Re: [AD] Breakpointing an app in the MSVC 6 debugger can get a key to be stuck in Windows 2000

[Andrei Ellman <ae-a-alleg@xxxxxxxxxx>]

Peter Wang wrote:
> On 2005-12-31, Andrei Ellman <ae-a-alleg@xxxxxxxxxx> wrote:
>
> > Peter Wang wrote:
> >
> > > You can try this test.  Using a windowed graphics driver, set a
> > > SWITCH_IN and SWITCH_OUT callback with set_display_switch_callback() and
> > > see if the callback is called before and after you enter the breakpoint.
> >
> > I tried the test, but it appears that in both Windows 98 and Windows 
> > 2000, neither the SWITCH_IN or SWITCH_OUT callbacks are called when the 
> > breakpoint is reached. However, when I bring another app to the 
> > foreground, the SWITCH_OUT callback is called, and when I switch back to 
> > the app, the SWITCH_IN callback is called.
>
>
> Maybe try setting breakpoints on handle_key_release() or
> _handle_key_release() to see if either get called after resuming from a
> breakpoint in Win98?
>
> Nothing in src/win/wkeybd.c modifies key[] directly.  For that,
> handle_key_press() and handle_key_release() call _handle_key_press() and
> _handle_key_release() respectively, which are defined in src/keyboard.c.
> If key[] is being set in Win98 it should happen via handle_key_release()
> or _handle_key_release().


OK. I finally got round to trying it out. Here are the results:

Windows 98:
Firstly, the breakpoint in the main code is reached. After resuming (I'm 
using the menu's restart option so I don't have to press F5 which would 
cause the Allegro keyboard-handler to register that as well), 
handle_key_release() and then _handle_key_release() get called. After 
that, execution returns to main code, where I need to resume from the 
breakpoint again. Without the breakpoint in the main code, both 
handle_key_release() and _handle_key_release() get called.

Windows 2000:
The breakpoint in the main code is reached, but when resuming, neither 
handle_key_release() or _handle_key_release() get called. The breakpoint 
is hit again even though F2 is no longer held down. Without the 
breakpoint in the main code, both handle_key_release() and 
_handle_key_release() get called.

Attatched is the test-program.

AE.

/***************************************************************************
 *
 * breakpointkbdtest.c
 * Test program to show the Allegro keyboard handler failing to release a key if it was released during a break by the debugger.
 *
 **************************************************************************/


/****************************************************************************
 Includes
 */

#include <allegro.h>


/****************************************************************************
  Types
 */

typedef int TeBool;


/****************************************************************************
 Defines
 */



void 
teDisplaySwitchInCallback(void)
{

	TRACE("Switching IN\n");

}



void 
teDisplaySwitchOutCallback(void)
{

	TRACE("Switching OUT\n");

}




TeBool
teSetupGfx()
{

	set_gfx_mode(GFX_AUTODETECT_WINDOWED, 640, 480, 0, 0);		

	set_palette(desktop_palette);
	

	if(set_display_switch_callback(SWITCH_IN, teDisplaySwitchInCallback))
	{
		TRACE("Error setting up the switch-in callback.\n");
		return FALSE;
	}


	if(set_display_switch_callback(SWITCH_OUT, teDisplaySwitchOutCallback))
	{
		TRACE("Error setting up the switch-out callback.\n");
		return FALSE;
	}

	return TRUE;
}



void
teCleanupGraphics()
{
	remove_display_switch_callback(teDisplaySwitchOutCallback);
	remove_display_switch_callback(teDisplaySwitchInCallback);
}



void
teDoTest()
{
	TRACE("Starting test...\n\n");

	
	textout_ex(screen, font, "Hold down F2 to display some text", 0, 0, 1, 0);


	while(!key[KEY_ESC] && !key[KEY_SPACE])
	{
		if(key[KEY_F2])
		{
			// Place a breakpoint on the line below to see F2 getting stuck on Windows 2000
			textout_ex(screen, font, "F2 is pressed", 30, 20, 0, 1);
		}
		else
		{
			rectfill(screen,30,20,30+(13*8),20+(1*8),0);
		}
	}


	TRACE("\nEnding test...\n");
}



TeBool
teSetup()
{
	if(allegro_init())
	{
		TRACE("Error Initialising Allegro.\n");
		return FALSE;
	}


	if(install_keyboard())
	{
		TRACE("Error Initialising Keyboard.\n");
		return FALSE;
	}


	if(!teSetupGfx())
	{
		TRACE("Error setting up the graphics.\n");
		return FALSE;
	}


	return TRUE;
}



void
teCleanUp()
{
	teCleanupGraphics();

	remove_keyboard();

	allegro_exit();
}



int main(void)
{
	if(!teSetup())
	{
		teCleanUp();
		return -1;
	}


	teDoTest();


	teCleanUp();

	return 0;
}
END_OF_MAIN();