C # screen capture [including desktop and window]

It is relatively simple to intercept desktop images. You can simply call graphics's copyfromscreen method;

 

It is easy to draw an image to a window, but few articles show that the image is captured from a window. The following describes how to intercept window images.

The bitblt function provided by the system is used to capture the image of the window. This function is used to copy a bitmap image from the context of the source device to the target device. For more information about the parameters, see the msdn documentation.

The following is the C # function introduction operation:

[Dllimport ("gdi32.dll", charset = charset. Auto, setlasterror = true, exactspelling = true)]
Public static extern int bitblt (handleref HDC, int X, int y, int nwidth, int nheight, handleref hsrcdc, int xsrc, int ysrc, int dwdrop );

 

The specific operation code is as follows:

Graphics gsrc = This. creategraphics (); // create a graphics object for the form
Handleref hdcsrc = new handleref (null, gsrc. gethdc ());

Int width = This. Width-SystemInformation.FrameBorderSize.Width; // get the width
Int Height = This. Height-SystemInformation.FrameBorderSize.Height; // get height

Const int srccopy = 0xcc0020; // copy the grating operation code of the graph block.

Bitmap bmsave = new Bitmap (width, height); // The bitmap object used to save the image
Graphics gsave = graphics. fromimage (bmsave); // create a graphics object for this bitmap
Handleref hdcsave = new handleref (null, gsave. gethdc (); // get the handle

Bitblt (hdcsave, 0, 0, width, height, hdcsrc, 0, 0, srccopy );

In this way, the image of the current form is saved in bmsave.

 

The following provides a detailed code

 

Using system; <br/> using system. collections. generic; <br/> using system. componentmodel; <br/> using system. data; <br/> using system. drawing; <br/> using system. text; <br/> using system. windows. forms; <br/> using system. runtime. interopservices; </P> <p> namespace screenshot <br/> {<br/> Public partial class form1: Form <br/>{< br/> Public form1 () <br/>{< br/> initializecomponent (); <br/>}</P> <p> private Void btnscreen_click (Object sender, eventargs e) <br/>{< br/> int screenwidth = system. windows. forms. systeminformation. virtualscreen. width; // screen width <br/> int screenheight = system. windows. forms. systeminformation. virtualscreen. height; // screen height </P> <p> bitmap bmsave = new Bitmap (screenwidth, screenheight); <br/> graphics G = graphics. fromimage (bmsave); </P> <p> G. copyfromscreen (0, 0, 0, 0, new size (scree Nwidth, screenheight), copypixeloperation. sourcecopy); <br/> G. dispose (); </P> <p> SaveFile (bmsave); <br/>}</P> <p> private void btnwindow_click (Object sender, eventargs E) <br/>{< br/> graphics gsrc = This. creategraphics (); // create the graphics object of the form <br/> handleref hdcsrc = new handleref (null, gsrc. gethdc (); </P> <p> int width = This. width-SystemInformation.FrameBorderSize.Width; // get the width <br/> int Height = This. height-SystemInformation.FrameBorderSize.Height; // get height </P> <p> const int srccopy = 0xcc0020; // copy the grating operation code of the graph block </P> <p> bitmap bmsave = new Bitmap (width, height ); // The bitmap object used to save the image <br/> graphics gsave = graphics. fromimage (bmsave); // create the graphics object for this bitmap <br/> handleref hdcsave = new handleref (null, gsave. gethdc (); // obtain the handle </P> <p> bitblt (hdcsave, 0, 0, width, height, hdcsrc, 0, 0, srccopy ); </P> <p> gsrc. relea Sehdc (); <br/> gsave. releasehdc (); </P> <p> gsrc. dispose (); <br/> gsave. dispose (); </P> <p> SaveFile (bmsave); <br/>}< br/> private void SaveFile (Bitmap bmsave) <br/>{< br/> If (dialogresult. OK = savefiledialog1.showdialog () <br/>{< br/> string filename = savefiledialog1.filename; <br/> if (1 = savefiledialog1.filterindex) <br/>{< br/> If (! Filename. endswith (". BMP ") <br/>{< br/> filename + = ". BMP "; <br/>}< br/> else if (2 = savefiledialog1.filterindex) <br/>{< br/> If (! Filename. endswith (". jpg ") <br/>{< br/> filename + = ". jpg "; <br/>}< br/> else if (3 = savefiledialog1.filterindex) <br/>{< br/> If (! Filename. endswith (". PNG ") <br/>{< br/> filename + = ". PNG "; <br/>}< br/> Save (bmsave, filename ); <br/>}< br/> private void save (Bitmap BM, string filename) <br/>{< br/> If (filename. endswith (". BMP ") <br/>{< br/> BM. save (filename, system. drawing. imaging. imageformat. BMP); <br/>}< br/> else if (filename. endswith (". jpg ") <br/>{< br/> BM. save (filename, system. drawing. imaging. imageformat. JPEG); <br/>}< br/> else if (filename. endswith (". PNG ") <br/>{< br/> BM. save (filename, system. drawing. imaging. imageformat. PNG); <br/>}< br/> BM. dispose (); <br/>}</P> <p> [dllimport ("gdi32.dll", charset = charset. auto, setlasterror = true, exactspelling = true)] <br/> Public static extern int bitblt (handleref HDC, int X, int y, int nwidth, int nheight, handleref hsrcdc, int xsrc, int ysrc, int dwrop); <br/>}< br/>}

 

The code for form design is omitted. The test form image is as follows: