XtraReports > 示例 > 如何： 创建 Drill-Down 报表

本指南描述了创建 drill-down 报表 的步骤。 在本例中，我们使用一个根据从报表带区创建的 主/从报表，它的每个类别的细节带区都可以通过 单击适当的链接 而被展开/折叠。 要查看总说明，请参阅 Drill-Down 报表。

要创建 drill-down 报表，则执行下列操作。

  1. 使用从报表带区创建一个主/从报表。

  2. 为了创建一个显示/隐藏从报表的链接，我们把一个标签控件拖放到报表的细节带区。

    把它的 XRControl.Text 属性修改为 Show Detail、XRControl.Name 属性修改为 lblShowHide，并把 (DataBindings)Tag.Binding 属性设置为 CategoryID 数据字段。

  3. 在完成上述步骤之后，报表的外观应该像下图所示的那样。

  4. 现在，以下列方式接管标签控件的 BeforePrint、PreviewClick 和 PreviewMouseMove 事件以及 DetailReport 的 BeforePrint 事件：

    C#CopyCode image复制代码
    using System.Collections;
using System.Windows.Forms;
using System.Drawing.Printing;
using DevExpress.XtraReports.UI;
// ...

// Declare two string constants, to store the label's Text value.
const string sShowDetail = "Show Detail";
const string sHideDetail = "Hide Detail";

// Create an array containing IDs of the categories being expanded.
ArrayList expandedValues = new ArrayList();

// This function returns a value indicating whether a certain 
// category's details should be expanded.
bool ShouldShowDetail(int catID) {
    return expandedValues.Contains(catID);
}

private void lbShowHide_BeforePrint(object sender, PrintEventArgs e) {
    XRLabel label = (XRLabel)sender;

    // Choose the label's text.
    if(ShouldShowDetail((int)label.Tag)) {
        label.Text = sHideDetail;
    }
    else {
        label.Text = sShowDetail;
    }
}

private void DetailReport_BeforePrint(object sender, PrintEventArgs e) {
    // Cancel the Detail Report band's printing if necessary.
    e.Cancel = !ShouldShowDetail((int)GetCurrentColumnValue("CategoryID"));
}

private void lbShowHide_PreviewClick(object sender, PreviewMouseEventArgs e) {
    // Obtain the category's ID stored in the label's Tag property.
    int index = (int)e.Brick.Value;

    // Determine whether the current category's details are shown.
    bool showDetail = ShouldShowDetail(index);

    // Toggle the visibility of the category's details.
    if(showDetail) {
        expandedValues.Remove(index);
    }
    else {
        expandedValues.Add(index);
    }

    // Re-create a document to apply the changes.
    CreateDocument();
}

// The following code changes the cursor to "hand" when it hovers the label, 
// so that it behaves as a common link.
private void lbShowHide_PreviewMouseMove(object sender, PreviewMouseEventArgs e) {
    Cursor.Current = Cursors.Hand;
}
    Visual BasicCopyCode image复制代码
    Imports System.Collections
Imports System.Windows.Forms
Imports System.Drawing.Printing
Imports DevExpress.XtraReports.UI
' ...

' Declare two string constants, to store the label's Text value.
Private Const sShowDetail As String = "Show Detail"
Private Const sHideDetail As String = "Hide Detail"

' Create an array containing IDs of the categories being expanded.
Private expandedValues As New ArrayList()

' This function returns a value indicating whether a certain 
' category's details should be expanded.
Private Function ShouldShowDetail(ByVal catID As Integer) As Boolean
    Return expandedValues.Contains(catID)
End Function

Private Sub lbShowHide_BeforePrint(ByVal sender As Object, ByVal e _ 
As PrintEventArgs) Handles lbShowHide.BeforePrint
    Dim label As XRLabel = CType(sender, XRLabel)

    ' Choose the label's text.
    If ShouldShowDetail(CInt(Fix(label.Tag))) Then
        label.Text = sHideDetail
    Else
        label.Text = sShowDetail
    End If
End Sub

Private Sub DetailReport_BeforePrint(ByVal sender As Object, ByVal e _ 
As PrintEventArgs) Handles DetailReport.BeforePrint
    ' Cancel the Detail Report band's printing if necessary.
    e.Cancel = Not ShouldShowDetail(CInt(Fix(GetCurrentColumnValue("CategoryID"))))
End Sub

Private Sub lbShowHide_PreviewClick(ByVal sender As Object, ByVal e _ 
As PreviewMouseEventArgs) Handles lbShowHide.PreviewClick
    ' Obtain the category's ID stored in the label's Tag property.
    Dim index As Integer = CInt(Fix(e.Brick.Value))
    ' Determine whether the current category's details are shown.
    Dim showDetail As Boolean = ShouldShowDetail(index)

    ' Toggle the visibility of the category's details.
    If showDetail Then
        expandedValues.Remove(index)
    Else
        expandedValues.Add(index)
    End If

    ' Re-create a document to apply the changes.
    CreateDocument()
End Sub

' The following code changes the cursor to "hand" when it hovers the label, 
' so that it behaves as a common link.
Private Sub lbShowHide_PreviewMouseMove(ByVal sender As Object, ByVal e _ 
As PreviewMouseEventArgs) Handles lbShowHide.PreviewMouseMove
    Cursor.Current = Cursors.Hand
End Sub

现在 drill-down 报表已经就绪。 运行打印预览窗体，并查看结果。

CodeCentralShow Me

在 DevExpress Code Central 数据库中可以找到完整的示例项目，网址是 http://www.devexpress.com/example=E769。 取决于目标平台类型 (ASP.NET、WinForms 等)，可以在线运行本示例，或者下载自动可执行的示例。

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