core-bundle/src/Resources/contao/library/Contao/Image.php
protected function prepareImportantPart()
	{
		$importantPart = $this->getImportantPart();

		if (substr_count($this->resizeMode, '_') === 1)
		{
			$importantPart = array
			(
				'x' => 0,
				'y' => 0,
				'width' => $this->fileObj->viewWidth,
				'height' => $this->fileObj->viewHeight,
			);

			$mode = explode('_', $this->resizeMode);

			if ($mode[0] === 'left')
			{
				$importantPart['width'] = 1;
			}
			elseif ($mode[0] === 'right')
			{
				$importantPart['x'] = $importantPart['width'] - 1;
				$importantPart['width'] = 1;
			}

			if ($mode[1] === 'top')
			{
				$importantPart['height'] = 1;
			}
			elseif ($mode[1] === 'bottom')
			{
				$importantPart['y'] = $importantPart['height'] - 1;
				$importantPart['height'] = 1;
			}
		}

		if (!$importantPart['width'] || !$importantPart['height'])
		{
			return null;
		}

		return new ImportantPart(
			new Point($importantPart['x'], $importantPart['y']),
			new Box($importantPart['width'], $importantPart['height'])
		);
	}
protected function prepareImportantPart()
	{
		$importantPart = $this->getImportantPart();

		if (substr_count($this->resizeMode, '_') === 1)
		{
			$importantPart = array
			(
				'x' => 0,
				'y' => 0,
				'width' => $this->fileObj->viewWidth,
				'height' => $this->fileObj->viewHeight,
			);

			$mode = explode('_', $this->resizeMode);

			if ($mode[0] === 'left')
			{
				$importantPart['width'] = 1;
			}
			elseif ($mode[0] === 'right')
			{
				$importantPart['x'] = $importantPart['width'] - 1;
				$importantPart['width'] = 1;
			}

			if ($mode[1] === 'top')
			{
				$importantPart['height'] = 1;
			}
			elseif ($mode[1] === 'bottom')
			{
				$importantPart['y'] = $importantPart['height'] - 1;
				$importantPart['height'] = 1;
			}
		}

		if (!$importantPart['width'] || !$importantPart['height'])
		{
			return null;
		}

		return new ImportantPart(
			new Point($importantPart['x'], $importantPart['y']),
			new Box($importantPart['width'], $importantPart['height'])
		);
	}
Prepare important part object.

@return ImportantPart