Added option to transcode extension and thumbnailing to choose the color to use to fill in the background when converting an image with an alpha channel to a format without

core/imageboard/misc.php

@@ -176,6 +176,7 @@ function create_scaled_image(string $inname, string $outname, array $tsize, stri
         $tsize[1],
         $resize_type,
         $output_mime,
+        $config->get_string(ImageConfig::THUMB_ALPHA_COLOR),
         $config->get_int(ImageConfig::THUMB_QUALITY),
         true,
         true

ext/image/config.php

@@ -11,6 +11,7 @@ abstract class ImageConfig
     const THUMB_QUALITY =    'thumb_quality';
     const THUMB_MIME =       'thumb_mime';
     const THUMB_FIT =        'thumb_fit';
+    const THUMB_ALPHA_COLOR ='thumb_alpha_color';
 
     const SHOW_META =        'image_show_meta';
     const ILINK =            'image_ilink';

ext/image/main.php

@@ -37,6 +37,7 @@ class ImageIO extends Extension
         $config->set_default_int(ImageConfig::THUMB_QUALITY, 75);
         $config->set_default_string(ImageConfig::THUMB_MIME, MimeType::JPEG);
         $config->set_default_string(ImageConfig::THUMB_FIT, Media::RESIZE_TYPE_FIT);
+        $config->set_default_string(ImageConfig::THUMB_ALPHA_COLOR, Media::DEFAULT_ALPHA_CONVERSION_COLOR);
 
         if (function_exists(self::EXIF_READ_FUNCTION)) {
             $config->set_default_bool(ImageConfig::SHOW_META, false);
@@ -275,6 +276,9 @@ class ImageIO extends Extension
 
         $sb->add_int_option(ImageConfig::THUMB_QUALITY, "Quality", true);
         $sb->add_int_option(ImageConfig::THUMB_SCALING, "High-DPI Scale %", true);
+        if ($config->get_string(ImageConfig::THUMB_MIME)===MimeType::JPEG) {
+            $sb->add_color_option(ImageConfig::THUMB_ALPHA_COLOR, "Alpha Conversion Color", true);
+        }
 
         $sb->end_table();
 

ext/media/events.php

@@ -10,6 +10,7 @@ class MediaResizeEvent extends Event
     public $target_width;
     public $target_height;
     public $target_quality;
+    public $alpha_color;
     public $minimize;
     public $allow_upscale;
     public $resize_type;
@@ -23,6 +24,7 @@ class MediaResizeEvent extends Event
         int $target_height,
         string $resize_type = Media::RESIZE_TYPE_FIT,
         string $target_mime = null,
+        string $alpha_color = Media::DEFAULT_ALPHA_CONVERSION_COLOR,
         int $target_quality = 80,
         bool $minimize = false,
         bool $allow_upscale = true
@@ -36,6 +38,10 @@ class MediaResizeEvent extends Event
         $this->target_height = $target_height;
         $this->target_width = $target_width;
         $this->target_mime = $target_mime;
+        if (empty($alpha_color)) {
+            $alpha_color = Media::DEFAULT_ALPHA_CONVERSION_COLOR;
+        }
+        $this->alpha_color = $alpha_color;
         $this->target_quality = $target_quality;
         $this->minimize = $minimize;
         $this->allow_upscale = $allow_upscale;

ext/media/main.php

@@ -16,12 +16,7 @@ class Media extends Extension
     /** @var MediaTheme */
     protected $theme;
 
-    const IMAGE_MEDIA_ENGINES = [
+    private const LOSSLESS_FORMATS = [
-        "GD" => MediaEngine::GD,
-        "ImageMagick" => MediaEngine::IMAGICK,
-    ];
-
-    const LOSSLESS_FORMATS = [
         MimeType::WEBP_LOSSLESS,
         MimeType::PNG,
         MimeType::PSD,
@@ -31,16 +26,17 @@ class Media extends Extension
         MimeType::GIF
     ];
 
-    const ALPHA_FORMATS = [
+    private const ALPHA_FORMATS = [
         MimeType::WEBP_LOSSLESS,
         MimeType::WEBP,
         MimeType::PNG,
     ];
 
-    const RESIZE_TYPE_FIT = "Fit";
+    public const RESIZE_TYPE_FIT = "Fit";
-    const RESIZE_TYPE_FIT_BLUR = "Fit Blur";
+    public const RESIZE_TYPE_FIT_BLUR = "Fit Blur";
-    const RESIZE_TYPE_FILL =  "Fill";
+    public const RESIZE_TYPE_FILL =  "Fill";
-    const RESIZE_TYPE_STRETCH =  "Stretch";
+    public const RESIZE_TYPE_STRETCH =  "Stretch";
+    public const DEFAULT_ALPHA_CONVERSION_COLOR = "#00000000";
 
     public static function imagick_available(): bool
     {
@@ -194,6 +190,7 @@ class Media extends Extension
                     $event->target_height,
                     $event->output_path,
                     $event->target_mime,
+                    $event->alpha_color,
                     $event->resize_type,
                     $event->target_quality,
                     $event->allow_upscale
@@ -210,6 +207,7 @@ class Media extends Extension
                     $event->target_height,
                     $event->output_path,
                     $event->target_mime,
+                    $event->alpha_color,
                     $event->resize_type,
                     $event->target_quality,
                     $event->minimize,
@@ -542,6 +540,7 @@ class Media extends Extension
         int $new_height,
         string $output_filename,
         string $output_mime = null,
+        string $alpha_color = Media::DEFAULT_ALPHA_CONVERSION_COLOR,
         string $resize_type = self::RESIZE_TYPE_FIT,
         int $output_quality = 80,
         bool $minimize = false,
@@ -563,7 +562,7 @@ class Media extends Extension
             $output_mime = MimeType::WEBP_LOSSLESS;
         }
 
-        $bg = "black";
+        $bg = "\"$alpha_color\"";
         if (self::supports_alpha($output_mime)) {
             $bg = "none";
         }
@@ -590,15 +589,15 @@ class Media extends Extension
         switch ($resize_type) {
             case Media::RESIZE_TYPE_FIT:
             case Media::RESIZE_TYPE_STRETCH:
-                $args .= "${resize_arg} ${new_width}x${new_height}${resize_suffix} ${file_arg}";
+                $args .= "${file_arg} ${resize_arg} ${new_width}x${new_height}${resize_suffix} -background ${bg} -flatten ";
                 break;
             case Media::RESIZE_TYPE_FILL:
-                $args .= "${resize_arg} ${new_width}x${new_height}\^ -background none -gravity center -extent ${new_width}x${new_height} ${file_arg}";
+                $args .= "${file_arg} ${resize_arg} ${new_width}x${new_height}\^ -background ${bg} -flatten -gravity center -extent ${new_width}x${new_height} ";
                 break;
             case Media::RESIZE_TYPE_FIT_BLUR:
                 $blur_size = max(ceil(max($new_width, $new_height) / 25), 5);
                 $args .= "${file_arg} ".
-                    "\( -clone 0 -resize ${new_width}x${new_height}\^ -background none -gravity center -fill black -colorize 50% -extent ${new_width}x${new_height} -blur 0x${blur_size} \) ".
+                    "\( -clone 0 -resize ${new_width}x${new_height}\^ -background ${bg} -flatten -gravity center -fill black -colorize 50% -extent ${new_width}x${new_height} -blur 0x${blur_size} \) ".
                     "\( -clone 0 -resize ${new_width}x${new_height} \) ".
                     "-delete 0 -gravity center -compose over -composite";
                 break;
@@ -615,7 +614,7 @@ class Media extends Extension
         }
 
 
-        $args .= " -quality ${output_quality} -background ${bg}";
+        $args .= " -quality ${output_quality} ";
 
 
         $output_ext = self::determine_ext($output_mime);
@@ -651,6 +650,7 @@ class Media extends Extension
         int $new_height,
         string $output_filename,
         string $output_mime = null,
+        string $alpha_color = Media::DEFAULT_ALPHA_CONVERSION_COLOR,
         string $resize_type = self::RESIZE_TYPE_FIT,
         int $output_quality = 80,
         bool $allow_upscale = true
@@ -769,6 +769,34 @@ class Media extends Extension
                 throw new MediaException("Unable to copy resized image data to new image");
             }
 
+            switch ($output_mime) {
+                case MimeType::BMP:
+                case MimeType::JPEG:
+                    // In case of alpha channels
+                    $width = imagesx($image_resized);
+                    $height = imagesy($image_resized);
+                    $new_image = imagecreatetruecolor($width, $height);
+                    if ($new_image===false) {
+                        throw new ImageTranscodeException("Could not create image with dimensions $width x $height");
+                    }
+
+                    $background_color = Media::hex_color_allocate($new_image, $alpha_color);
+                    if ($background_color===false) {
+                        throw new ImageTranscodeException("Could not allocate background color");
+                    }
+                    if (imagefilledrectangle($new_image, 0, 0, $width, $height, $background_color)===false) {
+                        throw new ImageTranscodeException("Could not fill background color");
+                    }
+                    if (imagecopy($new_image, $image_resized, 0, 0, 0, 0, $width, $height)===false) {
+                        throw new ImageTranscodeException("Could not copy source image to new image");
+                    }
+
+                    imagedestroy($image_resized);
+                    $image_resized = $new_image;
+                break;
+
+            }
+
             switch ($output_mime) {
                 case MimeType::BMP:
                     $result = imagebmp($image_resized, $output_filename, true);
@@ -904,4 +932,13 @@ class Media extends Extension
             $database->begin_transaction();
         }
     }
+
+    public static function hex_color_allocate($im, $hex)
+    {
+        $hex = ltrim($hex, '#');
+        $a = hexdec(substr($hex, 0, 2));
+        $b = hexdec(substr($hex, 2, 2));
+        $c = hexdec(substr($hex, 4, 2));
+        return imagecolorallocate($im, $a, $b, $c);
+    }
 }

ext/media/media_engine.php

@@ -7,6 +7,11 @@ abstract class MediaEngine
     public const FFMPEG = "ffmpeg";
     public const STATIC = "static";
 
+    const IMAGE_ENGINES = [
+        "GD" => MediaEngine::GD,
+        "ImageMagick" => MediaEngine::IMAGICK,
+    ];
+
     public const ALL = [
         MediaEngine::GD,
         MediaEngine::FFMPEG,

ext/resize/main.php

@@ -50,9 +50,9 @@ class ResizeImage extends Extension
     {
         $sb = new SetupBlock("Image Resize");
         $sb->start_table();
-        $sb->add_choice_option(ResizeConfig::ENGINE, Media::IMAGE_MEDIA_ENGINES, "Engine: ", true);
+        $sb->add_choice_option(ResizeConfig::ENGINE, MediaEngine::IMAGE_ENGINES, "Engine", true);
-        $sb->add_bool_option(ResizeConfig::ENABLED, "Allow resizing images: ", true);
+        $sb->add_bool_option(ResizeConfig::ENABLED, "Allow resizing images", true);
-        $sb->add_bool_option(ResizeConfig::UPLOAD, "Resize on upload: ", true);
+        $sb->add_bool_option(ResizeConfig::UPLOAD, "Resize on upload", true);
         $sb->end_table();
         $sb->start_table();
         $sb->add_table_header("Preset/Default Dimensions");

ext/setup/main.php

@@ -278,6 +278,17 @@ class SetupBlock extends Block
 
         $this->format_option($name, $html, $label, $table_row);
     }
+
+    public function add_color_option(string $name, string $label=null, bool $table_row = false)
+    {
+        global $config;
+        $val = html_escape($config->get_string($name));
+
+        $html = "<input type='color' id='{$name}' name='_config_{$name}' value='{$val}'>\n";
+        $html .= "<input type='hidden' name='_type_{$name}' value='string'>\n";
+
+        $this->format_option($name, $html, $label, $table_row);
+    }
 }
 
 class Setup extends Extension

ext/transcode/config.php

@@ -9,4 +9,5 @@ class TranscodeConfig
     const UPLOAD = "transcode_upload";
     const UPLOAD_PREFIX = "transcode_upload_";
     const QUALITY = "transcode_quality";
+    const ALPHA_COLOR = "transcode_alpha_color";
 }

ext/transcode/main.php

@@ -51,6 +51,7 @@ class TranscodeImage extends Extension
         $config->set_default_bool(TranscodeConfig::UPLOAD, false);
         $config->set_default_string(TranscodeConfig::ENGINE, MediaEngine::GD);
         $config->set_default_int(TranscodeConfig::QUALITY, 80);
+        $config->set_default_string(TranscodeConfig::ALPHA_COLOR, Media::DEFAULT_ALPHA_CONVERSION_COLOR);
 
         foreach (array_values(self::INPUT_MIMES) as $mime) {
             $config->set_default_string(self::get_mapping_name($mime), "");
@@ -142,9 +143,9 @@ class TranscodeImage extends Extension
 
         $sb = new SetupBlock("Image Transcode");
         $sb->start_table();
-        $sb->add_bool_option(TranscodeConfig::ENABLED, "Allow transcoding images: ", true);
+        $sb->add_bool_option(TranscodeConfig::ENABLED, "Allow transcoding images", true);
-        $sb->add_bool_option(TranscodeConfig::UPLOAD, "Transcode on upload: ", true);
+        $sb->add_bool_option(TranscodeConfig::UPLOAD, "Transcode on upload", true);
-        $sb->add_choice_option(TranscodeConfig::ENGINE, Media::IMAGE_MEDIA_ENGINES, "Engine", true);
+        $sb->add_choice_option(TranscodeConfig::ENGINE, MediaEngine::IMAGE_ENGINES, "Engine", true);
         foreach (self::INPUT_MIMES as $display=> $mime) {
             if (MediaEngine::is_input_supported($engine, $mime)) {
                 $outputs = $this->get_supported_output_mimes($engine, $mime);
@@ -152,6 +153,7 @@ class TranscodeImage extends Extension
             }
         }
         $sb->add_int_option(TranscodeConfig::QUALITY, "Lossy Format Quality", true);
+        $sb->add_color_option(TranscodeConfig::ALPHA_COLOR, "Alpha Conversion Color", true);
         $sb->end_table();
         $event->panel->add_block($sb);
     }
@@ -337,7 +339,7 @@ class TranscodeImage extends Extension
             throw new ImageTranscodeException("Source and target MIMEs are the same: ".$source_mime);
         }
 
-        $engine = $config->get_string("transcode_engine");
+        $engine = $config->get_string(TranscodeConfig::ENGINE);
 
 
 
@@ -385,11 +387,11 @@ class TranscodeImage extends Extension
                         throw new ImageTranscodeException("Could not create image with dimensions $width x $height");
                     }
                     try {
-                        $black = imagecolorallocate($new_image, 0, 0, 0);
+                        $background_color = Media::hex_color_allocate($new_image, $config->get_string(TranscodeConfig::ALPHA_COLOR));
-                        if ($black===false) {
+                        if ($background_color===false) {
                             throw new ImageTranscodeException("Could not allocate background color");
                         }
-                        if (imagefilledrectangle($new_image, 0, 0, $width, $height, $black)===false) {
+                        if (imagefilledrectangle($new_image, 0, 0, $width, $height, $background_color)===false) {
                             throw new ImageTranscodeException("Could not fill background color");
                         }
                         if (imagecopy($new_image, $image, 0, 0, 0, 0, $width, $height)===false) {
@@ -422,13 +424,14 @@ class TranscodeImage extends Extension
         }
         $ext = Media::determine_ext($target_mime);
 
-        $args = " -flatten -background ";
+        $args = " -background ";
 
         if (Media::supports_alpha($target_mime)) {
             $args .= "none ";
         } else {
-            $args .= "black ";
+            $args .= "\"".$config->get_string(TranscodeConfig::ALPHA_COLOR)."\" ";
         }
+        $args .= " -flatten ";
 
         switch ($target_mime) {
             case MimeType::PNG: