(PECL gmagick >= Unknown)
Gmagick::chopimage — Removes a region of an image and trims
Removes a region of an image and collapses the image to occupy the removed portion.
widthWidth of the chopped area
heightHeight of the chopped area
xX origo of the chopped area
yY origo of the chopped area
The chopped Gmagick object
错误时抛出 GmagickException。