Fix and unit test QPalette::resolve

The function is setting the brushes correctly in the return value, but
without updating the resolve_mask, making it return wrong results in
functions like isBrushSet or the debug operator.

Added a unit test for the member function, since the class is still
mostly untested, and clarified the reference documentation of what the
function is supposed to do.

Change-Id: Iaa820dc44f095e125f9375cb00da5569986803c6
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

2 files changed, 41 insertions, 1 deletions

diff --git a/src/gui/kernel/qpalette.cpp b/src/gui/kernel/qpalette.cpp
index 16b1f847bd..b4383c5bfc 100644
--- a/src/gui/kernel/qpalette.cpp
+++ b/src/gui/kernel/qpalette.cpp
@@ -941,7 +941,8 @@ qint64 QPalette::cacheKey() const
 }
 
 /*!
-    Returns a new QPalette that has attributes copied from \a other.
+    Returns a new QPalette that is a union of this instance and \a other.
+    Color roles set in this instance take precedence.
 */
 QPalette QPalette::resolve(const QPalette &other) const
 {
@@ -959,6 +960,7 @@ QPalette QPalette::resolve(const QPalette &other) const
         if (!(data.resolve_mask & (1<<role)))
             for(int grp = 0; grp < (int)NColorGroups; grp++)
                 palette.d->br[grp][role] = other.d->br[grp][role];
+    palette.data.resolve_mask |= other.data.resolve_mask;
 
     return palette;
 }
diff --git a/tests/auto/gui/kernel/qpalette/tst_qpalette.cpp b/tests/auto/gui/kernel/qpalette/tst_qpalette.cpp
index a0ac1b3631..7f29b1c24e 100644
--- a/tests/auto/gui/kernel/qpalette/tst_qpalette.cpp
+++ b/tests/auto/gui/kernel/qpalette/tst_qpalette.cpp
@@ -37,6 +37,7 @@ class tst_QPalette : public QObject
 private Q_SLOTS:
     void roleValues_data();
     void roleValues();
+    void resolve();
     void copySemantics();
     void moveSemantics();
     void setBrush();
@@ -80,6 +81,43 @@ void tst_QPalette::roleValues()
     QCOMPARE(role, value);
 }
 
+void tst_QPalette::resolve()
+{
+    QPalette p1;
+    p1.setBrush(QPalette::WindowText, Qt::green);
+    p1.setBrush(QPalette::Button, Qt::green);
+
+    QVERIFY(p1.isBrushSet(QPalette::Active, QPalette::WindowText));
+    QVERIFY(p1.isBrushSet(QPalette::Active, QPalette::Button));
+
+    QPalette p2;
+    p2.setBrush(QPalette::WindowText, Qt::red);
+
+    QVERIFY(p2.isBrushSet(QPalette::Active, QPalette::WindowText));
+    QVERIFY(!p2.isBrushSet(QPalette::Active, QPalette::Button));
+
+    QPalette p1ResolvedTo2 = p1.resolve(p2);
+    // p1ResolvedTo2 gets everything from p1 and nothing copied from p2 because
+    // it already has a WindowText. That is two brushes, and to the same value
+    // as p1.
+    QCOMPARE(p1ResolvedTo2, p1);
+    QVERIFY(p1ResolvedTo2.isBrushSet(QPalette::Active, QPalette::WindowText));
+    QCOMPARE(p1.windowText(), p1ResolvedTo2.windowText());
+    QVERIFY(p1ResolvedTo2.isBrushSet(QPalette::Active, QPalette::Button));
+    QCOMPARE(p1.button(), p1ResolvedTo2.button());
+
+    QPalette p2ResolvedTo1 = p2.resolve(p1);
+    // p2ResolvedTo1 gets the WindowText set, and to the same value as the
+    // original p2, however, Button gets set from p1.
+    QVERIFY(p2ResolvedTo1.isBrushSet(QPalette::Active, QPalette::WindowText));
+    QCOMPARE(p2.windowText(), p2ResolvedTo1.windowText());
+    QVERIFY(p2ResolvedTo1.isBrushSet(QPalette::Active, QPalette::Button));
+    QCOMPARE(p1.button(), p2ResolvedTo1.button());
+
+    QVERIFY(p2ResolvedTo1 != p1);
+    QVERIFY(p2ResolvedTo1 != p2);
+}
+
 void tst_QPalette::copySemantics()
 {
     QPalette src(Qt::red), dst;