Fix transparency issues with gd driver resizing

src/Colors/Rgb/Decoders/TransparentColorDecoder.php

@@ -18,6 +18,6 @@ class TransparentColorDecoder extends HexColorDecoder
             throw new DecoderException('Unable to decode input');
         }
 
-        return parent::decode('#00000000');
+        return parent::decode('#ff00ff00');
     }
 }

src/Drivers/Gd/Modifiers/CropModifier.php

@@ -7,9 +7,12 @@ use Intervention\Image\Interfaces\FrameInterface;
 use Intervention\Image\Interfaces\ImageInterface;
 use Intervention\Image\Interfaces\ModifierInterface;
 use Intervention\Image\Interfaces\SizeInterface;
+use Intervention\Image\Traits\CanBuildNewImage;
 
 class CropModifier implements ModifierInterface
 {
+    use CanBuildNewImage;
+
     public function __construct(
         protected int $width,
         protected int $height,
@@ -36,30 +39,28 @@ class CropModifier implements ModifierInterface
     protected function cropFrame(FrameInterface $frame, SizeInterface $resizeTo): void
     {
         // create new image
-        $modified = imagecreatetruecolor(
+        $modified = $this->imageFactory()->newCore(
             $resizeTo->width(),
             $resizeTo->height()
         );
 
-        // get current image
-        $current = $frame->core();
+        // get original image
+        $original = $frame->core();
 
         // preserve transparency
-        imagealphablending($modified, false);
-        $transIndex = imagecolortransparent($current);
+        $transIndex = imagecolortransparent($original);
 
         if ($transIndex != -1) {
             $rgba = imagecolorsforindex($modified, $transIndex);
             $transColor = imagecolorallocatealpha($modified, $rgba['red'], $rgba['green'], $rgba['blue'], 127);
             imagefill($modified, 0, 0, $transColor);
-        } else {
-            imagesavealpha($modified, true);
+            imagecolortransparent($modified, $transColor);
         }
 
         // copy content from resource
         imagecopyresampled(
             $modified,
-            $current,
+            $original,
             0,
             0,
             $resizeTo->pivot()->x() + $this->offset_x,
@@ -70,22 +71,6 @@ class CropModifier implements ModifierInterface
             $resizeTo->height(),
         );
 
-        if ($transIndex != -1) { // @todo refactor because of duplication
-            imagecolortransparent($modified, $transIndex);
-            for ($y = 0; $y < $resizeTo->height(); ++$y) {
-                for ($x = 0; $x < $resizeTo->width(); ++$x) {
-                    if (((imagecolorat($modified, $x, $y) >> 24) & 0x7F) >= 100) {
-                        imagesetpixel(
-                            $modified,
-                            $x,
-                            $y,
-                            $transIndex
-                        );
-                    }
-                }
-            }
-        }
-
         // set new content as recource
         $frame->setCore($modified);
     }

src/Drivers/Gd/Modifiers/FitModifier.php

@@ -7,9 +7,12 @@ use Intervention\Image\Interfaces\FrameInterface;
 use Intervention\Image\Interfaces\ImageInterface;
 use Intervention\Image\Interfaces\ModifierInterface;
 use Intervention\Image\Interfaces\SizeInterface;
+use Intervention\Image\Traits\CanBuildNewImage;
 
 class FitModifier extends AbstractFitModifier implements ModifierInterface
 {
+    use CanBuildNewImage;
+
     public function apply(ImageInterface $image): ImageInterface
     {
         $crop = $this->getCropSize($image);
@@ -25,30 +28,28 @@ class FitModifier extends AbstractFitModifier implements ModifierInterface
     protected function modifyFrame(FrameInterface $frame, SizeInterface $crop, SizeInterface $resize): void
     {
         // create new image
-        $modified = imagecreatetruecolor(
+        $modified = $this->imageFactory()->newCore(
             $resize->width(),
             $resize->height()
         );
 
-        // get current image
-        $current = $frame->core();
+        // get original image
+        $original = $frame->core();
 
         // preserve transparency
-        imagealphablending($modified, false);
-        $transIndex = imagecolortransparent($current);
+        $transIndex = imagecolortransparent($original);
 
         if ($transIndex != -1) {
             $rgba = imagecolorsforindex($modified, $transIndex);
             $transColor = imagecolorallocatealpha($modified, $rgba['red'], $rgba['green'], $rgba['blue'], 127);
             imagefill($modified, 0, 0, $transColor);
-        } else {
-            imagesavealpha($modified, true);
+            imagecolortransparent($modified, $transColor);
         }
 
         // copy content from resource
         imagecopyresampled(
             $modified,
-            $current,
+            $original,
             0,
             0,
             $crop->pivot()->x(),
@@ -59,22 +60,6 @@ class FitModifier extends AbstractFitModifier implements ModifierInterface
             $crop->height()
         );
 
-        if ($transIndex != -1) { // @todo refactor because of duplication
-            imagecolortransparent($modified, $transIndex);
-            for ($y = 0; $y < $resize->height(); ++$y) {
-                for ($x = 0; $x < $resize->width(); ++$x) {
-                    if (((imagecolorat($modified, $x, $y) >> 24) & 0x7F) >= 100) {
-                        imagesetpixel(
-                            $modified,
-                            $x,
-                            $y,
-                            $transIndex
-                        );
-                    }
-                }
-            }
-        }
-
         // set new content as resource
         $frame->setCore($modified);
     }

src/Drivers/Gd/Modifiers/PadModifier.php

@@ -4,22 +4,25 @@ namespace Intervention\Image\Drivers\Gd\Modifiers;
 
 use Intervention\Image\Drivers\Abstract\Modifiers\AbstractPadModifier;
 use Intervention\Image\Drivers\Gd\Traits\CanHandleColors;
+use Intervention\Image\Interfaces\ColorInterface;
 use Intervention\Image\Interfaces\FrameInterface;
 use Intervention\Image\Interfaces\ImageInterface;
 use Intervention\Image\Interfaces\ModifierInterface;
 use Intervention\Image\Interfaces\SizeInterface;
+use Intervention\Image\Traits\CanBuildNewImage;
 use Intervention\Image\Traits\CanHandleInput;
 
 class PadModifier extends AbstractPadModifier implements ModifierInterface
 {
     use CanHandleInput;
     use CanHandleColors;
+    use CanBuildNewImage;
 
     public function apply(ImageInterface $image): ImageInterface
     {
         $crop = $this->getCropSize($image);
         $resize = $this->getResizeSize($image);
-        $background = $this->colorToInteger($this->handleInput($this->background));
+        $background = $this->handleInput($this->background);
 
         foreach ($image as $frame) {
             $this->modify($frame, $crop, $resize, $background);
@@ -32,27 +35,34 @@ class PadModifier extends AbstractPadModifier implements ModifierInterface
         FrameInterface $frame,
         SizeInterface $crop,
         SizeInterface $resize,
-        int $background
+        ColorInterface $background
     ): void {
-        // create new image
-        $modified = imagecreatetruecolor(
+        // create new gd image
+        $modified = $this->imageFactory()->newCore(
             $resize->width(),
-            $resize->height()
+            $resize->height(),
+            $background
         );
 
-        imagefill($modified, 0, 0, $background);
+        // make image area transparent to keep transparency
+        // even if background-color is set
+        $transparent = imagecolorallocatealpha($modified, 255, 0, 255, 127);
+        imagealphablending($modified, false); // do not blend / just overwrite
+        imagecolortransparent($modified, $transparent);
+        imagefilledrectangle(
+            $modified,
+            $crop->pivot()->x(),
+            $crop->pivot()->y(),
+            $crop->pivot()->x() + $crop->width() - 1,
+            $crop->pivot()->y() + $crop->height() - 1,
+            $transparent
+        );
 
-        // get current image
-        $current = $frame->core();
-
-        // preserve transparency
-        imagealphablending($modified, false);
-        imagesavealpha($modified, true);
-
-        // copy content from resource
+        // copy image from original with blending alpha
+        imagealphablending($modified, true);
         imagecopyresampled(
             $modified,
-            $current,
+            $frame->core(),
             $crop->pivot()->x(),
             $crop->pivot()->y(),
             0,

src/Drivers/Gd/Modifiers/ResizeModifier.php

@@ -37,14 +37,15 @@ class ResizeModifier implements ModifierInterface
         $current = $frame->core();
 
         // preserve transparency
-        imagealphablending($modified, false);
         $transIndex = imagecolortransparent($current);
 
         if ($transIndex != -1) {
             $rgba = imagecolorsforindex($modified, $transIndex);
             $transColor = imagecolorallocatealpha($modified, $rgba['red'], $rgba['green'], $rgba['blue'], 127);
             imagefill($modified, 0, 0, $transColor);
+            imagecolortransparent($modified, $transColor);
         } else {
+            imagealphablending($modified, false);
             imagesavealpha($modified, true);
         }
 
@@ -62,22 +63,6 @@ class ResizeModifier implements ModifierInterface
             $frame->size()->height()
         );
 
-        if ($transIndex != -1) { // @todo refactor because of duplication
-            imagecolortransparent($modified, $transIndex);
-            for ($y = 0; $y < $resizeTo->height(); ++$y) {
-                for ($x = 0; $x < $resizeTo->width(); ++$x) {
-                    if (((imagecolorat($modified, $x, $y) >> 24) & 0x7F) >= 100) {
-                        imagesetpixel(
-                            $modified,
-                            $x,
-                            $y,
-                            $transIndex
-                        );
-                    }
-                }
-            }
-        }
-
         // set new content as recource
         $frame->setCore($modified);
     }

tests/Drivers/Gd/InputHandlerTest.php

@@ -120,6 +120,6 @@ class GdInputHandlerTest extends TestCase
         $input = 'transparent';
         $result = $handler->handle($input);
         $this->assertInstanceOf(RgbColor::class, $result);
-        $this->assertEquals([0, 0, 0, 0], $result->toArray());
+        $this->assertEquals([255, 0, 255, 0], $result->toArray());
     }
 }

tests/Drivers/Imagick/InputHandlerTest.php

@@ -120,6 +120,6 @@ class InputHandlerTest extends TestCase
         $input = 'transparent';
         $result = $handler->handle($input);
         $this->assertInstanceOf(RgbColor::class, $result);
-        $this->assertEquals([0, 0, 0, 0], $result->toArray());
+        $this->assertEquals([255, 0, 255, 0], $result->toArray());
     }
 }