c++ scrollbar to window - c++

Question

hey, here im creating a window:
_hWnd = CreateWindowEx(
WS_EX_CLIENTEDGE, //dwExStyle
(LPCWSTR) _wndClass, //lpClassName
L"", //lpWindowName
WS_CHILD | WS_HSCROLL | WS_VSCROLL , //dwStyle
CW_USEDEFAULT, //X
CW_USEDEFAULT, //Y
200, //nWidth
150, //nHeight
hWndParent, //hWndParent
NULL, //hMenu
hInstance, //hInstance
NULL //lpParam
);
i added the scrollbars (WS_HSCROLL | WS_VSCROLL), but how can i control them?

Answer 1

I think you should refer to MSDN for more information, but here is some short part of code I wrote one day (just for you to start from something).
Generally, the idea is about handling specific messages in your WindowProcedure routine (WM_HSCROLL, WM_VSCROLL). The easiest way to evaluate new scroller position (I mean, the WinAPI way) is to use a specific SCROLLINFO structure. In the following chunk of code, SCROLLINFO si is used.
case WM_HSCROLL:
{
TEXTHANDLER * handler = ((TEXTHANDLER *)GetProp(hWnd, "TEXTHANDLER"));
// If user is trying to scroll outside
// of scroll range, we don't have to
// invalidate window
BOOL needInvalidation = TRUE;
if (handler->renderer->wordWrap)
{
return 0;
}
si.cbSize = sizeof(si);
si.fMask = SIF_ALL;
GetScrollInfo(hWnd, SB_HORZ, &si);
switch (LOWORD(wParam))
{
case SB_LINELEFT:
si.nPos -= 1;
if (si.nPos < 0)
{
si.nPos = 0;
needInvalidation = FALSE;
}
break;
case SB_LINERIGHT:
si.nPos += 1;
if (si.nPos > si.nMax)
{
si.nPos = si.nMax;
needInvalidation = FALSE;
}
break;
case SB_THUMBTRACK:
si.nPos = si.nTrackPos;
break;
}
si.fMask = SIF_POS;
SetScrollInfo(hWnd, SB_HORZ, &si, TRUE);
// Set new text renderer parameters
handler->renderer->xPos = si.nPos;
if (needInvalidation) InvalidateRect(hWnd, NULL, FALSE);
return 0;
}
case WM_VSCROLL:
{
TEXTHANDLER * handler = ((TEXTHANDLER *)GetProp(hWnd, "TEXTHANDLER"));
BOOL needInvalidation = TRUE;
si.cbSize = sizeof(si);
si.fMask = SIF_ALL;
GetScrollInfo(hWnd, SB_VERT, &si);
switch (LOWORD(wParam))
{
case SB_LINEUP:
si.nPos -= 1;
if (si.nPos < 0)
{
si.nPos = 0;
needInvalidation = FALSE;
}
break;
case SB_LINEDOWN:
si.nPos += 1;
if (si.nPos > si.nMax)
{
si.nPos = si.nMax;
needInvalidation = FALSE;
}
break;
case SB_PAGEUP:
si.nPos -= handler->renderer->cyCount;
if (si.nPos < 0)
{
si.nPos = 0;
needInvalidation = FALSE;
}
break;
case SB_PAGEDOWN:
si.nPos += handler->renderer->cyCount;
if (si.nPos > si.nMax)
{
si.nPos = si.nMax;
needInvalidation = FALSE;
}
break;
case SB_THUMBTRACK:
si.nPos = si.nTrackPos;
break;
}
si.fMask = SIF_POS;
SetScrollInfo(hWnd, SB_VERT, &si, TRUE);
// Set new text renderer parameters
handler->renderer->yPos = si.nPos;
if (needInvalidation) InvalidateRect(hWnd, NULL, FALSE);
return 0;
}