scrollify.py

import xml.etree.ElementTree as ET
import xml.dom.minidom as minidom
import sys
import uuid

def main(argv):
  xibPath = ''
  tree = ''
  attemptFixup = False
  try:
    xibPath = argv[0]
    if(len(argv) == 2):
      attemptFixup = argv[1] == '--attempt-fixup'
    tree = ET.parse(xibPath)
  except Exception, e:
    print e
    sys.exit(2)

  # Returns a string of the format xxx-xx-xxx
  def getUUID():
    myid = str(uuid.uuid4()).strip('-')
    myid = myid[:8]
    myid = myid[:3] + '-' + myid[3:5] + '-' + myid[5:8]
    return myid

  '''
  copy and paste from http://effbot.org/zone/element-lib.htm#prettyprint
  it walks your tree and adds spaces and newlines so the tree is
  printed in a nice way
  '''
  def indent(elem, level=0):
    i = "\n" + level*"  "
    if len(elem):
      if not elem.text or not elem.text.strip():
        elem.text = i + "  "
      if not elem.tail or not elem.tail.strip():
        elem.tail = i
      for elem in elem:
        indent(elem, level+1)
      if not elem.tail or not elem.tail.strip():
        elem.tail = i
    else:
      if level and (not elem.tail or not elem.tail.strip()):
        elem.tail = i

  # Grab some relevant elements
  document = tree.getroot()
  objects = document.find("objects")
  superview = objects.find("view")
  superviewframe = superview.find('rect')
  superviewId = superview.attrib['id']
  subviews = superview.find("subviews")
  constraints = superview.find("constraints")

  if superview == None or subviews == None:
    print 'Cannot scrollify a xib with no views'
    sys.exit(2)

  # Keep track of the constraints currently linked to the superview
  constraintsToConvert = constraints.findall(".//constraint[@secondItem='" + superviewId+ "']")
  for constraint in constraints:
    # Some constraints which point to the superview don't specify a 'firstItem' attribute
    if constraint.get('firstItem') == None and constraint.get('secondItem') in (o.get('id') for o in subviews):
      constraintsToConvert.append(constraint)

  for constraint in constraintsToConvert:
    constraints.remove(constraint)

  # Keep track of the bottom-most subview for later
  currentBottom = 0
  bottomMostView = subviews[0]
  for view in subviews.findall(".//rect[@key='frame']/.."):
    rect = view.find("rect")
    bottom = float(rect.attrib['y']) + float(rect.attrib['height'])
    if bottom >= currentBottom:
      currentBottom = bottom
      bottomMostView = view

  # Create the scrollview
  scrollviewId = getUUID()
  scrollview = ET.Element('scrollView', {'clipsSubviews': 'YES', 'contentMode': 'scaleToFill', 'id' : scrollviewId, 'multipleTouchEnabled': 'YES', 'translatesAutoresizingMaskIntoConstraints': 'NO'})
  scrollview.insert(0, superviewframe)

  # Add a constraints section on the scrollview
  scrollviewConstraints = ET.Element('constraints')
  scrollview.append(scrollviewConstraints)

  # Add a subviews section on the scrollview
  scrollviewSubviews = ET.Element('subviews')
  scrollview.append(scrollviewSubviews)

  # Add scrollview constraints to superview
  for constraintAttribute in ['leading', 'trailing', 'top', 'bottom']:
    scrollviewConstraint = ET.Element('constraint', {'firstItem': scrollviewId, 'firstAttribute': constraintAttribute, 'secondItem': superviewId, 'secondAttribute': constraintAttribute, 'id': getUUID()})
    constraints.insert(0, scrollviewConstraint)

  # Create the container view
  containerViewId = getUUID()
  containerview = ET.Element('view', {'contentMode': 'scaleToFill', 'translatesAutoresizingMaskIntoConstraints': 'NO', 'id': containerViewId})
  # Add it to the scrollview's subviews
  scrollviewSubviews.insert(1, containerview)
  # Give it a background colour
  bgColour = ET.Element('color', {'key': 'backgroundColor', 'white': '1', 'alpha': '1', 'colorSpace': 'calibratedWhite'})
  containerview.insert(0, bgColour)
  # And a frame
  containerFrame = ET.Element('rect', {'key': 'frame', 'x': '0', 'y': '0', 'width': superviewframe.attrib['width'], 'height': str(currentBottom)})
  containerview.insert(1, containerFrame)
  # And its own subviews section
  containerSubviews = ET.Element('subviews')
  containerview.insert(2, containerSubviews)
  # And its own constraints section
  containerConstraints = ET.Element('constraints')
  containerview.insert(3, containerConstraints)

  # Move the original subviews to the container
  for view in subviews:
    containerSubviews.append(view)

  # Clear the old subviews
  subviews.clear()

  # Update the original subview constraints to point to our container
  for constraint in constraintsToConvert:
    if constraint.get('firstItem') != None:
      constraint.set('secondItem', containerViewId)
    containerConstraints.append(constraint)

  # Add width constraint for our container
  widthConstraint = ET.Element('constraint', {'firstItem': containerViewId, 'firstAttribute': 'width', 'secondItem': superviewId, 'secondAttribute': 'width', 'id': getUUID()})
  constraints.append(widthConstraint)

  # Set the container constraints on the scrollview
  for constraintAttribute in ['leading', 'trailing', 'top', 'bottom']:
    containerConstraint = ET.Element('constraint', {'firstItem': containerViewId, 'firstAttribute': constraintAttribute, 'secondItem': scrollviewId, 'secondAttribute': constraintAttribute, 'id': getUUID()})
    scrollviewConstraints.insert(0, containerConstraint)
  
  if attemptFixup:
    # Constrain the bottom of the container to the bottom-most item in our hierarchy
    bottomConstraint = ET.Element('constraint', {'firstItem': containerViewId, 'firstAttribute': 'bottom', 'secondItem': bottomMostView.get('id'), 'secondAttribute': 'bottom', 'id': getUUID()})
    containerConstraints.append(bottomConstraint)

  # Finally add the scrollview to the hierarchy
  subviews.insert(0, scrollview)

  indent(document)
  tree.write(xibPath, xml_declaration=True, encoding='utf-8', method="xml")

if __name__ == "__main__":
  main(sys.argv[1:])