如何使用箭头键在ASP.NET gridview中导航（向上或向下）？

Question

How to navigate (up or down) in ASP.NET gridview using arrow keys while highlighting the current row?

I am able to move through rows with up and down arrow keys using javascript code and C# code. I also implemented a begin request and end request JS code for maintaining scroll position on postback.

However, my problem is, scrollbar doesn't move up or down to show the highlighted row automatically. Suppose there are 100 rows, I select 15th row, but grid height is like it can show only 10 rows, unless we move scroll bar manually, it doesn't move automatically to display the selected row via arrow keys. How to ensure this synchronous or visibility of highlighted row by moving scroll bar?

My gridview doesn't have checkbox.

Please help me. Its my code here:

<asp:GridView ID="gvCycles" runat="server" AutoGenerateColumns="False" 
    CssClass="grid"
    AllowSorting="True"
    ShowHeader="False"
    ShowFooter="True"
    OnSelectedIndexChanged="gvDeductionList_SelectedIndexChanged" 
    OnRowDataBound="gvDeductionList_RowDataBound" DataKeyNames="CycleID" onselectedindexchanging="gvCycles_SelectedIndexChanging"
    >
    <Columns>               
        <asp:BoundField DataField="CycleID" HeaderText="CycleID"
            HtmlEncode="False"                    
            SortExpression="CycleID">
            <ItemStyle CssClass="GridViewHiddenColumn" />    
        </asp:BoundField> 

What I did to maintain the scroll position on postback is:

<script language="javascript" type="text/javascript">
    // This Script is used to maintain Grid Scroll on Partial Postback
    var scrollTop;
    //Register Begin Request and End Request 
    Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequestHandler);
    Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
    //Get The Div Scroll Position
    function BeginRequestHandler(sender, args) {
        var m = document.getElementById('divGrid');
        scrollTop = m.scrollTop;
    }
    //Set The Div Scroll Position
    function EndRequestHandler(sender, args) {
        var m = document.getElementById('divGrid');
        m.scrollTop = scrollTop;
    } 
</script>

Also, I have this in the keydown and keyup

 if (e.keyCode == '38') {
                document.getElementById('<%= controlCapture.ClientID %>').value = false;
                document.getElementById('<%= shiftCapture.ClientID %>').value = false;
                // up arrow
                __doPostBack(pageId, "up");
            }
else if (e.keyCode == '40') {
                document.getElementById('<%= controlCapture.ClientID %>').value = false;
                document.getElementById('<%= shiftCapture.ClientID %>').value = false;
                              // down arrow
                __doPostBack(pageId, "down");

Question: I do not know where to use the code you mentioned in the codeproject such that, when I press key down or up arrow keys, it should move scroll bar automatically. I do not have pagination.

Page_load Code

protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack) //on initial load, default dates to current fbt year
        {
            dpDateFrom.DateValue = currentBT;
            dpDateTo.DateValue = currentBTEnd;

            Searchclick();
        }
            //cursor keys
        else if (Request.Form["__EVENTARGUMENT"] == "up" || Request.Form["__EVENTARGUMENT"] == "down")
        {
            string eventArgument = Request.Form["__EVENTARGUMENT"];
            int intPayCycleId = 0;

            if (gvCycles.SelectedIndex >= 0 && gvCycles.SelectedIndex < gvCycles.Rows.Count)
            {
                if (eventArgument == "down")
                {
                    if (gvCycles.SelectedIndex < gvCycles.Rows.Count-1)
                    {
                        gvCycles.SelectedIndex += 1;

                    }
                }
                else if (eventArgument == "up")
                {
                    if (gvCycles.SelectedIndex > 0)
                    {
                        gvCycles.SelectedIndex -= 1;
                    }
                }

                hdnSelectedRow.Value = gvCycles.SelectedValue.ToString() + ","; //assign hidden value with selected row
                SetRowsStyle(gvCycles);

                if (int.TryParse(gvCycles.SelectedRow.Cells[0].Text, out intCycleId))
                {
                    ShowDeductions(intCycleId, false);
                }
            }
        }
    }

Answer 1

Have a look at this SO thread

And, here's a great sample code

UPDATE

I just had a look at the code here . Auto Scrolling works fine if you wrap the GridView with a DIV as shown below. (I'm using the same code as given in this link and just added the DIV with the CSS style. Also increased the no of records displayed in the grid by changing the for loop in the code behind to n < 100 )

<div class="scrollable">
        <asp:GridView ID="gridView" runat="server" AutoGenerateColumns="False" OnRowCreated="gridView_RowCreated"
            TabIndex="0" GridLines="Horizontal">
            <Columns>
                <asp:BoundField HeaderText="S#" DataField="sno">
                    <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="50px" />
                    <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="50px" />
                </asp:BoundField>
                <asp:BoundField HeaderText="Random No" DataField="rndno">
                    <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="150px" />
                    <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="150px" />
                </asp:BoundField>
                <asp:BoundField HeaderText="Date" DataField="date">
                    <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="100px" />
                    <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="100px" />
                </asp:BoundField>
                <asp:BoundField HeaderText="Time" DataField="time">
                    <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="100px" />
                    <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" Width="100px" />
                </asp:BoundField>
            </Columns>
            <RowStyle BackColor="#FFE0C0" />
            <HeaderStyle BackColor="#FF8000" Font-Bold="True" ForeColor="White" />
            <AlternatingRowStyle BackColor="#FFC080" />
        </asp:GridView>
      </div>

And, here's the CSS

<style type="text/css">
    .scrollable {
        height: 460px;
        width: 100%;
        overflow: auto;
        border: 0;
    }
    </style>

UPDATE 2

1. Comment your JavaScript code (It has a __doPostBack, which will do a postback and that causes your scroll bar to misbehave)

2. comment the else if section of your Page_Load event, which we'll not be using since you commented your JS code

3. Now add following code to your page

JavaScript

<script type="text/javascript">
    var SelectedRow = null;
    var SelectedRowIndex = null;
    var UpperBound = null;
    var LowerBound = null;

    window.onload = function()
    {
        UpperBound = parseInt('<%= this.gvCycles.Rows.Count %>') - 1;
        LowerBound = 0;
        SelectedRowIndex = -1;        
    }

    function SelectRow(CurrentRow, RowIndex)
    {        
        if(SelectedRow == CurrentRow || RowIndex > UpperBound || RowIndex < LowerBound) return;

        if(SelectedRow != null)
        {
            SelectedRow.style.backgroundColor = SelectedRow.originalBackgroundColor;
            SelectedRow.style.color = SelectedRow.originalForeColor;
        }

        if(CurrentRow != null)
        {
            CurrentRow.originalBackgroundColor = CurrentRow.style.backgroundColor;
            CurrentRow.originalForeColor = CurrentRow.style.color;
            CurrentRow.style.backgroundColor = '#DCFC5C';
            CurrentRow.style.color = 'Black';
        } 

        SelectedRow = CurrentRow;
        SelectedRowIndex = RowIndex;
        setTimeout("SelectedRow.focus();",0); 
    }

    function SelectSibling(e)
    { 
        var e = e ? e : window.event;
        var KeyCode = e.which ? e.which : e.keyCode;

        if(KeyCode == 40)
            SelectRow(SelectedRow.nextSibling, SelectedRowIndex + 1);
        else if(KeyCode == 38)
            SelectRow(SelectedRow.previousSibling, SelectedRowIndex - 1);

        return false;
    }
    </script>

Code Behind

protected void gvCycles_RowCreated(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow && (e.Row.RowState == DataControlRowState.Normal || e.Row.RowState == DataControlRowState.Alternate))
        {
            e.Row.TabIndex = -1;
            e.Row.Attributes["onclick"] = string.Format("javascript:SelectRow(this, {0});", e.Row.RowIndex);
            e.Row.Attributes["onkeydown"] = "javascript:return SelectSibling(event);";
            e.Row.Attributes["onselectstart"] = "javascript:return false;";
        }
    }

Hope this helps.