ThemeWriter.cs

/*
 * NanoXLSX is a small .NET library to generate and read XLSX (Microsoft Excel 2007 or newer) files in an easy and native way  
 * Copyright Raphael Stoeckli © 2026
 * This library is licensed under the MIT License.
 * You find a copy of the license in project folder or on: http://opensource.org/licenses/MIT
 */
 
using NanoXLSX.Colors;
using NanoXLSX.Interfaces;
using NanoXLSX.Interfaces.Writer;
using NanoXLSX.Registry;
using NanoXLSX.Registry.Attributes;
using NanoXLSX.Themes;
using NanoXLSX.Utils.Xml;
 
namespace NanoXLSX.Internal.Writers
{
    [NanoXlsxPlugIn(PlugInUUID = PlugInUUID.ThemeWriter)]
    internal class ThemeWriter : IPluginWriter
    {
 
        private IColorWriter colorWriter; // Currently NoOp (see TODO in GetColor)
 
        #region properties
        public Workbook Workbook { get; set; }

        public XmlElement XmlElement { get; private set; }
 
        #endregion
        #region constructors
        internal ThemeWriter()
        {
        }
 
        #endregion
        #region methods
        public void Init(IBaseWriter baseWriter)
        {
            this.Workbook = baseWriter.Workbook;
            this.colorWriter = PlugInLoader.GetPlugIn<IColorWriter>(PlugInUUID.ColorWriter, new ColorWriter());
        }

        public void Execute()
        {
            Theme workbookTheme = Workbook.WorkbookTheme;
            XmlElement = XmlElement.CreateElement("theme", "a");
            XmlElement.AddNameSpaceAttribute("a", "xmlns", "http://schemas.openxmlformats.org/drawingml/2006/main");
            XmlElement.AddAttribute("name", XmlUtils.SanitizeXmlValue(workbookTheme.Name));
            XmlElement themeElements = XmlElement.AddChildElement("themeElements", "a");
            themeElements.AddChildElement(GetColorSchemeElement(workbookTheme.Colors));
 
            WriterPlugInHandler.HandleInlineQueuePlugins(ref themeElements, Workbook, PlugInUUID.ThemeInlineWriter);
        }

        private static XmlElement GetColorSchemeElement(ColorScheme scheme)
        {
            XmlElement colorScheme = XmlElement.CreateElementWithAttribute("clrScheme", "name", XmlUtils.SanitizeXmlValue(scheme.Name), "a");
            colorScheme.AddChildElement(GetColor("dk1", scheme.Dark1, "a"));
            colorScheme.AddChildElement(GetColor("lt1", scheme.Light1, "a"));
            colorScheme.AddChildElement(GetColor("dk2", scheme.Dark2, "a"));
            colorScheme.AddChildElement(GetColor("lt2", scheme.Light2, "a"));
            colorScheme.AddChildElement(GetColor("accent1", scheme.Accent1, "a"));
            colorScheme.AddChildElement(GetColor("accent2", scheme.Accent2, "a"));
            colorScheme.AddChildElement(GetColor("accent3", scheme.Accent3, "a"));
            colorScheme.AddChildElement(GetColor("accent4", scheme.Accent4, "a"));
            colorScheme.AddChildElement(GetColor("accent5", scheme.Accent5, "a"));
            colorScheme.AddChildElement(GetColor("accent6", scheme.Accent6, "a"));
            colorScheme.AddChildElement(GetColor("hlink", scheme.Hyperlink, "a"));
            colorScheme.AddChildElement(GetColor("folHlink", scheme.FollowedHyperlink, "a"));
            return colorScheme;
        }

        private static XmlElement GetColor(string name, IColor color, string prefix)
        {
            // TODO check whether colorWriter should be used here
            XmlElement colorElement = XmlElement.CreateElement(name, prefix);
            if (color is SystemColor)
            {
                SystemColor sysColor = color as SystemColor;
                XmlElement sysColorElement = colorElement.AddChildElementWithAttribute("sysClr", "val", sysColor.StringValue, "a");
                if (!string.IsNullOrEmpty(sysColor.LastColor))
                {
                    sysColorElement.AddAttribute("lastClr", sysColor.LastColor);
                }
            }
            else if (color is SrgbColor)
            {
                colorElement.AddChildElementWithAttribute("srgbClr", "val", color.StringValue, "a");
            }
            return colorElement;
        }
 
        #endregion
    }
}