Re: [Gnustep-cvs] r29912 - in /libs/back/trunk: ChangeLog Source/win32/WIN32Server.m

[Doug Simons]

Capturing the mouse allows GNUstep to receive mouseDragged events when the mouse is outside of the window. Without this, the autoscroll mechanism doesn't work properly when a user moves the mouse out of the window while holding the button down.

I'm not at all expert (in fact I'm a complete newbie) with regards to the Windows event API, so I'm very open to other suggestions. The call to SetCapture() that I added solves the problem, and I was careful to call ReleaseCapture() when there are no longer any mouse buttons down. Hopefully that's done in such a way that it will always get called when the mouse is released.

I didn't see anything in Microsoft's documentation about what happens if SetCapture() is called more than once, so I was presuming it's a simple on/off toggle, with extra calls being ignored, but I don't know that for sure.

Let me know if anyone has a better idea for how to do this.

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Doug Simons
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On Mar 13, 2010, at 5:15 AM, Fred Kiefer wrote:

Am 12.03.2010 22:29, schrieb Doug Simons:

Author: dpsimons

Date: Fri Mar 12 22:29:37 2010

New Revision: 29912

URL: http://svn.gna.org/viewcvs/gnustep?rev=29912&view=rev

Log:

capture the mouse to get mouse moved events outside of window

Modified:

   libs/back/trunk/ChangeLog

   libs/back/trunk/Source/win32/WIN32Server.m

Hi Doug,

are you sure this is what you need to do? Capturing the mouse is a very
dangerous operation, you have to make sure you always get to the release
code as well. And if this code interacts with user code that actually
tries to capture the mouse, we may get into unclear states.

If I understand your comment then this is about getting the mouse up
event that follows a mouse down on a GNUstep window. When the mouse
moves out of the window this event wont get send to GNUstep, so we will
think the mouse is still up. Is this the problem you are trying to address?
There must be a difference in the event handling of X11, as we don't
need to capture the mouse there. Perhaps the mouse up event there is
always send to the window where the mouse went down?

Sorry, I am no longer familiar with all that code, it has been ages
since I last dug that deep into the difference of the event model of X11
and Windows.

Fred