feature cell coloring

src/generate-excel.ts

@@ -17,8 +17,8 @@ import { generateStyleXml } from "./xl/styles.xml";
 import { generateTheme1 } from "./xl/theme/theme1.xml";
 import { generateWorkBookXml } from "./xl/workbook.xml";
 import { generateSheetXml } from "./xl/worksheets/sheet.xml";
-import { ICellType, IPage, ISheet, IWorkbook, IBorder } from "./index";
-import { Equation, SkipCell, getBorderKey } from "./util";
+import { ICellType, IPage, ISheet, IWorkbook, IBorder, ICellStyle } from "./index";
+import { Equation, SkipCell, getBorderKey, getStyleKey } from "./util";
 
 /**
  * Generates the complete XML file structure for an Excel workbook
@@ -28,9 +28,9 @@ import { Equation, SkipCell, getBorderKey } from "./util";
  * @internal
  */
 const generateTree = (workbook: IWorkbook) => {
-  // Collect all unique border styles from the workbook
-  const borderStyles = new Map<string, IBorder>();
-  borderStyles.set("none", {}); // Default no-border style
+  // Collect all unique complete styles from the workbook
+  const styleMap = new Map<string, ICellStyle>();
+  styleMap.set("default", {}); // Default no-style
 
   // Check if workbook contains any date cells
   let hasDateCells = false;
@@ -43,10 +43,10 @@ const generateTree = (workbook: IWorkbook) => {
           hasDateCells = true;
         }
 
-        // Collect border styles
-        if ('style' in cell && cell.style?.border) {
-          const borderKey = getBorderKey(cell.style.border);
-          borderStyles.set(borderKey, cell.style.border);
+        // Collect complete styles (border, background, foreground colors)
+        if ('style' in cell && cell.style) {
+          const styleKey = getStyleKey(cell.style);
+          styleMap.set(styleKey, cell.style);
         }
       });
     });
@@ -59,10 +59,10 @@ const generateTree = (workbook: IWorkbook) => {
     "docProps/core.xml": generateCoreXml({}),
     "xl/_rels/workbook.xml.rels": generateWorkBookXmlRels(workbook),
     "xl/sharedStrings.xml": generateSharedStrings(workbook),
-    "xl/styles.xml": generateStyleXml(borderStyles, hasDateCells),
+    "xl/styles.xml": generateStyleXml(styleMap, hasDateCells),
     "xl/theme/theme1.xml": generateTheme1(),
     "xl/workbook.xml": generateWorkBookXml(workbook),
-    ...workbook.sheets.reduce((acc, sheet, idx) => ({ ...acc, [`xl/worksheets/sheet${idx + 1}.xml`]: generateSheetXml(sheet, borderStyles, hasDateCells) }), {})
+    ...workbook.sheets.reduce((acc, sheet, idx) => ({ ...acc, [`xl/worksheets/sheet${idx + 1}.xml`]: generateSheetXml(sheet, styleMap, hasDateCells) }), {})
   };
 };
 

src/index.ts

@@ -8,7 +8,7 @@
  */
 
 import { generateExcel, EnvironmentType } from "./generate-excel";
-import { SkipCell, skipCell, Equation, writeEquation, createBorder, createAllBorders, createTopBorder, createBottomBorder, createLeftBorder, createRightBorder, createStyledCell, createBorderedCell, createDateCell, createBorderedDateCell } from "./util";
+import { SkipCell, skipCell, Equation, writeEquation, createBorder, createAllBorders, createTopBorder, createBottomBorder, createLeftBorder, createRightBorder, createStyledCell, createBorderedCell, createDateCell, createBorderedDateCell, createBackgroundCell, createForegroundCell, createColoredCell, createBackgroundDateCell } from "./util";
 
 /**
  * Enum representing different cell types in Excel
@@ -72,6 +72,10 @@ interface IBorder {
 interface ICellStyle {
   /** Border configuration for the cell */
   border?: IBorder;
+  /** Background (fill) color in hex format (e.g., "#FFFF00" for yellow) */
+  backgroundColor?: string;
+  /** Foreground (font) color in hex format (e.g., "#000000" for black text) */
+  foregroundColor?: string;
 }
 
 /**
@@ -273,6 +277,53 @@ const sampleData = [
         'Mixed Content'
       ]
     ] 
+  },
+  // Demonstration of color functionality
+  { 
+    title: 'ColorDemo', 
+    content: [
+      [
+        // Header row with colors
+        'Feature',
+        'Background Color',
+        'Foreground Color',
+        'Both Colors'
+      ],
+      [
+        // Background colors
+        'Yellow Background',
+        createBackgroundCell('Highlighted', '#FFFF00'),
+        createForegroundCell('Red Text', '#FF0000'),
+        createColoredCell('Both', '#00FF00', '#FF0000')
+      ],
+      [
+        'More Colors',
+        createBackgroundCell('Blue BG', '#0000FF'),
+        createForegroundCell('Green Text', '#00FF00'),
+        createColoredCell('Purple/White', '#800080', '#FFFFFF')
+      ],
+      [
+        // Colored dates
+        'Date Colors',
+        createBackgroundDateCell(new Date(), '#FFCCCC'),
+        createDateCell(new Date('2024-12-25'), { 
+          backgroundColor: '#00FF00',
+          foregroundColor: '#FF0000'
+        }),
+        'Mixed with dates'
+      ],
+      [
+        // Combined with borders
+        'With Borders',
+        createStyledCell('Complex', {
+          backgroundColor: '#FFFFCC',
+          foregroundColor: '#0000FF',
+          border: createAllBorders(BorderStyle.thick, '#000000')
+        }),
+        'Plain text',
+        42
+      ]
+    ] 
   }
 ]
 
@@ -283,4 +334,4 @@ const sampleData = [
  * This includes the main generation function, sample data, environment types,
  * utility functions, and all border/styling helper functions
  */
-export { generateExcel, sampleData, EnvironmentType, skipCell, writeEquation, createBorder, createAllBorders, createTopBorder, createBottomBorder, createLeftBorder, createRightBorder, createStyledCell, createBorderedCell, createDateCell, createBorderedDateCell };
+export { generateExcel, sampleData, EnvironmentType, skipCell, writeEquation, createBorder, createAllBorders, createTopBorder, createBottomBorder, createLeftBorder, createRightBorder, createStyledCell, createBorderedCell, createDateCell, createBorderedDateCell, createBackgroundCell, createForegroundCell, createColoredCell, createBackgroundDateCell };

src/util.ts

@@ -234,6 +234,25 @@ const getBorderKey = (border?: IBorder): string => {
   return parts.join("-");
 };
 
+/**
+ * Generates a unique key string for complete cell style configuration
+ * Used internally to identify unique style combinations for Excel styling
+ * @param {ICellStyle} style - Complete style configuration object
+ * @returns {string} Unique key representing the complete style configuration
+ * @internal
+ */
+const getStyleKey = (style?: ICellStyle): string => {
+  if (!style) return "default";
+
+  const parts = [
+    getBorderKey(style.border),
+    style.backgroundColor || "no-bg",
+    style.foregroundColor || "no-fg"
+  ];
+
+  return parts.join("|");
+};
+
 /**
  * Creates a styled cell with custom styling options
  * @param {string | number} value - Cell value (string or number)
@@ -320,6 +339,68 @@ const createBorderedDateCell = (
   return createDateCell(date, { border });
 };
 
+/**
+ * Creates a cell with background color styling
+ * Convenience function for applying background color to cells
+ * @param {string | number} value - Cell value (string or number)
+ * @param {string} backgroundColor - Background color in hex format (e.g., "#FFFF00")
+ * @returns {ICell} Cell with background color styling applied
+ * @example createBackgroundCell('Highlighted', '#FFFF00')
+ */
+const createBackgroundCell = (
+  value: string | number,
+  backgroundColor: string
+): ICell => {
+  return createStyledCell(value, { backgroundColor });
+};
+
+/**
+ * Creates a cell with foreground (text) color styling
+ * Convenience function for applying text color to cells
+ * @param {string | number} value - Cell value (string or number)
+ * @param {string} foregroundColor - Text color in hex format (e.g., "#FF0000")
+ * @returns {ICell} Cell with text color styling applied
+ * @example createForegroundCell('Red Text', '#FF0000')
+ */
+const createForegroundCell = (
+  value: string | number,
+  foregroundColor: string
+): ICell => {
+  return createStyledCell(value, { foregroundColor });
+};
+
+/**
+ * Creates a cell with both background and foreground color styling
+ * Convenience function for applying both background and text colors
+ * @param {string | number} value - Cell value (string or number)
+ * @param {string} backgroundColor - Background color in hex format
+ * @param {string} foregroundColor - Text color in hex format
+ * @returns {ICell} Cell with color styling applied
+ * @example createColoredCell('Styled Text', '#FFFF00', '#FF0000')
+ */
+const createColoredCell = (
+  value: string | number,
+  backgroundColor: string,
+  foregroundColor: string
+): ICell => {
+  return createStyledCell(value, { backgroundColor, foregroundColor });
+};
+
+/**
+ * Creates a date cell with background color styling
+ * Convenience function for applying background color to date cells
+ * @param {Date} date - JavaScript Date object
+ * @param {string} backgroundColor - Background color in hex format
+ * @returns {ICell} Date cell with background color styling applied
+ * @example createBackgroundDateCell(new Date(), '#FFFF00')
+ */
+const createBackgroundDateCell = (
+  date: Date,
+  backgroundColor: string
+): ICell => {
+  return createDateCell(date, { backgroundColor });
+};
+
 /**
  * Export all utility functions and classes for external use
  * Includes positioning utilities, cell creation helpers, border functions, and internal utilities
@@ -341,9 +422,14 @@ export {
   createLeftBorder,
   createRightBorder,
   getBorderKey,
+  getStyleKey,
   createStyledCell,
   createBorderedCell,
   dateToExcelSerial,
   createDateCell,
-  createBorderedDateCell
+  createBorderedDateCell,
+  createBackgroundCell,
+  createForegroundCell,
+  createColoredCell,
+  createBackgroundDateCell
 }