Enable text stroke effect for animated images

src/Modifiers/TextModifier.php

@@ -6,70 +6,119 @@
 
 use Intervention\Image\Drivers\Vips\Core;
 use Intervention\Image\Drivers\Vips\FontProcessor;
+use Intervention\Image\Exceptions\RuntimeException;
 use Intervention\Image\Interfaces\FrameInterface;
 use Intervention\Image\Interfaces\ImageInterface;
 use Intervention\Image\Interfaces\SpecializedInterface;
 use Intervention\Image\Modifiers\TextModifier as GenericTextModifier;
 use Jcupitt\Vips\BlendMode;
 use Jcupitt\Vips\Image as VipsImage;
+use Jcupitt\Vips\Exception as VipsException;
 
 class TextModifier extends GenericTextModifier implements SpecializedInterface
 {
     /**
      * {@inheritdoc}
      *
      * @see Intervention\Image\Interfaces\ModifierInterface::apply()
+     * @throws RuntimeException
+     * @throws VipsException
      */
     public function apply(ImageInterface $image): ImageInterface
     {
         $fontProcessor = new FontProcessor();
         $color = $this->driver()->handleInput($this->font->color());
+        $strokeColor = $this->driver()->handleInput($this->font->strokeColor());
         $lines = $fontProcessor->textBlock($this->text, $this->font, $this->position);
 
         foreach ($lines as $line) {
             // build vips image from text
             $text = $fontProcessor->textToVipsImage((string) $line, $this->font, $color);
 
-            // original line height from vips image
+            // original line height from vips image before rotation
             $height = $text->height;
 
             // apply rotation
-            $text = match ($this->font->angle()) {
-                0 => $text,
-                90.0, -270.0 => $text->rot90(),
-                180.0, -180.0 => $text->rot180(),
-                -90.0, 270.0 => $text->rot270(),
-                default => $text->similarity(['angle' => $this->font->angle()]),
-            };
+            $text = $this->maybeRotateText($text);
+
+            if ($this->font->hasStrokeEffect()) {
+                // build stroke text image if applicable
+                $stroke = $fontProcessor->textToVipsImage((string) $line, $this->font, $strokeColor);
+
+                // original line height from vips image before rotation
+                $strokeHeight = $stroke->height;
+
+                // apply rotation for stroke effect
+                $stroke = $this->maybeRotateText($stroke);
+            }
 
             if (!$image->isAnimated()) {
-                // place line on image
+                $modified = $image->core()->first();
+
+                if (isset($stroke) && isset($strokeHeight)) {
+                    // draw stroke effect with offsets
+                    foreach ($this->strokeOffsets($this->font) as $offset) {
+                        $modified = $this->placeTextOnFrame(
+                            $stroke,
+                            $modified,
+                            $line->position()->x() - $offset->x(),
+                            $line->position()->y() - $strokeHeight - $offset->y(),
+                        );
+                    }
+                }
+
+                // place text image on original image
                 $modified = $this->placeTextOnFrame(
                     $text,
-                    $image->core()->first(),
+                    $modified,
                     $line->position()->x(),
                     $line->position()->y() - $height,
-                )->native();
+                );
+
+                $modified = $modified->native();
             } else {
                 $frames = [];
                 foreach ($image as $frame) {
-                    $frames[] = $this->placeTextOnFrame(
+                    $modifiedFrame = $frame;
+                    if (isset($stroke) && isset($strokeHeight)) {
+                        // draw stroke effect with offsets
+                        foreach ($this->strokeOffsets($this->font) as $offset) {
+                            $modifiedFrame = $this->placeTextOnFrame(
+                                $stroke,
+                                $modifiedFrame,
+                                $line->position()->x() - $offset->x(),
+                                $line->position()->y() - $strokeHeight - $offset->y(),
+                            );
+                        }
+                    }
+                    // place text image on original image
+                    $modifiedFrame = $this->placeTextOnFrame(
                         $text,
-                        $frame,
+                        $modifiedFrame,
                         $line->position()->x(),
                         $line->position()->y() - $height,
                     );
+
+                    $frames[] = $modifiedFrame;
                 }
 
                 $modified = Core::replaceFrames($image->core()->native(), $frames);
             }
+            $image->core()->setNative($modified);
         }
 
-        $image->core()->setNative($modified);
-
         return $image;
     }
 
+    /**
+     * Place given text image at given position on given frame
+     *
+     * @param VipsImage $text
+     * @param FrameInterface $frame
+     * @param int $x
+     * @param int $y
+     * @return FrameInterface
+     */
     private function placeTextOnFrame(VipsImage $text, FrameInterface $frame, int $x, int $y): FrameInterface
     {
         $frame->setNative(
@@ -78,4 +127,22 @@ private function placeTextOnFrame(VipsImage $text, FrameInterface $frame, int $x
 
         return $frame;
     }
+
+    /**
+     * Maybe rotate text image according to current font angle
+     *
+     * @param VipsImage $text
+     * @return VipsImage
+     * @throws VipsException
+     */
+    private function maybeRotateText(VipsImage $text): VipsImage
+    {
+        return match ($this->font->angle()) {
+            0.0 => $text,
+            90.0, -270.0 => $text->rot90(),
+            180.0, -180.0 => $text->rot180(),
+            -90.0, 270.0 => $text->rot270(),
+            default => $text->similarity(['angle' => $this->font->angle()]),
+        };
+    }
 }