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How to Create Scroll Bars

  • Artikkel

When creating an overlapped, pop-up, or child window, you can add standard scroll bars by using the CreateWindowEx function and specifying WS_HSCROLL, WS_VSCROLL, or both styles.

What you need to know

Technologies

Prerequisites

  • C/C++
  • Windows User Interface Programming

Instructions

Create a Scroll Bar

The following example creates a window with standard horizontal and vertical scroll bars.

    hwnd = CreateWindowEx( 
        0,                     // no extended styles 
        g_szWindowClass,       // global string containing name of window class
        g_szTitle,             // global string containing title bar text 
        WS_OVERLAPPEDWINDOW |  
            WS_HSCROLL | WS_VSCROLL, // window styles 
        CW_USEDEFAULT,         // default horizontal position 
        CW_USEDEFAULT,         // default vertical position 
        CW_USEDEFAULT,         // default width 
        CW_USEDEFAULT,         // default height 
        (HWND) NULL,           // no parent for overlapped windows 
        (HMENU) NULL,          // use the window class menu 
        g_hInst,               // global instance handle  
        (PVOID) NULL           // pointer not needed 
    );

To process scroll bar messages for these scroll bars, you must include appropriate code in the main window procedure.

You can use the CreateWindowEx function to create a scroll bar by specifying the SCROLLBAR window class. This creates a horizontal or vertical scroll bar, depending on whether SBS_HORZ or SBS_VERT is specified as the window style. The scroll bar size and its position relative to its parent window can also be specified.

The following example creates a horizontal scroll bar that is positioned along the bottom of the parent window's client area.

// Description:
//   Creates a horizontal scroll bar along the bottom of the parent 
//   window's area.
// Parameters:
//   hwndParent - handle to the parent window.
//   sbHeight - height, in pixels, of the scroll bar.
// Returns:
//   The handle to the scroll bar.
HWND CreateAHorizontalScrollBar(HWND hwndParent, int sbHeight)
{
    RECT rect;

    // Get the dimensions of the parent window's client area;
    if (!GetClientRect(hwndParent, &rect))
        return NULL;

    // Create the scroll bar.
    return (CreateWindowEx( 
            0,                      // no extended styles 
            L"SCROLLBAR",           // scroll bar control class 
            (PTSTR) NULL,           // no window text 
            WS_CHILD | WS_VISIBLE   // window styles  
                | SBS_HORZ,         // horizontal scroll bar style 
            rect.left,              // horizontal position 
            rect.bottom - sbHeight, // vertical position 
            rect.right,             // width of the scroll bar 
            sbHeight,               // height of the scroll bar
            hwndParent,             // handle to main window 
            (HMENU) NULL,           // no menu 
            g_hInst,                // instance owning this window 
            (PVOID) NULL            // pointer not needed 
        )); 
}

Using Scroll Bars

Windows common controls demo (CppWindowsCommonControls)