libmythui: Fix rendering of gradient based rectangles.

The recent UI refactor didn't provide sufficient distinction between
gradient type rects and hence was returning false positives. This in
turn caused the wrong image to be displayed on screen. Most obviously an
issue with the MythCenter themes.

The rectangle 'hashing' and associated cacheing now looks a little more
complicated (and hence expensive) than originally intended, so this
would probably benefit from some profiling and optimisation.

mythtv/libs/libmythui/mythpainter.cpp

@@ -306,8 +306,29 @@ MythImage* MythPainter::GetImageFromRect(const QRect &area, int radius,
     uint64_t hash3 = ((0xffffffff & (uint64_t)linePen.color().rgba())) +
                      ((0xffffffff & (uint64_t)fillBrush.color().rgba()) << 32);
 
-    QString incoming = QString("RECT") + QString::number(hash1) +
-                       QString::number(hash2) + QString::number(hash3);
+    QString incoming("R");
+    if (fillBrush.style() == Qt::LinearGradientPattern && fillBrush.gradient())
+    {
+        const QLinearGradient *gradient = static_cast<const QLinearGradient*>(fillBrush.gradient());
+        if (gradient)
+        {
+            incoming = QString::number(
+                             ((0xfff & (uint64_t)gradient->start().x())) +
+                             ((0xfff & (uint64_t)gradient->start().y()) << 12) +
+                             ((0xfff & (uint64_t)gradient->finalStop().x()) << 24) +
+                             ((0xfff & (uint64_t)gradient->finalStop().y()) << 36));
+            QGradientStops stops = gradient->stops();
+            for (int i = 0; i < stops.size(); i++)
+            {
+                incoming += QString::number(
+                             ((0xfff * (uint64_t)(stops[i].first * 100))) +
+                             ((uint64_t)stops[i].second.rgba() << 12));
+            }
+        }
+    }
+
+    incoming += QString::number(hash1) + QString::number(hash2) +
+                QString::number(hash3);
 
     if (m_StringToImageMap.contains(incoming))
     {