[PATCH] dix: fix scale_to_desktop for edge ABS events

[Jeremy Huddleston Sequoia]

Yick.  This is why origin/size are better descriptors =(

Reviewed-by: Jeremy Huddleston Sequoia <jeremyhu at apple.com>

On Jul 20, 2012, at 16:41, Yufeng Shen <miletus at chromium.org> wrote:

> Scale_to_desktop() converts ABS events from device coordinates
> to screen coordinates:
> [dev_X_min, dev_X_max]  -> [screen_X_min, screen_X_max]
> [dev_Y_min, dev_Y_max]  -> [screen_Y_min, screen_Y_max]
> 
> An edge ABS event with X = dev_X_max (e.g., generated from the
> edge of a touchscreen) will be converted to have screen X value
> = screen_X_max, which, however, will be filterd out when xserver
> tries to find proper Window to receive the event, because the
> range check for a Window to receive events is
>       window_X_min <= event_screen_X < window_X_max
> Events with event_screen_X = screen_X_max will fail the test get
> and rejected by the Window.
> 
> To fix this, we change the device to screen coordinates mapping to
> [dev_X_min, dev_X_max]  -> [screen_X_min, screen_X_max-1]
> [dev_Y_min, dev_Y_max]  -> [screen_Y_min, screen_Y_max-1]
> 
> Signed-off-by: Yufeng Shen <miletus at chromium.org>
> ---
> dix/getevents.c |    4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/dix/getevents.c b/dix/getevents.c
> index b78d5ce..9898c6a 100644
> --- a/dix/getevents.c
> +++ b/dix/getevents.c
> @@ -890,9 +890,9 @@ scale_to_desktop(DeviceIntPtr dev, ValuatorMask *mask,
> 
>     /* scale x&y to desktop coordinates */
>     *screenx = rescaleValuatorAxis(x, dev->valuator->axes + 0, NULL,
> -                                   screenInfo.x, screenInfo.width);
> +                                   screenInfo.x, screenInfo.width - 1);
>     *screeny = rescaleValuatorAxis(y, dev->valuator->axes + 1, NULL,
> -                                   screenInfo.y, screenInfo.height);
> +                                   screenInfo.y, screenInfo.height - 1);
> 
>     *devx = x;
>     *devy = y;
> -- 
> 1.7.7.3
> 
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