(PECL gmagick >= Unknown)
Gmagick::setsize — Sets the size of the Gmagick object
   Sets the size of the Gmagick object. Set it before you read a raw image format such as Gmagick::COLORSPACE_RGB,
   Gmagick::COLORSPACE_GRAY, or Gmagick::COLORSPACE_CMYK. 
  
columnsThe width in pixels.
rowsThe height in pixels.
The Gmagick object.
错误时抛出 GmagickException。
