Question

如果组合框控件中的列表比组合框宽，我怎样才能在组合框的右侧绘制它？它始终保持对齐。例如 - 如果组合框位置靠近窗体的右侧，并且组合框中的列表比组合框的宽度宽，则列表的一部分对用户不可见。

Answer 1

经过一番搜索，我设法在另一个论坛上找到解决方案。我已经将它用于C＃并略有改变。

using System.Runtime.InteropServices;
using System.Windows.Forms;

//  Fix Combo dropdown list if (left or right) off screen.

public class ComboExtended : ComboBox 
{

    [DllImport("user32.dll")]
    private extern static bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, [MarshalAs(UnmanagedType.Bool)] bool bRepaint);

    [DllImport("user32.dll")]
    private extern static bool GetWindowRect(IntPtr hWnd, ref tagRECT lpRect);

    [StructLayout(LayoutKind.Sequential)]
    private struct tagRECT
    {
        public int left, top, right, bottom;
    }

    private const int WM_CTLCOLORLISTBOX = 308;
    private bool ListMoved = false;
    protected override void OnDropDownClosed(EventArgs e)
    {
        base.OnDropDownClosed(e);
        ListMoved = false;
    }

    protected override void WndProc(ref Message m)
    {
        base.WndProc(ref m);
        if (!ListMoved && m.Msg == WM_CTLCOLORLISTBOX)
        {
            tagRECT rc = new tagRECT();
            GetWindowRect(m.LParam, ref rc);
            Form parentForm = this.FindForm();
            int posLeft = rc.right - rc.left > this.Width ? rc.left - ((rc.right - rc.left) - this.Width) : rc.left;
            int posTop = rc.bottom - rc.top > parentForm.Height - rc.top ? (rc.top - (rc.bottom - rc.top)) - this.Height : rc.top;
            MoveWindow(m.LParam, posLeft, posTop, rc.right - rc.left, rc.bottom - rc.top, true);
            ListMoved = true;
        }
    }
}

C＃（winforms）组合框右侧的绘图列表

1 个答案: