First external release

src/Spout/Writer/Helper/XLSX/CellHelper.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Box\Spout\Writer\Helper\XLSX;
+
+/**
+ * Class CellHelper
+ * This class provides helper functions when working with cells
+ *
+ * @package Box\Spout\Writer\Helper\XLSX
+ */
+class CellHelper
+{
+    /**
+     * Returns the cell index (base 26) associated to the base 10 column index.
+     * Excel uses A to Z letters for column indexing, where A is the 1st column,
+     * Z is the 26th and AA is the 27th.
+     * The mapping is zero based, so that 0 maps to A, B maps to 1, Z to 25 and AA to 26.
+     *
+     * @param int $columnIndex The Excel column index (0, 42, ...)
+     * @return string The associated cell index ('A', 'BC', ...)
+     */
+    public static function getCellIndexFromColumnIndex($columnIndex)
+    {
+        $cellIndex = '';
+        $capitalAAsciiValue = ord('A');
+
+        do {
+            $modulus = $columnIndex % 26;
+            $cellIndex = chr($capitalAAsciiValue + $modulus) . $cellIndex;
+
+            // substracting 1 because it's zero-based
+            $columnIndex = intval($columnIndex / 26) - 1;
+        } while ($columnIndex >= 0);
+
+        return $cellIndex;
+    }
+}