[NUI] Add WebView APIs for video playback notification.

[huayongxu]

Description of Change

the related patch at binder side:
https://review.tizen.org/gerrit/c/platform/core/uifw/dali-csharp-binder/+/346532

API Changes

• ACR:

[gemini-code-assist]

Code Review

This pull request introduces support for playback video events in WebView by adding P/Invoke callback registrations and exposing corresponding C# events (Ready, Started, Finished, Stopped, and Paused). The review feedback suggests using EventArgs.Empty instead of instantiating new EventArgs() when raising these events to avoid unnecessary allocations and reduce garbage collection pressure.

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[gemini-code-assist]

Using new EventArgs() allocates a new instance of EventArgs every time the event is raised, which increases garbage collection pressure. Since EventArgs does not carry any event-specific data, it is highly recommended to use the cached EventArgs.Empty instead.

        private void OnPlaybackVideoReady()
        {
            playbackVideoReadyEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoStarted()
        {
            playbackVideoStartedEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoFinished()
        {
            playbackVideoFinishedEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoStopped()
        {
            playbackVideoStoppedEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoPaused()
        {
            playbackVideoPausedEventHandler?.Invoke(this, EventArgs.Empty);
        }

[TizenAPI-Bot]

Internal API Changed

Added: 5, Removed: 0, Changed: 0

Added

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoFinished

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoPaused

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoReady

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStarted

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStopped

[TizenAPI-Bot]

Internal API Changed

Added: 5, Removed: 0, Changed: 0

Added

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoFinished

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoPaused

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoReady

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStarted

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStopped

[TizenAPI-Bot]

Internal API Changed

Added: 5, Removed: 0, Changed: 0

Added

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoFinished

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoPaused

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoReady

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStarted

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStopped

[JoonghyunCho]

🤖 [AI Review]

Reviewed — no findings.

Scope checked:

• 5 new playback events (PlaybackVideoReady/Started/Finished/Stopped/Paused) are all [EditorBrowsable(EditorBrowsableState.Never)], so they are exempt from the public-API doc requirement; each still carries a <summary>.
• Delegate lifetime: each callback is stored in a private field before Marshal.GetFunctionPointerForDelegate, preventing GC of the delegate that native code invokes.
• add/remove symmetry: native Register*Callback is called with the function pointer on first subscribe and IntPtr.Zero on last unsubscribe, gated by the null-handler check — no double-register or dangling registration.
• new EventArgs() in the 5 new raisers is consistent with the 6 existing event raisers in this same file (convention-consistent; not flagged).
• Interop signatures (CSharp_Dali_WebView_RegisterPlaybackVideo*Callback, (HandleRef, IntPtr)) match the sibling WebView callback bindings.

No 🔴 critical issues, no 🟡 suggestions to flag.

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Automated review — final merge decision rests with human reviewers.