From 311d2b35ef4dda0be797064cdf6b1a63dff68ecd Mon Sep 17 00:00:00 2001
From: Karen Holland <karen@brickfieldlabs.ie>
Date: Mon, 17 Jul 2023 16:43:20 +0000
Subject: [PATCH] MDL-78785 tool_brickfield: Processing rgb & rgba color
 contrasts

  Including rgb(), rgba() processing for colour contrast checking.
  Including review requests :void and @covers for phpunit testing.
---
 .../brickfield_accessibility_color_test.php   |  40 +++++--
 .../common/checks/css_text_has_contrast.php   |  19 +--
 .../checks/css_text_has_contrast_test.php     | 111 ++++++++++++++++++
 3 files changed, 152 insertions(+), 18 deletions(-)

diff --git a/admin/tool/brickfield/classes/local/htmlchecker/common/brickfield_accessibility_color_test.php b/admin/tool/brickfield/classes/local/htmlchecker/common/brickfield_accessibility_color_test.php
index a392d1106e427..f93e43e2abc86 100644
--- a/admin/tool/brickfield/classes/local/htmlchecker/common/brickfield_accessibility_color_test.php
+++ b/admin/tool/brickfield/classes/local/htmlchecker/common/brickfield_accessibility_color_test.php
@@ -245,7 +245,6 @@ public function luminosity(string $r, string $r2, string $g, string $g2, string
         return $luminosity;
     }
 
-
     /**
      * Returns the decimal equivalents for a HEX color. Returns null if it cannot be determined.
      * @param string $color The hex color value
@@ -268,13 +267,21 @@ public function get_rgb(string $color): ?array {
      */
     public function convert_color(string $color): string {
         $color = trim($color);
-        if (strpos($color, ' ') !== false) {
-            $colors = explode(' ', $color);
-            foreach ($colors as $backgroundpart) {
-                if (substr(trim($backgroundpart), 0, 1) == '#' ||
-                    in_array(trim($backgroundpart), array_keys($this->colornames)) ||
-                    strtolower(substr(trim($backgroundpart), 0, 3)) == 'rgb') {
-                    $color = $backgroundpart;
+        // Search for color in rgb format first, as this can potentially contain a space.
+        if (strpos($color, 'rgb') !== false) {
+            $colors = explode('rgb', $color, 2); // Getting 2 only in array.
+            // Getting end point of rgb value, i.e. the end bracket.
+            $endpos = strpos($colors[1], ')');
+            $color = 'rgb' . substr($colors[1], 0, ($endpos + 1)); // Recompiling rgb value.
+        } else {
+            // Splitting multi-value css background value.
+            if (strpos($color, ' ') !== false) {
+                $colors = explode(' ', $color);
+                foreach ($colors as $backgroundpart) {
+                    if (substr(trim($backgroundpart), 0, 1) == '#' ||
+                        in_array(trim($backgroundpart), array_keys($this->colornames))) {
+                        $color = $backgroundpart;
+                    }
                 }
             }
         }
@@ -296,9 +303,20 @@ public function convert_color(string $color): string {
         }
         // RGB values.
         if (strtolower(substr($color, 0, 3)) == 'rgb') {
-            $colors = explode(',', trim(str_replace('rgb(', '', $color), '()'));
-            if (count($colors) != 3) {
-                return false;
+            if (strpos($color, 'rgba') !== false) {
+                $tmpbg = $this->get_rgb($this->defaultbackground);
+                $colors = explode(',', trim(str_replace('rgba(', '', $color), '()'));
+                if (count($colors) != 4) {
+                    return false;
+                }
+                $colors[0] = round(((1 - $colors[3]) * $tmpbg['r']) + ($colors[3] * $colors[0]));
+                $colors[1] = round((1 - $colors[3]) * $tmpbg['g']) + ($colors[3] * $colors[1]);
+                $colors[2] = round((1 - $colors[3]) * $tmpbg['b']) + ($colors[3] * $colors[2]);
+            } else {
+                $colors = explode(',', trim(str_replace('rgb(', '', $color), '()'));
+                if (count($colors) != 3) {
+                    return false;
+                }
             }
             $r = intval($colors[0]);
             $g = intval($colors[1]);
diff --git a/admin/tool/brickfield/classes/local/htmlchecker/common/checks/css_text_has_contrast.php b/admin/tool/brickfield/classes/local/htmlchecker/common/checks/css_text_has_contrast.php
index 76be8c8ca4f72..daacac098d742 100644
--- a/admin/tool/brickfield/classes/local/htmlchecker/common/checks/css_text_has_contrast.php
+++ b/admin/tool/brickfield/classes/local/htmlchecker/common/checks/css_text_has_contrast.php
@@ -62,9 +62,18 @@ public function check(): void {
         foreach ($entries as $element) {
             $style = $this->css->get_style($element);
 
-            if (isset($style['background-color']) || isset($style['color'])) {
+            if (isset($style['background-color']) || isset($style['color']) || isset($style['background'])) {
                 if (!isset($style['background-color'])) {
-                    $style['background-color'] = $this->defaultbackground;
+                    if (isset($style['background'])) {
+                        // Parsing background-color from CSS background shortcut string.
+                        $style['background-color'] = '#' . $this->convert_color($style['background']);
+                        // If value is empty after hash, then use defaultbackground.
+                        if ($style['background-color'] == '#') {
+                            $style['background-color'] = $this->defaultbackground;
+                        }
+                    } else {
+                        $style['background-color'] = $this->defaultbackground;
+                    }
                 }
 
                 if (!isset($style['color'])) {
@@ -82,11 +91,7 @@ public function check(): void {
                     $style['color'] = '#' . $this->convert_color($style['color']);
                     $style['background-color'] = '#' . $this->convert_color($background);
 
-                    if (substr($background, 0, 3) == "rgb") {
-                        $background = '#' . $this->convert_color($background);
-                    }
-
-                    $luminosity = $this->get_luminosity($style['color'], $background);
+                    $luminosity = $this->get_luminosity($style['color'], $style['background-color']);
                     $fontsize = 0;
                     $bold = false;
                     $italic = false;
diff --git a/admin/tool/brickfield/tests/local/htmlchecker/common/checks/css_text_has_contrast_test.php b/admin/tool/brickfield/tests/local/htmlchecker/common/checks/css_text_has_contrast_test.php
index 1654094e4b9e0..4f739f0b6f62e 100644
--- a/admin/tool/brickfield/tests/local/htmlchecker/common/checks/css_text_has_contrast_test.php
+++ b/admin/tool/brickfield/tests/local/htmlchecker/common/checks/css_text_has_contrast_test.php
@@ -30,6 +30,7 @@
 
 /**
  * Class test_css_text_has_contrast_test
+ * @covers \tool_brickfield\local\htmlchecker\brickfield_accessibility
  */
 class css_text_has_contrast_test extends all_checks {
     /** @var string The check type. */
@@ -347,4 +348,114 @@ public function test_check_for_largerbold_pass(): void {
         $results = $this->get_checker_results($this->largerboldpass);
         $this->assertEmpty($results);
     }
+
+    /**
+     * Test for rgb colors with insufficient contrast.
+     */
+    public function test_bad_rgbcolor(): void {
+        $html = '<body><p style="color:rgb(255, 255, 255); background-color:rgb(204, 204, 204);">
+            This is not contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertTrue($results[0]->element->tagName == 'p');
+    }
+
+    /**
+     * Test for rgb colors with sufficient contrast.
+     */
+    public function test_good_rgbcolor(): void {
+        $html = '<body><p style="color:rgb(255, 255, 255); background-color:rgb(0, 0, 0);">
+            This is contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertEmpty($results);
+    }
+
+    /**
+     * Test for named colors with insufficient contrast.
+     */
+    public function test_bad_namedcolor2(): void {
+        $html = '<body><p style="color:lightcyan; background-color:lavender;">
+            This is not contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertTrue($results[0]->element->tagName == 'p');
+    }
+
+    /**
+     * Test for named colors with sufficient contrast.
+     */
+    public function test_good_namedcolor2(): void {
+        $html = '<body><p style="color:linen; background-color:darkslategray;">
+            This is contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertEmpty($results);
+    }
+
+    /**
+     * Test for background value with insufficient contrast.
+     */
+    public function test_bad_backgroundcss(): void {
+        $html = '<body><p style="color:lightcyan; background:fixed lavender center;">
+            This is not contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertTrue($results[0]->element->tagName == 'p');
+    }
+
+    /**
+     * Test for background value with sufficient contrast.
+     */
+    public function test_good_backgroundcss(): void {
+        $html = '<body><p style="color:linen; background:fixed darkslategray center;">
+            This is contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertEmpty($results);
+    }
+
+    /**
+     * Test for background value with rgb with insufficient contrast.
+     */
+    public function test_bad_backgroundcssrgb(): void {
+        $html = '<body><p style="color:rgb(255, 255, 255); background:fixed rgb(204, 204, 204) center;">
+            This is not contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertTrue($results[0]->element->tagName == 'p');
+    }
+
+    /**
+     * Test for background value with rgb with sufficient contrast.
+     */
+    public function test_good_backgroundcssrgb(): void {
+        $html = '<body><p style="color:rgb(255, 255, 255); background:fixed rgb(0, 0, 0) center;">
+            This is contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertEmpty($results);
+    }
+
+    /**
+     * Test for text with insufficient contrast of 4.3.
+     */
+    public function test_bad_contrastrounding(): void {
+        $html = '<body><p style="color:#F50000; background-color:white; font-size: 12px">
+            This is not contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertTrue($results[0]->element->tagName == 'p');
+    }
+
+    /**
+     * Test for background value with rgba with insufficient contrast.
+     */
+    public function test_bad_backgroundcssrgba(): void {
+        $html = '<body><p style="color:rgba(255, 255, 255, 0.5); background:fixed rgba(0, 204, 204, 0.5) center;">
+            This is not contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertTrue($results[0]->element->tagName == 'p');
+    }
+
+    /**
+     * Test for background value with rgba with sufficient contrast.
+     */
+    public function test_good_backgroundcssrgba(): void {
+        $html = '<body><p style="color:rgba(255, 255, 255, 0.75); background:fixed rgba(0, 0, 0, 0.75) center;">
+            This is contrasty enough.</p></body>';
+        $results = $this->get_checker_results($html);
+        $this->assertEmpty($results);
+    }
 }