Class: RMX::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 = 
{
  "max" => UILayoutPriorityRequired, # = 1000
  "required" => UILayoutPriorityRequired, # = 1000
  "high" => UILayoutPriorityDefaultHigh, # = 750
  "med" => 500,
  "low" => UILayoutPriorityDefaultLow, # = 250
  "fit" => UILayoutPriorityFittingSizeLevel # = 50
}
PRIORITY_LOOKUP_INVERSE = 
PRIORITY_LOOKUP.invert
AXIS_LOOKUP = 
{
  "h" => UILayoutConstraintAxisHorizontal,
  "v" => UILayoutConstraintAxisVertical
}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Layout

Example: RMX::Layout.new do |layout|

...

end



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# File 'lib/motion/layout.rb', line 54

def initialize(&block)
  @block_owner = block.owner if block
  @visible_items = []
  @constraints = {}
  unless block.nil?
    block.call(self)
    block = nil
  end
end

Instance Attribute Details

#visible_items ⇒ Object

keeps track of views that are not #hidden? as constraints are built, so the special ‘last_visible` view name can be used in equations. exposed for advanced layout needs.



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# File 'lib/motion/layout.rb', line 48

def visible_items
  @visible_items
end

Class Method Details

.describe_constraint(subviews, constraint) ⇒ Object

transforms an NSLayoutConstraint into a string. this string is for debugging and produces a verbose translation. its not meant to be copied directly as an equation. pass the subviews hash just as you would to Layout#subviews=, followed by the NSLayoutConstraint



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# File 'lib/motion/layout.rb', line 320

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

.describe_view(subviews, view) ⇒ Object

transforms a view’s NSLayoutConstraints into strings. pass the subviews hash just as you would to Layout#subviews=, followed by the view to describe



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# File 'lib/motion/layout.rb', line 336

def self.describe_view(subviews, view)
  view.constraints.map do |constraint|
    describe_constraint(subviews, constraint)
  end.join("\n")
end

Instance Method Details

#clear! ⇒ Object 



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# File 'lib/motion/layout.rb', line 79

def clear!
  @view.removeConstraints(@view.constraints)
end

#describe_constraint(constraint) ⇒ Object 



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# File 'lib/motion/layout.rb', line 309

def describe_constraint(constraint)
  self.class.describe_constraint(@subviews, constraint)
end

#describe_view ⇒ Object 



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# File 'lib/motion/layout.rb', line 313

def describe_view
  self.class.describe_view(@subviews, @view)
end

#eq(str, remove = false) ⇒ Object

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



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# File 'lib/motion/layout.rb', line 123

def eq(str, remove=false)
  parts = str.split("#", 2).first.split(" ").select { |x| !x.empty? }
  return if parts.empty?

  item = nil
  item_attribute = nil
  related_by = nil
  to_item = nil
  to_item_attribute = nil
  multiplier = 1.0
  constant = 0.0
  
  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

  if item == "last_visible"
    item = @visible_items.first || "view"
  end

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

  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

  if to_item == "last_visible"
    to_item = @visible_items.detect { |x| x != item } || "view"
  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 = Float(multiplier)
  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

  internal_ident = "#{item}.#{item_attribute} #{related_by} #{to_item}.#{to_item_attribute} * #{multiplier} @ #{priority}"

  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 || "required"}"
    p "  internal_ident:      #{internal_ident}"
  end

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

  unless res_item.hidden?
    @visible_items.unshift(item)
  end

  if remove
    if constraint = @constraints[internal_ident]
      if debug
        p "status:"
        p "  existing (for removal)"
      end
      @view.removeConstraint(constraint)
    else
      raise "RMX::Layout could not find constraint to remove for internal_ident: `#{internal_ident}` (note: this is an internal representation of the constraint, not the exact string given).  Make sure the constraint was created first."
    end
  elsif constraint = @constraints[internal_ident]
    if debug
      p "status:"
      p "  existing (for modification)"
    end
    constraint.constant = res_constant
  else
    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 debug
      p "status:"
      p "  created"
    end
    @constraints[internal_ident] = constraint
    if res_priority
      constraint.priority = res_priority
    end
    @view.addConstraint(constraint)
  end

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

  constraint
end

#eqs(str) ⇒ Object

takes a string one or more equations separated by newlines and processes each. returns an array of constraints



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# File 'lib/motion/layout.rb', line 115

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

#remove(constraint) ⇒ Object 



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# File 'lib/motion/layout.rb', line 83

def remove(constraint)
  constraints = [ constraint ].flatten.compact
  @view.removeConstraints(constraints)
  @constraints.keys.each do |key|
    @constraints.delete(key) if constraints.include?(@constraints.fetch(key))
  end
  true
end

#reopen ⇒ Object

reopens the RMX::Layout instance for additional processing, ex:

@layout.reopen do |layout|
  ...
end

note: you would need to store your instance somewhere on creation to be able to reopen it later, ex:

@layout = RMX::Layout.new do |layout|
  ...
end



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# File 'lib/motion/layout.rb', line 72

def reopen
  if block_given?
    yield self
  end
  self
end

#subviews(subviews) ⇒ Object 



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# File 'lib/motion/layout.rb', line 100

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 109

def subviews=(views)
  subviews(views)
end

#view(view) ⇒ Object 



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# File 'lib/motion/layout.rb', line 92

def view(view)
  @view = view
end

#view=(v) ⇒ Object 



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# File 'lib/motion/layout.rb', line 96

def view=(v)
  view(v)
end

#xeq(str) ⇒ Object

removes the constraint matching equation string. constant is not considered. if no matching constraint is found, it will raise an exception.



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# File 'lib/motion/layout.rb', line 305

def xeq(str)
  eq(str, true)
end