GDTest.php
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<?php
/**
* Tests for the {@link GD} class.
*
* @package framework
* @subpackage tests
*/
class GDTest extends SapphireTest {
public static $filenames = array(
'gif' => 'test_gif.gif',
'jpg' => 'test_jpg.jpg',
'png8' => 'test_png8.png',
'png32' => 'test_png32.png'
);
/**
* Loads all images into an associative array of GD objects.
* Optionally applies an operation to each GD
* @param callable $callback Action to perform on each GD
* @return array List of GD
*/
protected function applyToEachImage($callback = null) {
$gds = array();
foreach(self::$filenames as $type => $file) {
$fullPath = realpath(dirname(__FILE__) . '/gdtest/' . $file);
$gd = new GD($fullPath);
if($callback) {
$gd = $callback($gd);
}
$gds[$type] = $gd;
}
return $gds;
}
/**
* Takes samples from the given GD at 5 pixel increments
* @param GD $gd The source image
* @param integer $horizontal Number of samples to take horizontally
* @param integer $vertical Number of samples to take vertically
* @return array List of colours for each sample, each given as an associative
* array with red, blue, green, and alpha components
*/
protected function sampleAreas(GD $gd, $horizontal = 4, $vertical = 4) {
$samples = array();
for($y = 0; $y < $vertical; $y++) {
for($x = 0; $x < $horizontal; $x++) {
$colour = imagecolorat($gd->getImageResource(), $x * 5, $y * 5);
$samples[] = ImageColorsforIndex($gd->getImageResource(), $colour);
}
}
return $samples;
}
/**
* Asserts that two colour channels are equivalent within a given tolerance range
* @param integer $expected
* @param integer $actual
* @param integer $tolerance
*/
protected function assertColourEquals($expected, $actual, $tolerance = 0) {
$match =
($expected + $tolerance >= $actual) &&
($expected - $tolerance <= $actual);
$this->assertTrue($match);
}
/**
* Asserts that all samples given correctly correspond to a greyscale version
* of the test image pattern
* @param array $samples List of 16 colour samples representing each of the
* 8 x 8 squares on the image pattern
* @param int $alphaBits Depth of alpha channel in bits
* @param int $tolerance Reasonable tolerance level for colour comparison
*/
protected function assertGreyscale($samples, $alphaBits = 0, $tolerance = 0) {
// Check that all colour samples match
foreach($samples as $sample) {
$matches =
($sample['red'] === $sample['green']) &&
($sample['blue'] === $sample['green']);
$this->assertTrue($matches, 'Assert colour is greyscale');
if(!$matches) return;
}
// check various sample points
$this->assertColourEquals(96, $samples[0]['red'], $tolerance);
$this->assertColourEquals(91, $samples[2]['red'], $tolerance);
$this->assertColourEquals(0, $samples[8]['red'], $tolerance);
$this->assertColourEquals(127, $samples[9]['red'], $tolerance);
// check alpha of various points
switch($alphaBits) {
case 0:
$this->assertColourEquals(0, $samples[2]['alpha'], $tolerance);
$this->assertColourEquals(0, $samples[12]['alpha'], $tolerance);
break;
case 1:
$this->assertColourEquals(0, $samples[2]['alpha'], $tolerance);
$this->assertColourEquals(127, $samples[12]['alpha'], $tolerance);
break;
default:
$this->assertColourEquals(63, $samples[2]['alpha'], $tolerance);
$this->assertColourEquals(127, $samples[12]['alpha'], $tolerance);
break;
}
}
/**
* Tests that images are correctly transformed to greyscale
*/
function testGreyscale() {
// Apply greyscaling to each image
$images = $this->applyToEachImage(function(GD $gd) {
return $gd->greyscale();
});
// Test GIF (256 colour, transparency)
$samplesGIF = $this->sampleAreas($images['gif']);
$this->assertGreyscale($samplesGIF, 1);
// Test JPG
$samplesJPG = $this->sampleAreas($images['jpg']);
$this->assertGreyscale($samplesJPG, 0, 4);
// Test PNG 8 (indexed with alpha transparency)
$samplesPNG8 = $this->sampleAreas($images['png8']);
$this->assertGreyscale($samplesPNG8, 8, 4);
// Test PNG 32 (full alpha transparency)
$samplesPNG32 = $this->sampleAreas($images['png32']);
$this->assertGreyscale($samplesPNG32, 8);
}
}