Make ViewComponent api better for expected use

- Exposing eventloop if user need to interact with it
- Add api/feature to set used view rect expand to
  full terminal width
- Add plain ProgressView samples
- Relates #995
- Fixes #997

spring-shell-core/src/main/java/org/springframework/shell/component/ViewComponent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2023-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
  */
 package org.springframework.shell.component;
 
+import org.jline.terminal.Size;
 import org.jline.terminal.Terminal;
 
 import org.springframework.shell.component.message.ShellMessageBuilder;
@@ -22,6 +23,7 @@ import org.springframework.shell.component.view.TerminalUI;
 import org.springframework.shell.component.view.control.View;
 import org.springframework.shell.component.view.control.ViewDoneEvent;
 import org.springframework.shell.component.view.event.EventLoop;
+import org.springframework.shell.geom.Rectangle;
 import org.springframework.util.Assert;
 
 /**
@@ -34,37 +36,65 @@ public class ViewComponent {
 	private final Terminal terminal;
 	private final View view;
 	private EventLoop eventLoop;
+	private TerminalUI ui;
+	private boolean useTerminalWidth = true;
 
+	/**
+	 * Construct view component with a given {@link Terminal} and {@link View}.
+	 *
+	 * @param terminal the terminal
+	 * @param view the main view
+	 */
 	public ViewComponent(Terminal terminal, View view) {
 		Assert.notNull(terminal, "terminal must be set");
 		Assert.notNull(view, "view must be set");
 		this.terminal = terminal;
 		this.view = view;
+		this.ui = new TerminalUI(terminal);
+		this.eventLoop = ui.getEventLoop();
 	}
 
 	/**
 	 * Run a view execution loop.
 	 */
 	public void run() {
-		TerminalUI ui = new TerminalUI(terminal);
-		eventLoop = ui.getEventLoop();
 		eventLoop.onDestroy(eventLoop.viewEvents(ViewDoneEvent.class, view)
 			.subscribe(event -> {
 					exit();
 				}
 			));
 		view.setEventLoop(eventLoop);
+		Size terminalSize = terminal.getSize();
+		Rectangle rect = view.getRect();
+		if (useTerminalWidth) {
+			view.setRect(rect.x(), rect.y(), terminalSize.getColumns() - rect.x(), rect.height());
+		}
 		ui.setRoot(view, false);
 		ui.run();
 	}
 
+	/**
+	 * Sets if full terminal width should be used for a view. Defaults to {@code true}.
+	 *
+	 * @param useTerminalWidth the use terminal width flag
+	 */
+	public void setUseTerminalWidth(boolean useTerminalWidth) {
+		this.useTerminalWidth = useTerminalWidth;
+	}
+
+	/**
+	 * Gets an {@link EventLoop} associated with this view component.
+	 *
+	 * @return event loop with this view component
+	 */
+	public EventLoop getEventLoop() {
+		return eventLoop;
+	}
+
 	/**
 	 * Request exit from an execution loop.
 	 */
 	public void exit() {
-		if (eventLoop == null) {
-			return;
-		}
 		eventLoop.dispatch(ShellMessageBuilder.ofInterrupt());
 	}