terom@85: """
terom@85:     State for thumbnails; derivates of Images
terom@85: """
terom@85: 
terom@125: import filesystem, exif
terom@85: 
terom@85: import PIL.Image
terom@85: 
terom@85: class Thumbnail (filesystem.File) :
terom@85:     """
terom@85:         A Thumbnail is a derivate of an Image, usually resized to some other size.
terom@85:     """
terom@85: 
terom@115:     def __init__ (self, image, subdir, target_size) :
terom@85:         """
terom@85:             Initialize to link against the given `image`.
terom@85:             
terom@85:             `subdir` specifies the directory to store this thumbnail in.
terom@115:             `target_size` determines the target resolution of the output thumbnail.
terom@85:         """
terom@85: 
terom@95:         # our file path, image name inside of the given subdir
terom@95:         super(Thumbnail, self).__init__(subdir, image.fsname)
terom@85: 
terom@85:         # store
terom@85:         self.image = image
terom@115:         self.target_size = target_size
terom@85: 
terom@85:     def stale (self) :
terom@85:         """
terom@85:             Tests if this thumbnail is stale
terom@85:         """
terom@85:         
terom@95:         if self.image.older_than(self) :
terom@95:             # both exist and this is newer
terom@95:             return False
terom@95:         
terom@95:         else :
terom@95:             # this thumb doesn't exist or is older
terom@95:             return True
terom@115:     
terom@125:     def calcsize (self, size) :
terom@115:         """
terom@125:             Compute the *real* size of this thumbnail, from the give actual size and our target size.
terom@115: 
terom@115:             Preserves the aspect ratio etc.
terom@115:         """
terom@115:         
terom@125:         # initial image size
terom@125:         width, height = size
terom@115: 
terom@115:         # target size
terom@115:         thumb_width, thumb_height = self.target_size
terom@115: 
terom@115:         # calc new size, preserving aspect ratio
terom@125:         # calculations ripped from PIL.Image.thumbnail :)
terom@125:         if width > thumb_width : 
terom@125:             height = max(height * thumb_width / width, 1)
terom@115:             width = thumb_width
terom@125:  
terom@125:         if height > thumb_height :
terom@125:             width = max(width * thumb_height / height, 1)
terom@115:             height = thumb_height
terom@115:         
terom@115:         return width, height 
terom@123:    
terom@123:     ## operations
terom@122:     def resize (self, img) :
terom@122:         """
terom@125:             Resize the given image as needed.
terom@122:         """
terom@122: 
terom@125:         return img.resize(self.calcsize(img.size), resample=PIL.Image.ANTIALIAS)
terom@122:     
terom@125:     def transform (self, img, orient_info) :
terom@122:         """
terom@125:             Transform this image into the output version, resizing, rotating and mirroring in a single step.
terom@122:         """
terom@122:         
terom@125:         # get sizes
terom@125:         img_width, img_height = img_size = img.size
terom@125:         
terom@122:         # unpack
terom@122:         mirroring, rotation = orient_info
terom@125:  
terom@122:         if mirroring :
terom@125:             # XXX: does anyone actually use this? Untested
terom@125:             # interaction with rotate is probably wrong
terom@125:             p0, p1 = {
terom@125:                 exif.MIRROR_HORIZONTAL: ((0, img_height), (img_width, 0)),
terom@125:                 exif.MIRROR_VERTICAL:   ((img_width, 0), (0, img_height)),
terom@125:             }
terom@125: 
terom@125:         if rotation in (exif.ROTATE_90, exif.ROTATE_270) :
terom@125:             # flip the dimensions to take rotate into account
terom@125:             img_size = img_height, img_width
terom@125: 
terom@125:         # calc new size
terom@125:         thumb_size = self.calcsize(img_size)
terom@125:  
terom@125:         if rotation in (exif.ROTATE_90, exif.ROTATE_270) :
terom@125:             # flip the dimensions back before rotate
terom@125:             thumb_size = thumb_size[1], thumb_size[0]
terom@125:        
terom@125:         if mirroring :
terom@125:             # perform the transform, can't use ANTIALIAS here :/
terom@125:             img = img.transform(thumb_size, PIL.Image.EXTENT, p0 + p1, PIL.Image.NEAREST)
terom@125: 
terom@125:         else :
terom@125:             # resize with ANTIALIAS
terom@125:             img = img.resize(thumb_size, resample=PIL.Image.ANTIALIAS)
terom@122: 
terom@122:         if rotation :
terom@125:             # transform can't rotate
terom@122:             # since these are in steps of 90 degrees, it should keep the right size
terom@122:             # but gah, PIL wants these as counter-clockwise!
terom@122:             img = img.rotate(360 - rotation)
terom@122:         
terom@122:         return img
terom@85: 
terom@85:     def update (self) :
terom@85:         """
terom@115:             Render new output thumbnail.
terom@85:         """
terom@85: 
terom@122:         # start with origional image
terom@122:         img = self.image.img
terom@122: 
terom@125:         if self.image.orientation and (self.image.orientation[0] or self.image.orientation[1]) :
terom@125:             # rotate
terom@125:             img = self.transform(img, self.image.orientation)
terom@122: 
terom@125:         else :
terom@125:             # just create resized copy of main image, using our size
terom@125:             img = self.resize(img)
terom@85: 
terom@115:         # write it out
terom@122:         img.save(self.path)
terom@95: