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Pillow/PIL/ImageDraw.py
Andrew Murray a05c2cf7ff Improved ImageDraw documentation
2017-07-16 15:22:46 +10:00

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#
# The Python Imaging Library
# $Id$
#
# drawing interface operations
#
# History:
# 1996-04-13 fl Created (experimental)
# 1996-08-07 fl Filled polygons, ellipses.
# 1996-08-13 fl Added text support
# 1998-06-28 fl Handle I and F images
# 1998-12-29 fl Added arc; use arc primitive to draw ellipses
# 1999-01-10 fl Added shape stuff (experimental)
# 1999-02-06 fl Added bitmap support
# 1999-02-11 fl Changed all primitives to take options
# 1999-02-20 fl Fixed backwards compatibility
# 2000-10-12 fl Copy on write, when necessary
# 2001-02-18 fl Use default ink for bitmap/text also in fill mode
# 2002-10-24 fl Added support for CSS-style color strings
# 2002-12-10 fl Added experimental support for RGBA-on-RGB drawing
# 2002-12-11 fl Refactored low-level drawing API (work in progress)
# 2004-08-26 fl Made Draw() a factory function, added getdraw() support
# 2004-09-04 fl Added width support to line primitive
# 2004-09-10 fl Added font mode handling
# 2006-06-19 fl Added font bearing support (getmask2)
#
# Copyright (c) 1997-2006 by Secret Labs AB
# Copyright (c) 1996-2006 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
import numbers
from . import Image, ImageColor
from ._util import isStringType
"""
A simple 2D drawing interface for PIL images.
<p>
Application code should use the <b>Draw</b> factory, instead of
directly.
"""
class ImageDraw(object):
def __init__(self, im, mode=None):
"""
Create a drawing instance.
:param im: The image to draw in.
:param mode: Optional mode to use for color values. For RGB
images, this argument can be RGB or RGBA (to blend the
drawing into the image). For all other modes, this argument
must be the same as the image mode. If omitted, the mode
defaults to the mode of the image.
"""
im.load()
if im.readonly:
im._copy() # make it writeable
blend = 0
if mode is None:
mode = im.mode
if mode != im.mode:
if mode == "RGBA" and im.mode == "RGB":
blend = 1
else:
raise ValueError("mode mismatch")
if mode == "P":
self.palette = im.palette
else:
self.palette = None
self.im = im.im
self.draw = Image.core.draw(self.im, blend)
self.mode = mode
if mode in ("I", "F"):
self.ink = self.draw.draw_ink(1, mode)
else:
self.ink = self.draw.draw_ink(-1, mode)
if mode in ("1", "P", "I", "F"):
# FIXME: fix Fill2 to properly support matte for I+F images
self.fontmode = "1"
else:
self.fontmode = "L" # aliasing is okay for other modes
self.fill = 0
self.font = None
def getfont(self):
"""
Get the current default font.
:returns: An image font."""
if not self.font:
# FIXME: should add a font repository
from . import ImageFont
self.font = ImageFont.load_default()
return self.font
def _getink(self, ink, fill=None):
if ink is None and fill is None:
if self.fill:
fill = self.ink
else:
ink = self.ink
else:
if ink is not None:
if isStringType(ink):
ink = ImageColor.getcolor(ink, self.mode)
if self.palette and not isinstance(ink, numbers.Number):
ink = self.palette.getcolor(ink)
ink = self.draw.draw_ink(ink, self.mode)
if fill is not None:
if isStringType(fill):
fill = ImageColor.getcolor(fill, self.mode)
if self.palette and not isinstance(fill, numbers.Number):
fill = self.palette.getcolor(fill)
fill = self.draw.draw_ink(fill, self.mode)
return ink, fill
def arc(self, xy, start, end, fill=None):
"""Draw an arc."""
ink, fill = self._getink(fill)
if ink is not None:
self.draw.draw_arc(xy, start, end, ink)
def bitmap(self, xy, bitmap, fill=None):
"""Draw a bitmap."""
bitmap.load()
ink, fill = self._getink(fill)
if ink is None:
ink = fill
if ink is not None:
self.draw.draw_bitmap(xy, bitmap.im, ink)
def chord(self, xy, start, end, fill=None, outline=None):
"""Draw a chord."""
ink, fill = self._getink(outline, fill)
if fill is not None:
self.draw.draw_chord(xy, start, end, fill, 1)
if ink is not None:
self.draw.draw_chord(xy, start, end, ink, 0)
def ellipse(self, xy, fill=None, outline=None):
"""Draw an ellipse."""
ink, fill = self._getink(outline, fill)
if fill is not None:
self.draw.draw_ellipse(xy, fill, 1)
if ink is not None:
self.draw.draw_ellipse(xy, ink, 0)
def line(self, xy, fill=None, width=0):
"""Draw a line, or a connected sequence of line segments."""
ink, fill = self._getink(fill)
if ink is not None:
self.draw.draw_lines(xy, ink, width)
def shape(self, shape, fill=None, outline=None):
"""(Experimental) Draw a shape."""
shape.close()
ink, fill = self._getink(outline, fill)
if fill is not None:
self.draw.draw_outline(shape, fill, 1)
if ink is not None:
self.draw.draw_outline(shape, ink, 0)
def pieslice(self, xy, start, end, fill=None, outline=None):
"""Draw a pieslice."""
ink, fill = self._getink(outline, fill)
if fill is not None:
self.draw.draw_pieslice(xy, start, end, fill, 1)
if ink is not None:
self.draw.draw_pieslice(xy, start, end, ink, 0)
def point(self, xy, fill=None):
"""Draw one or more individual pixels."""
ink, fill = self._getink(fill)
if ink is not None:
self.draw.draw_points(xy, ink)
def polygon(self, xy, fill=None, outline=None):
"""Draw a polygon."""
ink, fill = self._getink(outline, fill)
if fill is not None:
self.draw.draw_polygon(xy, fill, 1)
if ink is not None:
self.draw.draw_polygon(xy, ink, 0)
def rectangle(self, xy, fill=None, outline=None):
"""Draw a rectangle."""
ink, fill = self._getink(outline, fill)
if fill is not None:
self.draw.draw_rectangle(xy, fill, 1)
if ink is not None:
self.draw.draw_rectangle(xy, ink, 0)
def _multiline_check(self, text):
"""Draw text."""
split_character = "\n" if isinstance(text, str) else b"\n"
return split_character in text
def _multiline_split(self, text):
split_character = "\n" if isinstance(text, str) else b"\n"
return text.split(split_character)
def text(self, xy, text, fill=None, font=None, anchor=None,
*args, **kwargs):
if self._multiline_check(text):
return self.multiline_text(xy, text, fill, font, anchor,
*args, **kwargs)
ink, fill = self._getink(fill)
if font is None:
font = self.getfont()
if ink is None:
ink = fill
if ink is not None:
try:
mask, offset = font.getmask2(text, self.fontmode, *args, **kwargs)
xy = xy[0] + offset[0], xy[1] + offset[1]
except AttributeError:
try:
mask = font.getmask(text, self.fontmode, *args, **kwargs)
except TypeError:
mask = font.getmask(text)
self.draw.draw_bitmap(xy, mask, ink)
def multiline_text(self, xy, text, fill=None, font=None, anchor=None,
spacing=4, align="left", direction=None, features=None):
widths = []
max_width = 0
lines = self._multiline_split(text)
line_spacing = self.textsize('A', font=font)[1] + spacing
for line in lines:
line_width, line_height = self.textsize(line, font)
widths.append(line_width)
max_width = max(max_width, line_width)
left, top = xy
for idx, line in enumerate(lines):
if align == "left":
pass # left = x
elif align == "center":
left += (max_width - widths[idx]) / 2.0
elif align == "right":
left += (max_width - widths[idx])
else:
assert False, 'align must be "left", "center" or "right"'
self.text((left, top), line, fill, font, anchor,
direction=direction, features=features)
top += line_spacing
left = xy[0]
def textsize(self, text, font=None, spacing=4, direction=None,
features=None):
"""Get the size of a given string, in pixels."""
if self._multiline_check(text):
return self.multiline_textsize(text, font, spacing,
direction, features)
if font is None:
font = self.getfont()
return font.getsize(text, direction, features)
def multiline_textsize(self, text, font=None, spacing=4, direction=None,
features=None):
max_width = 0
lines = self._multiline_split(text)
line_spacing = self.textsize('A', font=font)[1] + spacing
for line in lines:
line_width, line_height = self.textsize(line, font, spacing,
direction, features)
max_width = max(max_width, line_width)
return max_width, len(lines)*line_spacing
def Draw(im, mode=None):
"""
A simple 2D drawing interface for PIL images.
:param im: The image to draw in.
:param mode: Optional mode to use for color values. For RGB
images, this argument can be RGB or RGBA (to blend the
drawing into the image). For all other modes, this argument
must be the same as the image mode. If omitted, the mode
defaults to the mode of the image.
"""
try:
return im.getdraw(mode)
except AttributeError:
return ImageDraw(im, mode)
# experimental access to the outline API
try:
Outline = Image.core.outline
except AttributeError:
Outline = None
def getdraw(im=None, hints=None):
"""
(Experimental) A more advanced 2D drawing interface for PIL images,
based on the WCK interface.
:param im: The image to draw in.
:param hints: An optional list of hints.
:returns: A (drawing context, drawing resource factory) tuple.
"""
# FIXME: this needs more work!
# FIXME: come up with a better 'hints' scheme.
handler = None
if not hints or "nicest" in hints:
try:
from . import _imagingagg as handler
except ImportError:
pass
if handler is None:
from . import ImageDraw2 as handler
if im:
im = handler.Draw(im)
return im, handler
def floodfill(image, xy, value, border=None, thresh=0):
"""
(experimental) Fills a bounded region with a given color.
:param image: Target image.
:param xy: Seed position (a 2-item coordinate tuple).
:param value: Fill color.
:param border: Optional border value. If given, the region consists of
pixels with a color different from the border color. If not given,
the region consists of pixels having the same color as the seed
pixel.
:param thresh: Optional threshold value which specifies a maximum
tolerable difference of a pixel value from the 'background' in
order for it to be replaced. Useful for filling regions of non-
homogeneous, but similar, colors.
"""
# based on an implementation by Eric S. Raymond
pixel = image.load()
x, y = xy
try:
background = pixel[x, y]
if _color_diff(value, background) <= thresh:
return # seed point already has fill color
pixel[x, y] = value
except (ValueError, IndexError):
return # seed point outside image
edge = [(x, y)]
if border is None:
while edge:
newedge = []
for (x, y) in edge:
for (s, t) in ((x+1, y), (x-1, y), (x, y+1), (x, y-1)):
try:
p = pixel[s, t]
except IndexError:
pass
else:
if _color_diff(p, background) <= thresh:
pixel[s, t] = value
newedge.append((s, t))
edge = newedge
else:
while edge:
newedge = []
for (x, y) in edge:
for (s, t) in ((x+1, y), (x-1, y), (x, y+1), (x, y-1)):
try:
p = pixel[s, t]
except IndexError:
pass
else:
if p != value and p != border:
pixel[s, t] = value
newedge.append((s, t))
edge = newedge
def _color_diff(rgb1, rgb2):
"""
Uses 1-norm distance to calculate difference between two rgb values.
"""
return abs(rgb1[0]-rgb2[0]) + abs(rgb1[1]-rgb2[1]) + abs(rgb1[2]-rgb2[2])
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