Question

我正在编写一个简单的C＃应用程序，我需要在Listview上使用onScroll事件。所以我创建了类ListviewEx女巫继承了原始的ListView。我发现如何从WinAPI检测滚动消息，我修改了WndProc方法。现在我有了这个WndProc：

protected override void WndProc(ref Message m) 
{ 
    base.WndProc(ref m); 

    if (m.Msg == WM_VSCROLL) 
    { 
        onScroll(this, new EventArgs()); 
    } 
}

但问题是，我不知道如何检测有关滚动的信息。这个数据应该在WParam中，但在C＃中没有像C ++那样的LOWORD宏，我需要切换来检测SB_ BOTTOM，SB_ ENDSCROLL，SB_PAGEUP等参数。

有没有办法在C＃中替换LOWORD宏？

或其他方式如何检测有关滚动的必要参数？

Answer 1

感谢您的回答。它真的帮了我:)现在我有我想要的......

这是代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using Microsoft.Win32;
using System.Reflection;

namespace ControlsEx
{
    public class ListViewEx : ListView
    {
        // Windows messages
        private const int WM_PAINT      = 0x000F;
        private const int WM_HSCROLL    = 0x0114;
        private const int WM_VSCROLL    = 0x0115;
        private const int WM_MOUSEWHEEL = 0x020A;
        private const int WM_KEYDOWN    = 0x0100;
        private const int WM_LBUTTONUP  = 0x0202;                 

        // ScrollBar types
        private const int SB_HORZ = 0;
        private const int SB_VERT = 1;

        // ScrollBar interfaces
        private const int SIF_TRACKPOS  = 0x10;
        private const int SIF_RANGE     = 0x01;
        private const int SIF_POS       = 0x04;
        private const int SIF_PAGE      = 0x02;
        private const int SIF_ALL       = SIF_RANGE | SIF_PAGE | SIF_POS | SIF_TRACKPOS;

        // ListView messages
        private const uint LVM_SCROLL       = 0x1014;
        private const int  LVM_FIRST        = 0x1000;                   
        private const int  LVM_SETGROUPINFO = (LVM_FIRST + 147);  

        public enum ScrollBarCommands : int
        {
            SB_LINEUP = 0,
            SB_LINELEFT = 0,
            SB_LINEDOWN = 1,
            SB_LINERIGHT = 1,
            SB_PAGEUP = 2,
            SB_PAGELEFT = 2,
            SB_PAGEDOWN = 3,
            SB_PAGERIGHT = 3,
            SB_THUMBPOSITION = 4,
            SB_THUMBTRACK = 5,
            SB_TOP = 6,
            SB_LEFT = 6,
            SB_BOTTOM = 7,
            SB_RIGHT = 7,
            SB_ENDSCROLL = 8
        }

        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);

            switch(m.Msg)
            {
                case WM_VSCROLL:
                    ScrollEventArgs sargs = new ScrollEventArgs(ScrollEventType.EndScroll, GetScrollPos(this.Handle, SB_VERT));
                    onScroll(this, sargs);
                    break;

                case WM_MOUSEWHEEL:
                    ScrollEventArgs sarg = new ScrollEventArgs(ScrollEventType.EndScroll, GetScrollPos(this.Handle, SB_VERT));
                    onScroll(this, sarg);
                    break;

                case WM_KEYDOWN:
                    switch (m.WParam.ToInt32())
                    {
                        case (int)Keys.Down:
                            onScroll(this, new ScrollEventArgs(ScrollEventType.SmallDecrement, GetScrollPos(this.Handle, SB_VERT)));
                            break;
                        case (int)Keys.Up:
                            onScroll(this, new ScrollEventArgs(ScrollEventType.SmallIncrement, GetScrollPos(this.Handle, SB_VERT)));
                            break;
                        case (int)Keys.PageDown:
                            onScroll(this, new ScrollEventArgs(ScrollEventType.LargeDecrement, GetScrollPos(this.Handle, SB_VERT)));
                            break;
                        case (int)Keys.PageUp:
                            onScroll(this, new ScrollEventArgs(ScrollEventType.LargeIncrement, GetScrollPos(this.Handle, SB_VERT)));
                            break;
                        case (int)Keys.Home:
                            onScroll(this, new ScrollEventArgs(ScrollEventType.First, GetScrollPos(this.Handle, SB_VERT)));
                            break;
                        case (int)Keys.End:
                            onScroll(this, new ScrollEventArgs(ScrollEventType.Last, GetScrollPos(this.Handle, SB_VERT)));
                            break;
                    }   
                    break;
            }

        }

        public int ScrollPosition 
        {
            get
            {
                return GetScrollPos(this.Handle, SB_VERT);
            }
            set
            {
                int prevPos;
                int scrollVal;

                if (ShowGroups == true)
                {
                    prevPos = GetScrollPos(this.Handle, SB_VERT);
                    scrollVal = -(prevPos - value);
                }
                else
                {
                  // TODO: Add setScrollPosition if ShowGroups == false
                }

                SendMessage(this.Handle, LVM_SCROLL, (IntPtr)0, (IntPtr)scrollVal);
            }
        }

        public event ScrollEventHandler onScroll;

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool GetScrollInfo(IntPtr hwnd, int fnBar, ref SCROLLINFO lpsi);

        [DllImport("user32.dll")]
        public static extern int SendMessage(
              int hWnd,      // handle to destination window
              uint Msg,       // message
              long wParam,  // first message parameter
              long lParam   // second message parameter
              );

        [DllImport("user32.dll")]
        static extern int SendMessage(IntPtr hWnd, int wMsg,
                                       int wParam, int lParam);

        [DllImport("user32.dll")]
        static extern int SendMessage(IntPtr hWnd, uint wMsg,
                                       IntPtr wParam, IntPtr lParam);

        [DllImport("user32.dll")]
        static extern int SetScrollPos(IntPtr hWnd, int nBar, int nPos, bool bRedraw);

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static extern int GetScrollPos(IntPtr hWnd, int nBar);


        [StructLayout(LayoutKind.Sequential)]
        struct SCROLLINFO
        {
            public uint cbSize;
            public uint fMask;
            public int nMin;
            public int nMax;
            public uint nPage;
            public int nPos;
            public int nTrackPos;
        }
    }
}

Answer 2

您可以按如下方式定义WParam常量：

private const int WM_HSCROLL = 0x114;
private const int WM_VSCROLL = 0x115;

private const int SB_HORZ = 0;
private const int SB_VERT = 1;

private const int SB_LINELEFT = 0;
private const int SB_LINERIGHT = 1;
private const int SB_PAGELEFT = 2;
private const int SB_PAGERIGHT = 3;
private const int SB_THUMBPOSITION = 4;
private const int SB_THUMBTRACK = 5;
private const int SB_LEFT = 6;
private const int SB_RIGHT = 7;
private const int SB_ENDSCROLL = 8;

private const int SIF_TRACKPOS = 0x10;
private const int SIF_RANGE = 0x1;
private const int SIF_POS = 0x4;
private const int SIF_PAGE = 0x2;
private const int SIF_ALL = SIF_RANGE | SIF_PAGE | SIF_POS | SIF_TRACKPOS;

检查WParam的实际代码是这样的：

if (m.Msg == WM_VSCROLL)
{

        ScrollInfoStruct si = new ScrollInfoStruct();
        si.fMask = SIF_ALL;
        si.cbSize = (uint)Marshal.SizeOf(si);
        GetScrollInfo(msg.HWnd, SB_VERT, ref si);
        if (msg.WParam.ToInt32() == SB_ENDSCROLL)
        {
            ScrollEventArgs sargs = new ScrollEventArgs(ScrollEventType.EndScroll, si.nPos);
            onScroll(this, sargs);
        }
}

pinvoke.net是一个很棒的网站，可以获取windows32 API中使用的常量值，而无需自己检查头文件。

See this example

Answer 3

Martijn的回答会起作用，但不会抓住所有滚动。仅当用户直接操作滚动条时，才会发送 WM_VSCROLL 消息。如果用户使用鼠标滚轮滚动，或使用UpArrow / DownArrow / PageUp / PageDown键，则不会发送 WM_VSCROLL 。

您可以通过侦听 LVN_BEGINSCROLL 通知消息来捕捉由滚动条和鼠标滚轮引起的滚动。

使用键时捕捉滚动更难。例如，当它响应PageUp键滚动时，没有消息被发送到控件。在这种情况下可以做的最好的事情是收听KeyPress事件，然后检查事件前后滚动条位置的变化。

当然，这可能是完全矫枉过正的目的。 WM_VSCROLL 消息可能完全足以满足您的需求。但是如果你想要捕捉所有可能的滚动，请查看ObjectListView中已经有Scroll事件捕获所有这些可能性的代码。

Answer 4

@Klinki

谢谢你的贡献我想你忘了处理水平滚动

Traceback (most recent call last):
  File "C:\Users\Jack 
Hanson\Desktop\Programming\Python\VocabFinder\main.py", line 16, in <module>
    possUnknWrds = knownWordsObject.getUnknownWords(vocabArray)
  File "C:\Users\Jack 
Hanson\Desktop\Programming\Python\VocabFinder\KnownWordsUpdater.py", line 
16, in getUnknownWords
    if (inArray[i] not in knownWords):
NameError: name 'knownWords' is not defined

ListView onScroll事件

4 个答案: