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javier-godoypaodb
javier-godoy
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paodb
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feat: add support for dynamic theme switching
1 parent 2783988 commit 156e423

5 files changed

Lines changed: 222 additions & 2 deletions

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‎src/main/java/com/flowingcode/vaadin/addons/demo/DynamicTheme.java‎

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package com.flowingcode.vaadin.addons.demo;
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import com.vaadin.flow.component.Component;
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import com.vaadin.flow.component.HasElement;
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import com.vaadin.flow.component.page.Inline.Position;
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import com.vaadin.flow.server.AppShellSettings;
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import com.vaadin.flow.server.VaadinSession;
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import com.vaadin.flow.server.Version;
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import lombok.Getter;
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import lombok.RequiredArgsConstructor;
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/**
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* Enumeration representing supported themes for dynamic switching.
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* <p>
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* This enum facilitates switching between themes (e.g., Lumo, Aura) at runtime.
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* </p>
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*/
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@RequiredArgsConstructor
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public enum DynamicTheme {
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/**
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* The standard Lumo theme.
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*/
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LUMO("lumo/lumo.css", "hsl(214, 35%, 21%)"),
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/**
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* The standard Aura theme.
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*/
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AURA("aura/aura.css", "oklch(0.2 0.01 260)"),
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/**
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* A base theme without specific styling.
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*/
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BASE(null, "#000");
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@Getter
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private final String href;
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@Getter
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private final String bgColor;
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private static void assertFeatureSupported() {
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if (!isFeatureSupported()) {
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throw new UnsupportedOperationException("Dynamic theme switching requires Vaadin 25+");
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}
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}
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/**
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* Checks if the dynamic theme feature is supported. The feature is supported in Vaadin 25.
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*
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* @return {@code true} if the feature is supported and initialized; {@code false} otherwise.
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*/
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public static boolean isFeatureSupported() {
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return Version.getMajorVersion() >= 25;
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}
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private static void assertFeatureInitialized() {
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assertFeatureSupported();
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if (!isFeatureInitialized()) {
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throw new IllegalStateException("Dynamic theme switching has not been initialized");
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}
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}
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/**
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* Checks if the dynamic theme feature has been initialized for the current session.
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*
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* @return {@code true} if the feature is supported and initialized; {@code false} otherwise.
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*/
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public static boolean isFeatureInitialized() {
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return isFeatureSupported()
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&& VaadinSession.getCurrent().getAttribute(DynamicTheme.class) != null;
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}
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/**
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* Return the current dynamic theme.
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*
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* @throws UnsupportedOperationException if the runtime Vaadin version is older than 25.
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* @return the current dynamic theme, or {@code null} if the feature has not been initialized.
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*/
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public static DynamicTheme getCurrent() {
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assertFeatureSupported();
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return VaadinSession.getCurrent().getAttribute(DynamicTheme.class);
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}
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/**
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* Initializes the theme settings.
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* <p>
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* This method performs a lazy initialization of the {@link DynamicTheme} within the
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* current {@link VaadinSession}. If no theme is present, it registers this instance
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* as the session default. Subsequently, it injects the corresponding CSS stylesheet
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* link into the {@link AppShellSettings}.
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* </p>
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*
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* @param settings the application shell settings to be modified
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* @throws UnsupportedOperationException if the runtime Vaadin version is older than 25
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*/
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public void initialize(AppShellSettings settings) {
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assertFeatureSupported();
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DynamicTheme theme = getCurrent();
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if (theme == null) {
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theme = this;
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VaadinSession.getCurrent().setAttribute(DynamicTheme.class, theme);
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}
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switch (theme) {
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case AURA:
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settings.addLink(Position.APPEND, "stylesheet", "aura/aura.css");
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break;
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case LUMO:
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settings.addLink(Position.APPEND, "stylesheet", "lumo/lumo.css");
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break;
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default:
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break;
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}
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}
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/**
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* Prepares the component for dynamic theme switching by preloading stylesheets.
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* <p>
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* Adds a client-side listener to the component that detects mouseover events.
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* When triggered, it preloads the theme stylesheets (Lumo and Aura) to ensure
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* they can be applied immediately when needed.
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* </p>
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*
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* @param component the component to attach the listener to
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* @throws IllegalStateException if the dynamic theme feature has not been initialized
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*/
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public static void prepare(Component component) {
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assertFeatureInitialized();
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component.addAttachListener(ev -> doPrepare(component));
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if (component.isAttached()) {
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doPrepare(component);
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}
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}
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private static void doPrepare(Component component) {
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component.getElement().executeJs("""
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this.addEventListener('mouseover', function() {
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["lumo/lumo.css", "aura/aura.css"].forEach(href=> {
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let link = document.querySelector(`link[href="${href}"]`);
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if (!link) {
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link = document.createElement("link");
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link.href = href;
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link.as = 'style';
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link.rel = 'preload';
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document.head.prepend(link);
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}
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});
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}, {once:true} );
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""");
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}
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/**
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* Applies this theme to the view.
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*
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* @param component a component in the view
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* @throws IllegalStateException if the dynamic theme feature has not been initialized
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*/
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public void apply(HasElement component) {
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assertFeatureInitialized();
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VaadinSession.getCurrent().setAttribute(DynamicTheme.class, this);
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component.getElement().executeJs("""
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const applyTheme = () => {
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["lumo/lumo.css", "aura/aura.css"].forEach(href=> {
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let link = document.querySelector(`link[href='${href}']`);
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if (!link) return;
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if (href === $0) {
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if (link.rel === 'preload') link.rel = 'stylesheet';
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if (link.disabled) link.disabled = false;
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} else if (link.rel === 'stylesheet' && !link.disabled) {
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link.disabled = true;
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}
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});
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};
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if (document.startViewTransition) {
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document.startViewTransition(applyTheme);
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} else {
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applyTheme();
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}
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""", href);
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}
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}

‎src/main/java/com/flowingcode/vaadin/addons/demo/TabbedDemo.java‎

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import com.vaadin.flow.component.button.Button;
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import com.vaadin.flow.component.button.ButtonVariant;
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import com.vaadin.flow.component.checkbox.Checkbox;
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import com.vaadin.flow.component.dependency.CssImport;
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import com.vaadin.flow.component.dependency.StyleSheet;
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import com.vaadin.flow.component.html.Div;
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import com.vaadin.flow.component.html.Span;
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import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
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import com.vaadin.flow.component.orderedlayout.VerticalLayout;
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import com.vaadin.flow.component.select.Select;
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import com.vaadin.flow.component.splitlayout.SplitLayout.Orientation;
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import com.vaadin.flow.dom.Element;
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import com.vaadin.flow.router.PageTitle;
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*/
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@StyleSheet("context://frontend/styles/commons-demo/shared-styles.css")
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@SuppressWarnings("serial")
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@CssImport(value = "./styles/commons-demo/vaadin-select-overlay.css", themeFor = "vaadin-select")
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public class TabbedDemo extends VerticalLayout implements RouterLayout {
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private static final Logger logger = LoggerFactory.getLogger(TabbedDemo.class);
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boolean useDarkTheme = themeCB.getValue();
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setColorScheme(this, useDarkTheme ? ColorScheme.DARK : ColorScheme.LIGHT);
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});
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footer = new HorizontalLayout();
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footer.setWidthFull();
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footer.setJustifyContentMode(JustifyContentMode.END);
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footerLeft.add(new Span(title + " " + version));
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}
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if (DynamicTheme.isFeatureInitialized()) {
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Select<DynamicTheme> themeSelect = new Select<>();
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themeSelect.addThemeName("demo-footer-theme-select");
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themeSelect.addThemeName("small");
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DynamicTheme.prepare(themeSelect);
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themeSelect.setItems(DynamicTheme.values());
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themeSelect.setValue(DynamicTheme.getCurrent());
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themeSelect.setWidth("85px");
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themeSelect.addValueChangeListener(ev -> ev.getValue().apply(this));
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footer.add(themeSelect);
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}
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this.add(tabs);
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this.add(new Div());
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this.add(footer);

‎src/main/resources/META-INF/resources/frontend/styles/commons-demo/shared-styles.css‎

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bottom: 0;
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left: 0;
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background: var(--lumo-base-color);
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align-items: center;
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}
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.demo-footer vaadin-select-value-button {
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mask-image:none;
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padding:0;
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}
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.helper-button {

‎src/main/resources/META-INF/resources/frontend/styles/commons-demo/vaadin-select-overlay.css‎

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/** Needed in order to prevent vaadin-select from remaining 'closing' when switching from Lumo to Aura/Base*/
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:host([theme~='demo-footer-theme-select']) vaadin-select-overlay {
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animation-name: none;
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}

‎src/test/java/com/flowingcode/vaadin/addons/demo/AppShellConfiguratorImpl.java‎

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package com.flowingcode.vaadin.addons.demo;
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import com.vaadin.flow.component.page.AppShellConfigurator;
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import com.vaadin.flow.theme.Theme;
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import com.vaadin.flow.server.AppShellSettings;
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@Theme
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public class AppShellConfiguratorImpl implements AppShellConfigurator {
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@Override
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public void configurePage(AppShellSettings settings) {
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if (DynamicTheme.isFeatureSupported()) {
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DynamicTheme.LUMO.initialize(settings);
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}
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}
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}

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