自学教程：C++ GetScrollPosition函数代码示例

		/*=============================================================================		-- Updates the ScrollBar.		=============================================================================*/		void ScrollBar::_Update()		{			double oldScrollPosition = GetScrollPosition();			//update the scroll position			int knobLength = (mSpanDirection == SpanDirection::HORIZONTAL) ? mKnobButton.lock()->GetWidth() : mKnobButton.lock()->GetHeight();			int knobMin = SCROLL_BAR_BUTTON_SIZE;			int knobMax = ((mSpanDirection == SpanDirection::HORIZONTAL) ? GetWidth() : GetHeight()) - SCROLL_BAR_BUTTON_SIZE - knobLength;			int innerRange = knobMax - knobMin;			Vector2D<int> knobRelPos = mKnobButton.lock()->GetRelPos();			int knobOffset = ((mSpanDirection == SpanDirection::HORIZONTAL) ? knobRelPos.x : knobRelPos.y) - SCROLL_BAR_BUTTON_SIZE;			mScrollPosition = DivideD((double)knobOffset,(double)innerRange);			//check if either increase/decrease button were pressed			if (mAdjustTimer.GetTimeAndEnd() > SCROLL_BAR_ADJUST_DELAY)			{				if (mButtonDecrease.lock()->GetState() == State::DOWN)					SetScrollPosition(GetScrollPosition() + 0.01);				else if (mButtonIncrease.lock()->GetState() == State::DOWN)					SetScrollPosition(GetScrollPosition() - 0.01);				mAdjustTimer.Start();			}			if (GetScrollPosition() != oldScrollPosition)				_SendElementMessageToListeners(ElementEvent::VALUE_CHANGED);		}

void CMapView::OnLButtonDown(UINT nFlags, CPoint point){    if (m_HandDown)    {        m_Tracking = true;        SetCapture();        m_LastPoint = point;    }    else    {        CPoint pt = point + GetScrollPosition();        int x  = pt.x / 40;        int y  = pt.y / 40;        int xe = (pt.x % 40) / 10;        int ye = (pt.y % 40) / 10;        CMapDoc* pDoc = GetDocument();        ASSERT_VALID(pDoc);        int w = pDoc->GetWidth();        int h = pDoc->GetHeight();        if (w > 0 && h > 0 && x >= 0 && y >= 0 && x < w && y < h && xe >= 0 && xe < 4 && ye >= 0 && ye < 4)        {            int r = y*w + x;            int e = ye*4 + xe;            if (m_ViewMode == VIEW_MODE_ELEVATION)            {                pDoc->SetTileElevation(r, g_Elevation);                CString str;                str.Format("Change %d to %dm", r, g_Elevation);                g_App.PrintStatus(str);                CRect rect(CPoint(x*40, y*40), CSize(40,40));                rect.OffsetRect(-GetScrollPosition());                InvalidateRect(rect, FALSE);            }            else            {                pDoc->SetTile(r,e, g_Tile);                CString str;                str.Format("Change %d [%d] to %s", r,e, g_App.m_Elements[g_Tile].Name);                g_App.PrintStatus(str);                CRect rect(CPoint(x*40 + xe*10, y*40 + ye*10), CSize(10,10));                rect.OffsetRect(-GetScrollPosition());                InvalidateRect(rect, FALSE);            }            m_Tracking = true;            SetCapture();        }    }    Inherited::OnLButtonDown(nFlags, point);}

void DisplayView::OnLButtonUp(UINT nFlags, CPoint point){    point += GetScrollPosition();    // check for an overlay icon    if (drag_mode == DisplayView::DRAG_OVERLAY_ICON) {        Filter	*current = graph.FindFilterByPos(point);        if (current && current == overlay_filter) {            int icon = current->CheckIcons(point);            if (icon >= 0) {                OnOverlayIconClick(current->overlay_icons[icon], point);            }        }    }    if (drag_mode == DisplayView::DRAG_CONNECTION) {        Pin *p1 = graph.FindPinByPos(new_connection_start);        Pin *p2 = graph.FindPinByPos(new_connection_end);        int ret = graph.ConnectPins(p1, p2);        if (ret < 0) {            // TODO: error message        }    }    new_connection_start = CPoint(-100,-100);    new_connection_end = CPoint(-101, -101);    drag_mode = DisplayView::DRAG_GROUP;    ReleaseCapture();    graph.Dirty();    Invalidate();}

BOOL CSpermView::OnMouseWheel(UINT nFlags, short zDelta, CPoint pt) {	// TODO: Add your message handler code here and/or call default	CSize sz1=GetTotalSize();	CRect rect;	GetClientRect(rect);	CSize sz2(rect.Width(),rect.Height());	if(sz1.cy<sz2.cy)		return CScrollView::OnMouseWheel(nFlags, zDelta, pt);;	SCROLLINFO si;	zDelta =  -zDelta;	GetScrollInfo(SB_VERT,&si);	si.nPos += zDelta/12;	SetScrollInfo(SB_VERT,&si);	CPoint sp=GetScrollPosition();	CRect rc;	GetClientRect(rc);	CDC* pDC=GetDC();	rc.bottom+=sp.y;	rc.right+=sp.x;	pDC->SetViewportOrg(-sp);	DrawMemDCImage(pDC,rc);	ReleaseDC(pDC);	return CScrollView::OnMouseWheel(nFlags, zDelta, pt);}

void CResizableFormView::GetTotalClientRect(LPRECT lpRect){	GetClientRect(lpRect);	// get dialog template's size	// (this is set in CFormView::Create)	CSize size = GetTotalSize();	// before initialization use dialog's size	if (!m_bInitDone)	{		lpRect->right = lpRect->left + size.cx;		lpRect->bottom = lpRect->top + size.cy;		return;	}	// otherwise, give the correct size if scrollbars active	if (m_nMapMode < 0)	// scrollbars disabled		return;	// enlarge reported client area when needed	CRect rect(lpRect);	if (rect.Width() < size.cx)		rect.right = rect.left + size.cx;	if (rect.Height() < size.cy)		rect.bottom = rect.top + size.cy;	rect.OffsetRect(-GetScrollPosition());	*lpRect = rect;}

void CMapView::OnRButtonDown(UINT, CPoint point){    CPoint pt = point + GetScrollPosition();    int x  = pt.x / 40;    int y  = pt.y / 40;    int xe = (pt.x % 40) / 10;    int ye = (pt.y % 40) / 10;    CMapDoc* pDoc = GetDocument();    ASSERT_VALID(pDoc);    int w = pDoc->GetWidth();    int h = pDoc->GetHeight();    if (w > 0 && h > 0 && x >= 0 && y >= 0 && x < w && y < h && xe >= 0 && xe < 4 && ye >= 0 && ye < 4)    {        int r = y*w + x;        int e = ye*4 + xe;        CTile Tile = pDoc->GetTile(r);        g_Tile = Tile.E[e];        g_Elevation = Tile.Elevation;        CString str;        str.Format("Select %s (%dm) from %d [%d]", g_App.m_Elements[g_Tile].Name, g_Elevation, r,e);        g_App.PrintStatus(str);    }}

void CUIDesignerView::OnDraw(CDC* pDrawDC){	CUIDesignerDoc* pDoc = GetDocument();	ASSERT_VALID(pDoc);	if (!pDoc)		return;	// TODO: 在此处为本机数据添加绘制代码	CMemDC memDC(*pDrawDC, this);	CDC* pDC = &memDC.GetDC();	CRect rectClient;	GetClientRect(rectClient);	CPoint point=GetScrollPosition();	rectClient.OffsetRect(point);	pDC->FillSolidRect(rectClient,RGB(255, 255, 255));	CSize szFormSize=m_LayoutManager.GetForm()->GetInitSize();	CSize szFormOffset(FORM_OFFSET_X,FORM_OFFSET_Y);	CDC hCloneDC;	HBITMAP hNewBitmap;	hCloneDC.CreateCompatibleDC(pDC);	hNewBitmap=::CreateCompatibleBitmap(pDC->GetSafeHdc(),szFormSize.cx,szFormSize.cy);	HBITMAP hOldBitmap=(HBITMAP)hCloneDC.SelectObject(hNewBitmap);	m_LayoutManager.Draw(&hCloneDC);	pDC->BitBlt(szFormOffset.cx,szFormOffset.cy,szFormSize.cx,szFormSize.cy,&hCloneDC,0,0,SRCCOPY);	hCloneDC.SelectObject(hOldBitmap);	::DeleteDC(hCloneDC);	::DeleteObject(hNewBitmap);	m_MultiTracker.Draw(pDC,&szFormOffset);}

void CWFView::OnContextMenu(CWnd* pWnd, CPoint point) {	CBTEditDoc* pDoc = GetDocument();	CHeightMap *HeightMap = pDoc->GetHeightMap();	RECT WindowRect;	CPoint SPos = GetScrollPosition();	// Make click point relative to window top left.	GetWindowRect(&WindowRect);	int ObjID = HeightMap->FindObjectHit2D(SPos.x,SPos.y,											point.x-WindowRect.left,											point.y-WindowRect.top);	// If found an object then   	if(ObjID >= 0) {		// Select it		HeightMap->DeSelectAll3DObjects();   		HeightMap->Select3DObject(ObjID);   		pDoc->Invalidate3D();		UpdateAndValidate();		// And bring up it's context menu.   		CMenu Menu;   		Menu.LoadMenu(IDR_2DPOPUP);   		Menu.GetSubMenu(0)->TrackPopupMenu(TPM_LEFTALIGN | TPM_RIGHTBUTTON,   							point.x,point.y,this);   		m_CurrentObjectID = ObjID;   	}}

void CPrime95View::OnDraw(CDC* pDC){	RECT	r;	CPoint	scroll_offset;	int	ypos;	int	first_line, skip_lines, i, j;	pDC->SetBkMode (TRANSPARENT);	pDC->SetTextColor (GetSysColor (COLOR_WINDOWTEXT));	GetClientRect (&r);	scroll_offset = GetScrollPosition ();/* If Lines[0] is empty, then output lines NumLines to 1 *//* If Lines[0] has text, then output lines NumLines-1 to 0 */	gwmutex_lock (&VIEW_LINES_MUTEX);	first_line = Lines[0][0] ? NumLines - 1 : NumLines;	skip_lines = (r.top + scroll_offset.y) / charHeight;	if (skip_lines < NumLines) {		i = first_line - skip_lines;		j = NumLines - skip_lines;		ypos = skip_lines * charHeight;		for ( ; j; i--, j--) {			pDC->TextOut (0, ypos, Lines[i], (int) strlen (Lines[i]));			ypos += charHeight;			if (ypos > r.bottom + scroll_offset.y) break;		}	}	gwmutex_unlock (&VIEW_LINES_MUTEX);}

void wxJigsawEditorCanvas::OnIdle( wxIdleEvent& event ){		do	{		if(!HasCapture()) break;		// get mouse in client coordinates		wxPoint currentPos = ScreenToClient(wxGetMousePosition());		//Update the offset to the next mouse down event		if(m_View->GetSelectedObject())		{			wxPoint diagramPoint = PointToViewPoint(currentPos);			wxPoint groupPosition = m_View->GetRealGroupPosition(m_View->GetSelectedObject());			m_SelectedObjectOffset = wxSize(				diagramPoint.x - groupPosition.x,				diagramPoint.y - groupPosition.y);		}		// get scroll position		wxPoint scrollPos = GetScrollPosition();				// auto scroll		// check current drag position and update scroll regularly		if(AutoScroll(currentPos, scrollPos))		{			event.RequestMore();		}		FixViewOffset();	}	while(false);}

void CPrime95View::OnUpdate(CView* pSender, LPARAM lHint, CObject* pHint){	CFrameWnd *parent;	CSize	sz;	CPoint	pos;	int	new_scroll_height, new_scroll_width;	parent = GetParentFrame();	if (parent != NULL) {		if (charHeight == 0) getCharSize ();		sz = GetTotalSize ();		new_scroll_height = NumLines * charHeight;		new_scroll_width = MaxLineSize * charWidth;		pos = GetScrollPosition ();		pos.y += (new_scroll_height - sz.cy);		if (pos.y < 0) pos.y = 0;		sz.cx = new_scroll_width;		sz.cy = new_scroll_height;		SetScrollSizes (MM_TEXT, sz);		ScrollToPosition (pos);		parent->RecalcLayout ();	}	CScrollView::OnUpdate (pSender, lHint, pHint);}

void CLeftView::OnLButtonDblClk(UINT nFlags, CPoint point) {	// TODO: この位置にメッセ
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