Include mouse cursor in screen capture - c++

Question

I use CreateDC / BitBlt / GetDIBits etc. to capture the screen, but the cursor is not captured. Is there some simple argument or something to have it included?

Answer 1

#include <Windows.h>
#include <stdio.h>
#include <assert.h>
void scrshot() {
HWND hwnd = GetDesktopWindow();
HDC hdc = GetWindowDC(hwnd);
HDC hdcMem = CreateCompatibleDC(hdc);
int cx = GetDeviceCaps(hdc, HORZRES);
int cy = GetDeviceCaps(hdc, VERTRES);
HBITMAP hbitmap(NULL);
hbitmap = CreateCompatibleBitmap(hdc, cx, cy);
SelectObject(hdcMem, hbitmap);
BitBlt(hdcMem, 0, 0, cx, cy, hdc, 0, 0, SRCCOPY);
CURSORINFO cursor = { sizeof(cursor) };
GetCursorInfo(&cursor);
if (cursor.flags == CURSOR_SHOWING) {
RECT rect;
GetWindowRect(hwnd, &rect);
ICONINFO info = { sizeof(info) };
GetIconInfo(cursor.hCursor, &info);
const int x = cursor.ptScreenPos.x - rect.left - rect.left - info.xHotspot;
const int y = cursor.ptScreenPos.y - rect.top - rect.top - info.yHotspot;
BITMAP bmpCursor = { 0 };
GetObject(info.hbmColor, sizeof(bmpCursor), &bmpCursor);
DrawIconEx(hdcMem, x, y, cursor.hCursor, bmpCursor.bmWidth, bmpCursor.bmHeight,
0, NULL, DI_NORMAL);
}
}
int main(){
scrshot();
return 0;
}

Answer 2

Further to the discussion that occurred in the comments, I had the chance to further investigate the question. As a result, I came up with the following code that will grab the current cursor's HBITMAP and draw it to the screen.
Since the cursor is actually an HICON, it comes with a mask. Initially, I just did a simple BitBlt - however, I got a 32x32 black sqaure with the cursor in the top left 1/4 or so.
I then investigated using MaskBlt. Depending on where the cursor is when the app is started, I get either the wait cursor, a NS resize cursor, or the standard pointer. I guess you could start a timer and add a WM_TIMER handler to fire a couple of times a second in order to get a real-time update of the cursor as it was used in other windows in the system. It seemed like a mere curiosity to do something like that so I didn't bother.
EDIT: I actually did start a timer in WM_INITDIALOG and handle it in WM_TIMER. You can now see the image updated 10 times a second. For some reason, the I-beam cursor doesn't seem to be displayed at all - a case for further investigation as needed, I guess.
Here's the complete listing (except for resource.rc and resource.h - just create a dialog app and make sure the dialog's resource ID is used inside Main in the call to DialogBox)
#include <windows.h>
#include <commctrl.h>
#include <stdio.h>
#include "resource.h"
HINSTANCE hInst;
HBITMAP getCursorHBITMAP(HBITMAP *maskBmp)
{
CURSORINFO pci;
ICONINFO iconinfo;
HBITMAP result;
pci.cbSize = sizeof(pci);
GetCursorInfo(&pci);
if (GetIconInfo(pci.hCursor,&iconinfo))
{
result = iconinfo.hbmColor;
if (maskBmp)
*maskBmp = iconinfo.hbmMask;
}
else
result = NULL;
return result;
}
BOOL CALLBACK DlgMain(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch(uMsg)
{
case WM_INITDIALOG:
{
SetTimer(hwndDlg, 1, 100, NULL);
}
return TRUE;
case WM_TIMER:
{
InvalidateRect(hwndDlg, NULL, true);
}
return 0;
case WM_ERASEBKGND:
{
HDC hdc = (HDC)wParam;
RECT mRect;
GetClientRect(hwndDlg, &mRect);
FillRect(hdc, &mRect, (HBRUSH)GetStockObject(GRAY_BRUSH));
}
return 1;
case WM_PAINT:
{
HBITMAP oldBm, cursorBmp, maskBmp;
cursorBmp = getCursorHBITMAP(&maskBmp);
if (cursorBmp)
{
HDC hdc;
PAINTSTRUCT ps;
HDC memDC;
BITMAP bm;
hdc = BeginPaint(hwndDlg, &ps);
memDC = CreateCompatibleDC(hdc);
oldBm = (HBITMAP) SelectObject(memDC, cursorBmp);
GetObject(cursorBmp, sizeof(bm), &bm);
// printf("Cursor size: %d x %d\n", bm.bmWidth, bm.bmHeight);
// BitBlt(hdc, 10,10, 32,32, memDC, 0,0, SRCCOPY);
MaskBlt(hdc, 10,10, bm.bmWidth, bm.bmHeight, memDC, 0,0, maskBmp, 0,0, MAKEROP4(SRCPAINT,SRCCOPY) );
SelectObject(memDC, oldBm);
DeleteDC(memDC);
EndPaint(hwndDlg, &ps);
}
}
return 0;
case WM_CLOSE:
{
EndDialog(hwndDlg, 0);
}
return TRUE;
case WM_COMMAND:
{
switch(LOWORD(wParam))
{
}
}
return TRUE;
}
return FALSE;
}
int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
hInst=hInstance;
InitCommonControls();
return DialogBox(hInst, MAKEINTRESOURCE(DLG_MAIN), NULL, (DLGPROC)DlgMain);
}