C # simulate printscreen and ALT + printscreen to capture screen images

C # simulate printscreen and ALT + printscreen to capture screen images

Keybd_event API function: This function is used to synthesize a key event. The system can use this synthetic key event to generate the wm_keyup or wm_keydown message. The interrupt handler of the keyboard driver calls the keybd_event function. In Windows NT, this function has been replaced by sendinput. Function prototype; void keybd_event (byte bvk, byte bscan, DWORD dwflags, DWORD dwextralnfo); parameter: bvk: defines a virtual key code. The key value must be 1 ~ In the range of 254.
Bscan: The hardware scan code that defines the key.
Dwflags: defines a flag set for all aspects of function operations. The application can use a combination of the following predefined constants to set the flag.
Keyeventf_extendedkey: if this value is specified, the first value of the scan code is the prefix byte of oxeo (224.
Keyeventf_keyup: if this value is specified, the key is released. If this value is not specified, the key is pressed.
Dwextralnfo: defines the 32-bit value associated with the strike key.
Return Value: this function has no return value. Complete code:

Using system; using system. collections. generic; using system. componentmodel; using system. data; using system. drawing; using system. text; using system. windows. forms; using system. runtime. interopservices; namespace printscreen {public partial class form1: FORM {[dllimport ("user32.dll")] Static extern void keybd_event (byte bvk, // virtual key value byte bscan, // hardware scan code uint dwflags, // action ID intptr dwextrainfo // auxiliary code associated with keyboard actions Add information); // <summary> // simulate the Print Screen Keyboard Message to capture a full screen image. /// </Summary> Public void printscreen () {keybd_event (byte) 0x2c, 0, 0x0, intptr. zero); // down application. doevents (); keybd_event (byte) 0x2c, 0, 0x2, intptr. zero); // up application. doevents () ;}//< summary> /// simulate the alt Print Screen Keyboard Message to capture the current window image. /// </Summary> Public void altprintscreen () {keybd_event (byte) keys. menu, 0, 0x0, intptr. zero); keybd_event (byte) 0x2c, 0, 0x0, intptr. zero); // down application. doevents (); application. doevents (); keybd_event (byte) 0x2c, 0, 0x2, intptr. zero); // up keybd_event (byte) keys. menu, 0, 0x2, intptr. zero); application. doevents (); application. doevents ();} public form1 () {initializecomponent ();} private void form1_load (Object sender, eventargs E) {}/// <summary> /// obtain an image from the clipboard /// </Summary> /// <returns> </returns> private bitmap getscreenimage () {idataobject newobject = NULL; bitmap newbitmap = NULL; try {application. doevents (); newobject = clipboard. getdataobject (); If (clipboard. containsimage () {newbitmap = (Bitmap) (clipboard. getimage (). clone ();} return newbitmap;} catch (exception ex) {console. writeline (ex. message); return NULL ;}} private void button#click (Object sender, eventargs e) {button1.enabled = false; picturebox1.image = NULL; printscreen (); picturebox1.image = getscreenimage (); button1.enabled = true; application. doevents ();} private void button2_click (Object sender, eventargs e) {button2.enabled = false; Enabled = NULL; altprintscreen (); picturebox1.image = getscreenimage (); button2.enabled = true; application. doevents ();}}}

Running effect:

Legacy problems:

Printscreen has no task problems, but when using altprintscreen, the correct image is always not available for the first time. I don't know why! I hope you can pass by and give me some advice. I am very grateful to you!

C # simulate printscreen and ALT + printscreen to capture screen images