组合框下拉位置 [英] ComboBox Dropdown Position
问题描述
我有(停靠在右上角),其中有组合框控件的最大化形式500px的宽度
I have a maximized form which has Combo-Box control (docked in top-right) with 500px Width
试图打开组合框后,列表的一半进入外的屏幕。我怎么能强制列表显示表单中?
After trying to open the combo-box , the half of the list goes out-of-screen . how can I force list shows within form?
推荐答案
棘手的问题。我无法找到一个很好的修复,只是一个解决方法。添加一个新类并粘贴如下所示的code。编译。从工具箱的上方新的控制到您的表单。
Tricky problem. I could not find a good fix for this, merely a workaround. Add a new class and paste the code shown below. Compile. Drop the new control from the top of the toolbox onto your form.
解决方法是不是非常好。问题是,在下拉窗口将忽略移动它,直到下拉动画完成的尝试。视觉效果不是很大,你会看到窗口的下拉,然后跳转到左边。我不知道一个其他的方式来拍它的头,也许别人呢。
The workaround is not a very good one. The problem is that the dropdown window will ignore the attempt to move it until the drop-down animation is complete. The visual effect is not great, you'll see the window drop down, then jump to the left. I don't know an other way to slap it over the head, maybe somebody else does.
C#版本:
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
public class MyComboBox : ComboBox {
protected override void OnDropDown(EventArgs e) {
// Is dropdown off the right side of the screen?
Point pos = this.PointToScreen(this.Location);
Screen scr = Screen.FromPoint(pos);
if (scr.WorkingArea.Right < pos.X + this.DropDownWidth) {
this.BeginInvoke(new Action(() => {
// Retrieve handle to dropdown list
COMBOBOXINFO info = new COMBOBOXINFO();
info.cbSize = Marshal.SizeOf(info);
SendMessageCb(this.Handle, 0x164, IntPtr.Zero, out info);
// Move the dropdown window
RECT rc;
GetWindowRect(info.hwndList, out rc);
int x = scr.WorkingArea.Right - (rc.Right - rc.Left);
SetWindowPos(info.hwndList, IntPtr.Zero, x, rc.Top, 0, 0, 5);
}));
}
base.OnDropDown(e);
}
// P/Invoke declarations
private struct COMBOBOXINFO {
public Int32 cbSize;
public RECT rcItem, rcButton;
public int buttonState;
public IntPtr hwndCombo, hwndEdit, hwndList;
}
private struct RECT {
public int Left, Top, Right, Bottom;
}
[DllImport("user32.dll", EntryPoint = "SendMessageW", CharSet = CharSet.Unicode)]
private static extern IntPtr SendMessageCb(IntPtr hWnd, int msg, IntPtr wp, out COMBOBOXINFO lp);
[DllImport("user32.dll")]
private static extern bool SetWindowPos(IntPtr hWnd, IntPtr after, int x, int y, int cx, int cy, int flags);
[DllImport("user32.dll")]
private static extern bool GetWindowRect(IntPtr hWnd, out RECT rc);
}
VB.Net版本:
Imports System
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Runtime.InteropServices
Public Class MyComboBox
Inherits ComboBox
'P/Invoke declarations
Private Structure COMBOBOXINFO
Public cbSize As Int32
Public rcItem As RECT
Public rcButton As RECT
Public buttonState As Integer
Public hwndCombo As IntPtr
Public hwndEdit As IntPtr
Public hwndList As IntPtr
End Structure
Private Structure RECT
Public Left As Integer
Public Top As Integer
Public Right As Integer
Public Bottom As Integer
End Structure
<DllImport("user32.dll", EntryPoint:="SendMessageW", CharSet:=CharSet.Unicode)>
Private Shared Function SendMessageCb(hWnd As IntPtr, msg As Integer, wp As IntPtr, ByRef lp As COMBOBOXINFO) As IntPtr
End Function
<DllImport("user32.dll")>
Private Shared Function SetWindowPos(hWnd As IntPtr, after As IntPtr, x As Integer, y As Integer, cx As Integer, cy As Integer, flags As Integer) As Boolean
End Function
<DllImport("user32.dll")>
Private Shared Function GetWindowRect(hWnd As IntPtr, ByRef rc As RECT) As Boolean
End Function
Protected Overrides Sub OnDropDown(e As EventArgs)
' Is dropdown off the right side of the screen?
Dim pos As Point = Me.PointToScreen(Me.Location)
Dim scr As Screen = Screen.FromPoint(pos)
If (scr.WorkingArea.Right < pos.X + Me.DropDownWidth) Then
Me.BeginInvoke(New Action(Sub()
'Retrieve handle to dropdown list
Dim info As COMBOBOXINFO = New COMBOBOXINFO()
info.cbSize = Marshal.SizeOf(info)
SendMessageCb(Me.Handle, &H164, IntPtr.Zero, info)
'Move the dropdown window
Dim rc As RECT
GetWindowRect(info.hwndList, rc)
Dim x As Integer = scr.WorkingArea.Right - (rc.Right - rc.Left)
SetWindowPos(info.hwndList, IntPtr.Zero, x, rc.Top, 0, 0, 5)
End Sub))
End If
MyBase.OnDropDown(e)
End Sub
End Class
这篇关于组合框下拉位置的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!