[Feature] Add a `force` option to `screenshot` methods

[KotlinIsland]

So basically I want to be able to take a screenshot immediately without any stability checks.

try:
    if not page.locator("#foo").is_visible():
        raise Exception("failed to find element")
except Exception:
    page.screenshot()  # the element appears before it takes the screenshot because screenshot is doing stability checks
    raise

What I want:

    page.screenshot(force=True)

[dgozman]

@KotlinIsland There are no stability checks when calling page.screenshot(). The checks are performed when calling elementHandle.screenshot(). Generally speaking, it seems like you have a race condition, so making screenshot faster will not help as it will still fail on slow CI machines.

If you use expect(locator).to_be_visible() and enable tracing, it should produce a snapshot as fast as possible - that would be your best bet to see what was happening in the page.

[rwoll]

Closed related issue in Python repo and moving the example from the user here for triaging: https://github.com/microsoft/playwright-python/issues/1420#issuecomment-1191053014

[dgozman]

@aslushnikov Could this be caret hiding that waits for some evaluate?

[dgozman]

Note that passing caret: 'initial' option could make screenshot a little bit faster, as a workaround. However, there are no strict guarantees about how long does a screenshot take, because browsers are very asynchronous internally.

[dgozman]

Closing per above, since there is no API changes required.

[KotlinIsland]

I've recently tested this, and even with caret: 'initial' I'm not seeing any change. @dgozman Do you think there could ever be any new approach that could improve the responsiveness/accuracy of screenshots?

[dgozman]

@KotlinIsland There's not much we can suggest here. Screenshots in the browser are asynchronous, complicated and time consuming, so there are no guarantees that it happens very fast, especially when your computer is under heavy load.

[DetachHead]

here's a workaround to take a screenshot with no delay:

const base64 = (await (await page.context().newCDPSession(page)).send('Page.captureScreenshot')).data

it would be nice if playwright's screenshot method had an option to behave like this

[KotlinIsland]

Wow, this is blazingly fast🔥! That's amazing 🚀.

[cyberw]

Great suggestion by @DetachHead . Complete code if someone else wanders here :)

    browser = playwright.chromium.launch(headless=True)
    context = browser.new_context()
    page = context.new_page()
    cdp = context.new_cdp_session(page)
    page.goto("https://www.google.com", wait_until="commit")
    b64_str = cdp.send("Page.captureScreenshot")["data"]
    b64_bytes = b64_str.encode("ascii")
    binary = base64.decodebytes(b64_bytes)
    with open("screenshot.png", "wb") as binary_file:
        binary_file.write(binary)