Screen

Screen records what the server draws over the player's game view besides chat: titles with their subtitles, action bars and boss bars. Install the screen unit and its Session dependency, or explicitly select the default capability unit. Every MCProtocolLib release Anvil ships has it.

Each kind keeps its own history, in order and across reconnects, and hands out its own watch. Text is flattened to plain text the same way Messages flattens chat.

Wait for a title

This fragment belongs in a live test after Alice has connected to a server whose plugin shows a title. It uses SimulatedPlayer alice, Messages messages and these imports:

import me.whereareiam.anvil.capability.screen.Screen;
import me.whereareiam.anvil.capability.screen.TitleWatch;
import me.whereareiam.anvil.capability.screen.model.Title;
import java.time.Duration;

Start the watch before the action, then wait for the title:

Screen screen = alice.capability(Screen.class);
TitleWatch titles = screen.watchTitles();
messages.command("example announce");
Title title = titles.shown("Announcement", Duration.ofSeconds(10));

shown(text) matches a title whose title or subtitle contains the text. Any predicate on the Title works too, so one wait can require both lines: titles.shown(shown -> shown.getTitle().contains("Announcement") && shown.getSubtitle().contains("Alice"), timeout). A Title also carries the fade-in, stay and fade-out ticks it was shown with.

A title is recorded when its text arrives, together with the subtitle shown under it. A subtitle shows only with a title, as on a client: a server that sends the subtitle first produces one record with both lines; a server that sends it after the title produces a record without and then one with the subtitle. A title stays for its times, so a subtitle arriving after it has faded is kept for the next title.

Wait for an action bar

ActionBarWatch actionBar = screen.watchActionBars();
messages.command("example follow Bob");
actionBar.shown("+1 follower", Duration.ofSeconds(10));

Import me.whereareiam.anvil.capability.screen.ActionBarWatch. The action-bar history holds the text a server sends through the action-bar packet, which the vanilla title <player> actionbar command uses, and the action-bar text it sends as chat, which is game-info chat before Minecraft 1.19 and overlay system chat from 1.19. Either way it is an action bar, never part of Messages.

Follow a boss bar

A boss bar is shown when the server adds it and each time the server changes its text, progress, style or flags. shown finds the first addition or change after the previous wait that leaves the bar in the state you need, and removed the moment it leaves the screen:

BossBarWatch bossBars = screen.watchBossBars();
messages.command("example event start");
BossBar event = bossBars.shown(bar -> bar.getText().contains("Event") && bar.getProgress() >= 0.5F,
		Duration.ofSeconds(10));
bossBars.removed(bar -> bar.getId().equals(event.getId()), Duration.ofSeconds(60));

Import me.whereareiam.anvil.capability.screen.BossBarWatch and me.whereareiam.anvil.capability.screen.model.BossBar. A BossBar has the server's ID for the bar, its text, its progress from 0 to 1, its BossBarColor and BossBarOverlay with vanilla names, and its sky, music and fog flags. screen.bossBars() lists the bars on the screen now, in the order they were added.

A bar belongs to one connection: when the connection ends, every bar it showed is recorded as removed, so a new connection starts without bars, as on a client.

Expect that something is not shown

Each watch has neverShown(...), which watches for a duration and fails as soon as a matching title, action bar or boss bar has been shown since the previous wait, naming it:

titles.neverShown("Error", Duration.ofSeconds(2));

It returns normally once the duration passes without one and does not move the watch. Choose the shortest duration in which the server would have shown it.

Expect one among other outcomes

expectShown(matcher) on every watch, and expectRemoved(matcher) on a boss bar watch, describe the next matching change without waiting. Pass them to player.awaitFirst(...) together with other expectations; see waiting for whichever outcome comes first.

Inspect failures

titles(), actionBars() and bossBarEvents() return immutable snapshots of the whole histories, and each watch's unread() lists what arrived since its previous wait. Include them in a failed assertion to see whether the server showed other text or nothing at all.