/**
* Generates a thumbnail for the given image string.
*
* If the GD library has at least version 2 and PNG support is available, the returned data
* is the content of a transparent PNG file containing the thumbnail. Otherwise, the function
* returns contents of a JPEG file with black background containing the thumbnail.
*
* @param resource $original The image to work on.
* @param array $imageinfo Contains [0] => originalwidth, [1] => originalheight.
* @param int $width The width of the requested thumbnail.
* @param int $height The height of the requested thumbnail.
* @return string|bool False if a problem occurs, the thumbnail image data otherwise.
*/
function generate_image_thumbnail_from_image($original, $imageinfo, $width, $height)
{
return resize_image_from_image($original, $imageinfo, $width, $height, true);
}
/**
* Generate a resized image for this stored_file.
*
* @param int|null $width The desired width, or null to only use the height.
* @param int|null $height The desired height, or null to only use the width.
* @return string|false False when a problem occurs, else the image data.
*/
public function resize_image($width, $height)
{
global $CFG;
require_once $CFG->libdir . '/gdlib.php';
// Fetch the image information for this image.
$imageinfo = @getimagesizefromstring($this->get_content());
if (empty($imageinfo)) {
return false;
}
// Create a new image from the file.
$original = @imagecreatefromstring($this->get_content());
// Generate the resized image.
return resize_image_from_image($original, $imageinfo, $width, $height);
}
public function test_resize_image_from_image()
{
global $CFG;
require_once $CFG->libdir . '/gdlib.php';
$pngpath = $this->fixturepath . 'gd-logo.png';
$origimageinfo = getimagesize($pngpath);
$imagecontent = file_get_contents($pngpath);
// Preferred height.
$imageresource = imagecreatefromstring($imagecontent);
$newpng = resize_image_from_image($imageresource, $origimageinfo, null, 24);
$this->assertTrue(is_string($newpng));
$imageinfo = getimagesizefromstring($newpng);
$this->assertEquals(89, $imageinfo[0]);
$this->assertEquals(24, $imageinfo[1]);
$this->assertEquals('image/png', $imageinfo['mime']);
// Preferred width.
$imageresource = imagecreatefromstring($imagecontent);
$newpng = resize_image_from_image($imageresource, $origimageinfo, 100, null);
$this->assertTrue(is_string($newpng));
$imageinfo = getimagesizefromstring($newpng);
$this->assertEquals(100, $imageinfo[0]);
$this->assertEquals(26, $imageinfo[1]);
$this->assertEquals('image/png', $imageinfo['mime']);
// Preferred width and height.
$imageresource = imagecreatefromstring($imagecontent);
$newpng = resize_image_from_image($imageresource, $origimageinfo, 50, 50);
$this->assertTrue(is_string($newpng));
$imageinfo = getimagesizefromstring($newpng);
$this->assertEquals(50, $imageinfo[0]);
$this->assertEquals(13, $imageinfo[1]);
$this->assertEquals('image/png', $imageinfo['mime']);
}