Add support for font color

src/Spout/Writer/Exception/InvalidColorException.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace Box\Spout\Writer\Exception;
+
+/**
+ * Class InvalidColorException
+ *
+ * @package Box\Spout\Writer\Exception
+ */
+class InvalidColorException extends WriterException
+{
+}

src/Spout/Writer/Style/Color.php

@@ -0,0 +1,76 @@
+<?php
+
+namespace Box\Spout\Writer\Style;
+
+use Box\Spout\Writer\Exception\InvalidColorException;
+
+/**
+ * Class Color
+ * This class provides constants and functions to work with colors
+ *
+ * @package Box\Spout\Writer\Style
+ */
+class Color
+{
+    /** Standard colors - based on Office Online */
+    const BLACK = 'FF000000';
+    const WHITE = 'FFFFFFFF';
+    const RED = 'FFFF0000';
+    const DARK_RED = 'FFC00000';
+    const ORANGE = 'FFFFC000';
+    const YELLOW = 'FFFFFF00';
+    const LIGHT_GREEN = 'FF92D040';
+    const GREEN = 'FF00B050';
+    const LIGHT_BLUE = 'FF00B0E0';
+    const BLUE = 'FF0070C0';
+    const DARK_BLUE = 'FF002060';
+    const PURPLE = 'FF7030A0';
+
+    /**
+     * Returns an ARGB color from R, G and B values
+     * Alpha is assumed to always be 1
+     *
+     * @param int $red Red component, 0 - 255
+     * @param int $green Green component, 0 - 255
+     * @param int $blue Blue component, 0 - 255
+     * @return string ARGB color
+     */
+    public static function rgb($red, $green, $blue)
+    {
+        self::throwIfInvalidColorComponentValue($red);
+        self::throwIfInvalidColorComponentValue($green);
+        self::throwIfInvalidColorComponentValue($blue);
+
+        return strtoupper(
+            'FF' .
+            self::convertColorComponentToHex($red) .
+            self::convertColorComponentToHex($green) .
+            self::convertColorComponentToHex($blue)
+        );
+    }
+
+    /**
+     * Throws an exception is the color component value is outside of bounds (0 - 255)
+     *
+     * @param int $colorComponent
+     * @return void
+     * @throws \Box\Spout\Writer\Exception\InvalidColorException
+     */
+    protected static function throwIfInvalidColorComponentValue($colorComponent)
+    {
+        if (!is_int($colorComponent) || $colorComponent < 0 || $colorComponent > 255) {
+            throw new InvalidColorException("The RGB components must be between 0 and 255. Received: $colorComponent");
+        }
+    }
+
+    /**
+     * Converts the color component to its corresponding hexadecimal value
+     *
+     * @param int $colorComponent Color component, 0 - 255
+     * @return string Corresponding hexadecimal value, with a leading 0 if needed. E.g "0f", "2d"
+     */
+    protected static function convertColorComponentToHex($colorComponent)
+    {
+        return str_pad(dechex($colorComponent), 2, '0', 0);
+    }
+}

src/Spout/Writer/Style/Style.php

@@ -12,6 +12,7 @@ class Style
 {
     /** Default font values */
     const DEFAULT_FONT_SIZE = 11;
+    const DEFAULT_FONT_COLOR = Color::BLACK;
     const DEFAULT_FONT_NAME = 'Arial';
 
     /** @var int|null Style ID */
@@ -42,6 +43,11 @@ class Style
     /** @var bool Whether the font size property was set */
     protected $hasSetFontSize = false;
 
+    /** @var string Font color */
+    protected $fontColor = self::DEFAULT_FONT_COLOR;
+    /** @var bool Whether the font color property was set */
+    protected $hasSetFontColor = false;
+
     /** @var string Font name */
     protected $fontName = self::DEFAULT_FONT_NAME;
     /** @var bool Whether the font name property was set */
@@ -169,6 +175,28 @@ class Style
         return $this;
     }
 
+    /**
+     * @return string
+     */
+    public function getFontColor()
+    {
+        return $this->fontColor;
+    }
+
+    /**
+     * Sets the font color.
+     *
+     * @param string $fontColor ARGB color (@see Color)
+     * @return Style
+     */
+    public function setFontColor($fontColor)
+    {
+        $this->fontColor = $fontColor;
+        $this->hasSetFontColor = true;
+        $this->shouldApplyFont = true;
+        return $this;
+    }
+
     /**
      * @return string
      */
@@ -265,6 +293,9 @@ class Style
         if (!$this->hasSetFontSize && $baseStyle->getFontSize() !== self::DEFAULT_FONT_SIZE) {
             $mergedStyle->setFontSize($baseStyle->getFontSize());
         }
+        if (!$this->hasSetFontSize && $baseStyle->getFontColor() !== self::DEFAULT_FONT_COLOR) {
+            $mergedStyle->setFontColor($baseStyle->getFontColor());
+        }
         if (!$this->hasSetFontName && $baseStyle->getFontName() !== self::DEFAULT_FONT_NAME) {
             $mergedStyle->setFontName($baseStyle->getFontName());
         }

src/Spout/Writer/Style/StyleBuilder.php

@@ -77,6 +77,18 @@ class StyleBuilder
         return $this;
     }
 
+    /**
+     * Sets the font color.
+     *
+     * @param string $fontColor ARGB color (@see Color)
+     * @return StyleBuilder
+     */
+    public function setFontColor($fontColor)
+    {
+        $this->style->setFontColor($fontColor);
+        return $this;
+    }
+
     /**
      * Sets the font name.
      *

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

@@ -150,9 +150,14 @@ EOD;
     {
         $content = '    <fonts count="' . count($this->styleIdToStyleMappingTable) . '">' . PHP_EOL;
 
+        /** @var \Box\Spout\Writer\Style\Style $style */
         foreach ($this->styleIdToStyleMappingTable as $style) {
             $content .= '        <font>' . PHP_EOL;
 
+            $content .= '            <sz val="' . $style->getFontSize() . '"/>' . PHP_EOL;
+            $content .= '            <color rgb="' . $style->getFontColor() . '"/>' . PHP_EOL;
+            $content .= '            <name val="' . $style->getFontName() . '"/>' . PHP_EOL;
+
             if ($style->isFontBold()) {
                 $content .= '            <b/>' . PHP_EOL;
             }
@@ -166,8 +171,6 @@ EOD;
                 $content .= '            <strike/>' . PHP_EOL;
             }
 
-            $content .= '            <sz val="' . $style->getFontSize() . '"/>' . PHP_EOL;
-            $content .= '            <name val="' . $style->getFontName() . '"/>' . PHP_EOL;
             $content .= '        </font>' . PHP_EOL;
         }