Avoid unnecessary color format conversion

If a color is not the rgb format, when QColor::red() QColor::blue()
QColor::green() is used continuously to obtain the values of different
channels, three times color conversions will occur. Therefore, use
QColor::toRgb() before that to ensure that only one conversion is
performed at most. Not only rgb, the conversion of other formats is the
same.

Change-Id: Ia969e1ca6f1524ad5d7e8dec915bcbc407875c66
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 7 insertions, 4 deletions

diff --git a/src/quickcontrols2impl/qquickcolor.cpp b/src/quickcontrols2impl/qquickcolor.cpp
index 8ae568fc1c..9d67b5c032 100644
--- a/src/quickcontrols2impl/qquickcolor.cpp
+++ b/src/quickcontrols2impl/qquickcolor.cpp
@@ -45,7 +45,8 @@ QQuickColor::QQuickColor(QObject *parent) :
 
 QColor QQuickColor::transparent(const QColor &color, qreal opacity) const
 {
-    return QColor(color.red(), color.green(), color.blue(),
+    const auto rgbColor = color.toRgb();
+    return QColor(rgbColor.red(), rgbColor.green(), rgbColor.blue(),
                   int(qreal(255) * qBound(qreal(0), opacity, qreal(1))));
 }
 
@@ -56,10 +57,12 @@ QColor QQuickColor::blend(const QColor &a, const QColor &b, qreal factor) const
     if (factor >= 1.0)
         return b;
 
+    const auto rgbA = a.toRgb();
+    const auto rgbB = b.toRgb();
     QColor color;
-    color.setRedF(a.redF() * (1.0 - factor) + b.redF() * factor);
-    color.setGreenF(a.greenF() * (1.0 - factor) + b.greenF() * factor);
-    color.setBlueF(a.blueF() * (1.0 - factor) + b.blueF() * factor);
+    color.setRedF(rgbA.redF() * (1.0 - factor) + rgbB.redF() * factor);
+    color.setGreenF(rgbA.greenF() * (1.0 - factor) + rgbB.greenF() * factor);
+    color.setBlueF(rgbA.blueF() * (1.0 - factor) + rgbB.blueF() * factor);
     return color;
 }