using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Tango.RemoteDesktop.Utils;
namespace Tango.RemoteDesktop
{
/// <summary>
/// Represents a generic screen capture engine.
/// The <see cref="TFrame"/> type will be the type of difference object delivered by the engine.
/// </summary>
/// <typeparam name="TFrame">The type of the frame.</typeparam>
/// <seealso cref="Tango.RemoteDesktop.IScreenCaptureEngine{TFrame}" />
public class ScreenCaptureEngine<TFrame> : IScreenCaptureEngine<TFrame> where TFrame : class, IFrame
{
private Thread _captureThread;
private Bitmap _previousBitmap;
private bool _isDisposed;
/// <summary>
/// Occurs when a new screen frame is available.
/// </summary>
public event EventHandler<ScreenCaptureFrameReceivedEventArgs<TFrame>> FrameReceived;
/// <summary>
/// Gets or sets the screen capture method.
/// </summary>
public ICaptureMethod CaptureMethod { get; set; }
/// <summary>
/// Gets or sets the screen capture region.
/// </summary>
public CaptureRegion CaptureRegion { get; set; }
/// <summary>
/// Gets a value indicating whether this instance is currently capturing.
/// </summary>
public bool IsStarted { get; private set; }
/// <summary>
/// Gets or sets the frame rate per second.
/// Default is 10.
/// </summary>
public int FrameRate { get; set; }
/// <summary>
/// Gets or sets a value indicating whether to include the cursor when capturing.
/// </summary>
public bool CaptureCursor { get; set; }
/// <summary>
/// Gets or sets the bitmap comparer.
/// </summary>
public IBitmapComparer<TFrame> Comparer { get; set; }
/// <summary>
/// Gets or sets a value indicating whether to enable image comparison.
/// </summary>
public bool EnableComparer { get; set; }
/// <summary>
/// Initializes a new instance of the <see cref="ScreenCaptureEngine{TFrame}"/> class using the specified <see cref="IBitmapComparer{TFrame}"/>.
/// </summary>
/// <param name="comparer">The comparer.</param>
public ScreenCaptureEngine(IBitmapComparer<TFrame> comparer)
{
FrameRate = 10;
CaptureMethod = new CaptureMethods.GdiScreenCapture();
CaptureRegion = new CaptureRegion(System.Windows.Forms.Screen.PrimaryScreen.Bounds);
Comparer = comparer;
CaptureCursor = true;
if (Comparer != null)
{
EnableComparer = true;
}
}
/// <summary>
/// Start capturing.
/// </summary>
/// <exception cref="ObjectDisposedException">Screen capture engine cannot be started after disposed.</exception>
public void Start()
{
if (_isDisposed)
{
throw new ObjectDisposedException("Screen capture engine cannot be started after disposed.");
}
if (!IsStarted)
{
IsStarted = true;
_captureThread = new Thread(CaptureThreadMethod);
_captureThread.IsBackground = true;
_captureThread.Name = "Screen Capture Thread";
_captureThread.Start();
}
}
/// <summary>
/// Stop capturing.
/// </summary>
public void Stop()
{
if (IsStarted)
{
IsStarted = false;
}
}
/// <summary>
/// Releases unmanaged and - optionally - managed resources.
/// </summary>
public void Dispose()
{
if (!_isDisposed)
{
_isDisposed = true;
Stop();
CaptureMethod?.Dispose();
}
}
private void CaptureThreadMethod()
{
Stopwatch watch = new Stopwatch();
while (IsStarted)
{
watch.Restart();
try
{
var bitmap = CaptureMethod.GetDesktopBitmap(CaptureRegion);
if (CaptureCursor)
{
using (Graphics g = Graphics.FromImage(bitmap))
{
CursorUtils.ApplyCursor(g, bitmap, CaptureRegion.Left, CaptureRegion.Top);
}
}
if (EnableComparer && Comparer != null)
{
if (_previousBitmap == null)
{
_previousBitmap = bitmap.Clone() as Bitmap;
OnFrameReceived(bitmap, null, 0);
}
else
{
try
{
BitmapComparerResult<TFrame> result = Comparer.CreateDifference(_previousBitmap, bitmap);
_previousBitmap.Dispose();
_previousBitmap = bitmap.Clone() as Bitmap;
OnFrameReceived(bitmap, result.Frame, result.DifferenceCount);
}
catch (MaxDifferencesReachedException)
{
_previousBitmap.Dispose();
_previousBitmap = bitmap.Clone() as Bitmap;
OnFrameReceived(bitmap, null, (uint)(bitmap.Width * bitmap.Height));
}
}
}
else
{
OnFrameReceived(bitmap, null, 0);
}
}
catch (Exception ex)
{
Debug.WriteLine($"Error in screen capture engine: {ex.Message}");
_previousBitmap = null;
}
int delay = Math.Max(5, (1000 / FrameRate) - (int)watch.ElapsedMilliseconds);
Thread.Sleep(delay);
}
_previousBitmap = null;
}
private void OnFrameReceived(Bitmap currentBitmap, TFrame diffFrame, uint differenceCount)
{
if (!IsStarted) return;
FrameReceived?.Invoke(this, new ScreenCaptureFrameReceivedEventArgs<TFrame>()
{
Frame = new ScreenCaptureFrame<TFrame>(currentBitmap, diffFrame)
{
DifferenceCount = differenceCount
}
});
}
}
}
