QSizePolicy: add a transposed() method

In some situations, this allows for nicer code. It's also possible to
make this constexpr in C++11, whereas the mutable transpose() would
require C++14-style constexpr.

The new function should also be faster, since it just swaps the member
variables.

Because of constexpr-function limitations, the way the return value is
constructed needs to depend on the level of the compiler's C++11 support.
This is not the only class that requires uniform init to provide a fully
constexpr interface (QUuid and QBasicAtomic come to mind), so this should
probably be generalized across Qt at some point.

Added tests.

[ChangeLog][QtWidgets][QSizePolicy] Added transposed() method.

Change-Id: Ic1077a0d5a861e7c63bd1daeeb42b97c3a2f71ef
Reviewed-by: Sérgio Martins <sergio.martins@kdab.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/tests/auto/widgets/kernel/qsizepolicy/tst_qsizepolicy.cpp b/tests/auto/widgets/kernel/qsizepolicy/tst_qsizepolicy.cpp
index 15bd0a8c1c..98b765a6c6 100644
--- a/tests/auto/widgets/kernel/qsizepolicy/tst_qsizepolicy.cpp
+++ b/tests/auto/widgets/kernel/qsizepolicy/tst_qsizepolicy.cpp
@@ -45,6 +45,8 @@ private Q_SLOTS:
     void defaultValues();
     void getSetCheck_data() { data(); }
     void getSetCheck();
+    void transposed_data() { data(); }
+    void transposed();
     void dataStream();
     void horizontalStretch();
     void verticalStretch();
@@ -161,6 +163,26 @@ void tst_QSizePolicy::getSetCheck()
     QCOMPARE(sp.expandingDirections(), ed);
 }
 
+void tst_QSizePolicy::transposed()
+{
+    FETCH_TEST_DATA;
+
+    const QSizePolicy tr = sp.transposed();
+
+    QCOMPARE(tr.horizontalPolicy(),    vp);  // swapped
+    QCOMPARE(tr.verticalPolicy(),      hp);  // swapped
+    QCOMPARE(tr.horizontalStretch(),   vst); // swapped
+    QCOMPARE(tr.verticalStretch(),     hst); // swapped
+    QCOMPARE(tr.controlType(),         ct);  // not swapped
+    QCOMPARE(tr.hasHeightForWidth(),   hfw); // not swapped (historic behavior)
+    QCOMPARE(tr.hasWidthForHeight(),   wfh); // not swapped (historic behavior)
+    QCOMPARE(tr.expandingDirections(), ed);  // swapped
+
+    // destructive test - keep last:
+    sp.transpose();
+    QCOMPARE(sp, tr);
+}
+
 static void makeRow(QSizePolicy sp, QSizePolicy::Policy hp, QSizePolicy::Policy vp,
                     int hst, int vst, QSizePolicy::ControlType ct, bool hfw, bool wfh,
                     Qt::Orientations orients)