Fix conversion QVariant(QColor) to QString.

QVariant was using QColor::name() to convert a color to string, which by
default loses alpha value. The patch is fixing the problem by always
including the alpha value in the string when required.

[ChangeLog][Core][Variant] QVariant(QColor)::toString() uses
QColor::HexArgb format when the alpha component is different from 1.

Task-number: QTBUG-37851
Change-Id: I887460c1ea151180ba99d64dd873ba9d6e2268f2
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/src/gui/kernel/qguivariant.cpp b/src/gui/kernel/qguivariant.cpp
index ce4a0ec09e..a0769ca671 100644
--- a/src/gui/kernel/qguivariant.cpp
+++ b/src/gui/kernel/qguivariant.cpp
@@ -175,7 +175,8 @@ static bool convert(const QVariant::Private *d, int t,
     switch (t) {
     case QVariant::ByteArray:
         if (d->type == QVariant::Color) {
-            *static_cast<QByteArray *>(result) = v_cast<QColor>(d)->name().toLatin1();
+            const QColor *c = v_cast<QColor>(d);
+            *static_cast<QByteArray *>(result) = c->name(c->alpha() != 255 ? QColor::HexArgb : QColor::HexRgb).toLatin1();
             return true;
         }
         break;
@@ -190,9 +191,11 @@ static bool convert(const QVariant::Private *d, int t,
         case QVariant::Font:
             *str = v_cast<QFont>(d)->toString();
             return true;
-        case QVariant::Color:
-            *str = v_cast<QColor>(d)->name();
+        case QVariant::Color: {
+            const QColor *c = v_cast<QColor>(d);
+            *str = c->name(c->alpha() != 255 ? QColor::HexArgb : QColor::HexRgb);
             return true;
+        }
         default:
             break;
         }