用python画渐变的圆_Python成像库(PIL)绘图 – 带渐变的圆角矩形

这是一种非常强力的方法,但它完成了工作.产生梯度的代码是从

here借来的.

from PIL import Image, ImageDraw

def channel(i, c, size, startFill, stopFill):

"""calculate the value of a single color channel for a single pixel"""

return startFill[c] + int((i * 1.0 / size) * (stopFill[c] - startFill[c]))

def color(i, size, startFill, stopFill):

"""calculate the RGB value of a single pixel"""

return tuple([channel(i, c, size, startFill, stopFill) for c in range(3)])

def round_corner(radius):

"""Draw a round corner"""

corner = Image.new('RGBA', (radius, radius), (0, 0, 0, 0))

draw = ImageDraw.Draw(corner)

draw.pieslice((0, 0, radius * 2, radius * 2), 180, 270, fill="blue")

return corner

def apply_grad_to_corner(corner, gradient, backwards = False, topBottom = False):

width, height = corner.size

widthIter = range(width)

if backwards:

widthIter.reverse()

for i in xrange(height):

gradPos = 0

for j in widthIter:

if topBottom:

pos = (i,j)

else:

pos = (j,i)

pix = corner.getpixel(pos)

gradPos+=1

if pix[3] != 0:

corner.putpixel(pos,gradient[gradPos])

return corner

def round_rectangle(size, radius, startFill, stopFill, runTopBottom = False):

"""Draw a rounded rectangle"""

width, height = size

rectangle = Image.new('RGBA', size)

if runTopBottom:

si = height

else:

si = width

gradient = [ color(i, width, startFill, stopFill) for i in xrange(si) ]

if runTopBottom:

modGrad = []

for i in xrange(height):

modGrad += [gradient[i]] * width

rectangle.putdata(modGrad)

else:

rectangle.putdata(gradient*height)

origCorner = round_corner(radius)

# upper left

corner = origCorner

apply_grad_to_corner(corner,gradient,False,runTopBottom)

rectangle.paste(corner, (0, 0))

# lower left

if runTopBottom:

gradient.reverse()

backwards = True

else:

backwards = False

corner = origCorner.rotate(90)

apply_grad_to_corner(corner,gradient,backwards,runTopBottom)

rectangle.paste(corner, (0, height - radius))

# lower right

if not runTopBottom:

gradient.reverse()

corner = origCorner.rotate(180)

apply_grad_to_corner(corner,gradient,True,runTopBottom)

rectangle.paste(corner, (width - radius, height - radius))

# upper right

if runTopBottom:

gradient.reverse()

backwards = False

else:

backwards = True

corner = origCorner.rotate(270)

apply_grad_to_corner(corner,gradient,backwards,runTopBottom)

rectangle.paste(corner, (width - radius, 0))

return rectangle

img = round_rectangle((200, 200), 70, (255,0,0), (0,255,0), True)

img.save("test.png", 'PNG')

从左到右运行(runTopBottom = False)：

从上到下运行(runTopBottom = True)：

最后

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