BitBlt 函数 详解, StretchBlt、SetStretchBltM…
2018-06-23 23:53:44来源:未知 阅读 ()
BitBlt
函数原型
[DllImport("gdi32.dll")] public static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest, int nWidth, int nHeight,
IntPtr hObjectSource, int nXSrc, int nYSrc, int dwRop);
参数
返回值
按句柄截图 、直接截取缩略图
public static class ImageHelper { public static Bitmap CaptureWindow(IntPtr handle, int width, int height) { try { // get the hDC of the target window IntPtr hdcSrc = User32.GetWindowDC(handle); // create a device context we can copy to IntPtr hdcDest = GDI32.CreateCompatibleDC(hdcSrc); // create a bitmap we can copy it to, // using GetDeviceCaps to get the width/height IntPtr hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc, width, height); // select the bitmap object IntPtr hOld = GDI32.SelectObject(hdcDest, hBitmap); // bitblt over GDI32.BitBlt(hdcDest, 0, 0, width, height, hdcSrc, 0, 0, GDI32.SRCCOPY); // restore selection GDI32.SelectObject(hdcDest, hOld); // clean up GDI32.DeleteDC(hdcDest); User32.ReleaseDC(handle, hdcSrc); // get a .NET image object for it Bitmap img = Image.FromHbitmap(hBitmap); // free up the Bitmap object GDI32.DeleteObject(hBitmap); return img; } catch (Exception ex) { LogHelper.Execption(ex, nameof(ImageHelper)); } return null; } public static Bitmap CaptureWindow(IntPtr handle, int widthSrc, int heightSrc, int widthDest, int heightDest) { try { // get the hDC of the target window IntPtr hdcSrc = User32.GetWindowDC(handle); // create a device context we can copy to IntPtr hdcDest = GDI32.CreateCompatibleDC(hdcSrc); // create a bitmap we can copy it to, // using GetDeviceCaps to get the width/height IntPtr hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc, widthDest, heightDest); // select the bitmap object IntPtr hOld = GDI32.SelectObject(hdcDest, hBitmap); GDI32.SetStretchBltMode(hdcDest, GDI32.STRETCH_HALFTONE); GDI32.POINTAPI point; GDI32.SetBrushOrgEx(hdcDest, 0, 0, out point); // bitblt over GDI32.StretchBlt(hdcDest, 0, 0, widthDest, heightDest, hdcSrc, 0, 0, widthSrc, heightSrc, GDI32.SRCCOPY); // restore selection GDI32.SelectObject(hdcDest, hOld); // clean up GDI32.DeleteDC(hdcDest); User32.ReleaseDC(handle, hdcSrc); // get a .NET image object for it Bitmap img = Image.FromHbitmap(hBitmap); // free up the Bitmap object GDI32.DeleteObject(hBitmap); return img; } catch (Exception ex) { LogHelper.Execption(ex, nameof(ImageHelper)); } return null; } /// <summary> /// Helper class containing Gdi32 API functions /// </summary> public class GDI32 { public const int CAPTUREBLT = 1073741824; public const int SRCCOPY = 0x00CC0020; // BitBlt dwRop parameter [DllImport("gdi32.dll")] public static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hObjectSource, int nXSrc, int nYSrc, int dwRop); [DllImport("gdi32.dll")] public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC, int nWidth, int nHeight); [DllImport("gdi32.dll")] public static extern IntPtr CreateCompatibleDC(IntPtr hDC); [DllImport("gdi32.dll")] public static extern bool DeleteDC(IntPtr hDC); [DllImport("gdi32.dll")] public static extern bool DeleteObject(IntPtr hObject); [DllImport("gdi32.dll")] public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject); /// <summary> /// 缩放截图 /// </summary> /// <param name="hdcDest"></param> /// <param name="nXOriginDest"></param> /// <param name="nYOriginDest"></param> /// <param name="nWidthDest"></param> /// <param name="nHeightDest"></param> /// <param name="hdcSrc"></param> /// <param name="nXOriginSrc"></param> /// <param name="nYOriginSrc"></param> /// <param name="nWidthSrc"></param> /// <param name="nHeightSrc"></param> /// <param name="dwRop"></param> /// <returns></returns> [DllImport("gdi32.dll")] public static extern bool StretchBlt(IntPtr hdcDest, int nXOriginDest, int nYOriginDest, int nWidthDest, int nHeightDest, IntPtr hdcSrc, int nXOriginSrc, int nYOriginSrc, int nWidthSrc, int nHeightSrc, int dwRop); public const int STRETCH_ANDSCANS = 0x01; public const int STRETCH_ORSCANS = 0x02; public const int STRETCH_DELETESCANS = 0x03; public const int STRETCH_HALFTONE = 0x04; /// <summary> /// 设置缩放模式 /// </summary> /// <param name="hdc"></param> /// <param name="iStretchMode"></param> /// <returns>失败返回0</returns> [DllImport("gdi32.dll")] public static extern int SetStretchBltMode(IntPtr hdc, int iStretchMode); [StructLayout(LayoutKind.Sequential)] public struct POINTAPI { public int x; public int y; } [DllImport("gdi32.dll")] public static extern bool SetBrushOrgEx(IntPtr hdc, int nXOrg, int nYOrg, out POINTAPI lppt); } /// <summary> /// Helper class containing User32 API functions /// </summary> public class User32 { [StructLayout(LayoutKind.Sequential)] public struct RECT { public int left; public int top; public int right; public int bottom; } [DllImport("user32.dll")] public static extern IntPtr GetDesktopWindow(); [DllImport("user32.dll")] public static extern IntPtr GetWindowDC(IntPtr hWnd); [DllImport("user32.dll")] public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDC); [DllImport("user32.dll")] public static extern IntPtr GetWindowRect(IntPtr hWnd, ref RECT rect); public const int WM_PAINT = 0x000F; [DllImport("user32.dll", EntryPoint = "SendMessageA")] public static extern uint SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam); [DllImport("user32.dll")] public static extern bool PrintWindow( IntPtr hwnd, // Window to copy,Handle to the window that will be copied. IntPtr hdcBlt, // HDC to print into,Handle to the device context. UInt32 nFlags // Optional flags,Specifies the drawing options. It can be one of the following values. ); [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)] public static extern int ShowWindow(IntPtr hwnd, int nCmdShow); #region 窗口关联 // nCmdShow的含义 //0 关闭窗口 //1 正常大小显示窗口 //2 最小化窗口 //3 最大化窗口 //使用实例: ShowWindow(myPtr, 0); #endregion } }
StretchBlt
SetStretchBltMode
SetBrushOrgEx
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