我正在使用以下代码捕获屏幕并将其复制到BitmapSource中。每400ms通过DispatcherTimer连续调用该方法。首先，我在.NET Framework 3.5中使用了此代码，然后切换到Framework 4.0。当程序运行一段时间（假设15分钟）时，在调用GetHBitmap期间突然崩溃，出现“GDI +中的通用错误”。
当我切换到.NET 4.0时，我不得不注释掉了CloseHandle（）调用，它引发了一个SEHException。也许这会导致问题，也许不会。
所以，这是我的代码。我希望有人能帮忙......
// The code is based on an example by Charles Petzold
// http://www.charlespetzold.com/pwcs/ReadingPixelsFromTheScreen.html
// Import external Win32 functions
// BitBlt is used for the bit by bit block copy of the screen content
[DllImport("gdi32.dll")]
private static extern bool BitBlt(IntPtr hdcDst, int xDst, int yDst, int cx, int cy,
IntPtr hdcSrc, int xSrc, int ySrc, uint ulRop);
// DeleteObject is used to delete the bitmap handle
[DllImport("gdi32.dll")]
private static extern bool DeleteObject(IntPtr hObject);
// CreateDC is used to create a graphics handle to the screen
[DllImport("gdi32.dll")]
private static extern IntPtr CreateDC(string lpszDriver, string lpszDevice, string lpszOutput, IntPtr lpInitData);
// CloseHandle is used to close the bitmap handle, which does not work with Framework 4 :(
// [DllImport("Kernel32")]
// private static extern bool CloseHandle(IntPtr handle);
public static void getBitmap(ref BitmapSource bms)
{
// define the raster-operation code for the BitBlt method
// SRCOPY copies the source directly to the destination
const int SRCCOPY = 0x00CC0020;
// The screenshot will be stored here
Bitmap bm;
// Get a Graphics object associated with the screen
Screen s = UIHelper.getScreenHandle();
Graphics grfxScreen = Graphics.FromHdc(CreateDC(null, s.DeviceName, null,
IntPtr.Zero));
// Create a bitmap the size of the screen.
bm = new Bitmap((int)grfxScreen.VisibleClipBounds.Width,
(int)grfxScreen.VisibleClipBounds.Height, grfxScreen);
// Create a Graphics object associated with the bitmap
Graphics grfxBitmap = Graphics.FromImage(bm);
// Get handles associated with the Graphics objects
IntPtr hdcScreen = grfxScreen.GetHdc();
IntPtr hdcBitmap = grfxBitmap.GetHdc();
// Do the bitblt from the screen to the bitmap
BitBlt(hdcBitmap, 0, 0, bm.Width, bm.Height,
hdcScreen, 0, 0, SRCCOPY);
// Release the device contexts.
grfxBitmap.ReleaseHdc(hdcBitmap);
grfxScreen.ReleaseHdc(hdcScreen);
// convert the Bitmap to BitmapSource
IntPtr hBitmap = bm.GetHbitmap(); // Application crashes here after a while...
//System.Runtime.InteropServices.ExternalException was unhandled
// Message=Generic Error in GDI+.
// Source=System.Drawing
// ErrorCode=-2147467259
// StackTrace:
// at System.Drawing.Bitmap.GetHbitmap(Color background)
// at System.Drawing.Bitmap.GetHbitmap()
if (bms != null) bms = null; // Dispose bms if it holds content
bms = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
hBitmap,
IntPtr.Zero,
Int32Rect.Empty,
System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
// tidy up
// CloseHandle throws SEHException using Framework 4
// CloseHandle(hBitmap);
DeleteObject(hBitmap);
hBitmap = IntPtr.Zero;
bm.Dispose();
hdcBitmap = IntPtr.Zero;
hdcScreen = IntPtr.Zero;
grfxBitmap.Dispose();
grfxScreen.Dispose();
GC.Collect();
}
答案 0 :(得分：10)
您的代码泄漏了CreateDC（）返回的句柄。它必须通过调用DeleteDC（）来释放。程序泄漏10,000个句柄后，Windows将不再提供它。您可以使用TaskMgr.exe，Processes选项卡诊断这些泄漏。查看+选择列以添加句柄，用户对象和GDI对象的列。 GDI Objects正在稳步增长。
使用Graphics.CopyFromScreen（）绝对是遇到这种麻烦的较小方法。但是，它有一个错误。它和您当前的代码都不会捕获任何分层窗口。这需要CAPTUREBLT选项与托管代码中的BitBlt（），CopyPixelOperation.CaptureBlt选项。 CopyFromScreen（）摸索了这个选项，不允许你传递它。
回到BitBlt（）来解决这个问题。您可以在我this web page的答案中找到已知工作代码。
答案 1 :(得分：1)
可能需要一段时间GDI需要更多时间。 要测试它，可以增加Timer.Interval。
但是为什么Petzold如此复杂？
using System.Drawing.Imaging;
private static Bitmap bmp;
private static Graphics gfx;
然后在你的方法中：
bmp = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, PixelFormat.Format32bppArgb);
gfx = Graphics.FromImage(bmp);
gfx.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size, CopyPixelOperation.SourceCopy);
答案 2 :(得分：1)
以下是重写的代码，将Petzold的代码与Hans Passant的示例混合（仍然缺少CloseHandle（hBitmap）调用）：
[DllImport("gdi32.dll")]
static extern bool BitBlt(IntPtr hdcDest, int xDest, int yDest, int
wDest, int hDest, IntPtr hdcSource, int xSrc, int ySrc, CopyPixelOperation rop);
[DllImport("gdi32.dll")]
static extern IntPtr DeleteDC(IntPtr hDc);
[DllImport("gdi32.dll")]
static extern IntPtr DeleteObject(IntPtr hDc);
[DllImport("gdi32.dll")]
static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight);
[DllImport("gdi32.dll")]
static extern IntPtr CreateCompatibleDC(IntPtr hdc);
[DllImport("gdi32.dll")]
static extern IntPtr SelectObject(IntPtr hdc, IntPtr bmp);
[DllImport("gdi32.dll")]
private static extern IntPtr CreateDC(string lpszDriver, string lpszDevice, string lpszOutput, IntPtr lpInitData);
// get the screen handle and size
Screen s = UIHelper.getScreenHandle();
Size sz = s.Bounds.Size;
// capture the screen
IntPtr hSrce = CreateDC(null, s.DeviceName, null, IntPtr.Zero);
IntPtr hDest = CreateCompatibleDC(hSrce);
IntPtr hBmp = CreateCompatibleBitmap(hSrce, sz.Width, sz.Height);
IntPtr hOldBmp = SelectObject(hDest, hBmp);
bool b = BitBlt(hDest, 0, 0, sz.Width, sz.Height, hSrce, 0, 0, CopyPixelOperation.SourceCopy | CopyPixelOperation.CaptureBlt);
Bitmap bm = Bitmap.FromHbitmap(hBmp);
SelectObject(hDest, hOldBmp);
// convert the Bitmap to BitmapSource
IntPtr hBitmap = bm.GetHbitmap();
// Dispose bms if it holds content, Garbage Collector will do the cleaning
if (bms != null) bms = null;
// create BitmapSource from Bitmap
bms = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
hBitmap,
IntPtr.Zero,
Int32Rect.Empty,
System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
// tidy up
// CloseHandle throws SEHException using Framework 4
// CloseHandle(hBitmap);
DeleteObject(hBitmap);
hBitmap = IntPtr.Zero;
DeleteObject(hBmp);
DeleteDC(hDest);
DeleteDC(hSrce);
bm.Dispose();
GC.Collect();