Crate envision 

Envision

A ratatui framework for collaborative TUI development with headless testing support.

Envision provides a custom CaptureBackend that implements ratatui’s Backend trait, enabling you to:

• Capture rendered frames as inspectable text or structured data
• Track frame history and compute diffs between renders
• Annotate widgets with semantic information
• Simulate user input for testing
• Run applications in headless mode for CI/testing

Quick Start

use envision::backend::CaptureBackend;
use ratatui::Terminal;
use ratatui::widgets::Paragraph;

// Create a headless terminal
let backend = CaptureBackend::new(80, 24);
let mut terminal = Terminal::new(backend).unwrap();

// Render something
terminal.draw(|frame| {
    frame.render_widget(Paragraph::new("Hello, Envision!"), frame.area());
}).unwrap();

// Capture the output
let output = terminal.backend().to_string();
println!("{}", output);

Input Simulation

use envision::input::{EventQueue, KeyCode};

let mut queue = EventQueue::new();
queue.type_str("hello");
queue.enter();

// Events can be consumed by your app's event loop
while let Some(event) = queue.pop() {
    // handle event...
}

Re-exports

pub use adapter::DualBackend;

pub use annotation::Annotate;

pub use annotation::Annotation;

pub use annotation::AnnotationRegistry;

pub use annotation::WidgetType;

pub use app::App;

pub use app::AsyncCommandHandler;

pub use app::AsyncRuntime;

pub use app::AsyncRuntimeConfig;

pub use app::Command;

pub use app::DebounceSubscription;

pub use app::FilterSubscription;

pub use app::IntervalImmediateSubscription;

pub use app::Runtime;

pub use app::RuntimeConfig;

pub use app::Subscription;

pub use app::SubscriptionExt;

pub use app::TakeSubscription;

pub use app::TerminalEventSubscription;

pub use app::ThrottleSubscription;

pub use app::TickSubscription;

pub use app::TimerSubscription;

pub use backend::CaptureBackend;

pub use backend::EnhancedCell;

pub use backend::FrameSnapshot;

pub use component::Component;

pub use component::Focusable;

pub use component::InputField;

pub use component::InputFieldState;

pub use component::InputMessage;

pub use component::InputOutput;

pub use component::ListMessage;

pub use component::ListOutput;

pub use component::SelectableList;

pub use component::SelectableListState;

pub use component::Toggleable;

pub use harness::Assertion;

pub use harness::AsyncTestHarness;

pub use harness::Snapshot;

pub use harness::TestHarness;

pub use input::EventQueue;

pub use input::SimulatedEvent;

Modules

adapter

Dual adapter for simultaneous real and capture backends.

annotation

Widget annotation system for semantic UI understanding.

app

TEA (The Elm Architecture) application framework.

backend

Backend module providing the CaptureBackend implementation.

component

Composable UI components for TUI applications.

harness

Test harness for headless TUI testing.

input

Input simulation module for programmatic event injection.

prelude

Prelude module for convenient imports