在JES中裁剪图像(Python)

Question

所以我是Python的新手，我正在使用JES，并试图弄清楚如何裁剪图像。我一直收到"show (croppedPicture)“无效的错误，此时我可以使用任何我能得到的帮助。这是我到目前为止的代码：

def main():
print "Select the Media Folder"
  setMediaFolder()
  print "Select the picture (.jpg) file to crop"
  fileName = pickAFile()
  pict = makePicture(fileName)
  show(pict)

  startX = requestIntegerInRange("Enter X coordinate of upper, left-hand corner",0,getWidth(pict)-1)
  startY = requestIntegerInRange("Enter Y coordinate of upper, left-hand corner",0,getHeight(pict)-1)

  endX = requestIntegerInRange("Enter X coordinate of lower, right-hand corner",startX,getWidth(pict)-1)
  endY = requestIntegerInRange("Enter Y coordinate of lower, right-hand corner",startY,getHeight(pict)-1)      



  print "Please wait while picture is cropped from (",startX,",",startY,") to (",endX,",",endY,")."
  croppedPicture = makeCroppedPicture(pict, startX, startY, endX, endY)
  show(croppedPicture)

  newFileName = getMediaPath('croppedPicture.jpg')
  writePictureTo(croppedPicture, newFileName)

def makeCroppedPicture(pict, startX, startY, endX, endY):
  """ Makes and returns a cropped rectangular region of a picture into a new picture """

  target = makeEmptyPicture

def crop(picture):
  def crop(picture):
  width = getWidth(pict)
  height = getHeight(pict)
  canvas = makeEmptyPicture(width, height)
  targetX = 100
  for sourceX in range(100,30):
    targetY = 100
    for sourceY in range(311,433):
      color = getColor(getPixel(pict, sourceX, sourceY))
      setColor(getPixel(canvas, targetX, targetY),color)
      targetY = targetY + 1
    targetX = targetX + 1
  show(pict)
  return canvas  

  return target   # returns the cropped picture

main() # starts the program

Answer 1

代码的粘贴似乎出了点问题；第2行缺少缩进，第3行有一个虚假的"Add code here“字符串(裁剪()函数的定义也出现了一些奇怪的问题，因为在代码运行之前需要纠正缩进！)。

也就是说，通过删除第29-43行来删除crop()函数，因为它们当前不被使用，那么问题就会变得更容易看到……

   def makeCroppedPicture(pict, startX, startY, endX, endY):
       target = makeEmptyPicture
       return target   # returns the cropped picture

target = makeEmptyPicture行的用法是将变量makeEmptyPicture赋给实际的函数target，而不是调用该函数返回的内容。

感兴趣的是，在post Assigning a function to a variable中有更多关于如何/为什么要这样做的信息。

要解决这个问题，只需在makeEmptyPicture调用中添加两个用于裁剪图像的高度和宽度的参数。注:你可以先硬编码几个数字来检查它是否正常工作。即target = makeEmptyPicture(50, 50)