[Development] Function to merge two QColor?

[Christian Ehrlicher]

Hi,

thx you both - I'll add a custom function in the win11 plugin.
 From the responses I think it's worth thinking about a new function for 
QColor... :)


Christian

Am 23.11.2025 um 20:26 schrieb Kai Uwe Broulik:
> Hi,
>
> Qt Quick has Qt.tint but I don’t see an equivalent in QColor. Perhaps 
> a C++ API should be added. In any case, it’s trivial, just doing alpha 
> blending:
>
> QColor QQuickColorValueType::tint(const QColor &tintColor) const
> {
>     int tintAlpha = tintColor.alpha();
>     if (tintAlpha == 0xFF)
>         return tintColor;
>     else if (tintAlpha == 0x00)
>         return *this;
>
>     // tint the base color and return the final color
>     const QColor baseColor = QColor::toRgb();
>     const qreal a = tintColor.alphaF();
>     const qreal inv_a = 1.0 - a;
>
>     const qreal r = tintColor.redF() * a + baseColor.redF() * inv_a;
>     const qreal g = tintColor.greenF() * a + baseColor.greenF() * inv_a;
>     const qreal b = tintColor.blueF() * a + baseColor.blueF() * inv_a;
>
>     return QColor::fromRgbF(r, g, b, a + inv_a * baseColor.alphaF());
> }
>
> Cheers
> Kai Uwe
>
> Am 23.11.25 um 20:17 schrieb Christian Ehrlicher via Development:
>> Hi,
>>
>> for the window11 style plugin I like to merge two QColors to avoid a 
>> double painting. The first color has no alpha but the second. Is 
>> there anything ready to use in Qt (internals) or do I have to write 
>> something by my own?
>>
>>
>> Thx,
>> Christian
>