cvkg-layout

cvkg-layout provides a high-performance, flexbox-inspired layout engine for CVKG, supporting complex hierarchical positioning with minimal overhead.

Boundaries and Responsibilities

This crate handles the spatial arrangement of views. It does NOT perform drawing operations or manage state. Its responsibilities include:

• Implementing horizontal (HStack), vertical (VStack), and depth (ZStack) stacking.
• Calculating grid-based arrangements.
• Managing flexible space distribution via flex weights.
• Providing a cached layout pass to avoid redundant calculations.

Public API Overview

Layout Containers

• HStack: Distributes children horizontally with configurable spacing, alignment, and distribution.
• VStack: Distributes children vertically.
• ZStack: Overlays children on top of each other.
• Grid: Arranges children in a fixed-cell 2D grid.

Layout Logic

• LayoutView: The trait implemented by layout containers and views to participate in the layout pass.
• SizeProposal: Communicates available space and constraints to child views.
• LayoutCache: Stores computed sizes to optimize multi-pass layout algorithms.

Support Types

• Alignment: Controls positioning perpendicular to the stack axis (Top, Bottom, Leading, Trailing, Center).
• Distribution: Controls spacing along the stack axis (Leading, Trailing, Center, Fill, SpaceBetween, SpaceAround).

Usage Example

use cvkg_layout::{HStack, VStack, Spacer};
use cvkg_core::{Alignment, Distribution};

// Create a vertical stack with horizontal leading alignment
let layout = VStack::new(10.0, Alignment::Leading, Distribution::Leading);

// In a real View, this is handled via the layout() method
// and placement happens during the render pass.

Known Limitations

• Circular dependencies in layout (e.g., a parent sized by children that are sized by the parent) are resolved via the SizeProposal mechanism but may require explicit frame constraints.
• Grid layout currently assumes fixed-size cells.