使用Python进行图像裁剪
我刚开始学习Python编程，现在正在写一个程序，目的是裁剪用户输入的图片，然后把裁剪后的图片保存到指定位置。目前，我是通过结合使用PIL和pygame来实现这个功能。但是，我遇到了一个问题：在pygame窗口中选择图片时，选择区域是完全不透明的，我无法看到我正在选择的区域。这让我的老板很困扰，因为他希望在选择时能够看到下面的内容。为了让大家更好地理解这个问题，我在这里写下我的代码：
import pygame, sys
from PIL import Image
pygame.init()
def displayImage( screen, px, topleft):
screen.blit(px, px.get_rect())
if topleft:
pygame.draw.rect( screen, (128,128,128), pygame.Rect(topleft[0], topleft[1], pygame.mouse.get_pos()[0] - topleft[0], pygame.mouse.get_pos()[1] - topleft[1]))
pygame.display.flip()
def setup(path):
px = pygame.image.load(path)
screen = pygame.display.set_mode( px.get_rect()[2:] )
screen.blit(px, px.get_rect())
pygame.display.flip()
return screen, px
def mainLoop(screen, px):
topleft = None
bottomright = None
n=0
while n!=1:
for event in pygame.event.get():
if event.type == pygame.MOUSEBUTTONUP:
if not topleft:
topleft = event.pos
else:
bottomright = event.pos
n=1
displayImage(screen, px, topleft)
return ( topleft + bottomright )
if __name__ == "__main__":
input_loc="C:\pic1.PNG"
output_loc="C:\pic2.PNG"
screen, px = setup(input_loc)
left, upper, right, lower = mainLoop(screen, px)
im = Image.open(input_loc)
im = im.crop(( left, upper, right, lower))
pygame.display.quit()
im.save(output_loc)
任何帮助都非常感谢。祝好。
2 个回答
1
samplebias的回答对我帮助很大。我在这个基础上进行了扩展，增加了对大图片的缩放和平移功能。
import pygame, sys
from pygame.locals import K_a, K_s,K_w,K_d,K_LEFTBRACKET,K_RIGHTBRACKET
from PIL import Image
pygame.init()
BG_COLOR = (0,0,0)
def displayRect(screen, px, topleft, prior,pos,scale):
# ensure that the rect always has positive width, height
#topleft = [(val-pos[i])/scale for i,val in enumerate(topleft)]
topleft = [(val/scale-pos[i]) for i,val in enumerate(topleft)]
x, y = topleft
bottomright = pygame.mouse.get_pos()
width = bottomright[0] - topleft[0]
height = bottomright[1] - topleft[1]
if width < 0:
x += width
width = abs(width)
if height < 0:
y += height
height = abs(height)
# eliminate redundant drawing cycles (when mouse isn't moving)
current = x, y, width, height
if not (width and height):
return current
if current == prior:
return current
# draw transparent box and blit it onto canvas
rect = px.get_rect()
px = pygame.transform.scale(px,[rect.width/scale, rect.height/scale])
screen.blit(px, (rect[0]-pos[0],rect[1]-pos[1]))
im = pygame.Surface((width, height))
im.fill((128, 128, 128))
pygame.draw.rect(im, (32, 32, 32), im.get_rect(), 1)
im.set_alpha(128)
screen.blit(im, (x, y))
pygame.display.flip()
# return current box extents
return (x, y, width, height)
def setup(px):
screen = pygame.display.set_mode( px.get_rect()[2:] )
screen.blit(px, px.get_rect())
pygame.display.flip()
return screen, px
def move(pos,scale,px,screen):
x,y = pos
#print pos,x
rect = px.get_rect()
screen.fill(BG_COLOR)
px = pygame.transform.scale(px,[rect.width/scale, rect.height/scale])
screen.blit(px, (rect[0]-x,rect[1]-y))
pygame.display.flip()
#px.rect.topleft = pr.rect.topleft[0] - x,
def mainLoop(screen, px, filelist):
topleft = bottomright = prior = None
n=0
scale = 1
pos = [0,0]
while n!=1:
for event in pygame.event.get():
if event.type == pygame.MOUSEBUTTONUP:
if not topleft:
topleft = [(val+pos[i])*scale for i,val in enumerate(event.pos)]
print "tr: ",topleft
else:
bottomright = [(val+pos[i])*scale for i,val in enumerate(event.pos)]
print "br: ",bottomright
n=1
if event.type == pygame.KEYDOWN and event.key == K_a:
pos = [pos[0]-200,pos[1]]
move(pos,scale,px,screen)
if event.type == pygame.KEYDOWN and event.key == K_d:
pos = [pos[0]+200,pos[1]]
move(pos,scale,px,screen)
if event.type == pygame.KEYDOWN and event.key == K_w:
pos = [pos[0],pos[1]-200]
move(pos,scale,px,screen)
if event.type == pygame.KEYDOWN and event.key == K_s:
pos = [pos[0],pos[1]+200]
move(pos,scale,px,screen)
if event.type == pygame.KEYDOWN and event.key == K_RIGHTBRACKET:
scale = scale/1.25
move(pos,scale,px,screen)
if event.type == pygame.KEYDOWN and event.key == K_LEFTBRACKET:
scale = scale*1.25
move(pos,scale,px,screen)
if topleft:
prior = displayRect(screen, px, topleft, prior,pos,scale)
return ( topleft + bottomright )
使用samplebias提供的main函数。
谢谢Stack Overflow!
14
我快速看了一下，并顺便修复了一些其他问题。简单来说，我的修改做了以下几件事：
- 在一个临时的图像上画出边框框，设置它的透明度，然后把这个框覆盖到主图像上。
- 避免不必要的绘图循环（当鼠标不动的时候，就没有必要再画一遍同样的图像）。
- 确保宽度和高度始终是正数。如果在拖动鼠标向左或向上时绘制矩形，你的代码可能会得到负的宽度和/或高度，这样在尝试生成最终图像时就会出错。
这是运行修复后代码的截图：
我把代码分成了两部分，以避免出现滚动条：
import pygame, sys
from PIL import Image
pygame.init()
def displayImage(screen, px, topleft, prior):
# ensure that the rect always has positive width, height
x, y = topleft
width = pygame.mouse.get_pos()[0] - topleft[0]
height = pygame.mouse.get_pos()[1] - topleft[1]
if width < 0:
x += width
width = abs(width)
if height < 0:
y += height
height = abs(height)
# eliminate redundant drawing cycles (when mouse isn't moving)
current = x, y, width, height
if not (width and height):
return current
if current == prior:
return current
# draw transparent box and blit it onto canvas
screen.blit(px, px.get_rect())
im = pygame.Surface((width, height))
im.fill((128, 128, 128))
pygame.draw.rect(im, (32, 32, 32), im.get_rect(), 1)
im.set_alpha(128)
screen.blit(im, (x, y))
pygame.display.flip()
# return current box extents
return (x, y, width, height)
第二部分（接在上面）：
def setup(path):
px = pygame.image.load(path)
screen = pygame.display.set_mode( px.get_rect()[2:] )
screen.blit(px, px.get_rect())
pygame.display.flip()
return screen, px
def mainLoop(screen, px):
topleft = bottomright = prior = None
n=0
while n!=1:
for event in pygame.event.get():
if event.type == pygame.MOUSEBUTTONUP:
if not topleft:
topleft = event.pos
else:
bottomright = event.pos
n=1
if topleft:
prior = displayImage(screen, px, topleft, prior)
return ( topleft + bottomright )
if __name__ == "__main__":
input_loc = 'stack.png'
output_loc = 'out.png'
screen, px = setup(input_loc)
left, upper, right, lower = mainLoop(screen, px)
# ensure output rect always has positive width, height
if right < left:
left, right = right, left
if lower < upper:
lower, upper = upper, lower
im = Image.open(input_loc)
im = im.crop(( left, upper, right, lower))
pygame.display.quit()
im.save(output_loc)