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Message: [QUOTE="Guest, post: 5603045"] I'm capturing the screen using the following code , but the problem i have that after 43 calls of the functions the NULL reference object is returned , SIZE size; //Here we get the handle to the desktop device context. IntPtr hDC = PlatformInvokeUSER32.GetDC(PlatformInvokeUSER32.GetDesktopWindow()); //Here we make a compatible device context in memory for screen device context. IntPtr hMemDC = PlatformInvokeGDI32.CreateCompatibleDC(hDC); //We pass SM_CXSCREEN constant to GetSystemMetrics to get the X coordinates of screen. size.cx = PlatformInvokeUSER32.GetSystemMetrics(PlatformInvokeUSER32.SM_CXSCREEN); //We pass SM_CYSCREEN constant to GetSystemMetrics to get the Y coordinates of screen. size.cy = PlatformInvokeUSER32.GetSystemMetrics(PlatformInvokeUSER32.SM_CYSCREEN); //We create a compatible bitmap of screen size and using screen device context. m_HBitmap = PlatformInvokeGDI32.CreateCompatibleBitmap(hDC, size.cx, size.cy); //Here m_HBitmap return be NULL(Zero) after 43 calls of the function...WHY? //As m_HBitmap is IntPtr we can not check it against null. For this purspose IntPtr.Zero is used. if (m_HBitmap!=IntPtr.Zero) { //Here we select the compatible bitmap in memeory device context and keeps the refrence to Old bitmap. IntPtr hOld = (IntPtr) PlatformInvokeGDI32.SelectObject(hMemDC, m_HBitmap); //We copy the Bitmap to the memory device context. PlatformInvokeGDI32.BitBlt(hMemDC, 0, 0,size.cx,size.cy, hDC, 0, 0, PlatformInvokeGDI32.SRCCOPY); //We select the old bitmap back to the memory device context. PlatformInvokeGDI32.SelectObject(hMemDC, hOld); //We delete the memory device context. PlatformInvokeGDI32.DeleteDC(hMemDC); //We release the screen device context. PlatformInvokeUSER32.ReleaseDC(PlatformInvokeUSER32.GetDesktopWindow(), hDC); //Image is created by Image bitmap handle and returned. return System.Drawing.Image.FromHbitmap(m_HBitmap); } //If m_HBitmap is null retunrn null. return null; [/QUOTE]

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