Hello

I've created a widget system using SDL. Everything was working happily until I started using a touchscreen. The touchscreen is installed as a standard USB HID mouse so SDL does not know there's a touchscreen in the system. The touchscreen works perfectly in Windows.

When I click the touchscreen somewhere away from the current mouse position, SDL first sends event SDL_MOUSEBUTTONDOWN with the old co-ordinates, followed by event MOUSEMOTION containing the correct co-ordinates. Obviously, this is wrong. Here's an except of my program's log:

00000018	5:49:57.343 PM	[1316] [CAWRDPOS    ] SDL event: type 05 - SDL_MOUSEBUTTONDOWN	
00000019	5:49:57.343 PM	[1316] [CAWRDPOS    ]            (348,0)	
00000020	5:49:57.343 PM	[1316] [CAWRDPOS    ] SDL event: type 04 - SDL_MOUSEMOTION	
00000021	5:49:57.343 PM	[1316] [CAWRDPOS    ]            (629,287)	
00000022	5:49:57.437 PM	[1316] [CAWRDPOS    ] SDL event: type 06 - SDL_MOUSEBUTTONUP	
00000023	5:49:57.437 PM	[1316] [CAWRDPOS    ]            (629,287)	

You can see SDL_MOUSEBUTTONDOWN comes with the old co-ordinates (348,0) followed by SDL_MOUSEMOTION with the actual co-ordinates where I touched the screen (629,287). This is a major problem. It disrupts the proper working of a widget kit.

I can repeat this situation 100%.

For the sake of clarity, I also checked the generated Win32 messages using a test program. When I click the touchscreen, it first generates a WM_MOUSEMOVE for the new co-ordinates, followed by WM_LBUTTONDOWN for the same co-ordinates. This is normal behaviour for touchscreens.

I also installed the vendor-supplied drivers for the touchscreen. I tried different modes of behaviour including mouse emulation. However the results remained the same; SDL still generates incorrect events.

I'm using an ELO 1515. However, since the touchscreen is installed as a generic USB mouse (using standard Windows drivers), I'm afraid SDL will have problems with other touchscreens as well because they generate similar events.

BR