为什么这种方法不起作用？

如何解决为什么这种方法不起作用？

| 我想在列表视图的标题中显示一个排序箭头，发现了这一点：如何使用C＃在列表视图列的标题中显示排序箭头？而且有效。我试图将代码修改为：

const Int32 HDF_SORTDOWN = 0x200;
const Int32 HDF_SORTUP = 0x400;
const Int32 HDI_FORMAT = 0x4;
const Int32 HDM_GETITEM = 0x120b;
const Int32 HDM_SETITEM = 0x120c;
const Int32 LVM_GETHEADER = 0x101f;

[DllImport(\"user32.dll\",CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd,UInt32 msg,IntPtr wParam,IntPtr lParam);

[DllImport(\"user32.dll\",CharSet = CharSet.Auto,EntryPoint = \"SendMessage\")]
static extern IntPtr SendMessageLVCOLUMN(IntPtr hWnd,ref LVCOLUMN lParam);

struct LVCOLUMN
{
    public UInt32 mask;
    public Int32 fmt;
    public Int32 cx;
    public String pszText;
    public Int32 cchTextMax;
    public Int32 iSubItem;
    public Int32 iImage;
    public Int32 iOrder;
    public Int32 cxMin;
    public Int32 cxDefault;
    public Int32 cxIdeal;
}

private void SetSortIcon(ListView lstVw,int column,SortOrder sorting)
{
    IntPtr clmHdr = SendMessage(lstVw.Handle,LVM_GETHEADER,IntPtr.Zero,IntPtr.Zero);

    for (int i = 0; i < lstVw.Columns.Count; i++)
    {
        IntPtr clmPtr = new IntPtr(i);
        LVCOLUMN lvColumn = new LVCOLUMN();

        lvColumn.mask = HDI_FORMAT;
        SendMessageLVCOLUMN(clmHdr,HDM_GETITEM,clmPtr,ref lvColumn);
        if (sorting != SortOrder.None && i == column)
        {
            if (sorting == SortOrder.Ascending)
            {
                lvColumn.fmt &= ~HDF_SORTDOWN;
                lvColumn.fmt |= HDF_SORTUP;
            }
            else
            {
                lvColumn.fmt &= ~HDF_SORTUP;
                lvColumn.fmt |= HDF_SORTDOWN;
            }
        }
        else
        {
            lvColumn.fmt &= ~HDF_SORTDOWN & ~HDF_SORTUP;
        }
        SendMessageLVCOLUMN(clmHdr,HDM_SETITEM,ref lvColumn);
    }
}

这不起作用。原始版本是扩展方法，不是。我想知道为什么这个不起作用。

解决方法

您需要更正LVCOLUMN结构的布局，将其更改为与原始示例相同的顺序和类型。

[System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]    
private struct LVCOLUMN    
{        
    public Int32 mask;        
    public Int32 cx;        
    [System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPTStr)]
    public string pszText;
    public IntPtr hbm;
    public Int32 cchTextMax;
    public Int32 fmt;
    public Int32 iSubItem;
    public Int32 iImage;
    public Int32 iOrder;
}

, 轻松解决，我敢打赌，您需要将编译器的Any CPU设置为32或86。它将正常工作。您正在使用win32库。需要将内部版本设置为32或86。如果这样不起作用，请告诉我，我向sow再次看一下代码，如果可以，则将其标记为已回答。