QQuickScrollBar: ensure '0 ≤ size ≤ 1' and '0 ≤ minimumSize ≤ 1'

It doesn't make sense for these properties to be negative or larger
than 1.0.

The size property is meant to be the size of the scrollbar relative to
the scroll area size, either horizontally or vertically, and should be
in the value range 0 ≤ x ≤ 1, where 1 means that it covers the whole
scrollbar area, and 0, meaning it's invisible. This property can be set
from qml, or by QQuickFlickable with a scrollbar assigned to the
Scrollbar.vertical or Scrollbar.horizontal properties.

The minimumSize property can be set by the qml user, to force the
scrollbar to be larger than the Flickable size / contentSize ratio.
It makes sense to force the 0 ≤ x ≤ 1 constraint for this property's
value as well.

amends ef69623648f6f5ef5ab10dd9dee72f044334d53d

As an additional sanity check, I've added a qt_is_finite() check for all
qreal properties as well, just to prevent our API users from
accidentally setting a property to an invalid floating point value.

Pick-to: 6.3 6.2
Change-Id: I9f2880333483bf584986801d6b7204fea8d66e58
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

2 files changed, 43 insertions, 8 deletions

diff --git a/src/quicktemplates2/qquickscrollbar.cpp b/src/quicktemplates2/qquickscrollbar.cpp
index f20805a8f0..14d4e3a86f 100644
--- a/src/quicktemplates2/qquickscrollbar.cpp
+++ b/src/quicktemplates2/qquickscrollbar.cpp
@@ -165,7 +165,8 @@ static const QQuickItemPrivate::ChangeTypes verticalChangeTypes = changeTypes |
 QQuickScrollBarPrivate::VisualArea QQuickScrollBarPrivate::visualArea() const
 {
     qreal visualPos = position;
-    if (minimumSize > size)
+
+    if (minimumSize > size && size != 1.0)
         visualPos = position / (1.0 - size) * (1.0 - minimumSize);
 
     qreal visualSize = qBound<qreal>(0, qMax(size, minimumSize) + qMin<qreal>(0, visualPos),
@@ -178,7 +179,7 @@ QQuickScrollBarPrivate::VisualArea QQuickScrollBarPrivate::visualArea() const
 
 qreal QQuickScrollBarPrivate::logicalPosition(qreal position) const
 {
-    if (minimumSize > size)
+    if (minimumSize > size && minimumSize != 1.0)
         return position * (1.0 - size) / (1.0 - minimumSize);
     return position;
 }
@@ -434,11 +435,11 @@ qreal QQuickScrollBar::size() const
 void QQuickScrollBar::setSize(qreal size)
 {
     Q_D(QQuickScrollBar);
-    if (qFuzzyCompare(d->size, size))
+    if (!qt_is_finite(size) || qFuzzyCompare(d->size, size))
         return;
 
     auto oldVisualArea = d->visualArea();
-    d->size = size;
+    d->size = qBound(0.0, size, 1.0);
     if (isComponentComplete())
         d->resizeContent();
     emit sizeChanged();
@@ -466,7 +467,7 @@ qreal QQuickScrollBar::position() const
 void QQuickScrollBar::setPosition(qreal position)
 {
     Q_D(QQuickScrollBar);
-    if (qFuzzyCompare(d->position, position))
+    if (!qt_is_finite(position) || qFuzzyCompare(d->position, position))
         return;
 
     auto oldVisualArea = d->visualArea();
@@ -493,7 +494,7 @@ qreal QQuickScrollBar::stepSize() const
 void QQuickScrollBar::setStepSize(qreal step)
 {
     Q_D(QQuickScrollBar);
-    if (qFuzzyCompare(d->stepSize, step))
+    if (!qt_is_finite(step) || qFuzzyCompare(d->stepSize, step))
         return;
 
     d->stepSize = step;
@@ -737,11 +738,11 @@ qreal QQuickScrollBar::minimumSize() const
 void QQuickScrollBar::setMinimumSize(qreal minimumSize)
 {
     Q_D(QQuickScrollBar);
-    if (qFuzzyCompare(d->minimumSize, minimumSize))
+    if (!qt_is_finite(minimumSize) || qFuzzyCompare(d->minimumSize, minimumSize))
         return;
 
     auto oldVisualArea = d->visualArea();
-    d->minimumSize = minimumSize;
+    d->minimumSize = qBound(0.0, minimumSize, 1.0);
     if (isComponentComplete())
         d->resizeContent();
     emit minimumSizeChanged();
diff --git a/tests/auto/quickcontrols2/controls/data/tst_scrollbar.qml b/tests/auto/quickcontrols2/controls/data/tst_scrollbar.qml
index d49658762c..d453f017e7 100644
--- a/tests/auto/quickcontrols2/controls/data/tst_scrollbar.qml
+++ b/tests/auto/quickcontrols2/controls/data/tst_scrollbar.qml
@@ -964,4 +964,38 @@ TestCase {
         compare(vertical.visualPosition, 0.2)
         compare(vertical.contentItem.y, vertical.topPadding + 0.2 * vertical.availableHeight)
     }
+
+    function test_setting_invalid_property_values() {
+        var control = createTemporaryObject(scrollBar, testCase, {size: 2.0, minimumSize: -1.0})
+        verify(control)
+
+        // check that the values are within the expected range
+        compare(control.size, 1.0)
+        compare(control.minimumSize, 0)
+
+        control.minimumSize = 2.0
+        compare(control.minimumSize, 1.0)
+
+        // test if setting NaN is prevented
+        control.size = NaN
+        control.minimumSize = NaN
+        compare(control.size, 1.0)
+        compare(control.minimumSize, 1.0)
+
+
+        // test if setting float infinity is prevented
+        control.size = Number.POSITIVE_INFINITY
+        control.minimumSize = Number.POSITIVE_INFINITY
+        compare(control.size, 1.0)
+        compare(control.minimumSize, 1.0)
+
+        let oldPosition = control.position;
+        let oldStepSize = control.stepSize;
+
+        control.position = NaN;
+        control.stepSize = NaN;
+
+        compare(oldPosition, control.position)
+        compare(oldStepSize, control.stepSize)
+    }
 }