Class: RMExtensions::Layout

Inherits:
Object
  • Object
show all
Defined in:
lib/motion/layout.rb

Constant Summary collapse

ATTRIBUTE_LOOKUP = 
{
  "left" => NSLayoutAttributeLeft,
  "right" => NSLayoutAttributeRight,
  "top" => NSLayoutAttributeTop,
  "bottom" => NSLayoutAttributeBottom,
  "leading" => NSLayoutAttributeLeading,
  "trailing" => NSLayoutAttributeTrailing,
  "width" => NSLayoutAttributeWidth,
  "height" => NSLayoutAttributeHeight,
  "centerX" => NSLayoutAttributeCenterX,
  "centerY" => NSLayoutAttributeCenterY,
  "baseline" => NSLayoutAttributeBaseline,
  nil => NSLayoutAttributeNotAnAttribute
}
ATTRIBUTE_LOOKUP_INVERSE = 
ATTRIBUTE_LOOKUP.invert

{
  "<=" => NSLayoutRelationLessThanOrEqual,
  "==" => NSLayoutRelationEqual,
  ">=" => NSLayoutRelationGreaterThanOrEqual
}

RELATED_BY_LOOKUP.invert
PRIORITY_LOOKUP = 
{
  "required" => UILayoutPriorityRequired, # = 1000
  "high" => UILayoutPriorityDefaultHigh, # = 750
  "low" => UILayoutPriorityDefaultLow, # = 250
  "fit" => UILayoutPriorityFittingSizeLevel # = 50
}
PRIORITY_LOOKUP_INVERSE = 
PRIORITY_LOOKUP.invert
AXIS_LOOKUP = 
{
  "h" => UILayoutConstraintAxisHorizontal,
  "v" => UILayoutConstraintAxisVertical
}

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Layout

Returns a new instance of Layout.



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# File 'lib/motion/layout.rb', line 43

def initialize
  if block_given?
    yield self
  end
end

Instance Method Details

#describe(constraint) ⇒ Object 



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# File 'lib/motion/layout.rb', line 218

def describe(constraint)
  subviews_inverse = subviews.invert
  item = subviews_inverse[constraint.firstItem]
  item_attribute = ATTRIBUTE_LOOKUP_INVERSE[constraint.firstAttribute]
  related_by = RELATED_BY_LOOKUP_INVERSE[constraint.relation]
  to_item = subviews_inverse[constraint.secondItem]
  to_item_attribute = ATTRIBUTE_LOOKUP_INVERSE[constraint.secondAttribute]
  multiplier = constraint.multiplier
  constant = constraint.constant
  priority = PRIORITY_LOOKUP_INVERSE[constraint.priority] || constraint.priority
  "#{item}.#{item_attribute} #{related_by} #{to_item}.#{to_item_attribute} * #{multiplier} + #{constant} @ #{priority}"
end

#eq(str) ⇒ Object

Constraints are of the form “view1.attr1 <relation> view2.attr2 * multiplier + constant @ priority”



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# File 'lib/motion/layout.rb', line 77

def eq(str)
  item = nil
  item_attribute = nil
  related_by = nil
  to_item = nil
  to_item_attribute = nil
  multiplier = nil
  constant = nil
  
  parts = str.split("#", 2).first.split(" ").select { |x| !x.empty? }

  debug = parts.delete("?")

  # first part should always be view1.attr1
  part = parts.shift
  item, item_attribute = part.split(".", 2)

  # second part should always be relation
  related_by = parts.shift

  # now things get more complicated

  # look for priority
  if idx = parts.index("@")
    priority = parts[idx + 1]
    parts.delete_at(idx)
    parts.delete_at(idx)
  end

  # look for negative or positive constant
  if idx = parts.index("-")
    constant = "-#{parts[idx + 1]}"
    parts.delete_at(idx)
    parts.delete_at(idx)
  elsif idx = parts.index("+")
    constant = parts[idx + 1]
    parts.delete_at(idx)
    parts.delete_at(idx)
  end

  # look for multiplier
  if idx = parts.index("*")
    multiplier = parts[idx + 1]
    parts.delete_at(idx)
    parts.delete_at(idx)
  end

  # now we need to_item, to_item_attribute

  if part = parts.shift
    # if part includes a . it could be either view2.attr2 or a float like 10.5
    l, r = part.split(".", 2)
    if !r || (r && r =~ /\d/)
      # assume a solo constant was on the right side
      constant = part
    else
      # assume view2.attr2
      to_item, to_item_attribute = l, r
    end
  end

  # if we dont have to_item and the item_attribute is something that requires a to_item, then
  # assume superview
  if !to_item
    unless item_attribute == "height" || item_attribute == "width"
      to_item = "view"
      to_item_attribute = item_attribute
    end
  end

  # normalize

  res_item = view_for_item(item)
  res_constant = constant ? Float(PRIORITY_LOOKUP[constant] || constant) : 0.0

  if res_item
    case item_attribute
    when "resistH"
      return res_item.setContentCompressionResistancePriority(res_constant, forAxis:UILayoutConstraintAxisHorizontal)
    when "resistV"
      return res_item.setContentCompressionResistancePriority(res_constant, forAxis:UILayoutConstraintAxisVertical)
    when "hugH"
      return res_item.setContentHuggingPriority(res_constant, forAxis:UILayoutConstraintAxisHorizontal)
    when "hugV"
      return res_item.setContentHuggingPriority(res_constant, forAxis:UILayoutConstraintAxisVertical)
    end
  end

  res_item_attribute = ATTRIBUTE_LOOKUP[item_attribute]
  res_related_by = RELATED_BY_LOOKUP[related_by]
  res_to_item = to_item ? view_for_item(to_item) : nil
  res_to_item_attribute = ATTRIBUTE_LOOKUP[to_item_attribute]
  res_multiplier = multiplier ? Float(multiplier) : 1.0
  res_priority = priority ? Integer(PRIORITY_LOOKUP[priority] || priority) : nil

  errors = []
  errors.push("Invalid view1: #{item}") unless res_item
  errors.push("Invalid attr1: #{item_attribute}") unless res_item_attribute
  errors.push("Invalid relatedBy: #{related_by}") unless res_related_by
  errors.push("Invalid view2: #{to_item}") if to_item && !res_to_item
  errors.push("Invalid attr2: #{to_item_attribute}") unless res_to_item_attribute

  if errors.size > 0 || debug
    p "======================== constraint debug ========================"
    p "given:"
    p "  #{str}"
    p "interpreted:"
    p "  item:                #{item}"
    p "  item_attribute:      #{item_attribute}"
    p "  related_by:          #{related_by}"
    p "  to_item:             #{to_item}"
    p "  to_item_attribute:   #{to_item_attribute}"
    p "  multiplier:          #{multiplier}"
    p "  constant:            #{constant}"
    p "  priority:            #{priority}"
  end

  if errors.size > 0
    raise(errors.join(", "))
  end

  constraint = NSLayoutConstraint.constraintWithItem(res_item,
     attribute:res_item_attribute,
     relatedBy:res_related_by,
        toItem:res_to_item,
     attribute:res_to_item_attribute,
    multiplier:res_multiplier,
      constant:res_constant)
  if res_priority
    constraint.priority = res_priority
  end

  if debug
    p "implemented:"
    p "  #{constraint.description}"
  end

  @view.addConstraint(constraint)
  constraint
end

#eqs(str) ⇒ Object 



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# File 'lib/motion/layout.rb', line 70

def eqs(str)
  str.split("\n").map(&:strip).select { |x| !x.empty? }.map do |line|
    eq(line)
  end
end

#subviews(subviews) ⇒ Object 



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# File 'lib/motion/layout.rb', line 57

def subviews(subviews)
  @subviews = subviews
  @subviews.values.each do |subview|
    subview.translatesAutoresizingMaskIntoConstraints = false
    @view.addSubview(subview)
  end
  @subviews
end

#subviews=(views) ⇒ Object 



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# File 'lib/motion/layout.rb', line 66

def subviews=(views)
  subviews(views)
end

#view(view) ⇒ Object 



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# File 'lib/motion/layout.rb', line 49

def view(view)
  @view = view
end

#view=(v) ⇒ Object 



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# File 'lib/motion/layout.rb', line 53

def view=(v)
  view(v)
end