Screenshots

xa11y can capture pixel-level snapshots of the screen alongside its accessibility APIs. This is useful for attaching screenshots to test failures, feeding vision-language models with the same frame the agent is reasoning about, or visually diffing a region around a specific control.

Three entry points:

• Full screen — capture the entire primary display.
• Region — capture an explicit rectangle in logical screen coordinates.
• Element — capture the pixels under an accessibility element’s current bounds.

Screenshots are decoupled from the accessibility and input layers. The target window is not raised or activated before capture — whatever pixels are at the requested coordinates are returned, including any occluding windows. Bring the target to the foreground yourself if you need a clean capture.

Permissions

Platform	Requirement
macOS	Screen & System Audio Recording for the terminal/IDE
Windows	None for normal user sessions
Linux (X11)	DISPLAY set to a reachable X server
Linux (Wayland)	xdg-desktop-portal with screenshot support (user consent dialog may appear)

Capturing

Rust

use xa11y::*;

fn main() -> Result<()> {
    // Full primary display
    let shot = screenshot()?;
    shot.save_png("full.png")?;

    // Explicit region
    let shot = screenshot_region(Rect { x: 0, y: 0, width: 400, height: 300 })?;
    shot.save_png("corner.png")?;

    // Pixels under an accessibility element
    let app = App::by_name("Calculator")?;
    let display = app.locator("static_text[name='Result']").element()?;
    let shot = screenshot_element(&display)?;
    shot.save_png("result.png")?;

    Ok(())
}

Python

import xa11y

# Full primary display
shot = xa11y.screenshot()
shot.save_png("full.png")

# Explicit region: (x, y, width, height)
shot = xa11y.screenshot(region=(0, 0, 400, 300))
shot.save_png("corner.png")

# Pixels under an accessibility element
app = xa11y.App.by_name("Calculator")
display = app.locator("static_text[name='Result']").element()
shot = xa11y.screenshot(element=display)
shot.save_png("result.png")

Passing both element and region raises ValueError.

JavaScript

import { screenshot, App } from '@crowecawcaw/xa11y';

// Full primary display
const full = await screenshot();
await full.savePng('full.png');

// Explicit region: { x, y, width, height }
const region = await screenshot({ region: { x: 0, y: 0, width: 400, height: 300 } });
await region.savePng('corner.png');

// Pixels under an accessibility element
const app = await App.byName('Calculator');
const display = await app.locator("static_text[name='Result']").element();
const elShot = await screenshot({ element: display });
await elShot.savePng('result.png');

Passing both element and region throws InvalidActionDataError.

Working with the pixel buffer

A Screenshot carries raw RGBA8 pixels along with dimensions and a scale factor. width and height are physical (device) pixels — the same resolution the compositor renders at — so on HiDPI displays they exceed the logical bounds passed in. scale records the physical-to-logical ratio (1.0 on standard displays, 2.0 on typical Retina, 1.5 / 1.75 / 2.0 on common Windows and Linux HiDPI configurations). pixels.len() equals width * height * 4.

Rust

let shot = screenshot()?;
println!("{} x {} @ {}x", shot.width, shot.height, shot.scale);

// Encode as PNG bytes (e.g. to upload or embed)
let png_bytes: Vec<u8> = shot.to_png()?;

// Or write directly to disk
shot.save_png("out.png")?;

// Raw RGBA for custom processing
let rgba: &[u8] = &shot.pixels;

Python

shot = xa11y.screenshot()
print(f"{shot.width} x {shot.height} @ {shot.scale}x")

# Encode as PNG bytes (e.g. to upload or embed)
png_bytes: bytes = shot.to_png()

# Or write directly to disk (accepts str, bytes, or os.PathLike)
shot.save_png("out.png")

# Raw RGBA for custom processing
rgba: bytes = shot.pixels

JavaScript

const shot = await screenshot();
console.log(`${shot.width} x ${shot.height} @ ${shot.scale}x`);

// Encode as PNG bytes (e.g. to upload or embed)
const pngBytes = await shot.toPng();          // Buffer

// Or write directly to disk
await shot.savePng('out.png');

// Raw RGBA for custom processing
const rgba = shot.pixels;                     // Buffer

Example: screenshot on test failure

A common pattern is to capture the full screen (or the app under test) whenever an assertion fails, and attach it to the test report.

Rust

fn capture_on_fail(name: &str, test: impl FnOnce() -> Result<()>) -> Result<()> {
    match test() {
        Ok(()) => Ok(()),
        Err(e) => {
            if let Ok(shot) = screenshot() {
                let _ = shot.save_png(format!("target/failures/{name}.png"));
            }
            Err(e)
        }
    }
}

Python

import pytest

@pytest.hookimpl(hookwrapper=True)
def pytest_runtest_makereport(item, call):
    outcome = yield
    report = outcome.get_result()
    if report.when == "call" and report.failed:
        try:
            xa11y.screenshot().save_png(f"artifacts/{item.name}.png")
        except xa11y.XA11yError:
            pass

JavaScript

import { screenshot } from '@crowecawcaw/xa11y';

afterEach(async function () {
  if (this.currentTest?.state === 'failed') {
    try {
      const shot = await screenshot();
      await shot.savePng(`artifacts/${this.currentTest.title}.png`);
    } catch { /* capture failure shouldn't mask the test failure */ }
  }
});

Error handling

Error	When
PermissionDenied	macOS Screen Recording not granted, or Wayland portal denied consent
Unsupported	No capture backend available for the session (no DISPLAY, no working Wayland portal, etc.)
NoElementBounds	The element passed to screenshot_element has no bounds
Platform	Raw OS / FFI failure during capture or PNG encode