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feature improvement: improved performance of ImageDraw.floodfill with Python built-in set() datatype.

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This commit is contained in:
yo1995 2018-08-06 18:13:57 +08:00
parent 69918dcbef
commit 24388addb6
1 changed files with 31 additions and 21 deletions
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24
src/PIL/ImageDraw.py
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@ -341,6 +341,7 @@ def floodfill(image, xy, value, border=None, thresh=0):
homogeneous, but similar, colors. homogeneous, but similar, colors.
""" """
# based on an implementation by Eric S. Raymond # based on an implementation by Eric S. Raymond
# amended by yo1995 @20180806
pixel = image.load() pixel = image.load()
x, y = xy x, y = xy
try: try:
@ -350,12 +351,15 @@ def floodfill(image, xy, value, border=None, thresh=0):
pixel[x, y] = value pixel[x, y] = value
except (ValueError, IndexError): except (ValueError, IndexError):
return # seed point outside image return # seed point outside image
edge = [(x, y)] edge = {(x, y)}
full_edge = set() # use a set to record each unique pixel processed
if border is None: if border is None:
while edge: while edge:
newedge = [] new_edge = set()
for (x, y) in edge: for (x, y) in edge: # 4 adjacent method
for (s, t) in ((x+1, y), (x-1, y), (x, y+1), (x, y-1)): for (s, t) in ((x+1, y), (x-1, y), (x, y+1), (x, y-1)):
if (s, t) in full_edge:
continue # if already processed, skip
try: try:
p = pixel[s, t] p = pixel[s, t]
except IndexError: except IndexError:
@ -363,13 +367,17 @@ def floodfill(image, xy, value, border=None, thresh=0):
else: else:
if _color_diff(p, background) <= thresh: if _color_diff(p, background) <= thresh:
pixel[s, t] = value pixel[s, t] = value
newedge.append((s, t)) new_edge.add((s, t))
edge = newedge full_edge.add((s, t))
full_edge = edge # do not record useless pixels to reduce memory consumption
edge = new_edge
else: else:
while edge: while edge:
newedge = [] new_edge = set()
for (x, y) in edge: for (x, y) in edge:
for (s, t) in ((x+1, y), (x-1, y), (x, y+1), (x, y-1)): for (s, t) in ((x+1, y), (x-1, y), (x, y+1), (x, y-1)):
if (s, t) in full_edge:
continue
try: try:
p = pixel[s, t] p = pixel[s, t]
except IndexError: except IndexError:
@ -377,7 +385,9 @@ def floodfill(image, xy, value, border=None, thresh=0):
else: else:
if p != value and p != border: if p != value and p != border:
pixel[s, t] = value pixel[s, t] = value
newedge.append((s, t)) new_edge.add((s, t))
full_edge.add((s, t))
full_edge = edge
edge = newedge edge = newedge