core-bundle/src/Resources/contao/classes/FileUpload.php
protected function resizeUploadedImage($strImage)
	{
		// The feature is disabled
		if (Config::get('imageWidth') < 1 && Config::get('imageHeight') < 1)
		{
			return false;
		}

		$objFile = new File($strImage);

		// Not an image
		if (!$objFile->isSvgImage && !$objFile->isGdImage)
		{
			return false;
		}

		$arrImageSize = $objFile->imageSize;

		// The image is too big to be handled by the GD library
		if ($objFile->isGdImage && ($arrImageSize[0] > Config::get('gdMaxImgWidth') || $arrImageSize[1] > Config::get('gdMaxImgHeight')))
		{
			Message::addInfo(sprintf($GLOBALS['TL_LANG']['MSC']['fileExceeds'], $objFile->basename));
			$this->log('File "' . $strImage . '" is too big to be resized automatically', __METHOD__, TL_FILES);

			return false;
		}

		$blnResize = false;

		// The image exceeds the maximum image width
		if ($arrImageSize[0] > Config::get('imageWidth'))
		{
			$blnResize = true;
			$intWidth = Config::get('imageWidth');
			$intHeight = round(Config::get('imageWidth') * $arrImageSize[1] / $arrImageSize[0]);
			$arrImageSize = array($intWidth, $intHeight);
		}

		// The image exceeds the maximum image height
		if ($arrImageSize[1] > Config::get('imageHeight'))
		{
			$blnResize = true;
			$intWidth = round(Config::get('imageHeight') * $arrImageSize[0] / $arrImageSize[1]);
			$intHeight = Config::get('imageHeight');
			$arrImageSize = array($intWidth, $intHeight);
		}

		// Resized successfully
		if ($blnResize)
		{
			$container = System::getContainer();
			$rootDir = $container->getParameter('kernel.project_dir');
			$container->get('contao.image.image_factory')->create($rootDir . '/' . $strImage, array($arrImageSize[0], $arrImageSize[1]), $rootDir . '/' . $strImage);

			Message::addInfo(sprintf($GLOBALS['TL_LANG']['MSC']['fileResized'], $objFile->basename));
			$this->log('File "' . $strImage . '" was scaled down to the maximum dimensions', __METHOD__, TL_FILES);
			$this->blnHasResized = true;

			return true;
		}

		return false;
	}
protected function resizeUploadedImage($strImage)
	{
		// The feature is disabled
		if (Config::get('imageWidth') < 1 && Config::get('imageHeight') < 1)
		{
			return false;
		}

		$objFile = new File($strImage);

		// Not an image
		if (!$objFile->isSvgImage && !$objFile->isGdImage)
		{
			return false;
		}

		$arrImageSize = $objFile->imageSize;

		// The image is too big to be handled by the GD library
		if ($objFile->isGdImage && ($arrImageSize[0] > Config::get('gdMaxImgWidth') || $arrImageSize[1] > Config::get('gdMaxImgHeight')))
		{
			Message::addInfo(sprintf($GLOBALS['TL_LANG']['MSC']['fileExceeds'], $objFile->basename));
			$this->log('File "' . $strImage . '" is too big to be resized automatically', __METHOD__, TL_FILES);

			return false;
		}

		$blnResize = false;

		// The image exceeds the maximum image width
		if ($arrImageSize[0] > Config::get('imageWidth'))
		{
			$blnResize = true;
			$intWidth = Config::get('imageWidth');
			$intHeight = round(Config::get('imageWidth') * $arrImageSize[1] / $arrImageSize[0]);
			$arrImageSize = array($intWidth, $intHeight);
		}

		// The image exceeds the maximum image height
		if ($arrImageSize[1] > Config::get('imageHeight'))
		{
			$blnResize = true;
			$intWidth = round(Config::get('imageHeight') * $arrImageSize[0] / $arrImageSize[1]);
			$intHeight = Config::get('imageHeight');
			$arrImageSize = array($intWidth, $intHeight);
		}

		// Resized successfully
		if ($blnResize)
		{
			$container = System::getContainer();
			$rootDir = $container->getParameter('kernel.project_dir');
			$container->get('contao.image.image_factory')->create($rootDir . '/' . $strImage, array($arrImageSize[0], $arrImageSize[1]), $rootDir . '/' . $strImage);

			Message::addInfo(sprintf($GLOBALS['TL_LANG']['MSC']['fileResized'], $objFile->basename));
			$this->log('File "' . $strImage . '" was scaled down to the maximum dimensions', __METHOD__, TL_FILES);
			$this->blnHasResized = true;

			return true;
		}

		return false;
	}
Resize an uploaded image if neccessary

@param string $strImage

@return boolean