C#中对 API函数的调用

 1                                              C#中对 API函数的调用
 2
 3
 4    using System;
 5    using System.Runtime.InteropServices;
 6
 7GDI32#region    GDI32 
 8  [DllImport("gdi32.dll",EntryPoint="DeleteDC")] 
 9  public static extern IntPtr DeleteDC(IntPtr hDc); 
10
11  [DllImport("gdi32.dll",EntryPoint="DeleteObject")] 
12  public static extern IntPtr DeleteObject(IntPtr hDc); 
13
14  [DllImport("gdi32.dll",EntryPoint="BitBlt")] 
15  public static extern bool BitBlt(IntPtr hdcDest,int xDest,int yDest,int wDest,int hDest,IntPtr hdcSource,int xSrc,int ySrc,int RasterOp); 
16
17  [DllImport ("gdi32.dll",EntryPoint="CreateCompatibleBitmap")] 
18  public static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight); 
19
20  [DllImport ("gdi32.dll",EntryPoint="CreateCompatibleDC")] 
21  public static extern IntPtr CreateCompatibleDC(IntPtr hdc); 
22
23  [DllImport ("gdi32.dll",EntryPoint="SelectObject")] 
24  public static extern IntPtr SelectObject(IntPtr hdc,IntPtr bmp); 
25  [DllImport("gdi32.dll")] 
26  public static extern Int32 GetDeviceCaps(IntPtr hdc, Int32 capindex); 
27
28  #endregion
29
30USER32#region USER32
31  [DllImport("user32.dll", EntryPoint="GetDesktopWindow")]
32  public static extern IntPtr GetDesktopWindow();
33
34  [DllImport("user32.dll",EntryPoint="GetDC")]
35  public static extern IntPtr GetDC(IntPtr ptr);
36
37  [DllImport("user32.dll",EntryPoint="GetSystemMetrics")]
38  public static extern int GetSystemMetrics(int abc);
39
40  [DllImport("user32.dll",EntryPoint="GetWindowDC")]
41  public static extern IntPtr GetWindowDC(Int32 ptr);
42
43  [DllImport("user32.dll",EntryPoint="ReleaseDC")]
44  public static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hDc);
45  
46  #endregion
47
48public struct SIZE
49 {
50  public int x;
51  public int y;
52 }
53
54  public  const int SM_CXSCREEN=0;
55  public  const int SM_CYSCREEN=1;
56  public  const int SM_CXMAXIMIZED=3;
57  public  const int SM_CYMAXIMIZED=4;
58  private const int PHYSICALOFFSETX = 112;
59  private const int PHYSICALOFFSETY = 113;
60  public  const int SRCCOPY = 13369376;
61  public  int       HardMarginLeft;
62  public  int       HardMarginTop; 
63
64  public  int      WindowsWidth=0;
65  public  int      WindowsHeight=0;
66
67//获取所需的数据
68private void InvokeApiFunction()
69{
70   SIZE size;  
71   IntPtr  hDC = GetDC(GetDesktopWindow()); 
72   IntPtr hMemDC =CreateCompatibleDC(hDC);
73   size.cx = GetSystemMetrics(SM_CXSCREEN);
74   size.cy = GetSystemMetrics(SM_CYSCREEN);
75   this.WindowsHeight=GetSystemMetrics(SM_CYMAXIMIZED )  ;
76   this.WindowsWidth =GetSystemMetrics(SM_CXMAXIMIZED  )  ;
77   HardMarginLeft = GetDeviceCaps(hDC , PHYSICALOFFSETX);
78   HardMarginTop  = GetDeviceCaps(hDC , PHYSICALOFFSETY);
79   hBitmap = CreateCompatibleBitmap(hDC, size.x, size.y);
80   if (hBitmap!=IntPtr.Zero)
81   {
82    IntPtr hOld = (IntPtr) SelectObject(hMemDC, hBitmap);
83    BitBlt(hMemDC, 0, 0,size.x,size.y, hDC, 0, 0, SRCCOPY);
84    SelectObject(hMemDC, hOld);
85    DeleteDC(hMemDC);
86    ReleaseDC(GetDesktopWindow(), hDC);
87    Bitmap bmp = System.Drawing.Image.FromHbitmap(hBitmap); 
88    DeleteObject(hBitmap);   
89    GC.Collect();
90    }
91}
92   附:
    GetSystemMetrics的相关参数说明:
    http://vbworld.sxnw.gov.cn/vbapi/detail/GetSystemMetrics.htm