lteyssie@POLYSLO.CALPOLY.EDU (Luke Teyssier) (10/11/89)
Your responses to my previous inquiry about tiling window managers were very helpful. I am currently working with rtl from siemens and it is a good environment. According to the X Toolkit intrinsics, page 66, XtAppAddTimeOut allows a timeout procedure to be specified. The manual shows that the timeout procedure can be specified in terms of milliseconds. I am running X11 R3 on a sun 3/50 and a sun3/60, and I am trying to interface to a real time program written in Ada that will be running on a machine connected to the sun. My question is this: can I really get millisecond response time granularity? Is that a gurantee of the maximum time to the timeout, or the minimum time to the timeout, or in some range? Does this work even if you are in a callback procedure, or only if you are in the XtMainLoop sitting idle? There was a discussion on Comp.windows.x for some time on how to make transparent widows. I missed part of the discussion. What I would like to do is have a window underneath another window and have both of them visible in the opaque regions and yet be able to change the pattern on either one, sort of like having two overhead transparancies stacked one on top of the other. Failing that, I would like to be able to construct a widget such that a predefined pattern would be displayed permanently in the background, such as a grid or a crosshairs with tick marks on it. My idea is that you would write on the foreground and then you could erase the foreground picture and the background would still be intact. It would have to be able to deal with resize and expose events of course. Thanks for your help. Luke Teyssier (lteyssie@polyslo.calpoly.edu 129.65.17.1)
swick@ATHENA.MIT.EDU (Ralph R. Swick) (10/11/89)
> According to the X Toolkit intrinsics, page 66, XtAppAddTimeOut allows > a timeout procedure to be specified. ... > can I really get millisecond response time > granularity? Probably not. It's a function of the underlying OS; the value is passed directly to select(). > Is that a gurantee of the maximum time to the timeout, or the > minimum time to the timeout, or in some range? Minimum, if anything; the timer may expire during dispatching of some other event (timer, alternate input callback, or XEvent) which can take arbitrarily long. > Does this work even if > you are in a callback procedure, or only if you are in the XtMainLoop > sitting idle? The most recent timer event to expire is processed by XtAppProcessEvent or XtAppNextEvent; there is no preemption. > What I would like > to do is have a window underneath another window and have both of them > visible in the opaque regions and yet be able to change the pattern on either > one, sort of like having two overhead transparancies stacked one on top of > the other. Not supported by the core X11 protocol. > Failing that, I would like to be able to construct a widget > such that a predefined pattern would be displayed permanently in the > background, such as a grid or a crosshairs with tick marks on it. Pretty simple; create a Pixmap (be careful about depth), draw your static graphics into it, then make it be the window background. You'll use up a lot of server resources if you make lots of these, but then you'd probably expect that to be the case.