RFR: 8351907: [XWayland] [OL10] Robot.mousePress() is delivered to wrong place

[Sergey Bylokhov]

On Fri, 16 May 2025 10:40:22 GMT, Alexander Zvegintsev <azvegint at openjdk.org> wrote:

> The issue is the inability to move the mouse cursor using `java.awt.Robot` on Oracle Linux 10 (which has not yet been released). FIY, the OL10 is no longer provides an Xorg session, so only Wayland is available.
> It is a JCK conformance failure. 
> 
> ---
> 
> In our robot implementation, we emulate mouse/keyboard actions using the XTEST extension protocol.
> 
> The XTEST calls are now wired to [libEI](https://libinput.pages.freedesktop.org/libei/api/index.html):
> 
> 1.
> 
> It now asks for a user confirmation to allow interaction, so we should now be able to click on native applications, window titles, etc.
> 
> However, our robot implementation is mostly uses XTEST, but there is an exception:
> for mouse move we use XWarpPointer, which is not part of the XTEST, thus it is not propagated outside of Xwayland server.
> 
> So we have a situation where mouse is moving only inside Xwayland server, and we see the mouse enter/exit events,
> on mouse press we call XTestFakeButtonEvent and it is handled by libei,
> so the click happens where is the actual mouse cursor is in the system. That is why the test fails.
> 
> To avoid this situation we should use XTestFakeMotionEvent for mouseMove in Xwayland case.
> 
> It would be a simple solution, but
> 
> 
> 2.
> 
> This permission granted by a user doesn't persist across reboots, it timeouts after a period of inactivity.
> 
> It still seems to conform to the specifications, but we will not be able to conveniently run automated tests in this case.
> 
> ---
> 
> So as a solution we can switch the [Remote Desktop XDG portal](https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.RemoteDesktop.html).
> It has session and `restore_token` functionality to keep permissions granted by a user, similar to what we use in a [Screencast](https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.ScreenCast.html) for taking screenshots.
> Most of the code can be reused, and it has everything we need.
> 
> 
> * It is only enabled by default on Wayland and Gnome Shell 47 and higher due to XTEST API complications that first arose in this version. For earlier versions, Screencast is used instead.
> * A new value has been introduced for the `awt.robot.screenshotMethod` system property - `dbusRemoteDesktop`. It works on Ubuntu 24.04 with Gnome 46, but is not enabled by default.
> * extra mouse buttons are not supported yet, [JDK-8357142](https://bugs.openjdk.org/browse/JDK-8357142)
> * Since we are now moving the mouse using a non-X11 API and `MouseInfo.getPointerInfo().getLo...

src/java.desktop/unix/classes/sun/awt/UNIXToolkit.java line 259:

> 257:         try {
> 258:             Process process =
> 259:                 new ProcessBuilder("/usr/bin/gnome-shell", "--version")

Before the patch the getGnomeShellMajorVersion was guarded by the "gnome.equals(getDesktop()))" should we do the same in XdgDesktopPortal? or maybe we can at least check if gnome-shell exists so we don't waste time launching it? or is ProcessBuilder's performance good enough?

BTW how it is expected to work on KDE + wayland?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25265#discussion_r2093555459