QQuickFlickable: fix division by zero

The issue could be seen when enabling exceptions and running the
following QML code:

    Flickable {
        id: flickable
        anchors.fill: parent
        contentWidth: 1000
        contentHeight: 1000

        Text {
            text: flickable.visibleArea.xPosition
        }
    }

Change-Id: I615f9f9dc84903fb3a902f416a55e3ce3fece64c
Fixes: QTBUG-81098
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 15 insertions, 4 deletions

diff --git a/src/quick/items/qquickflickable.cpp b/src/quick/items/qquickflickable.cpp
index d9ec7de611..52f7c29aa4 100644
--- a/src/quick/items/qquickflickable.cpp
+++ b/src/quick/items/qquickflickable.cpp
@@ -128,8 +128,13 @@ void QQuickFlickableVisibleArea::updateVisible()
     // Vertical
     const qreal viewheight = flickable->height();
     const qreal maxyextent = -flickable->maxYExtent() + flickable->minYExtent();
-    qreal pagePos = (-p->vData.move.value() + flickable->minYExtent()) / (maxyextent + viewheight);
-    qreal pageSize = viewheight / (maxyextent + viewheight);
+    const qreal maxYBounds = maxyextent + viewheight;
+    qreal pagePos = 0;
+    qreal pageSize = 0;
+    if (!qFuzzyIsNull(maxYBounds)) {
+        pagePos = (-p->vData.move.value() + flickable->minYExtent()) / maxYBounds;
+        pageSize = viewheight / maxYBounds;
+    }
 
     if (pageSize != m_heightRatio) {
         m_heightRatio = pageSize;
@@ -143,8 +148,14 @@ void QQuickFlickableVisibleArea::updateVisible()
     // Horizontal
     const qreal viewwidth = flickable->width();
     const qreal maxxextent = -flickable->maxXExtent() + flickable->minXExtent();
-    pagePos = (-p->hData.move.value() + flickable->minXExtent()) / (maxxextent + viewwidth);
-    pageSize = viewwidth / (maxxextent + viewwidth);
+    const qreal maxXBounds = maxxextent + viewwidth;
+    if (!qFuzzyIsNull(maxXBounds)) {
+        pagePos = (-p->hData.move.value() + flickable->minXExtent()) / maxXBounds;
+        pageSize = viewwidth / maxXBounds;
+    } else {
+        pagePos = 0;
+        pageSize = 0;
+    }
 
     if (pageSize != m_widthRatio) {
         m_widthRatio = pageSize;