WM_LBUTTONDOWN no produce QMouseEvent after last Windows 10 update

[miguelorenes]

Qt Version: 5.9.3
I am getting a problem after lastest update of Windows 10:
Version: 1790
OS Build 16.299.125

On previous Windows 10 versions, when I use an external pen device I was getting the events on QT layer as QMouseEvent but after this update, I am not getting anything.

I have been checking by a QAbstractNativeEventFilter and I am receiving the proper messages:

• WM_LBUTTONDOWN
• WM_MOUSEMOVE
• WM_LBUTTONUP

But, for some reason I have stopped to receive QMouseEvent on Qt Layer.

This is very critical for my project as I am implementing some special behaviour by GetMessageExtraInfo flags and it is full based on receiving the proper QMouseEvent on Qt layer.

[mrjj]

Hi
Sounds like the update broke something ( that update killed my debugger)
Since its sounds like Pen device is still in Mouse Mode since
WM_LBUTTONDOWN are reported, it sounds inside Qt.

Would it be possible to try with 5.10 ?

[miguelorenes]

Checked with Qt_5_10_0_MSVC2015_32 and happen the same.
Something on this Windows update has broken this.

[miguelorenes]

A little more information about this issue, QMouseEvent is not generated when GetMessageExtraInfo() != 0. That is, when trying to extract pen information as described in https://msdn.microsoft.com/en-us/library/windows/desktop/ms703320(v=vs.85).aspx

[mrjj]

Hi
Its just odd if nativeEventfilter can see them that rest of Qt do not.

I assume you checked if there is no newer driver for the pen device and
also that it works at it should in a pen enabled app.

Sorry i have zero idea of what to check.
Reinstalling Qt also seems pointless as it worked before the update and unless
it broke something in Qt, it wont help.

[miguelorenes]

thanks @mrjj

On any case I have to get in deep on this.

I am checking what I am getting on GetMessageExtraInfo() also the code of "QWindowsMouseHandler::translateMouseEvent" and I think my issue is provoked because of this piece of code:

// Check for events synthesized from touch. Lower byte is touch index, 0 means pen.
    static const bool passSynthesizedMouseEvents =
            !(QWindowsIntegration::instance()->options() & QWindowsIntegration::DontPassOsMouseEventsSynthesizedFromTouch);
    // Check for events synthesized from touch. Lower 7 bits are touch/pen index, bit 8 indicates touch.
    // However, when tablet support is active, extraInfo is a packet serial number. This is not a problem
    // since we do not want to ignore mouse events coming from a tablet.
    // See https://msdn.microsoft.com/en-us/library/windows/desktop/ms703320.aspx
    const quint64 extraInfo = quint64(GetMessageExtraInfo());
    if ((extraInfo & signatureMask) == miWpSignature) {
        if (extraInfo & 0x80) { // Bit 7 indicates touch event, else tablet pen.
            source = Qt::MouseEventSynthesizedBySystem;
            if (!passSynthesizedMouseEvents)
                return false;
        }
    }

Values got with GetMessageExtraInfo:

• Touch: 0xFF51578B
• Pen: 0xFF515796

For some reason my pen actions now are interpretated as touch event because "if (extraInfo & 0x80)" is returning true, so, they are discarded.

I cannot imagine why Windows 10 is changing this with the latest update.

Could someone give me a little of light on this?