Method OnPopupColorConverttograyscale

ColorCop/ColorCopDlg.cpp:2378–2420

}

void CColorCopDlg::OnPopupColorConverttograyscale() {
    CString strStatus;

    // Converts the current color to grayscale.
    //
    // If R, G, and B are already equal, the color is already gray.
    if ((m_Reddec == m_Greendec) && (m_Greendec == m_Bluedec)) {
        strStatus.LoadString(IDS_COLOR_GRAY);
        SetStatusBarText(strStatus);
    } else {
        strStatus.LoadString(IDS_COLOR_CONVERT_GRAY);
        SetStatusBarText(strStatus);

        //
        // grayscale values have identical R, G, B values.
        //
        // This implementation uses the "lightness" definition from HSL:
        //     L = (max(R,G,B) + min(R,G,B)) / 2
        //
        // This picks the midpoint on the neutral axis between the darkest
        // and brightest channel. After this desaturation, the RGB channels
        // all receive the same value, producing a grayscale color.
        //

        // Compute channel extrema in int.
        const int Max = std::max({m_Reddec, m_Greendec, m_Bluedec});
        const int Min = std::min({m_Reddec, m_Greendec, m_Bluedec});

        // Compute grayscale lightness in int.
        const int L = (Min + Max) / 2;

        // Apply grayscale value to all channels.
        m_Reddec = L;
        m_Greendec = L;
        m_Bluedec = L;

        // Push updated values to UI and recalc dependent fields.
        UpdateData(false);
        OnconvertRGB();
        OnCopytoclip();
    }
    return;
}

void CColorCopDlg::OnFileAbout() {
    CAboutDlg dlg;