Crate float_pigment_layout

Layout engine with common CSS block and flexbox support.

Note: it is not a full web-compatible layout engine because it supports a subset of web layout algorithms.

Supported layout strategies:

• display: block
• display: flex
• display: none
• position: absolute
• with an optional external text layout engine:
  • display: inline
  • display: inline-block
  • display: inline-flex

Basic Usages

This crate does not construct node trees itself. You should firstly:

• write a node tree struct that implements LayoutTreeNode, each node should owns a LayoutNode inside it;
• or use the float-pigment-forest crate (the float_pigment_forest::node::Node is a good implementation).

Each tree node has a corresponding LayoutNode. Calls the Layoutnode::update or Layoutnode::update_with_containing_size of tree root node every time you need a new layout result. (The all results in the tree will be updated when Layoutnode::update* is called on the tree root.) Then you can read any result in any node with LayoutNode::result* and LayoutNode::computed_style.

When any property of any node has been updated, calls the LayoutNode::mark_dirty. The next Layoutnode::update* call on the tree root will carefully read the new properties and update the results.

About Text Layout

Text layout means to compose text glyphs and other structures (images, inline-blocks, etc.) in lines. It is a complex problem and deeply coupled with system environment interfaces.

This crate does not solve text layout problems. Thus by default it does not support display: inline and similar features. However, you are informed the inline layout parts so that you can implement a text layout engine to handle them.

Structs

• ComputedStyle
  The computed margin padding border width.
• Edge
  Four edge lengths.
• EdgeOption
  Four edge lengths, each edge can be undetermined.
• LayoutNode
  The layout information of a tree node.
• MeasureResult
  The result of the measure function.
• OptionNum
  A number or undetermined.

Enums

• DefLength
  A length type that can be undefined or auto.

Traits

• InlineMeasure
  A helper type to measure inline nodes.
• InlineUnit
  A helper type as the inline form of a tree node.
• LayoutStyle
  The styles of a tree node.
• LayoutTreeNode
  The main tree node type.
• LayoutTreeVisitor
  A helper type for tree traversal.
• ScreenQuery
  A type to get screen size.

Functions

• is_independent_positioning
  Returns if the node has a special position, e.g. display: none or position: absolute.

Type Aliases

• OptionSize
  Size, but each value can be None for undetermined.
• Point
  Position.
• Rect
  Position with size.
• Size
  Size.
• Vector
  2D Vector.