C # capture screen images using windowsapi

Add reference

Using system. Data;
Using system. Drawing. imaging;

Call the API and save the image

[System. runtime. interopservices. dllimportattribute ("gdi32.dll")]

Private Static extern bool bitblt (

Intptr hdcdest, // The destination DC handle

Int nxdest, // X coordinate in the upper left corner of the Target Image

Int nydest, // y coordinate in the upper left corner of the Target Image

Int nwidth, // The width of the rectangle of the Target Image

Int nheight, // The height of the rectangle of the Target Image

Intptr hdcsrc, // source DC handle

Int nxsrc, // X coordinate in the upper left corner of the source Image

Int nysrc, // X coordinate in the upper left corner of the source Image

System. int32 dwdrop // grating operation code

);

Private void button#click (Object sender, system. eventargs E)
{

Graphics G1 = This. creategraphics (); // obtain the form image object

Image myimage = new Bitmap (this. clientrectangle. Width, this. clientrectangle. Height, G1 );

Graphics g2 = graphics. fromimage (myimage); // create a bitmap image object

Intptr DC1 = g1.gethdc (); // obtain the context device of the form

Intptr DC2 = g2.gethdc (); // context device for obtaining bitmap files

Bitblt (DC2, 0, 0, this. clientrectangle. Width, this. clientrectangle. Height, DC1, 0, 0, 13369376); // write in-place Graph

G1.releasehdc (DC1); // release the context device of the form

G2.releasehdc (DC2); // The context device that releases the bitmap file.

Myimage. Save (@ "C:/captured.jpg", imageformat. JPEG); // save as a jpeg file

MessageBox. Show ("saving the image ends! ");

}