On Mon, 4 Jan 2021 08:39:10 GMT, Sergey Bylokhov <s...@openjdk.org> wrote:
>> Please, review this small fix for drag-n-drop on Linux with HiDPI turned on! >> >> This bug is due to the following reason: while scaling Java recalculates >> resolution (W x H) according to sun.java2d.uiScale (W/SCALE x H/SCALE) and >> works inside these new coordinates but at the same time the events, that >> come from the system, continue reporting positions in the old coordinates (W >> x H). >> >> The idea of the suggested fix is in division of coordinates on the scale >> when they come from the system to Java and multiplying them on the scale >> when they go back from Java to the system. It is similar to processing >> events from mouse and buttons. >> >> Testing is quite complicated because for reproducing this bug the following >> conditions should be met: >> 1. HiDPI is turned on >> 2. sun.java2d.uiScale.enabled = true and sun.java2d.uiScale != 100% >> 3. the source of drag-n-drop is non-java application >> >> The step-by-step guide how to reproduce this bug is added to >> https://bugs.openjdk.java.net/browse/JDK-8257414. > > src/java.desktop/unix/classes/sun/awt/X11/XDnDDropTargetProtocol.java line > 616: > >> 614: /* Translate mouse position from root coordinates >> 615: to the target window coordinates. */ >> 616: Point p = xwindow.toLocal(xwindow.scaleDown(x), >> xwindow.scaleDown(y)); > > I guess some clarification here is required. It is unclear what the > coordinate system is used by the x/y above. Looks like before the fix the > device space was always used, and after the fix the mix of device/user's > space will be used. > If the user's space should always be used(the scaled version of the device), > then I suggest to scale these coordinates here: > x = (int)(xclient.get_data(2) >> 16); > y = (int)(xclient.get_data(2) & 0xFFFF); > But you will need to check that all usage of the new coordinate system will > be valid across the method. Sergey, thank you! Could you give me a hint please concerning some use case of drag-and-drop to meet the (xwindow == 0) condition in XDnDDropTargetProtocol::processXdndPosition(..)? I'm unable to do it by means of the tests' apps I have. ------------- PR: https://git.openjdk.java.net/jdk/pull/1907
