Enables the GD support for resolution options group for PHP >= 7.2

docs/usage/introduction.rst

@@ -29,7 +29,7 @@ Install the dependencies using composer.phar and use Imagine :
 .. code-block:: none
 
     php composer.phar install
-    
+
 .. code-block:: php
 
     <?php
@@ -138,7 +138,7 @@ You can optionally specify the fill color for the new image, which defaults to o
    $size  = new Imagine\Image\Box(400, 300);
    $color = $palette->color('#000', 0);
    $image = $imagine->create($size, $color);
-   
+
 To use a solid background color, for example orange, provide an alpha of 100.
 
 .. code-block:: php
@@ -173,7 +173,7 @@ Three options groups are currently supported : quality, resolution and flatten.
    Default values are 75 for Jpeg quality, 7 for Png compression level, 75 for webp quality and 72 dpi for x/y-resolution.
 
 .. NOTE::
-   GD does not support resolution options group
+   GD does support resolution options group only with PHP 7 >= 7.2, PHP 8
 
 The following example demonstrates the basic quality settings.
 

src/Gd/DriverInfo.php

@@ -94,9 +94,15 @@ protected function checkFeature($feature)
             case static::FEATURE_MULTIPLELAYERS:
                 throw new NotSupportedException('GD does not support layer sets');
             case static::FEATURE_CUSTOMRESOLUTION:
-                throw new NotSupportedException('GD does not support setting custom resolutions');
+                if (!function_exists('imageresolution')) {
+                    throw new NotSupportedException('GD driver for PHP older than 7.2 does not support setting custom resolutions');
+                }
+                break;
             case static::FEATURE_EXPORTWITHCUSTOMRESOLUTION:
-                throw new NotSupportedException('GD driver does not support exporting images with custom resolutions');
+                if (!function_exists('imageresolution')) {
+                    throw new NotSupportedException('GD driver for PHP older than 7.2 does not support exporting images with custom resolutions');
+                }
+                break;
             case static::FEATURE_DRAWFILLEDCHORDSCORRECTLY:
                 throw new NotSupportedException('The GD Drawer can NOT draw correctly filled chords');
             case static::FEATURE_DRAWUNFILLEDCIRCLESWITHTICHKESSCORRECTLY:

src/Gd/Image.php

@@ -188,7 +188,7 @@ final public function paste(ImageInterface $image, PointInterface $start, $alpha
                 throw new RuntimeException('Image paste operation failed');
             }
         } elseif ($alpha > 0) {
-            if (imagecopymerge(/*dst_im*/$this->resource, /*src_im*/$image->resource, /*dst_x*/$start->getX(), /*dst_y*/$start->getY(), /*src_x*/0, /*src_y*/0, /*src_w*/$size->getWidth(), /*src_h*/$size->getHeight(), /*pct*/$alpha) === false) {
+            if (imagecopymerge(/*dst_im*/$this->resource, /*src_im*/ $image->resource, /*dst_x*/ $start->getX(), /*dst_y*/ $start->getY(), /*src_x*/ 0, /*src_y*/ 0, /*src_w*/ $size->getWidth(), /*src_h*/ $size->getHeight(), /*pct*/ $alpha) === false) {
                 throw new RuntimeException('Image paste operation failed');
             }
         }
@@ -747,6 +747,21 @@ private function finalizeOptions(Format $format, array $options)
                 break;
         }
 
+        if (isset($options['resolution-units']) && isset($options['resolution-x']) && function_exists('imageresolution')) {
+            $resolutionX = $options['resolution-x'];
+            $resolutionY = isset($options['resolution-y']) ? $options['resolution-y'] : $resolutionX;
+            switch ($options['resolution-units']) {
+                case ImageInterface::RESOLUTION_PIXELSPERCENTIMETER:
+                    imageresolution($this->resource, $resolutionX * ImageInterface::RESOLUTION_PPC_TO_PPI_MULTIPLIER, $resolutionY * ImageInterface::RESOLUTION_PPC_TO_PPI_MULTIPLIER);
+                    break;
+                case ImageInterface::RESOLUTION_PIXELSPERINCH:
+                    imageresolution($this->resource, $resolutionX, $resolutionY);
+                    break;
+                default:
+                    throw new RuntimeException('Unsupported image unit format');
+            }
+        }
+
         return $result;
     }
 

src/Image/ImageInterface.php

@@ -32,6 +32,13 @@ interface ImageInterface extends ManipulatorInterface
      */
     const RESOLUTION_PIXELSPERCENTIMETER = 'ppc';
 
+    /**
+     * Multiplier for converting resolution from ppc to ppi.
+     *
+     * @var float
+     */
+    const RESOLUTION_PPC_TO_PPI_MULTIPLIER = 2.54;
+
     /**
      * Image interlacing: none.
      *

tests/tests/Gd/ImageTest.php

@@ -48,6 +48,12 @@ protected function getImagine()
      */
     protected function getImageResolution(ImageInterface $image)
     {
+        $resolutions = imageresolution($image->getGdResource());
+
+        return array(
+            'x' => $resolutions[0],
+            'y' => $resolutions[1],
+        );
     }
 
     /**

tests/tests/Image/AbstractImageTest.php

@@ -952,10 +952,14 @@ public function testResolutionOnSave($source)
 
     public function provideVariousSources()
     {
-        return array(
-            array(IMAGINE_TEST_FIXTURESFOLDER . '/example.svg'),
+        $result = array(
             array(IMAGINE_TEST_FIXTURESFOLDER . '/100-percent-black.png'),
         );
+        if ($this->getImagine() instanceof \Imagine\Imagick\Imagine) {
+            $result[] = array(IMAGINE_TEST_FIXTURESFOLDER . '/example.svg');
+        }
+
+        return $result;
     }
 
     public function testFillAlphaPrecision()