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>

1 files changed, 28 insertions, 15 deletions

diff --git a/src/widgets/kernel/qtooltip.cpp b/src/widgets/kernel/qtooltip.cpp
index 97a279d65d..1ec3612457 100644
--- a/src/widgets/kernel/qtooltip.cpp
+++ b/src/widgets/kernel/qtooltip.cpp
@@ -53,11 +53,14 @@
 #endif
 #include <qtextdocument.h>
 #include <qdebug.h>
+#include <qpa/qplatformscreen.h>
+#include <qpa/qplatformcursor.h>
 #include <private/qstylesheetstyle_p.h>
 
 #ifndef QT_NO_TOOLTIP
 #include <qlabel.h>
 #include <QtWidgets/private/qlabel_p.h>
+#include <QtGui/private/qhighdpiscaling_p.h>
 #include <qtooltip.h>
 
 QT_BEGIN_NAMESPACE
@@ -398,24 +401,34 @@ void QTipLabel::placeTip(const QPoint &pos, QWidget *w)
     }
 #endif //QT_NO_STYLE_STYLESHEET
 
-
-    QRect screen = QDesktopWidgetPrivate::screenGeometry(getTipScreen(pos, w));
-
     QPoint p = pos;
-    p += QPoint(2, 16);
-
-    if (p.x() + this->width() > screen.x() + screen.width())
+    int screenNumber = getTipScreen(pos, w);
+    QScreen *screen = QGuiApplication::screens().at(screenNumber);
+    if (screen) {
+        const QPlatformScreen *platformScreen = screen->handle();
+        const QSize cursorSize = QHighDpi::fromNativePixels(platformScreen->cursor()->size(),
+                                                            platformScreen);
+        QPoint offset(2, cursorSize.height());
+        // assuming an arrow shape, we can just move to the side for very large cursors
+        if (cursorSize.height() > 2 * this->height())
+            offset = QPoint(cursorSize.width() / 2, 0);
+
+        p += offset;
+
+        QRect screenRect = screen->geometry();
+        if (p.x() + this->width() > screenRect.x() + screenRect.width())
         p.rx() -= 4 + this->width();
-    if (p.y() + this->height() > screen.y() + screen.height())
+        if (p.y() + this->height() > screenRect.y() + screenRect.height())
         p.ry() -= 24 + this->height();
-    if (p.y() < screen.y())
-        p.setY(screen.y());
-    if (p.x() + this->width() > screen.x() + screen.width())
-        p.setX(screen.x() + screen.width() - this->width());
-    if (p.x() < screen.x())
-        p.setX(screen.x());
-    if (p.y() + this->height() > screen.y() + screen.height())
-        p.setY(screen.y() + screen.height() - this->height());
+        if (p.y() < screenRect.y())
+            p.setY(screenRect.y());
+        if (p.x() + this->width() > screenRect.x() + screenRect.width())
+            p.setX(screenRect.x() + screenRect.width() - this->width());
+        if (p.x() < screenRect.x())
+            p.setX(screenRect.x());
+        if (p.y() + this->height() > screenRect.y() + screenRect.height())
+            p.setY(screenRect.y() + screenRect.height() - this->height());
+    }
     this->move(p);
 }