RFR: 8289115: Touch events is not dispatched after upgrade to JAVAFX17+

[Kevin Rushforth]

On Tue, 21 May 2024 14:25:51 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

> This PR fixes a bug ([JDK-8289115](https://bugs.openjdk.org/browse/JDK-8289115)) that was introduced with #394, which changed the following line in the `NotifyTouchInput` function (ViewContainer.cpp):
> 
> - const bool isDirect = true;
> + const bool isDirect = IsTouchEvent();
> 
> 
> `IsTouchEvent` is a small utility function that uses the Windows SDK function `GetMessageExtraInfo` to distinguish between mouse events and pen events as described in this article: https://learn.microsoft.com/en-us/windows/win32/tablet/system-events-and-mouse-messages
> 
> I think that using this function to distinguish between touchscreen events and pen events is erroneous. The linked article states:
> _"When your application receives a **mouse message** (such as WM_LBUTTONDOWN) [...]"_
> 
> But we are not receiving a mouse message in `NotifyTouchInput`, we are receiving a `WM_TOUCH` message.
> I couldn't find any information on whether this API usage is also supported for `WM_TOUCH` messages, but my testing shows that that's probably not the case (I tested this with a XPS 15 touchscreen laptop, where `GetMessageExtraInfo` returns 0 for `WM_TOUCH` messages).
> 
> My suggestion is to check the `TOUCHEVENTF_PEN` flag of the `TOUCHINPUT` structure instead:
> 
> const bool isDirect = (ti->dwFlags & TOUCHEVENTF_PEN) == 0;

It seems reasonable to get this fix in and then file a new "redo" bug for [JDK-8249737](https://bugs.openjdk.org/browse/JDK-8249737), with the bug title:


[REDO] java.lang.RuntimeException: Too many touch points reported


That new bug can be linked as "related to" [JDK-8289115](https://bugs.openjdk.org/browse/JDK-8289115) and [JDK-8249737](https://bugs.openjdk.org/browse/JDK-8249737).

-------------

Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1459#pullrequestreview-2154868189