module RMExtensions class Layout 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 RELATED_BY_LOOKUP = { "<=" => NSLayoutRelationLessThanOrEqual, "==" => NSLayoutRelationEqual, ">=" => NSLayoutRelationGreaterThanOrEqual } RELATED_BY_LOOKUP_INVERSE = RELATED_BY_LOOKUP.invert PRIORITY_LOOKUP = { "max" => UILayoutPriorityRequired, # = 1000 "required" => UILayoutPriorityRequired, # = 1000 "high" => UILayoutPriorityDefaultHigh, # = 750 "low" => UILayoutPriorityDefaultLow, # = 250 "fit" => UILayoutPriorityFittingSizeLevel # = 50 } PRIORITY_LOOKUP_INVERSE = PRIORITY_LOOKUP.invert AXIS_LOOKUP = { "h" => UILayoutConstraintAxisHorizontal, "v" => UILayoutConstraintAxisVertical } def initialize @visible_items = [] if block_given? yield self end end def clear! @view.removeConstraints(@view.constraints) end def view(view) @view = view end def view=(v) view(v) end def subviews(subviews) @subviews = subviews @subviews.values.each do |subview| subview.translatesAutoresizingMaskIntoConstraints = false @view.addSubview(subview) end @subviews end def subviews=(views) subviews(views) end def eqs(str) str.split("\n").map(&:strip).select { |x| !x.empty? }.map do |line| eq(line) end end # Constraints are of the form "view1.attr1 view2.attr2 * multiplier + constant @ priority" def eq(str) 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 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"}" end if errors.size > 0 raise(errors.join(", ")) end unless res_item.hidden? @visible_items.unshift(item) 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 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 private def view_for_item(item) if item == "view" @view elsif v = (@subviews && @subviews[item]) v end end end end