CScrollView::SetScrollSizes

  • Article

Call SetScrollSizes when the view is about to be updated.

void SetScrollSizes( 
   int nMapMode, 
   SIZE sizeTotal, 
   const SIZE& sizePage = sizeDefault, 
   const SIZE& sizeLine = sizeDefault  
);

Parameters

  • nMapMode
    The mapping mode to set for this view. Possible values include:

    Mapping Mode

    Logical Unit

    Positive y-axis Extends...

    MM_TEXT

    1 pixel

    Downward

    MM_HIMETRIC

    0.01 mm

    Upward

    MM_TWIPS

    1/1440 in

    Upward

    MM_HIENGLISH

    0.001 in

    Upward

    MM_LOMETRIC

    0.1 mm

    Upward

    MM_LOENGLISH

    0.01 in

    Upward

    All of these modes are defined by Windows. Two standard mapping modes, MM_ISOTROPIC and MM_ANISOTROPIC, are not used for CScrollView. The class library provides the SetScaleToFitSize member function for scaling the view to window size. Column three in the table above describes the coordinate orientation.

  • sizeTotal
    The total size of the scroll view. The cx member contains the horizontal extent. The cy member contains the vertical extent. Sizes are in logical units. Both cx and cy must be greater than or equal to 0.

  • sizePage
    The horizontal and vertical amounts to scroll in each direction in response to a mouse click in a scroll-bar shaft. The cx member contains the horizontal amount. The cy member contains the vertical amount.

  • sizeLine
    The horizontal and vertical amounts to scroll in each direction in response to a mouse click in a scroll arrow. The cx member contains the horizontal amount. The cy member contains the vertical amount.

Remarks

Call it in your override of the OnUpdate member function to adjust scrolling characteristics when, for example, the document is initially displayed or when it changes size.

You will typically obtain size information from the view's associated document by calling a document member function, perhaps called GetMyDocSize, that you supply with your derived document class. The following code shows this approach:

CMyScrollDoc* pMyDoc = (CMyScrollDoc*)GetDocument();
SetScrollSizes(nMapMode, pMyDoc->GetMyDocSize());

Alternatively, you might sometimes need to set a fixed size, as in the following code:

SetScrollSizes(nMapMode, CSize(100, 100));

You must set the mapping mode to any of the Windows mapping modes except MM_ISOTROPIC or MM_ANISOTROPIC. If you want to use an unconstrained mapping mode, call the SetScaleToFitSize member function instead of SetScrollSizes.

Example

void CMyScrollView::OnUpdate(CView* /*pSender*/, LPARAM /*lHint*/, 
   CObject* /*pHint*/)
{
   // Implement a GetMyDocSize() member function in  
   // your document class; it returns a CSize.
   CMyScrollDoc* pMyDoc = (CMyScrollDoc*)GetDocument();
   SetScrollSizes(MM_LOENGLISH, pMyDoc->GetMyDocSize());
   ResizeParentToFit();   // Default bShrinkOnly argument
}

void CMyScrollView::OnInitialUpdate()
{
   CScrollView::OnInitialUpdate();

   // The GetMyDocSize() member function is implemented in  
   // your document class. The return type is CSize.
   CMyScrollDoc* pMyDoc = (CMyScrollDoc*)GetDocument();
   SetScrollSizes(MM_TEXT, pMyDoc->GetMyDocSize());
}

Requirements

Header: afxwin.h

See Also

Reference

CScrollView Class

Hierarchy Chart

CScrollView::SetScaleToFitSize

CScrollView::GetDeviceScrollSizes

CScrollView::GetTotalSize