🚀 go-pugleaf

In article <1992Dec18.131216.3058@cs.wayne.edu>, pbh@pandora.cs.wayne.edu (Patrick B. Haggood) writes:
|> Borland's OWL includes two Windows messages; WM_LBUTTONDBLCLK AND
|> WM_RBUTTONDBLCLK.  See the OWL manual p.42 or any of a bunch of 
|> third party books on OWL.

To have double click messages sent to a window, you must set the correct
class style: CS_DBLCLICK I think, but I'm not sure of the exact name.

Windows deals with double clicks by sending four messages to the window:
WM_LBUTTONDOWN, WM_LBUTTONUP, WM_LBUTTONDBLCLK & WM_LBUTTONUP. (for the
left mouse button, for instance.) When the program receives the 
WM_LBUTTONDBLCLK message, must handle the fact that the previous two messages 
were part of the double click, as is the next button-up message. The latter 
can be handles with a  boolean flag. 

The former is a little harder. I used double clicks to end the drawing of
a multi-point line in an object-oriented drawing package (actually a garden
designer). Every button up message added a point to the line, unless the last
message processed was a double-click. When I received a double click message,
I knew I had collected all the points and so processed them. Therefore I didn't
need to deal with/remember the previous two button-down/button-up messages,
since the double-click was an extension of a single-click; ie: single-click = 
"new point", double-click = "last point". 

I have found that in practise, most uses of double clicks are like this. 
Anything else is complicated to write and nasty to use.



|> -- 
|> Patrick B. Haggood				Wayne State University
|> "Again, the kingdom of heaven is like unto a net," | DoD #1966	
|> 	Matthew 13:47                              | pbh@prjup.uucp
-- 
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  ///                     Nat Pryce (np2@doc.ic.ac.uk)                  
 ( oo  It is essential to dig the most for if you do not dig you lose your
 |\_|  superiority over the square and so are less likely to be cool - Kerouac