/// <summary>
/// Attempts to create a capture handle if it does not already exist. Returns false if the capture handle could not be created.
/// </summary>
private bool CreateCaptureHandleIfNecessary()
{
if (deviceContext == null)
{
deviceContext = AutoDisposeHandle.Create(NativeMethods.GetDC(IntPtr.Zero), h => NativeMethods.ReleaseDC(IntPtr.Zero, h));
}
return(deviceContext != null);
}
private void ClearCaptureHandle()
{
if (deviceContext != null)
{
deviceContext.Dispose();
}
deviceContext = null;
}
/// <summary>
/// If the current thread's desktop is not the desktop that receives input, then change it. Returns true if the desktop was changed.
/// </summary>
public static bool AssociateCurrentThreadWithDefaultDesktop()
{
using (AutoDisposeHandle inputDesktop = GetInputDesktop())
{
string inputDesktopName = GetDesktopName(inputDesktop);
string currentThreadDesktopName = GetDesktopName(GetThreadDesktop());
if (currentThreadDesktopName != inputDesktopName)
{
if (NativeMethods.SetThreadDesktop(inputDesktop))
{
return(true);
}
Win32Helper.ThrowLastWin32Error("Unable to set thread desktop");
}
}
return(false);
}
/// <summary>
/// Attempts to capture a screenshot of the current desktop.
/// </summary>
/// <returns></returns>
private Screenshot CaptureScreenshot(int x, int y, int width, int height)
{
BasicEventTimer bet = new BasicEventTimer("0.000");
bet.Start("Setup");
if (!CreateCaptureHandleIfNecessary())
{
return(null);
}
NativeMethods.BITMAPINFO bmpInfo = new NativeMethods.BITMAPINFO();
using (AutoDisposeHandle bmp = AutoDisposeHandle.Create(NativeMethods.CreateCompatibleBitmap(deviceContext, 1, 1), h => NativeMethods.DeleteObject(h)))
{
bmpInfo.bmiHeader.biSize = Marshal.SizeOf(typeof(NativeMethods.BITMAPINFOHEADER));
if (0 == NativeMethods.GetDIBits(deviceContext, bmp, 0, 1, null, ref bmpInfo, NativeMethods.DIB_Color_Mode.DIB_RGB_COLORS))
{
Win32Helper.ThrowLastWin32Error();
}
bmpInfo.bmiHeader.biSize = Marshal.SizeOf(typeof(NativeMethods.BITMAPINFO));
if (0 == NativeMethods.GetDIBits(deviceContext, bmp, 0, 1, null, ref bmpInfo, NativeMethods.DIB_Color_Mode.DIB_RGB_COLORS))
{
Win32Helper.ThrowLastWin32Error();
}
}
bmpInfo.bmiHeader.biWidth = width;
bmpInfo.bmiHeader.biHeight = -height;
bmpInfo.bmiHeader.biSizeImage = 0;
// Create memory device context. When done, delete it.
using (AutoDisposeHandle dc = AutoDisposeHandle.Create(NativeMethods.CreateCompatibleDC(IntPtr.Zero), h => NativeMethods.DeleteDC(h)))
{
if (dc == null)
{
Win32Helper.ThrowLastWin32Error("Failed to create memory device context");
}
// Create "DIB Section" (a Bitmap, more or less). When done, delete it.
IntPtr ppvBits = new IntPtr();
using (AutoDisposeHandle newDib = AutoDisposeHandle.Create(NativeMethods.CreateDIBSection(dc, ref bmpInfo, 0U, out ppvBits, IntPtr.Zero, 0U), h => NativeMethods.DeleteObject(h)))
//using (AutoDisposeHandle newDib = AutoDisposeHandle.Create(NativeMethods.CreateCompatibleBitmap(deviceContext, width, height), h => NativeMethods.DeleteObject(h)))
{
if (newDib == null)
{
Win32Helper.ThrowLastWin32Error("Failed to create DIB Section");
}
// Assign new DIB Section to our memory device context. When done, put back the old DIB Section.
using (AutoDisposeHandle oldDib = AutoDisposeHandle.Create(NativeMethods.SelectObject(dc, newDib), h => NativeMethods.SelectObject(dc, h)))
{
if (oldDib == null)
{
Win32Helper.ThrowLastWin32Error("Failed to assign new DIB Section to memory device context");
}
bet.Start("BitBlt");
// Copy data from the screen to our memory device context
if (!NativeMethods.BitBlt(dc, 0, 0, width, height, deviceContext, x, y, CopyPixelOperation.SourceCopy | CopyPixelOperation.CaptureBlt))
{
Logger.Debug("BitBlt failed with error code: " + Win32Helper.GetLastWin32Error());
ClearCaptureHandle();
DesktopManager.ShouldReassociate = true;
}
else
{
bet.Start("new Screenshot/Copy bits");
Screenshot screenshot = new Screenshot(width, height, bmpInfo.bmiHeader.biBitCount);
Marshal.Copy(ppvBits, screenshot.Buffer, 0, screenshot.Buffer.Length);
bet.Stop();
//Logger.Info(bet.ToString(Environment.NewLine));
return(screenshot);
}
}
}
}
return(null);
}
/// <summary>
/// Gets a handle to the desktop that receives user input.
/// </summary>
/// <returns></returns>
private static AutoDisposeHandle GetInputDesktop()
{
return(AutoDisposeHandle.Create(NativeMethods.OpenInputDesktop(0, false, (uint)NativeMethods.ACCESS_MASK.DESKTOP_ALL_ACCESS), h => NativeMethods.CloseDesktop(h)));
}
/// <summary>
/// Retrieves a handle to the desktop assigned to the current thread. This handle does not need to be closed.
/// </summary>
/// <returns></returns>
private static AutoDisposeHandle GetThreadDesktop()
{
// The value returned by GetThreadDesktop does not need to be closed, so we pass null for the onRelease method.
return(AutoDisposeHandle.Create(NativeMethods.GetThreadDesktop(NativeMethods.GetCurrentThreadId()), null));
}