** Description changed: Mouse event compression stopped working in Qt 5, a regression from Qt 4: - https://bugreports.qt.io/browse/QTBUG-40889 + https://bugreports.qt.io/browse/QTBUG-40889 The bug was fixed in Qt 5.6 https://codereview.qt- - project.org/#/c/126136/ where it has been thoroughly tested by now. + project.org/#/c/126136/ where the fix has been thoroughly tested by now. Attached is a debdiff against 5.5.1+dfsg-16ubuntu7.2 which includes a backport of the 5.6 patch (only one trivial hunk failed, which was easily fixed). [Impact] The bug affects any program that relies on the event compression Qt normally does. For example, VTK programs (ParaView, Tomviz, ...) do their rendering in response to mouse events during camera movements, and with event compression at the Qt level suddenly gone, camera movements become very slow, since the application is now flooded with mouse events and the rendering lags behind. The problem is not limited to these programs however; it can be observed by simply putting two regular, slightly slow-to-render, widgets into a QSplitter and moving the splitter handle. The result is a syrup-like experience as the widgets try to keep up with the onslaught of resize events due to the lack of mouse event compression. [Test Case] The attached test application can be used to check if event compression is functioning. It performs some artificial work on each mouse move and prints a message. Click and drag the mouse a little. After releasing the mouse, you'll notice that the printouts keeps coming for quite a while, as the program is catching up with the flood of events. With the attached patch (and with Qt 4), the problem is gone - the mouse event stream is compressed and the printouts are no longer lagging behind. [Regression Potential] There's a small risk that some applications have made workarounds for the faulty behavior, and that unwanted behavior is introduced if this bug is fixed. But chances are high that such workarounds will keep working, as the obvious workaround is to do timer based rendering instead of event based. The workarounds will then simply become unnecessary, but shouldn't cause problems. I'm asking for someone to nominate this bug for an SRU of 16.04 LTS.
** Description changed: Mouse event compression stopped working in Qt 5, a regression from Qt 4: https://bugreports.qt.io/browse/QTBUG-40889 The bug was fixed in Qt 5.6 https://codereview.qt- project.org/#/c/126136/ where the fix has been thoroughly tested by now. Attached is a debdiff against 5.5.1+dfsg-16ubuntu7.2 which includes a backport of the 5.6 patch (only one trivial hunk failed, which was easily fixed). [Impact] The bug affects any program that relies on the event compression Qt - normally does. For example, VTK programs (ParaView, Tomviz, ...) do + normally performs. For example, VTK programs (ParaView, Tomviz, ...) do their rendering in response to mouse events during camera movements, and with event compression at the Qt level suddenly gone, camera movements become very slow, since the application is now flooded with mouse events and the rendering lags behind. The problem is not limited to these programs however; it can be observed by simply putting two regular, slightly slow-to-render, widgets into a QSplitter and moving the splitter handle. The result is a syrup-like experience as the widgets try to keep up with the onslaught of resize events due to the lack of mouse event compression. [Test Case] The attached test application can be used to check if event compression is functioning. It performs some artificial work on each mouse move and prints a message. Click and drag the mouse a little. After releasing the mouse, you'll notice that the printouts keeps coming for quite a while, as the program is catching up with the flood of events. With the attached patch (and with Qt 4), the problem is gone - the mouse event stream is compressed and the printouts are no longer lagging behind. [Regression Potential] There's a small risk that some applications have made workarounds for the faulty behavior, and that unwanted behavior is introduced if this bug is fixed. But chances are high that such workarounds will keep working, as the obvious workaround is to do timer based rendering instead of event based. The workarounds will then simply become unnecessary, but shouldn't cause problems. I'm asking for someone to nominate this bug for an SRU of 16.04 LTS. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1598173 Title: Please consider SRU of "xcb: Compress mouse motion and touch update events" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qtbase-opensource-src/+bug/1598173/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
