Printscreen / alt+Printscreen including Cursor , in C++

05-26-2004, 11:24 AM
An example of taking a screenshot of either the entire desktop , or a window by it's handle. included in the screenshot is the Cursor at it's position at the time of the shot ( unlike windows , which doesn't show the Cursor )
This for me has proved to be the most challenging of projects, i've built it all in C++ ( .NET win forms , but using standard C++ api calls etc... )

// at the very top of the Form's .h file ...
#pragma once
#include <windows.h>
#include "Winuser.h"

// then to use the sample ( i've used a button and 2 radio buttons in this case ) ...
private: void button1_Click(System::Object * sender, System::EventArgs * e)
IntPtr handle = IntPtr::Zero;
int width = NULL;
int height = NULL;
int x = NULL;
int y = NULL;

if(radioButton1->Checked == true)
// specify the handle of the Form
// and the form's sizes / positions.
handle = this->get_Handle();
width = this->get_Width();
height = this->get_Height();
x = this->get_Location().get_X();
y = this->get_Location().get_Y();
// specify the handle of the Desktop
// and the Desktop's sizes / positions.
handle = GetDesktopWindow();
Screen *r = Screen::PrimaryScreen;
width = r->Bounds.get_Width();
height = r->Bounds.get_Height();
x = 0;
y = 0;
// now lets try to make a Screenshot which includes the Cursor ( unlike the Screenshot that Windows takes )
Snapshot(handle , width , height , x , y);

private: void Snapshot(IntPtr hHandle , int width , int height , int x , int y)
//The GetWindowDC function retrieves the device context (DC) for the entire window, including title bar, menus, and scroll bars.
///See Msdn Article for more info ...
HDC srcHDC = GetWindowDC((HWND)hHandle.ToInt32());
//The CreateCompatibleDC function creates a memory device context (DC) compatible with the specified device.
///See Msdn Article for more info ...
HDC destHDC = CreateCompatibleDC(srcHDC);
//The CreateCompatibleBitmap function creates a bitmap compatible with the device that is associated with the specified device context.
///See Msdn Article for more info ...
HBITMAP bmpDC = CreateCompatibleBitmap(srcHDC , width , height);
//The SelectObject function selects an object into the specified device context (DC). The new object replaces the previous object of the same type.
///See Msdn Article for more info ...
HGDIOBJ objHDC = SelectObject(destHDC, bmpDC);
//The BitBlt function performs a bit-block transfer of the color data corresponding to a rectangle of pixels from the specified source device context into a destination device context.
///See Msdn Article for more info ...
BitBlt(destHDC, 0, 0, width, height, srcHDC, 0, 0, SRCCOPY);
SelectObject(destHDC, objHDC);
// here i cast a Bitmap ( .NET / C# type Bitmap ) from the C++ style HBITMAP
/// for this i use " dynamic_cast " , which is seen in .NET as DirectCast.
Bitmap *bmp = dynamic_cast<Bitmap*>(Bitmap::FromHbitmap(bmpDC));
//now i create a Graphics object , to enable the Cursor to be Drawn in it's Correct Position.
Graphics *g = dynamic_cast<Graphics*>(Graphics::FromImage(bmp));
System::Windows::Forms::Cursor *csr=Cursor::get_Current();
System::Drawing::Point pnt = (System::Drawing::Point)csr->get_Position();
// this was quite tricky as creating a new Rectangle threw alsorts of problems, until i found the FromLTRB property.
System::Drawing::Rectangle r= System::Drawing::Rectangle::FromLTRB((int)(pnt.get_X() - 10) - x,(int)(pnt.get_Y() - 10) - y,(int)csr->get_Size().get_Width() ,(int)csr->get_Size().get_Width());
// now i draw the Cursor on to the Graphics object of the bitmap.
csr->Draw( g , r);
//next i clean up any Resources used by the above calls.
ReleaseDC((HWND)hHandle.ToInt32(), srcHDC);
// finally i save the Bitmap ( this was the Reason for using a .NET Bitmap , makes saving alot simpler ) .
bmp->Save("C:\\test123.bmp" , System::Drawing::Imaging::ImageFormat::Bmp );
MessageBox(NULL , "ScreenShot Complete","Dynamic's C++ ScreenShot App",MB_ICONINFORMATION);


i've included a sample project ( it's VS2003 , so VS2002 users would need to convert the project or copy the code in to their version )

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