Theme XLColor to System.Drawing.Color

Is there a way to convert a cell’s fill background color if it is a theme ColorType to system.drawing.color ?

XLColor c = XLColor.FromTheme(cell.Style.Fill.BackgroundColor.ThemeColor, cell.Style.Fill.BackgroundColor.ThemeTint);
return c.Color;

fails : "Cannot convert theme color to Color."

Thanks!

[igitur]

Look at #210 :

workbook.Theme.ResolveThemeColor(XLThemeColor themeColor)

[Moonlgum]

A method in ClosedXml would be nice to have. The color won’t be correct until it has the theme color tint applied to it.

Something like this is close to the System.Color returned from Excel Interop for a themed cell.

       private System.Drawing.Color GetColor(IXLCell cell)
    {
        if (cell.Style.Fill.BackgroundColor.ColorType == XLColorType.Color)
        {
            return cell.Style.Fill.BackgroundColor.Color;
        }
        if (cell.Style.Fill.BackgroundColor.ColorType == XLColorType.Indexed)
        {
            XLColor c = XLColor.FromIndex(cell.Style.Fill.BackgroundColor.Indexed);
            System.Drawing.Color color = c.Color;
            return color;
        }
        if (cell.Style.Fill.BackgroundColor.ColorType == XLColorType.Theme)
        {
            XLWorkbook workbook = cell.Worksheet.Workbook;

            try
            {
                double tint = cell.Style.Fill.BackgroundColor.ThemeTint;
                XLThemeColor themeColor = cell.Style.Fill.BackgroundColor.ThemeColor;
                
                System.Drawing.Color color;
                if (themeColor == XLThemeColor.Accent1)
                {
                    color = workbook.Theme.Accent1.Color;
                }
                else if (themeColor == XLThemeColor.Accent2)
                {
                    color = workbook.Theme.Accent2.Color;
                }
                else if (themeColor == XLThemeColor.Accent3)
                {
                    color = workbook.Theme.Accent3.Color;
                }
                else if (themeColor == XLThemeColor.Accent4)
                {
                    color = workbook.Theme.Accent4.Color;
                }
                else if (themeColor == XLThemeColor.Accent5)
                {
                    color = workbook.Theme.Accent5.Color;
                }
                else if (themeColor == XLThemeColor.Accent6)
                {
                    color = workbook.Theme.Accent6.Color;
                }
                else if (themeColor == XLThemeColor.Background1)
                {
                    color = workbook.Theme.Background1.Color;
                }
                else if (themeColor == XLThemeColor.Background2)
                {
                    color = workbook.Theme.Background2.Color;
                }
                else if (themeColor == XLThemeColor.FollowedHyperlink)
                {
                    color = workbook.Theme.FollowedHyperlink.Color;
                }
                else if (themeColor == XLThemeColor.Hyperlink)
                {
                    color = workbook.Theme.Hyperlink.Color;
                }
                else if (themeColor == XLThemeColor.Text1)
                {
                    color = workbook.Theme.Text1.Color;
                }
                else if (themeColor == XLThemeColor.Text2)
                {
                    color = workbook.Theme.Text2.Color;
                }
                return color.ApplyTint(tint);
            }
            finally
            {
                workbook?.Dispose();
            }
        }
    }
	
	
    public static Color ApplyTint(this Color color, double tint)
    {
        if (tint < -1.0) tint = -1.0;
        if (tint > 1.0) tint = 1.0;

        Color colorRgb = color;
        double fHue = colorRgb.GetHue();
        double fSat = colorRgb.GetSaturation();
        double fLum = colorRgb.GetBrightness();
        if (tint < 0)
        {
            fLum = fLum * (1.0 + tint);
        }
        else
        {
            fLum = fLum * (1.0 - tint) + (1.0 - 1.0 * (1.0 - tint));
        }
        return ToColor(fHue, fSat, fLum);
    }

    internal static Color ToColor(double hue, double saturation, double luminance)
    {
        double chroma = (1.0 - Math.Abs(2.0 * luminance - 1.0)) * saturation;
        double fHue = hue / 60.0;
        double fHueMod2 = fHue;
        while (fHueMod2 >= 2.0) fHueMod2 -= 2.0;
        double fTemp = chroma * (1.0 - Math.Abs(fHueMod2 - 1.0));

        double fRed, fGreen, fBlue;
        if (fHue < 1.0)
        {
            fRed = chroma;
            fGreen = fTemp;
            fBlue = 0;
        }
        else if (fHue < 2.0)
        {
            fRed = fTemp;
            fGreen = chroma;
            fBlue = 0;
        }
        else if (fHue < 3.0)
        {
            fRed = 0;
            fGreen = chroma;
            fBlue = fTemp;
        }
        else if (fHue < 4.0)
        {
            fRed = 0;
            fGreen = fTemp;
            fBlue = chroma;
        }
        else if (fHue < 5.0)
        {
            fRed = fTemp;
            fGreen = 0;
            fBlue = chroma;
        }
        else if (fHue < 6.0)
        {
            fRed = chroma;
            fGreen = 0;
            fBlue = fTemp;
        }
        else
        {
            fRed = 0;
            fGreen = 0;
            fBlue = 0;
        }

        double fMin = luminance - 0.5 * chroma;
        fRed += fMin;
        fGreen += fMin;
        fBlue += fMin;

        fRed *= 255.0;
        fGreen *= 255.0;
        fBlue *= 255.0;

        var red = Convert.ToInt32(Math.Truncate(fRed));
        var green = Convert.ToInt32(Math.Truncate(fGreen));
        var blue = Convert.ToInt32(Math.Truncate(fBlue));

        red = Math.Min(255, Math.Max(red, 0));
        green = Math.Min(255, Math.Max(green, 0));
        blue = Math.Min(255, Math.Max(blue, 0));

        return Color.FromArgb(red, green, blue);
    }