QWindowsXP/VistaStyle: Fix detection of item view delegate line edits.

The old code tried to check the 2nd parent for inheritance from
QAbstractItemView. This also triggers for line edits on a QDialog parented
on the item view. Introduce convenience function that checks for
top levels in the chain.

Task-number: QTBUG-37504

Change-Id: I932f8efdb4764e9b1eea84c802bf7e8718338e1d
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>
(cherry picked from qtbase/176342e70a1ba7864a5b5dac14d12d4091ef5bd9)

3 files changed, 17 insertions, 15 deletions

diff --git a/src/gui/styles/qwindowsvistastyle.cpp b/src/gui/styles/qwindowsvistastyle.cpp
index abe729b..c380dc7 100644
--- a/src/gui/styles/qwindowsvistastyle.cpp
+++ b/src/gui/styles/qwindowsvistastyle.cpp
@@ -646,14 +646,7 @@ void QWindowsVistaStyle::drawPrimitive(PrimitiveElement element, const QStyleOpt
             anim->paint(painter, option);
         } else {
             QPainter *p = painter;
-            QWidget *parentWidget = 0;
-            if (widget) {
-                parentWidget = widget->parentWidget();
-                if (parentWidget)
-                    parentWidget = parentWidget->parentWidget();
-            }
-            if (widget && widget->inherits("QLineEdit")
-                && parentWidget && parentWidget->inherits("QAbstractItemView")) {
+            if (QWindowsXPStylePrivate::isItemViewDelegateLineEdit(widget)) {
                 // we try to check if this lineedit is a delegate on a QAbstractItemView-derived class.
                 QPen oldPen = p->pen();
                 // Inner white border
diff --git a/src/gui/styles/qwindowsxpstyle.cpp b/src/gui/styles/qwindowsxpstyle.cpp
index f65fd79..99ec5d6 100644
--- a/src/gui/styles/qwindowsxpstyle.cpp
+++ b/src/gui/styles/qwindowsxpstyle.cpp
@@ -287,6 +287,19 @@ void QWindowsXPStylePrivate::cleanupHandleMap()
     handleMap = 0;
 }
 
+bool QWindowsXPStylePrivate::isItemViewDelegateLineEdit(const QWidget *widget)
+{
+    if (!widget)
+        return false;
+    const QWidget *parent1 = widget->parentWidget();
+    // Exlude dialogs or other toplevels parented on item views.
+    if (!parent1 || parent1->isWindow())
+        return false;
+    const QWidget *parent2 = parent1->parentWidget();
+    return parent2 && widget->inherits("QLineEdit")
+        && parent2->inherits("QAbstractItemView");
+}
+
 /*! \internal
     This function will always return a valid window handle, and might
     create a limbo widget to do so.
@@ -1466,13 +1479,7 @@ case PE_Frame:
     }
     case PE_FrameLineEdit: {
         // we try to check if this lineedit is a delegate on a QAbstractItemView-derived class.
-        QWidget *parentWidget = 0;
-        if (widget)
-            parentWidget = widget->parentWidget();
-        if (parentWidget)
-            parentWidget = parentWidget->parentWidget();
-        if (widget && widget->inherits("QLineEdit")
-            && parentWidget && parentWidget->inherits("QAbstractItemView")) {
+        if (QWindowsXPStylePrivate::isItemViewDelegateLineEdit(widget)) {
             QPen oldPen = p->pen();
             // Inner white border
             p->setPen(QPen(option->palette.base().color(), 1));
diff --git a/src/gui/styles/qwindowsxpstyle_p.h b/src/gui/styles/qwindowsxpstyle_p.h
index 13d0c94..91560ce 100644
--- a/src/gui/styles/qwindowsxpstyle_p.h
+++ b/src/gui/styles/qwindowsxpstyle_p.h
@@ -321,6 +321,8 @@ public:
     bool fixAlphaChannel(const QRect &rect);
     bool swapAlphaChannel(const QRect &rect, bool allPixels = false);
 
+    static bool isItemViewDelegateLineEdit(const QWidget *widget);
+
     QRgb groupBoxTextColor;
     QRgb groupBoxTextColorDisabled;
     QRgb sliderTickColor;