[Vm-dev] [Pharo-dev] How to listen for windows messages?

Tue Mar 14 23:04:41 UTC 2017

On Tue, Mar 14, 2017 at 4:27 PM, Eliot Miranda <eliot.miranda at gmail.com>
wrote:

> Hi Phil, Hi All,
>
> On Tue, Feb 28, 2017 at 4:29 AM, phil at highoctane.be <phil at highoctane.be>
> wrote:
>
>> Hi,
>>
>> Pharo is itself a Windows application (under Windows of course).
>>
>> So Window event loop is picking up the events and transforming them into
>> Pharo events.
>>
>
> Right, but this is *not good enough* :-)  It is a fundamentally different
> architecture.  The processing of Windows events in the Windows VM
> transforms *event callbacks* into   an *event queue*.  This is fine for
> events such as mouse clicks, keyboard presses, etc.  But it is
> fundamentally broken for events such as those that ask an application to
> quit because the OS is about to exit, or events that try to obtain mouse
> feedback while moving a native window, etc, etc.
>
> So one either needs to extend the VM event queue so that one can install
> callbacks for certain kinds of events still providing a cross-platform
> interface), or, as Vassili did for Newspeak native windows (which was fully
> working in 2008, with the ability to switch a window between emulated
> (Morphic) and native at will or on image startup), interface to the native
> Windows event pump via callbacks.
>

Yes, I understand that. But there is some bit rot in the basics already,
so, first things first.  And Pharo lowcode VM is also replacing a lot of
this with other ways (which kind of bury the Windows thing even deeper in
way I guess).

Would the VM core be a libray, we could have more options. Look at V8
ending up in Chrome, NodeJS and Electron.
Or Lua getting all over the place. Tcl also is pretty cool on that front.

Phil

>
>
>
>> You can check this in https://github.com/pharo-project/pharo-vm
>>
>> in opensmalltalk-vm\platforms\win32\vm\sqWin32Window.c
>>
>> https://github.com/pharo-project/pharo-vm/blob/master/opensm
>> alltalk-vm/platforms/win32/vm/sqWin32Window.c
>>
>> Like L235...
>>
>> LRESULT CALLBACK MainWndProcW(HWND hwnd,
>> UINT message,
>> WPARAM wParam,
>> LPARAM lParam)
>>
>> You'll see that we stick a lot of stuff into evt->... in various ways.
>>
>> There is a default fallback at the end.
>>
>> default:
>> /* Unprocessed messages may be processed outside the current
>> module. If firstMessageHook is non-NULL and returns a non
>> zero value, the message has been successfully processed */
>> if(firstMessageHook)
>> if((*firstMessageHook)(hwnd, message, wParam, lParam))
>> return 1;
>> return DefWindowProcW(hwnd,message,wParam,lParam);
>>
>> {
>>
>>
>> So, if firstMessageHook exists, one can do whatever.
>>
>> Now, a Windows manager may need other stuff and so on.
>> What you are looking at is how to hook this VM side with more of the
>> general Windows system.
>>
>> These hooks are globals, so should be accessible.
>>
>> /***********************************************************
>> *****************/
>> /* Message Processing */
>> /***********************************************************
>> *****************/
>> /* The last dispatched event. It is used for the event processing
>> mechanism. */
>> MSG *lastMessage = NULL;
>> /* The entry to the message hooks called from the window procedure.
>> If another module requires to process messages by itself, it should
>> put its message procedure in this place. */
>> messageHook firstMessageHook = 0;
>> /* The entry to a pre-message hook. Can be used to intercept any messages
>> to the squeak main window. Useful for modules that wish to be notified
>> about certain messages before they are processed. */
>> messageHook preMessageHook = 0;
>>
>> Never played with these but any Windows integration is of interest to me.
>>
>> So, go ahead. Nothing would resist focused work.
>>
>> Be aware that there is another VM underway with a cleanup of all of this
>> but this is not released yet.
>>
>> Keep us posted.
>> Phil
>>
>>
>>
>>
>> On Tue, Feb 28, 2017 at 9:33 AM, Torsten Bergmann <astares at gmx.de> wrote:
>> >
>> > Hi,
>> >
>> > I guess what you want to achieve will not be an easy task for you if
>> you are new to programming.
>> > But it is always good to have a goal and if you have time to learn I'm
>> pretty sure you will master
>> > it.
>> >
>> > Even when OS-Windows inspire you for automizing tasks in other Windows
>> processes (like autoit) you
>> > should not start with my OS-Windows project directly as contributing to
>> it requires knowledge
>> > on your side on Smalltalk as well as Win32 C programming.
>> >
>> > First start with learning Smalltalk and Pharo
>> >   - http://files.pharo.org/books/
>> >   - http://pharo.pharocloud.com/pharobooks
>> >   - http://stephane.ducasse.free.fr/FreeBooks.html
>> >
>> > After having an idea about Smalltalk and Pharo you should try to learn
>> UFFI which
>> > is Pharos unified foreign function interface and ability to call C
>> DLL's.
>> >
>> > https://ci.inria.fr/pharo-contribution/view/Books/job/PharoB
>> ookWorkInProgress/lastSuccessfulBuild/artifact/book-result/UnifiedFFI/
>> >
>> > Sideways start learning about the Win32 API and C as this helps to
>> better understand
>> > how things are done on the Windows side. There are many, many tutorials
>> out there.
>> > Try to call or wrap some simple DLL functions on you own first.
>> >
>> > There is a nice and tiny C compiler if you want to try out some C
>> samples
>> > http://www.pellesc.de/index.php?page=download&lang=en
>> >
>> > With this initial knowledge you can try to understand why and how
>> OS-Windows was done.
>> > I wrote many tests - just add a breakpoint and run them to debug
>> through the code to understand.
>> > Google for the API descriptions of the Win32 functions that are called
>> to get an understanding
>> > how Pharo and C get connected.
>> >
>> > Also check how you work with callbacks in UFFI (as this would be
>> required for a hook).
>> >
>> > If you are then still interested in interception windows messages you
>> should start reading here
>> > https://msdn.microsoft.com/en-us/library/windows/desktop/ms6
>> 32589(v=vs.85).aspx
>> >
>> > Primarily one has to wrap SetWindowsHookEx API function and friends and
>> wrap a good API
>> > for them in Pharo.
>> >
>> > Hope that helps to get started.
>> >
>> > Regards
>> > Torsten
>> >
>> > > Gesendet: Dienstag, 28. Februar 2017 um 06:04 Uhr
>> > > Von: lw1990 <lukewallace1990 at gmail.com>
>> > > An: pharo-dev at lists.pharo.org
>> > > Betreff: [Pharo-dev] How to listen for windows messages?
>> > >
>> > > In the OS-Windows package, there exists the ability to use the
>> windows api in
>> > > Pharo.
>> > > This is very powerful, and I intend to add more of the windows api
>> into it
>> > > (it's only partially implemented).
>> > >
>> > > This appears to all have been done with DllCalls (FFI calls) so far.
>> > >
>> > > A big part of interacting with windows is listening to/intercepting
>> and
>> > > responding to windows messages.
>> > > For example, every time a user presses a key on the keyboard, a
>> windows
>> > > message will happen in the background for that key. If Pharo was
>> aware of
>> > > these messages, then Pharo could do things in response to hotkeys
>> pressed on
>> > > Windows (outside of a pharo window).
>> > >
>> > > It would also make reacting to events potentially nicer. Like making a
>> > > windows-desktop-manager in Pharo that can tell when a new window is
>> created
>> > > by windows (maybe they opened notepad). It would certainly be better
>> than an
>> > > infinite loop or timer of 'get active window and compare to last
>> active
>> > > window and see if it changed'. Instead it would be 'when receive the
>> > > WM_MESSAGE for new window created, notify Pharo so it can react'.
>> > >
>> > > How can I set up a windows message hook in Pharo?
>> > > Please keep in mind I'm very new to programming, but I work from home
>> and
>> > > have lots of time to learn :-)
>> > >
>> > >
>> > >
>> > > --
>> > > View this message in context: http://forum.world.st/How-to-l
>> isten-for-windows-messages-tp4936285.html
>> > > Sent from the Pharo Smalltalk Developers mailing list archive at
>> Nabble.com.
>> > >
>> > >
>> >
>>
>
>
>
> --
> _,,,^..^,,,_
> best, Eliot
>
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