Move the tooltip out of the way of very large mouse cursors

Users that have large mouse pointers configured in their settings
can not see tooltips, as they are obscured by the pointer.
Native applications on Windows and macOS have the same problem,
which includes the tooltips for the minimize/maximize/close controls
in the window frame of e.g. Explorer.

Introduce QPlatformCursor::size that returns a value that is based
on the user's settings, or a default value. We can then use that
value to move the tooltip out of the way.

On Windows, the calculation of the cursor size is based on
experimenting with the settings, which are in logical independent
pixels. The placement of the tooltip attempts to keep existing
behavior, and to not end up with a tooltip that's very far away
from the tip of the arrow even for very large mouse cursors.

[ChangeLog][QtWidgets][QToolTip] Make sure that the tooltip
is not obscured by very large mouse pointers on Windows and macOS.

Change-Id: I8e13b7a166bfe8b59cef4765c950f90fefeaef9d
Fixes: QTBUG-79627
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

2 files changed, 9 insertions, 0 deletions

diff --git a/src/gui/kernel/qplatformcursor.cpp b/src/gui/kernel/qplatformcursor.cpp
index 49eff2ad23..aabf28a727 100644
--- a/src/gui/kernel/qplatformcursor.cpp
+++ b/src/gui/kernel/qplatformcursor.cpp
@@ -131,6 +131,14 @@ void QPlatformCursor::setPos(const QPoint &pos)
     QWindowSystemInterface::handleMouseEvent(0, pos, pos, Qt::NoButton, Qt::NoButton, QEvent::MouseMove);
 }
 
+/*!
+    Returns the size of the cursor, in native pixels.
+*/
+QSize QPlatformCursor::size() const
+{
+    return QSize(16, 16);
+}
+
 // End of display and pointer event handling code
 // Beginning of built-in cursor graphics
 // from src/gui/embedded/QGraphicsSystemCursorImage_qws.cpp
diff --git a/src/gui/kernel/qplatformcursor.h b/src/gui/kernel/qplatformcursor.h
index f36a73c861..f3871d8780 100644
--- a/src/gui/kernel/qplatformcursor.h
+++ b/src/gui/kernel/qplatformcursor.h
@@ -96,6 +96,7 @@ public:
 #endif // QT_NO_CURSOR
     virtual QPoint pos() const;
     virtual void setPos(const QPoint &pos);
+    virtual QSize size() const;
 
     static Capabilities capabilities() { return m_capabilities; }
     static void setCapabilities(Capabilities c) { m_capabilities = c; }