from core.lib.png import Reader, Writer, write_chunks
import pickle
import sys
from core.appfw.transforms import *

filename = r"C:\path\to\image.png"
r = Reader(filename=filename)


#newChunk = ('tEXt',pickle.dumps([[Attributes.TYPE_SEARCH_PREV, {'value':Attributes.SPACIAL_ABOVE, 'proximity':50}]\
#                                    ]))

#newChunk = ('tEXt',pickle.dumps([[Attributes.SIMILARITY, {'value':1.0}]]))


transforms = {
                Transforms.CONTEXT_PREVIOUS: [ \
                    RegionNearby(10),
                                              ], \
                Transforms.CONTEXT_CURRENT: [ \
                   PatternSimilarity(0.75),
#                    PatternTargetOffset(0,-10)
                                             ], \
                Transforms.CONTEXT_NEXT: [ \
#                    RegionBelow(200),
#                    RegionLeft()
#                    RegionNearby(10)
                                          ] \
              }

newChunk = ('tEXt',pickle.dumps(transforms))


found = False
chunks = []
for chunk in r.chunks():

    print chunk
    if chunk[0] == 'tEXt':
        #print 'here', chunk
        chunk = newChunk
        found = True
    elif chunk[0] == 'IEND':
        if not found:
            chunks.append(newChunk)

    chunks.append(chunk)


f=open(filename, 'wb')
write_chunks(f, chunks)