qpa: enhance mouse event with type and button data

... and deprecate QWSI APIs that accepts mouse event without mouse button/
type data.

In the early days of Qt5 it was decided to centralize mouse button/type
handling in QGuiApplication (because of limitation of some now unknown
platform). This has proven to be problematic as mouse handling details
differ across platforms (e.g on X11 we do not receive mouse release event
when closing popup windows or ordinary windows that are closed from the
mouse press event). Instead of hacking around platform specific behaviors
in Qt Gui, we should move this task back to platform plugins (similar to
how this was done in Qt4 with native APIs sending mouse details directly
to QApplication). There are even cases where it simply is not possible
to deduce (from QGuiApplication) which button caused the event (e.g. when
more than one button is involved and some event goes missing). Besisdes,
throwing away information which is already available at QPA level (for free)
and trying to deduce it again at Qt Gui level seems impractical, fagile
(as probably noticed by people fixing all the unexpected issues) and adds
unnecessary complexity.

Note:

Removing the deprecated QWSI APIs from offscreen plugin depends on fixing
autotests that rely on QOffscreenCursor::setPos() logic.

For the convenience of testing use QT_QPA_DISABLE_ENHANCED_MOUSE to restore
to the old code path where QGuiApplication does the mouse state deducing.

Other platforms have similar issues. I do not have all supported platform
available on my desk, so other platform maintainers will need to take care
of porting those platforms to the new APIs. And mainly, I don't want to deal
with all the hacks that other platforms have added to workaround this broken
mouse logic.

In Qt6 we need to remove deprecated code path from QGuiApplication.

This patch:

- Extends QWindowSystemInterfacePrivate::MouseEvent ctor with QEvent::Type
and Qt::MouseButton. We use this extra data when processing mouse events in
QGuiApplication. This actually is similar to KeyEvent, where we do pass the
type (press or release) to QtGui.

- Refactors QGuiApplicationPrivate::processMouseEvent and qtestlib to use
the new APIs.

Task-number: QTBUG-59277
Task-number: QTBUG-62329
Task-number: QTBUG-63467
Change-Id: If94fd46a7cccfea8264dcb1368804c73334558b8
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 7 insertions, 4 deletions

diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index 176f9a234c..b89dddf72f 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -146,7 +146,7 @@ public:
     QXcbWindow *toWindow() override;
 
     void handleMouseEvent(xcb_timestamp_t time, const QPoint &local, const QPoint &global,
-                          Qt::KeyboardModifiers modifiers, Qt::MouseEventSource source);
+                          Qt::KeyboardModifiers modifiers, QEvent::Type type, Qt::MouseEventSource source);
 
     void updateNetWmUserTime(xcb_timestamp_t timestamp);
 
@@ -221,13 +221,16 @@ protected:
     bool compressExposeEvent(QRegion &exposeRegion);
 
     void handleButtonPressEvent(int event_x, int event_y, int root_x, int root_y,
-                                int detail, Qt::KeyboardModifiers modifiers, xcb_timestamp_t timestamp, Qt::MouseEventSource source = Qt::MouseEventNotSynthesized);
+                                int detail, Qt::KeyboardModifiers modifiers, xcb_timestamp_t timestamp,
+                                QEvent::Type type, Qt::MouseEventSource source = Qt::MouseEventNotSynthesized);
 
     void handleButtonReleaseEvent(int event_x, int event_y, int root_x, int root_y,
-                                  int detail, Qt::KeyboardModifiers modifiers, xcb_timestamp_t timestamp, Qt::MouseEventSource source = Qt::MouseEventNotSynthesized);
+                                  int detail, Qt::KeyboardModifiers modifiers, xcb_timestamp_t timestamp,
+                                  QEvent::Type type, Qt::MouseEventSource source = Qt::MouseEventNotSynthesized);
 
     void handleMotionNotifyEvent(int event_x, int event_y, int root_x, int root_y,
-                                 Qt::KeyboardModifiers modifiers, xcb_timestamp_t timestamp, Qt::MouseEventSource source = Qt::MouseEventNotSynthesized);
+                                 Qt::KeyboardModifiers modifiers, xcb_timestamp_t timestamp,
+                                 QEvent::Type type, Qt::MouseEventSource source = Qt::MouseEventNotSynthesized);
 
     void handleEnterNotifyEvent(int event_x, int event_y, int root_x, int root_y,
                                 quint8 mode, quint8 detail, xcb_timestamp_t timestamp);