What kind of Window message is sent when one changes the trackbar position (the equivament of WM_TIMER for a timer). Many thanks in advance. Christophe
Re: TTrackBar and Event
Author: Remy Lebeau (TeamB)
Date: Fri, 12 May 2006 08:12
Date: Fri, 12 May 2006 08:12
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"Christophe MINETTI" <cminetti@ulb.ac.be> wrote in message news:4464226B.8A469DBC@ulb.ac.be... > I am using the function PeekMessage() to remove the huge amount > of event sent by the OnChange event of a TrackBar component. Why are you doing that? > What kind of Window message is sent when one changes the trackbar position As specified in the Win32 API documentation, a TrackBar control sends WM_HSCROLL and WM_VSCROLL messages to its parent window. Since the parent window is a VCL window in this situation, the VCL repackages the messages as CN_HSCROLL and CN_VSCROLL and sends them back to the TTrackBar for handling. Using Spy++, I also see WM_MOUSEMOVE, WM_NCHITTEST, WM_USER, WM_PAINT, WM_CAPTURECHANGED and WM_SETCURSOR messages being sent to the TTrackBar as well while the thumb is being dragged by the user. Gambit
Re: TTrackBar and Event
Author: Christophe MINETTI
Date: Fri, 12 May 2006 08:30
Date: Fri, 12 May 2006 08:30
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> > I am using the function PeekMessage() to remove the huge amount > > of event sent by the OnChange event of a TrackBar component. > > Why are you doing that? Simply because the process called during the OnChange Event of the TrackBar is quite long and I remove the queue of Events to avoid the application to be blocked until all the events have been processed ...
Re: TTrackBar and Event
Author: Remy Lebeau (TeamB)
Date: Fri, 12 May 2006 09:55
Date: Fri, 12 May 2006 09:55
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"Christophe MINETTI" <cminetti@ulb.ac.be> wrote in message news:446447B6.F0E4E7F4@ulb.ac.be... > Simply because the process called during the OnChange Event of the > TrackBar is quite long and I remove the queue of Events to avoid > the application to be blocked until all the events have been processed ... You should use a thread for that instead. Gambit
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