photino.NET/Photino.NET/PhotinoNetDelegates.cs

using System.Drawing;
using System.Runtime.InteropServices;

namespace Photino.NET;

public partial class PhotinoWindow
{
    //FLUENT EVENT HANDLER REGISTRATION
    public event EventHandler<Point> WindowLocationChanged;

    /// <summary>
    /// Registers user-defined handler methods to receive callbacks from the native window when its location changes.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterLocationChangedHandler(EventHandler<Point> handler)
    {
        WindowLocationChanged += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window's location changes.
    /// </summary>
    /// <param name="left">Position from left in pixels</param>
    /// <param name="top">Position from top in pixels</param>
    internal void OnLocationChanged(int left, int top)
    {
        var location = new Point(left, top);
        WindowLocationChanged?.Invoke(this, location);
    }

    public event EventHandler<Size> WindowSizeChanged;
    /// <summary>
    /// Registers user-defined handler methods to receive callbacks from the native window when its size changes.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterSizeChangedHandler(EventHandler<Size> handler)
    {
        WindowSizeChanged += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window's size changes.
    /// </summary>
    internal void OnSizeChanged(int width, int height)
    {
        var size = new Size(width, height);
        WindowSizeChanged?.Invoke(this, size);
    }

    public event EventHandler WindowFocusIn;

    /// <summary>
    /// Registers registered user-defined handler methods to receive callbacks from the native window when it is focused in.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterFocusInHandler(EventHandler handler)
    {
        WindowFocusIn += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window focuses in.
    /// </summary>
    internal void OnFocusIn()
    {
        WindowFocusIn?.Invoke(this, EventArgs.Empty);
    }

    public event EventHandler WindowMaximized;

    /// <summary>
    /// Registers user-defined handler methods to receive callbacks from the native window when it is maximized.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterMaximizedHandler(EventHandler handler)
    {
        WindowMaximized += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window is maximized.
    /// </summary>
    internal void OnMaximized()
    {
        WindowMaximized?.Invoke(this, EventArgs.Empty);
    }

    public event EventHandler WindowRestored;
    /// <summary>
    /// Registers user-defined handler methods to receive callbacks from the native window when it is restored.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterRestoredHandler(EventHandler handler)
    {
        WindowRestored += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window is restored.
    /// </summary>
    internal void OnRestored()
    {
        WindowRestored?.Invoke(this, EventArgs.Empty);
    }

    public event EventHandler WindowFocusOut;

    /// <summary>
    /// Registers registered user-defined handler methods to receive callbacks from the native window when it is focused out.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterFocusOutHandler(EventHandler handler)
    {
        WindowFocusOut += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window focuses out.
    /// </summary>
    internal void OnFocusOut()
    {
        WindowFocusOut?.Invoke(this, EventArgs.Empty);
    }

    public event EventHandler WindowMinimized;

    /// <summary>
    /// Registers user-defined handler methods to receive callbacks from the native window when it is minimized.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterMinimizedHandler(EventHandler handler)
    {
        WindowMinimized += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window is minimized.
    /// </summary>
    internal void OnMinimized()
    {
        WindowMinimized?.Invoke(this, EventArgs.Empty);
    }

    public event EventHandler<string> WebMessageReceived;

    /// <summary>
    /// Registers user-defined handler methods to receive callbacks from the native window when it sends a message.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <remarks>
    /// Messages can be sent from JavaScript via <code>window.external.sendMessage(message)</code>
    /// </remarks>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterWebMessageReceivedHandler(EventHandler<string> handler)
    {
        WebMessageReceived += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window sends a message.
    /// </summary>
    internal void OnWebMessageReceived(string message)
    {
        WebMessageReceived?.Invoke(this, message);
    }

    public delegate bool NetClosingDelegate(object sender, EventArgs e);

    public event NetClosingDelegate WindowClosing;

    /// <summary>
    /// Registers user-defined handler methods to receive callbacks from the native window when the window is about to close.
    /// Handler can return true to prevent the window from closing.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="NetClosingDelegate"/></param>
    public PhotinoWindow RegisterWindowClosingHandler(NetClosingDelegate handler)
    {
        WindowClosing += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods when the native window is about to close.
    /// </summary>
    internal byte OnWindowClosing()
    {
        //C++ handles bool values as a single byte, C# uses 4 bytes
        byte noClose = 0;
        var doNotClose = WindowClosing?.Invoke(this, null);
        if (doNotClose ?? false)
            noClose = 1;

        return noClose;
    }

    public event EventHandler WindowCreating;

    /// <summary>
    /// Registers user-defined handler methods to receive callbacks before the native window is created.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterWindowCreatingHandler(EventHandler handler)
    {
        WindowCreating += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods before the native window is created.
    /// </summary>
    internal void OnWindowCreating()
    {
        WindowCreating?.Invoke(this, null);
    }

    public event EventHandler WindowCreated;

    /// <summary>
    /// Registers user-defined handler methods to receive callbacks after the native window is created.
    /// </summary>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="handler"><see cref="EventHandler"/></param>
    public PhotinoWindow RegisterWindowCreatedHandler(EventHandler handler)
    {
        WindowCreated += handler;
        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods after the native window is created.
    /// </summary>
    internal void OnWindowCreated()
    {
        WindowCreated?.Invoke(this, null);
    }


    //NOTE: There is 1 callback from C++ to C# which is automatically registered. The .NET callback appropriate for the custom scheme is handled in OnCustomScheme().

    public delegate Stream NetCustomSchemeDelegate(object sender, string scheme, string url, out string contentType);
    internal Dictionary<string, NetCustomSchemeDelegate> CustomSchemes = new Dictionary<string, NetCustomSchemeDelegate>();

    /// <summary>
    /// Registers user-defined custom schemes (other than 'http', 'https' and 'file') and handler methods to receive callbacks
    /// when the native browser control encounters them.
    /// </summary>
    /// <remarks>
    /// Only 16 custom schemes can be registered before initialization. Additional handlers can be added after initialization.
    /// </remarks>
    /// <returns>
    /// Returns the current <see cref="PhotinoWindow"/> instance.
    /// </returns>
    /// <param name="scheme">The custom scheme</param>
    /// <param name="handler"><see cref="EventHandler"/></param>
    /// <exception cref="ArgumentException">Thrown if no scheme or handler was provided</exception>
    /// <exception cref="ApplicationException">Thrown if more than 16 custom schemes were set</exception>
    public PhotinoWindow RegisterCustomSchemeHandler(string scheme, NetCustomSchemeDelegate handler)
    {
        if (string.IsNullOrWhiteSpace(scheme))
            throw new ArgumentException("A scheme must be provided. (for example 'app' or 'custom'");

        if (handler == null)
            throw new ArgumentException("A handler (method) with a signature matching NetCustomSchemeDelegate must be supplied.");

        scheme = scheme.ToLower();

        if (_nativeInstance == IntPtr.Zero)
        {
            if (CustomSchemes.Count > 15 && !CustomSchemes.ContainsKey(scheme))
                throw new ApplicationException($"No more than 16 custom schemes can be set prior to initialization. Additional handlers can be added after initialization.");
            else
            {
                if (!CustomSchemes.ContainsKey(scheme))
                    CustomSchemes.Add(scheme, null);
            }
        }
        else
        {
            Photino_AddCustomSchemeName(_nativeInstance, scheme);
        }

        CustomSchemes[scheme] += handler;

        return this;
    }

    /// <summary>
    /// Invokes registered user-defined handler methods for user-defined custom schemes (other than 'http','https', and 'file')
    /// when the native browser control encounters them.
    /// </summary>
    /// <param name="url">URL of the Scheme</param>
    /// <param name="numBytes">Number of bytes of the response</param>
    /// <param name="contentType">Content type of the response</param>
    /// <returns><see cref="IntPtr"/></returns>
    /// <exception cref="ApplicationException">
    /// Thrown when the URL does not contain a colon.
    /// </exception>
    /// <exception cref="ApplicationException">
    /// Thrown when no handler is registered.
    /// </exception>
    public IntPtr OnCustomScheme(string url, out int numBytes, out string contentType)
    {
        var colonPos = url.IndexOf(':');

        if (colonPos < 0)
            throw new ApplicationException($"URL: '{url}' does not contain a colon.");

        var scheme = url.Substring(0, colonPos).ToLower();

        if (!CustomSchemes.ContainsKey(scheme))
            throw new ApplicationException($"A handler for the custom scheme '{scheme}' has not been registered.");

        var responseStream = CustomSchemes[scheme].Invoke(this, scheme, url, out contentType);

        if (responseStream == null)
        {
            // Webview should pass through request to normal handlers (e.g., network)
            // or handle as 404 otherwise
            numBytes = 0;
            return default;
        }

        // Read the stream into memory and serve the bytes
        // In the future, it would be possible to pass the stream through into C++
        using (responseStream)
        using (var ms = new MemoryStream())
        {
            responseStream.CopyTo(ms);

            numBytes = (int)ms.Position;
            var buffer = Marshal.AllocHGlobal(numBytes);
            Marshal.Copy(ms.GetBuffer(), 0, buffer, numBytes);
            //_hGlobalToFree.Add(buffer);
            return buffer;
        }
    }
}