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Let gd's PngEncoder encode binary transparency in indexed mode

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This commit is contained in:
Oliver Vogel
2024-08-11 13:24:31 +02:00
parent 20dae08304
commit 78534a3b0c
1 changed files with 6 additions and 35 deletions
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43
src/Drivers/Gd/Encoders/PngEncoder.php
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@@ -5,9 +5,6 @@ declare(strict_types=1);
namespace Intervention\Image\Drivers\Gd\Encoders;
use GdImage;
use Intervention\Image\Colors\Rgb\Channels\Blue;
use Intervention\Image\Colors\Rgb\Channels\Green;
use Intervention\Image\Colors\Rgb\Channels\Red;
use Intervention\Image\Drivers\Gd\Cloner;
use Intervention\Image\EncodedImage;
use Intervention\Image\Encoders\PngEncoder as GenericPngEncoder;
@@ -48,39 +45,13 @@ class PngEncoder extends GenericPngEncoder implements SpecializedInterface
*/
private function prepareOutput(ImageInterface $image): GdImage
{
if ($this->indexed === false) {
if ($this->indexed) {
$output = clone $image;
$output->reduceColors(255);
return $output->core()->native();
}
return Cloner::clone($image->core()->native());
}
// clone output instance
$output = Cloner::cloneEmpty($image->core()->native());
// Decode configured blending color
$blendingColor = $image->blendingColor();
// allocate blending color with slighty different alpha value
// to avoid "overwriting" pixels with the same color in the
// original image with transprency
$blendingIndex = imagecolorallocatealpha(
$output,
$blendingColor->channel(Red::class)->value(),
$blendingColor->channel(Green::class)->value(),
$blendingColor->channel(Blue::class)->value(),
1,
);
// fill with blending color
imagefill($output, 0, 0, $blendingIndex);
// define blending index as transparent
imagecolortransparent($output, $blendingIndex);
// copy original into output
imagecopy($output, $image->core()->native(), 0, 0, 0, 0, imagesx($output), imagesy($output));
// reduce to indexed color palette
imagetruecolortopalette($output, true, 255);
return $output;
}
}