support dark mode for images with alpha channel

14 files changed, 164 insertions, 55 deletions

diff --git a/cli_util.php b/cli_util.php
index 97885ff..0c42bb5 100755
--- a/cli_util.php
+++ b/cli_util.php
@@ -57,6 +57,14 @@ function posts_html(): void {
     }
 }
 
+function posts_images(): void {
+    $kw = ['include_hidden' => true];
+    $posts = posts::getPosts(0, posts::getPostsCount(...$kw), ...$kw);
+    foreach ($posts as $p) {
+        $p->updateImagePreviews(true);
+    }
+}
+
 function pages_html(): void {
     $pages = pages::getAll();
     foreach ($pages as $p) {
diff --git a/engine/Skin.php b/engine/Skin.php
index 917eef7..a8924d4 100644
--- a/engine/Skin.php
+++ b/engine/Skin.php
@@ -23,8 +23,8 @@ class Skin {
         else
             $js = null;
 
-        $theme = ($_COOKIE['theme'] ?? 'auto');
-        if (!in_array($theme, ['auto', 'dark', 'light']))
+        $theme = themes::getUserTheme();
+        if ($theme != 'auto' && !themes::themeExists($theme))
             $theme = 'auto';
 
         $layout_ctx = new SkinContext('\\skin\\base');
diff --git a/engine/themes.php b/engine/themes.php
new file mode 100644
index 0000000..839377f
--- /dev/null
+++ b/engine/themes.php
@@ -0,0 +1,38 @@
+<?php
+
+class themes {
+
+    public static array $Themes = [
+        'dark' => [
+            'bg' => 0x222222,
+            // 'alpha' => 0x303132,
+            'alpha' => 0x222222,
+        ],
+        'light' => [
+            'bg' => 0xffffff,
+            // 'alpha' => 0xf2f2f2,
+            'alpha' => 0xffffff,
+        ]
+    ];
+
+    public static function getThemes(): array {
+        return array_keys(self::$Themes);
+    }
+
+    public static function themeExists(string $name): bool {
+        return array_key_exists($name, self::$Themes);
+    }
+
+    public static function getThemeAlphaColorAsRGB(string $name): array {
+        $color = self::$Themes[$name]['alpha'];
+        $r = ($color >> 16) & 0xff;
+        $g = ($color >> 8) & 0xff;
+        $b = $color & 0xff;
+        return [$r, $g, $b];
+    }
+
+    public static function getUserTheme(): string {
+        return ($_COOKIE['theme'] ?? 'auto');
+    }
+
+}
\ No newline at end of file
diff --git a/handler/Auto.php b/handler/Auto.php
index 9903993..361cc17 100644
--- a/handler/Auto.php
+++ b/handler/Auto.php
@@ -68,7 +68,7 @@ class Auto extends RequestHandler {
         return $s->renderPage('main/post',
             title: $post->title,
             id: $post->id,
-            unsafe_html: $post->getHtml($this->isRetina()),
+            unsafe_html: $post->getHtml($this->isRetina(), \themes::getUserTheme()),
             date: $post->getFullDate(),
             tags: $tags,
             visible: $post->visible,
@@ -98,7 +98,7 @@ class Auto extends RequestHandler {
 
         $this->skin->title = $page ? $page->title : '???';
         return $this->skin->renderPage('main/page',
-            unsafe_html: $page->getHtml($this->isRetina()),
+            unsafe_html: $page->getHtml($this->isRetina(), \themes::getUserTheme()),
             page_url: $page->getUrl(),
             short_name: $page->shortName);
     }
diff --git a/htdocs/js/common/35-theme-switcher.js b/htdocs/js/common/35-theme-switcher.js
index e716e4b..c612152 100644
--- a/htdocs/js/common/35-theme-switcher.js
+++ b/htdocs/js/common/35-theme-switcher.js
@@ -15,6 +15,11 @@ var ThemeSwitcher = (function() {
     var systemState = null;
 
     /**
+     * @type {function[]}
+     */
+    var changeListeners = [];
+
+    /**
      * @returns {boolean}
      */
     function isSystemModeSupported() {
@@ -71,6 +76,13 @@ var ThemeSwitcher = (function() {
         var onDone = function() {
             window.requestAnimationFrame(function() {
                 removeClass(document.body, 'theme-changing');
+                changeListeners.forEach(function(f) {
+                    try {
+                        f(dark)
+                    } catch (e) {
+                        console.error('[ThemeSwitcher->changeTheme->onDone] error while calling user callback:', e)
+                    }
+                })
             })
         };
 
@@ -171,7 +183,7 @@ var ThemeSwitcher = (function() {
             currentModeIndex = (currentModeIndex + 1) % modes.length;
             switch (modes[currentModeIndex]) {
                 case 'auto':
-                    if (systemState !== null)
+                    if (systemState !== null && systemState !== isDarkModeApplied())
                         changeTheme(systemState);
                     break;
 
@@ -190,6 +202,13 @@ var ThemeSwitcher = (function() {
             setCookie('theme', modes[currentModeIndex]);
 
             return cancelEvent(e);
+        },
+
+        /**
+         * @param {function} f
+         */
+        addOnChangeListener: function(f) {
+            changeListeners.push(f);
         }
     };
 })();
\ No newline at end of file
diff --git a/lib/MyParsedown.php b/lib/MyParsedown.php
index c2c0112..11e86d6 100644
--- a/lib/MyParsedown.php
+++ b/lib/MyParsedown.php
@@ -99,6 +99,7 @@ class MyParsedown extends ParsedownHighlight {
                 nolabel: $opts['nolabel'],
                 align: $opts['align'],
                 padding_top: round($h / $w * 100, 4),
+                may_have_alpha: $image->imageMayHaveAlphaChannel(),
 
                 url: $image_url,
                 direct_url: $image->getDirectUrl(),
diff --git a/lib/markup.php b/lib/markup.php
index 52ccf24..2f25c6c 100644
--- a/lib/markup.php
+++ b/lib/markup.php
@@ -16,12 +16,15 @@ class markup {
         return $text;
     }
 
-    public static function htmlRetinaFix(string $html): string {
+    public static function htmlImagesFix(string $html, bool $is_retina, string $user_theme): string {
         global $config;
+        $is_dark_theme = $user_theme === 'dark';
         return preg_replace_callback(
-            '/('.preg_quote($config['uploads_host'], '/').'\/\w{8}\/p)(\d+)x(\d+)(\.jpg)/',
-            function($match) {
-                return $match[1].(intval($match[2])*2).'x'.(intval($match[3])*2).$match[4];
+            '/('.preg_quote($config['uploads_host'], '/').'\/\w{8}\/)([ap])(\d+)x(\d+)(\.jpg)/',
+            function($match) use ($is_retina, $is_dark_theme) {
+                $mult = $is_retina ? 2 : 1;
+                $is_alpha = $match[2] == 'a';
+                return $match[1].$match[2].(intval($match[3])*$mult).'x'.(intval($match[4])*$mult).($is_alpha && $is_dark_theme ? '_dark' : '').$match[5];
             },
             $html
         );
diff --git a/lib/posts.php b/lib/posts.php
index bf8d149..1537749 100644
--- a/lib/posts.php
+++ b/lib/posts.php
@@ -23,6 +23,9 @@ class posts {
         return (int)$db->result($db->query($sql, $tag_id));
     }
 
+    /**
+     * @return Post[]
+     */
     public static function getPosts(int $offset = 0, int $count = -1, bool $include_hidden = false): array {
         $db = getDb();
         $sql = "SELECT * FROM posts";
diff --git a/model/Page.php b/model/Page.php
index 6711a2c..f516836 100644
--- a/model/Page.php
+++ b/model/Page.php
@@ -24,10 +24,9 @@ class Page extends Model {
         return $this->updateTs && $this->updateTs != $this->ts;
     }
 
-    public function getHtml(bool $retina): string {
+    public function getHtml(bool $is_retina, string $user_theme): string {
         $html = $this->html;
-        if ($retina)
-            $html = markup::htmlRetinaFix($html);
+        $html = markup::htmlImagesFix($html, $is_retina, $user_theme);
         return $html;
     }
 
diff --git a/model/Post.php b/model/Post.php
index 10a396b..b0360ac 100644
--- a/model/Post.php
+++ b/model/Post.php
@@ -22,8 +22,8 @@ class Post extends Model {
         $data['update_ts'] = $cur_ts;
 
         if ($data['md'] != $this->md) {
-            $data['html'] = \markup::markdownToHtml($data['md']);
-            $data['text'] = \markup::htmlToText($data['html']);
+            $data['html'] = markup::markdownToHtml($data['md']);
+            $data['text'] = markup::htmlToText($data['html']);
         }
 
         parent::edit($data);
@@ -31,15 +31,15 @@ class Post extends Model {
     }
 
     public function updateHtml() {
-        $html = \markup::markdownToHtml($this->md);
+        $html = markup::markdownToHtml($this->md);
         $this->html = $html;
 
         getDb()->query("UPDATE posts SET html=? WHERE id=?", $html, $this->id);
     }
 
     public function updateText() {
-        $html = \markup::markdownToHtml($this->md);
-        $text = \markup::htmlToText($html);
+        $html = markup::markdownToHtml($this->md);
+        $text = markup::htmlToText($html);
         $this->text = $text;
 
         getDb()->query("UPDATE posts SET text=? WHERE id=?", $text, $this->id);
@@ -81,10 +81,9 @@ class Post extends Model {
         return date('j F Y', $this->updateTs);
     }
 
-    public function getHtml(bool $retina): string {
+    public function getHtml(bool $is_retina, string $theme): string {
         $html = $this->html;
-        if ($retina)
-            $html = markup::htmlRetinaFix($html);
+        $html = markup::htmlImagesFix($html, $is_retina, $theme);
         return $html;
     }
 
@@ -173,9 +172,8 @@ class Post extends Model {
             foreach ($images[$u->randomId] as $s) {
                 list($w, $h) = $s;
                 list($w, $h) = $u->getImagePreviewSize($w, $h);
-                if ($u->createImagePreview($w, $h, $update)) {
+                if ($u->createImagePreview($w, $h, $update, $u->imageMayHaveAlphaChannel()))
                     $images_affected++;
-                }
             }
         }
 
diff --git a/model/Upload.php b/model/Upload.php
index 441a14d..06b348b 100644
--- a/model/Upload.php
+++ b/model/Upload.php
@@ -38,7 +38,8 @@ class Upload extends Model {
             $h *= 2;
         }
 
-        return 'https://'.$config['uploads_host'].'/'.$this->randomId.'/p'.$w.'x'.$h.'.jpg';
+        $prefix = $this->imageMayHaveAlphaChannel() ? 'a' : 'p';
+        return 'https://'.$config['uploads_host'].'/'.$this->randomId.'/'.$prefix.$w.'x'.$h.'.jpg';
     }
 
     // TODO remove?
@@ -73,6 +74,12 @@ class Upload extends Model {
         return in_array(extension($this->name), self::$ImageExtensions);
     }
 
+    // assume all png images have alpha channel
+    // i know this is wrong, but anyway
+    public function imageMayHaveAlphaChannel(): bool {
+        return strtolower(extension($this->name)) == 'png';
+    }
+
     public function isVideo(): bool {
         return in_array(extension($this->name), self::$VideoExtensions);
     }
@@ -94,36 +101,40 @@ class Upload extends Model {
         return [$w, $h];
     }
 
-    /**
-     * @param ?int $w
-     * @param ?int $h
-     * @param bool $update Whether to proceed if preview already exists
-     * @return bool
-     */
-    public function createImagePreview(?int $w = null, ?int $h = null, bool $update = false): bool {
+    public function createImagePreview(?int $w = null,
+                                       ?int $h = null,
+                                       bool $force_update = false,
+                                       bool $may_have_alpha = false): bool {
         global $config;
 
         $orig = $config['uploads_dir'].'/'.$this->randomId.'/'.$this->name;
         $updated = false;
 
-        for ($mult = 1; $mult <= 2; $mult++) {
-            $dw = $w * $mult;
-            $dh = $h * $mult;
-            $dst = $config['uploads_dir'].'/'.$this->randomId.'/p'.$dw.'x'.$dh.'.jpg';
+        foreach (themes::getThemes() as $theme) {
+            if (!$may_have_alpha && $theme == 'dark')
+                continue;
 
-            if (file_exists($dst)) {
-                if (!$update)
-                    continue;
-                unlink($dst);
-            }
+            for ($mult = 1; $mult <= 2; $mult++) {
+                $dw = $w * $mult;
+                $dh = $h * $mult;
+
+                $prefix = $may_have_alpha ? 'a' : 'p';
+                $dst = $config['uploads_dir'].'/'.$this->randomId.'/'.$prefix.$dw.'x'.$dh.($theme == 'dark' ? '_dark' : '').'.jpg';
 
-            $img = imageopen($orig);
-            imageresize($img, $dw, $dh, [255, 255, 255]);
-            imagejpeg($img, $dst, $mult == 1 ? 93 : 67);
-            imagedestroy($img);
+                if (file_exists($dst)) {
+                    if (!$force_update)
+                        continue;
+                    unlink($dst);
+                }
 
-            setperm($dst);
-            $updated = true;
+                $img = imageopen($orig);
+                imageresize($img, $dw, $dh, themes::getThemeAlphaColorAsRGB($theme));
+                imagejpeg($img, $dst, $mult == 1 ? 93 : 67);
+                imagedestroy($img);
+
+                setperm($dst);
+                $updated = true;
+            }
         }
 
         return $updated;
@@ -138,7 +149,7 @@ class Upload extends Model {
         $files = scandir($dir);
         $deleted = 0;
         foreach ($files as $f) {
-            if (preg_match('/^p(\d+)x(\d+)\.jpg$/', $f)) {
+            if (preg_match('/^[ap](\d+)x(\d+)(?:_dark)?\.jpg$/', $f)) {
                 if (is_file($dir.'/'.$f))
                     unlink($dir.'/'.$f);
                 else
diff --git a/skin/admin.skin.php b/skin/admin.skin.php
index f03d7ce..5619dd0 100644
--- a/skin/admin.skin.php
+++ b/skin/admin.skin.php
@@ -26,9 +26,9 @@ $html = <<<HTML
 </form>
 HTML;
 
-$js = <<<JAVASCRIPT
+$js = <<<JS
 ge('as_password').focus();
-JAVASCRIPT;
+JS;
 
 return [$html, $js];
 }
@@ -264,9 +264,9 @@ $html = <<<HTML
 HTML;
 
 $js_params = json_encode(['pages' => true, 'edit' => $is_edit]);
-$js = <<<JAVASCRIPT
+$js = <<<JS
 AdminWriteForm.init({$js_params});
-JAVASCRIPT;
+JS;
 
 return [$html, $js];
 }
diff --git a/skin/main.skin.php b/skin/main.skin.php
index 5236bf0..552c61f 100644
--- a/skin/main.skin.php
+++ b/skin/main.skin.php
@@ -116,12 +116,14 @@ HTML;
 // --------
 
 function page($ctx, $page_url, $short_name, $unsafe_html) {
-return <<<HTML
+$html = <<<HTML
 <div class="page">
     {$ctx->if_admin($ctx->pageAdminLinks, $page_url, $short_name)}
     <div class="blog-post-text">{$unsafe_html}</div>
 </div>
 HTML;
+
+return [$html, markdownThemeChangeListener()];
 }
 
 function pageAdminLinks($ctx, $url, $short_name) {
@@ -139,7 +141,7 @@ HTML;
 // ---------
 
 function post($ctx, $id, $title, $unsafe_html, $date, $visible, $url, $tags, $email, $urlencoded_reply_subject) {
-return <<<HTML
+$html = <<<HTML
 <div class="blog-post">
     <div class="blog-post-title">
         <h1>{$title}</h1>
@@ -158,6 +160,8 @@ return <<<HTML
     {$ctx->langRaw('blog_comments_text', $email, $urlencoded_reply_subject)}
 </div>
 HTML;
+
+return [$html, markdownThemeChangeListener()];
 }
 
 function postAdminLinks($ctx, $url, $id) {
@@ -171,7 +175,32 @@ function postTag($ctx, $url, $name) {
 return <<<HTML
 <a href="{$url}"><span>#</span>{$name}</a>
 HTML;
+}
 
+function markdownThemeChangeListener() {
+return <<<JS
+ThemeSwitcher.addOnChangeListener(function(isDark) {
+    var nodes = document.querySelectorAll('.md-image-wrap');
+    for (var i = 0; i < nodes.length; i++) {
+        var node = nodes[i];
+        var alpha = parseInt(node.getAttribute('data-alpha'), 10);
+        if (!alpha)
+            continue;
+        var div = node.querySelector('a > div');
+        if (!div) {
+            console.warn('could not found a>div on this node:', node);
+            continue;
+        }
+        var style = div.getAttribute('style');
+        if (isDark) {
+            style = style.replace(/(a[\d]+x[\d]+)\.jpg/, '$1_dark.jpg');
+        } else {
+            style = style.replace(/(a[\d]+x[\d]+)_dark\.jpg/, '$1.jpg');
+        }
+        div.setAttribute('style', style);
+    }
+});
+JS;
 }
 
 
diff --git a/skin/markdown.skin.php b/skin/markdown.skin.php
index 02d3a0f..58801f5 100644
--- a/skin/markdown.skin.php
+++ b/skin/markdown.skin.php
@@ -14,14 +14,14 @@ HTML;
 
 function image($ctx,
                // options
-               $align, $nolabel, $w, $padding_top,
+               $align, $nolabel, $w, $padding_top, $may_have_alpha,
                // image data
                $direct_url, $url, $note) {
 return <<<HTML
 <div class="md-image align-{$align}">
-    <div class="md-image-wrap">
+    <div class="md-image-wrap" data-alpha="{$ctx->if_then_else($may_have_alpha, '1', '0')}">
         <a href="{$direct_url}">
-            <div style="background: #f2f2f2 url('{$url}') no-repeat; background-size: contain; width: {$w}px; padding-top: {$padding_top}%;"></div>
+            <div style="background: url('{$url}') no-repeat; background-size: contain; width: {$w}px; padding-top: {$padding_top}%;"></div>
         </a>
         {$ctx->if_true(
             $note != '' && !$nolabel,