我添加的控件和控件本身都不包含<%=%>或<% %>块。我为什么要这个？这是我的图表页面的代码隐藏，其中包含有问题的行（标有注释），Charts.asx.cs：
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Telerik.Web.UI;
namespace DashboardX.pages
{
public partial class Charts : System.Web.UI.UserControl
{
protected void Page_Init(object sender, EventArgs e)
{
// PROBLEM IS HERE!!!
PlaceHolder1.Controls.Add(ColumnPanel);
}
protected void Page_Load(object sender, EventArgs e)
{
DataBind();
}
public void DownloadColumnChart(object sender, EventArgs e)
{
DownloadImage(sender, e, RadHtmlChart1, DropDownList1);
}
public void DownloadPieChart(object sender, EventArgs e)
{
DownloadImage(sender, e, RadHtmlChart2, DropDownList2);
}
public void DownloadBarChart(object sender, EventArgs e)
{
DownloadImage(sender, e, RadHtmlChart3, DropDownList3);
}
public void DownloadLineChart(object sender, EventArgs e)
{
DownloadImage(sender, e, RadHtmlChart4, DropDownList4);
}
/// <summary>
/// Downloads an image of the given RadHtmlChart (with the given dropdown
/// providing the format specification [PNG/PDF]) by launching Inkscape and
/// passing some command line arguments.
/// </summary>
/// <param name="sender">Who ran this function?</param>
/// <param name="e">Event data.</param>
/// <param name="chart">The chart of which to generate an image.</param>
/// <param name="ddl">The dropdown list with the format desired selected.</param>
public void DownloadImage(object sender, EventArgs e, RadHtmlChart chart, DropDownList ddl)
{
//obtain the necessary settings for exporting the chart
HtmlChartExportSettings currentSettings = new HtmlChartExportSettings();
if (chart.Height != null && chart.Width != null)
{
currentSettings.Height = (int)chart.Height.Value;
currentSettings.Width = (int)chart.Width.Value;
}
//decodes the SVG string saved from the client
string svgText = HttpUtility.UrlDecode(svgHolder.Value);
//create a temporary SVG file that Inkscape will use
currentSettings.SvgFilePath = Server.MapPath("~/App_Data/temp.svg");
System.IO.File.WriteAllText(currentSettings.SvgFilePath, svgText);
//get the export format - png or pdf
currentSettings.Extension = ddl.SelectedValue;
//the output file Inkscape will use, hardcoded to use App_Data as a temporary folder
currentSettings.OutputFilePath = (@"C:\chart." + currentSettings.Extension);
//you can change the name of the file the user will receive here. Extension is automatically added
currentSettings.ClientFileName = "chart";
//the actual file is created
HtmlChartExporter.ExportHtmlChart(currentSettings);
//read the exported file and send it to the client
byte[] fileForClient = HtmlChartExporter.ReadFile(currentSettings.OutputFilePath);
Response.ContentType = HtmlChartExportSettings.ContentTypeList[currentSettings.Extension];
Response.AddHeader("Content-Disposition", "attachment;filename=" + currentSettings.ClientFileName);
Response.BinaryWrite(fileForClient);
//delete the temporary files to avoid flooding the server
File.Delete(currentSettings.OutputFilePath);
File.Delete(currentSettings.SvgFilePath);
svgHolder.Value = "";
}
}
}
以下是父母的代码：
<div id="graphs">
<asp:PlaceHolder ID="PlaceHolder1" runat="server">
</asp:PlaceHolder>
<asp:PlaceHolder ID="PlaceHolder2" runat="server">
</asp:PlaceHolder>
<asp:PlaceHolder ID="PlaceHolder3" runat="server">
</asp:PlaceHolder>
<asp:PlaceHolder ID="PlaceHolder4" runat="server">
</asp:PlaceHolder>
</div>
以下是孩子们：
<asp:Panel ID="ColumnPanel" runat="server" Height="405px" Width="450px" CssClass="left hidden">
<div id="column" class="graph">
<div class="download-image">
<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem Text="PNG" Value="png" Selected="true"></asp:ListItem>
<asp:ListItem Text="PDF" Value="pdf"></asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button1" runat="server" Text="Download Image" OnClick="DownloadColumnChart" OnClientClick="getSvgContent(this, 'RadHtmlChart1'); return false;" />
</div>
<telerik:RadHtmlChart ID="RadHtmlChart1" runat="server" DataSourceID="SqlDataSource_TotalSales">
<PlotArea>
<Series>
<telerik:ColumnSeries DataFieldY="TotalSales">
<LabelsAppearance DataFormatString="{0:C}" Visible="false" />
<TooltipsAppearance DataFormatString="{0:C}" />
</telerik:ColumnSeries>
</Series>
<XAxis DataLabelsField="SubmitDate" MajorTickType="Outside" Step="1" MinorTickType="None">
<MinorGridLines Visible="false" />
<MajorGridLines Visible="false" />
<LabelsAppearance RotationAngle="-70" DataFormatString="{0}">
</LabelsAppearance>
</XAxis>
<YAxis>
<LabelsAppearance DataFormatString="${0}">
</LabelsAppearance>
</YAxis>
</PlotArea>
<Legend>
<Appearance Visible="false">
</Appearance>
</Legend>
</telerik:RadHtmlChart>
</div>
</asp:Panel>
<asp:Panel ID="PiePanel" runat="server" Height="405px" Width="450px" CssClass="hidden">
<div id="pie" class="graph">
<div class="download-image">
<asp:DropDownList ID="DropDownList2" runat="server">
<asp:ListItem Text="PNG" Value="png" Selected="true"></asp:ListItem>
<asp:ListItem Text="PDF" Value="pdf"></asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button2" runat="server" Text="Download Image" OnClick="DownloadPieChart" OnClientClick="getSvgContent(this, 'RadHtmlChart2'); return false;" />
</div>
<telerik:RadHtmlChart ID="RadHtmlChart2" runat="server"
Transitions="true" DataSourceID="SqlDataSource_TotalSales">
<PlotArea>
<Series>
<telerik:PieSeries DataFieldY="TotalSales" StartAngle="90">
<LabelsAppearance ClientTemplate="#=dataItem.SubmitDate#" Position="Circle"
DataFormatString="{0:C}">
</LabelsAppearance>
<TooltipsAppearance DataFormatString="{0:C}" />
</telerik:PieSeries>
</Series>
<XAxis DataLabelsField="SubmitDate" Visible="true">
</XAxis>
<YAxis>
<LabelsAppearance DataFormatString="{0:C}">
</LabelsAppearance>
</YAxis>
</PlotArea>
<Legend>
<Appearance Visible="false">
</Appearance>
</Legend>
</telerik:RadHtmlChart>
</div>
</asp:Panel>
<asp:Panel ID="BarPanel" runat="server" Height="405px" Width="450px" CssClass="left hidden">
<div id="bar" class="graph">
<div class="download-image">
<asp:DropDownList ID="DropDownList3" runat="server">
<asp:ListItem Text="PNG" Value="png" Selected="true"></asp:ListItem>
<asp:ListItem Text="PDF" Value="pdf"></asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button3" runat="server" Text="Download Image" OnClick="DownloadBarChart" OnClientClick="getSvgContent(this, 'RadHtmlChart3'); return false;" />
</div>
<telerik:RadHtmlChart ID="RadHtmlChart3" runat="server" DataSourceID="SqlDataSource_TotalSales">
<PlotArea>
<Series>
<telerik:BarSeries DataFieldY="TotalSales">
<LabelsAppearance DataFormatString="{0:C}" Visible="false" />
<TooltipsAppearance DataFormatString="{0:C}" />
</telerik:BarSeries>
</Series>
<XAxis DataLabelsField="SubmitDate" MajorTickType="None" MinorTickType="None">
<MinorGridLines Visible="false" />
<MajorGridLines Visible="false" />
<LabelsAppearance RotationAngle="0" DataFormatString="{0}">
</LabelsAppearance>
</XAxis>
<YAxis>
<LabelsAppearance DataFormatString="${0}">
</LabelsAppearance>
</YAxis>
</PlotArea>
<Legend>
<Appearance Visible="false">
</Appearance>
</Legend>
</telerik:RadHtmlChart>
</div>
</asp:Panel>
<asp:Panel ID="LinePanel" runat="server" Height="405px" Width="450px" CssClass="hidden">
<div id="line" class="graph">
<div class="download-image">
<asp:DropDownList ID="DropDownList4" runat="server">
<asp:ListItem Text="PNG" Value="png" Selected="true"></asp:ListItem>
<asp:ListItem Text="PDF" Value="pdf"></asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button4" runat="server" Text="Download Image" OnClick="DownloadLineChart" OnClientClick="getSvgContent(this, 'RadHtmlChart4'); return false;" />
</div>
<telerik:RadHtmlChart ID="RadHtmlChart4" runat="server" DataSourceID="SqlDataSource_TotalSales">
<PlotArea>
<Series>
<telerik:LineSeries DataFieldY="TotalSales">
<LabelsAppearance DataFormatString="{0:C}" Visible="false" />
<TooltipsAppearance DataFormatString="{0:C}" />
</telerik:LineSeries>
</Series>
<XAxis DataLabelsField="SubmitDate" MajorTickType="Outside" MinorTickType="None">
<MinorGridLines Visible="false" />
<MajorGridLines Visible="false" />
<LabelsAppearance RotationAngle="-70" DataFormatString="{0}">
</LabelsAppearance>
</XAxis>
<YAxis>
<LabelsAppearance DataFormatString="${0}">
</LabelsAppearance>
</YAxis>
</PlotArea>
<Legend>
<Appearance Visible="false">
</Appearance>
</Legend>
</telerik:RadHtmlChart>
</div>
</asp:Panel>