feat: Add Web Share API support

[Artur-]

Summary

• Adds a WebShare facade for the browser's Web Share API: WebShare.onClick(button).share(ShareContent.create().title("...").text("...").url("...")) opens the native share sheet when the user clicks, optionally reporting the outcome back to the server through onShared/onError callbacks.
• The share call runs through the trigger/action framework (a new internal ShareAction extending PromiseAction), so navigator.share() executes inside the client-side click handler and inherits the transient user gesture the API requires — a server round-trip via Page.executeJs() would lose the activation and the browser would reject the call.
• WebShare.supportSignal() exposes feature detection as a read-only signal, seeded during the bootstrap handshake via a new v-ws parameter (Flow.ts → ExtendedClientDetails → a ValueSignal<WebShareSupport> on UIInternals), so views can decide whether to show a share affordance before any view code runs.

Details

• ShareContent is a builder with title/text/url slots; each slot accepts either a string literal or a HasValue component, in which case the component's value property is read on the client at gesture time. At least one slot must be set — the Web Share API rejects an empty payload, so this is validated server-side.
• onError deliberately fires for the AbortError the browser reports when the user dismisses the share sheet without picking a target, not only for true failures; this matches browser semantics and is documented on the callback.
• The support signal mirrors the existing geolocation/wake-lock pattern: UNKNOWN only before the first handshake, then a stable SUPPORTED/UNSUPPORTED for the rest of the session. The read-only wrapper is cached on UIInternals for stable identity.
• Unit tests cover the rendered navigator.share({...}) payload composition (literal and property-backed slots, partial payloads, promise observation wrapping) and the signal seeding.

API Changes: feature/web-share vs origin/main

6 classes affected — 5 new public types, 2 methods added to an existing class.

com.vaadin.flow.component.internal.UIInternals

// Added
public Signal<WebShareSupport> getWebShareSupportSignalReadOnly()
public void setWebShareSupport(WebShareSupport support) // framework use only

com.vaadin.flow.component.trigger.internal.ShareAction

// Added
public class ShareAction extends PromiseAction<Void> // internal trigger-framework action
public ShareAction(Action.@Nullable Input<String> titleInput, Action.@Nullable Input<String> textInput, Action.@Nullable Input<String> urlInput)
public ShareAction(Action.@Nullable Input<String> titleInput, Action.@Nullable Input<String> textInput, Action.@Nullable Input<String> urlInput, SerializableRunnable onShared, SerializableConsumer<Error> onError)
protected JsFunction toPromiseJs(Trigger trigger)

com.vaadin.flow.component.webshare.ShareContent

// Added
public final class ShareContent implements Serializable
public static ShareContent create()
public ShareContent title(String literal)
public <C extends Component & HasValue<?, String>> ShareContent title(C source)
public ShareContent text(String literal)
public <C extends Component & HasValue<?, String>> ShareContent text(C source)
public ShareContent url(String literal)
public <C extends Component & HasValue<?, String>> ShareContent url(C source)

com.vaadin.flow.component.webshare.WebShare

// Added
public final class WebShare implements Serializable
public static <T extends Component & ClickNotifier<?>> WebShareBinding onClick(T component)
public static Signal<WebShareSupport> supportSignal()
public static Signal<WebShareSupport> supportSignal(UI ui)

com.vaadin.flow.component.webshare.WebShareBinding

// Added
public final class WebShareBinding implements Serializable
public void share(ShareContent content)
public void share(ShareContent content, SerializableRunnable onShared, SerializableConsumer<Error> onError)

com.vaadin.flow.component.webshare.WebShareSupport

// Added
public enum WebShareSupport
UNKNOWN // initial value before the first bootstrap handshake
SUPPORTED
UNSUPPORTED

[github-actions]

Test Results

 1 442 files  + 2   1 442 suites  +2   1h 25m 53s ⏱️ + 4m 45s
10 136 tests +10  10 068 ✅ +10  68 💤 ±0  0 ❌ ±0 
10 608 runs  +10  10 539 ✅ +10  69 💤 ±0  0 ❌ ±0 

Results for commit 6c0ea96. ± Comparison against base commit 2cf1c20.

♻️ This comment has been updated with latest results.

[Artur-]

This should be based on trigger/action type API

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud