第一个WM_SIZE消息(SDK学习笔记)

昨天在学习在sdk下创建状态栏， 在《windows程序设计》中没有相关内容， 只好求助于msdn， 我装的是6.0中文版的，不过翻译的很不完全，还不如不翻译。 在Platform SDk/User Interface Services/Common Controls/Status Bars 中我找到了相关介绍， 庆幸的是还有示例代码，如下：

// DoCreateStatusBar – creates a status bar and divides it into 

//     the specified number of parts. 

// Returns the handle to the status bar. 

// hwndParent – parent window for the status bar. 

// nStatusID – child window identifier. 

// hinst – handle to the application instance. 

// nParts – number of parts into which to divide the status bar. 

HWND DoCreateStatusBar(HWND hwndParent, int nStatusID, 

    HINSTANCE hinst, int nParts) 

{ 

    HWND hwndStatus; 

    RECT rcClient; 

    HLOCAL hloc; 

    LPINT lpParts; 

    int i, nWidth;

    // Ensure that the common control DLL is loaded. 

    InitCommonControls();

 
    // Create the status bar. 

    hwndStatus = CreateWindowEx( 

        0,                       // no extended styles 

        STATUSCLASSNAME,         // name of status bar class 

        (LPCTSTR) NULL,          // no text when first created 

        SBARS_SIZEGRIP |         // includes a sizing grip 

        WS_CHILD,                // creates a child window 

        0, 0, 0, 0,              // ignores size and position 

        hwndParent,              // handle to parent window 

        (HMENU) nStatusID,       // child window identifier 

        hinst,                   // handle to application instance 

        NULL);                   // no window creation data

 
    // Get the coordinates of the parent window’s client area. 

    GetClientRect(hwndParent, &rcClient);

 
    // Allocate an array for holding the right edge coordinates. 

    hloc = LocalAlloc(LHND, sizeof(int) * nParts); 

    lpParts = LocalLock(hloc);

 
    // Calculate the right edge coordinate for each part, and 

    // copy the coordinates to the array. 

    nWidth = rcClient.right / nParts; 

    for (i = 0; i < nParts; i++) { 

        lpParts[i] = nWidth; 

        nWidth += nWidth; 

    } 

 
    // Tell the status bar to create the window parts. 

    SendMessage(hwndStatus, SB_SETPARTS, (WPARAM) nParts, 

        (LPARAM) lpParts);

 
    // Free the array, and return. 

    LocalUnlock(hloc); 

    LocalFree(hloc); 

    return hwndStatus; 

}

注意到上面43-44行 程序的本意是想等分状态栏成nParts， 但lpParts[i]，每等分的起始位置，却在循环中呈2的倍数增长。 当nParts==4时，实际效果只有3块。 于是我改了一下， for (i = 0; i < nParts; i++) { lpParts[i] = nWidth*(i+1); } 这样显示就正常了。

另外：如要在状态栏中显示其他信息，可以通过SendMessage函数发送SB_SETTEXT消息，在WPARAM中指定状态栏的索引，LPARAM中指定将要显示的字符串。