DrawListViewSubItemEventArgs 类

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

为 DrawSubItem 事件提供数据。

public ref class DrawListViewSubItemEventArgs : EventArgs

public class DrawListViewSubItemEventArgs : EventArgs

type DrawListViewSubItemEventArgs = class
    inherit EventArgs

Public Class DrawListViewSubItemEventArgs
Inherits EventArgs

继承

Object

EventArgs

DrawListViewSubItemEventArgs

示例

下面的代码示例演示如何为 ListView 控件提供自定义绘图。 示例中的 ListView 控件具有渐变背景。 具有负值的子项具有红色前景和黑色背景。

事件的处理程序 ListView.DrawItem 绘制整个项的背景。 事件的处理程序 ListView.DrawSubItem 为具有负值的子项绘制文本值以及文本和背景。 事件的处理程序 DrawColumnHeader 绘制每个列标题。

组件 ContextMenu 提供了一种在详细信息视图和列表视图之间切换的方法。 在列表视图中，仅 ListView.DrawItem 触发 事件。 在这种情况下，文本和背景均在 事件处理程序中 ListView.DrawItem 绘制。

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Globalization;
using System.Windows.Forms;

public class ListViewOwnerDraw : Form
{
    private ListView listView1 = new ListView();
    private ContextMenu contextMenu1 = new ContextMenu();

    public ListViewOwnerDraw()
    {
        // Initialize the ListView control.
        listView1.BackColor = Color.Black;
        listView1.ForeColor = Color.White;
        listView1.Dock = DockStyle.Fill;
        listView1.View = View.Details;
        listView1.FullRowSelect = true;

        // Add columns to the ListView control.
        listView1.Columns.Add("Name", 100, HorizontalAlignment.Center);
        listView1.Columns.Add("First", 100, HorizontalAlignment.Center);
        listView1.Columns.Add("Second", 100, HorizontalAlignment.Center);
        listView1.Columns.Add("Third", 100, HorizontalAlignment.Center);

        // Create items and add them to the ListView control.
        ListViewItem listViewItem1 = new ListViewItem(new string[] { "One", "20", "30", "-40" }, -1);
        ListViewItem listViewItem2 = new ListViewItem(new string[] { "Two", "-250", "145", "37" }, -1);
        ListViewItem listViewItem3 = new ListViewItem(new string[] { "Three", "200", "800", "-1,001" }, -1);
        ListViewItem listViewItem4 = new ListViewItem(new string[] { "Four", "not available", "-2", "100" }, -1);
        listView1.Items.AddRange(new ListViewItem[] { listViewItem1, listViewItem2, listViewItem3, listViewItem4 });

        // Initialize the shortcut menu and 
        // assign it to the ListView control.
        contextMenu1.MenuItems.Add("List",
            new EventHandler(menuItemList_Click));
        contextMenu1.MenuItems.Add("Details",
            new EventHandler(menuItemDetails_Click));
        listView1.ContextMenu = contextMenu1;

        // Configure the ListView control for owner-draw and add 
        // handlers for the owner-draw events.
        listView1.OwnerDraw = true;
        listView1.DrawItem += new
            DrawListViewItemEventHandler(listView1_DrawItem);
        listView1.DrawSubItem += new
            DrawListViewSubItemEventHandler(listView1_DrawSubItem);
        listView1.DrawColumnHeader += new
            DrawListViewColumnHeaderEventHandler(listView1_DrawColumnHeader);

        // Add a handler for the MouseUp event so an item can be 
        // selected by clicking anywhere along its width.
        listView1.MouseUp += new MouseEventHandler(listView1_MouseUp);

        // Add handlers for various events to compensate for an 
        // extra DrawItem event that occurs the first time the mouse 
        // moves over each row. 
        listView1.MouseMove += new MouseEventHandler(listView1_MouseMove);
        listView1.ColumnWidthChanged += new ColumnWidthChangedEventHandler(listView1_ColumnWidthChanged);
        listView1.Invalidated += new InvalidateEventHandler(listView1_Invalidated);

        // Initialize the form and add the ListView control to it.
        this.ClientSize = new Size(450, 150);
        this.FormBorderStyle = FormBorderStyle.FixedSingle;
        this.MaximizeBox = false;
        this.Text = "ListView OwnerDraw Example";
        this.Controls.Add(listView1);
    }

    // Clean up any resources being used.        
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            contextMenu1.Dispose();
        }
        base.Dispose(disposing);
    }

    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.Run(new ListViewOwnerDraw());
    }

    // Sets the ListView control to the List view.
    private void menuItemList_Click(object sender, EventArgs e)
    {
        listView1.View = View.List;
        listView1.Invalidate();
    }

    // Sets the ListView control to the Details view.
    private void menuItemDetails_Click(object sender, EventArgs e)
    {
        listView1.View = View.Details;

        // Reset the tag on each item to re-enable the workaround in
        // the MouseMove event handler.
        foreach (ListViewItem item in listView1.Items)
        {
            item.Tag = null;
        }
    }

    // Selects and focuses an item when it is clicked anywhere along 
    // its width. The click must normally be on the parent item text.
    private void listView1_MouseUp(object sender, MouseEventArgs e)
    {
        ListViewItem clickedItem = listView1.GetItemAt(5, e.Y);
        if (clickedItem != null)
        {
            clickedItem.Selected = true;
            clickedItem.Focused = true;
        }
    }

    // Draws the backgrounds for entire ListView items.
    private void listView1_DrawItem(object sender,
        DrawListViewItemEventArgs e)
    {
        if ((e.State & ListViewItemStates.Selected) != 0)
        {
            // Draw the background and focus rectangle for a selected item.
            e.Graphics.FillRectangle(Brushes.Maroon, e.Bounds);
            e.DrawFocusRectangle();
        }
        else
        {
            // Draw the background for an unselected item.
            using (LinearGradientBrush brush =
                new LinearGradientBrush(e.Bounds, Color.Orange,
                Color.Maroon, LinearGradientMode.Horizontal))
            {
                e.Graphics.FillRectangle(brush, e.Bounds);
            }
        }

        // Draw the item text for views other than the Details view.
        if (listView1.View != View.Details)
        {
            e.DrawText();
        }
    }

    // Draws subitem text and applies content-based formatting.
    private void listView1_DrawSubItem(object sender,
        DrawListViewSubItemEventArgs e)
    {
        TextFormatFlags flags = TextFormatFlags.Left;

        using (StringFormat sf = new StringFormat())
        {
            // Store the column text alignment, letting it default
            // to Left if it has not been set to Center or Right.
            switch (e.Header.TextAlign)
            {
                case HorizontalAlignment.Center:
                    sf.Alignment = StringAlignment.Center;
                    flags = TextFormatFlags.HorizontalCenter;
                    break;
                case HorizontalAlignment.Right:
                    sf.Alignment = StringAlignment.Far;
                    flags = TextFormatFlags.Right;
                    break;
            }

            // Draw the text and background for a subitem with a 
            // negative value. 
            double subItemValue;
            if (e.ColumnIndex > 0 && Double.TryParse(
                e.SubItem.Text, NumberStyles.Currency,
                NumberFormatInfo.CurrentInfo, out subItemValue) &&
                subItemValue < 0)
            {
                // Unless the item is selected, draw the standard 
                // background to make it stand out from the gradient.
                if ((e.ItemState & ListViewItemStates.Selected) == 0)
                {
                    e.DrawBackground();
                }

                // Draw the subitem text in red to highlight it. 
                e.Graphics.DrawString(e.SubItem.Text,
                    listView1.Font, Brushes.Red, e.Bounds, sf);

                return;
            }

            // Draw normal text for a subitem with a nonnegative 
            // or nonnumerical value.
            e.DrawText(flags);
        }
    }

    // Draws column headers.
    private void listView1_DrawColumnHeader(object sender,
        DrawListViewColumnHeaderEventArgs e)
    {
        using (StringFormat sf = new StringFormat())
        {
            // Store the column text alignment, letting it default
            // to Left if it has not been set to Center or Right.
            switch (e.Header.TextAlign)
            {
                case HorizontalAlignment.Center:
                    sf.Alignment = StringAlignment.Center;
                    break;
                case HorizontalAlignment.Right:
                    sf.Alignment = StringAlignment.Far;
                    break;
            }

            // Draw the standard header background.
            e.DrawBackground();

            // Draw the header text.
            using (Font headerFont =
                        new Font("Helvetica", 10, FontStyle.Bold))
            {
                e.Graphics.DrawString(e.Header.Text, headerFont,
                    Brushes.Black, e.Bounds, sf);
            }
        }
        return;
    }

    // Forces each row to repaint itself the first time the mouse moves over 
    // it, compensating for an extra DrawItem event sent by the wrapped 
    // Win32 control. This issue occurs each time the ListView is invalidated.
    private void listView1_MouseMove(object sender, MouseEventArgs e)
    {
        ListViewItem item = listView1.GetItemAt(e.X, e.Y);
        if (item != null && item.Tag == null)
        {
            listView1.Invalidate(item.Bounds);
            item.Tag = "tagged";
        }
    }

    // Resets the item tags. 
    void listView1_Invalidated(object sender, InvalidateEventArgs e)
    {
        foreach (ListViewItem item in listView1.Items)
        {
            if (item == null) return;
            item.Tag = null;
        }
    }

    // Forces the entire control to repaint if a column width is changed.
    void listView1_ColumnWidthChanged(object sender, 
        ColumnWidthChangedEventArgs e)
    {
        listView1.Invalidate();
    }
}

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Globalization
Imports System.Windows.Forms

Public Class ListViewOwnerDraw
    Inherits Form
    Private WithEvents listView1 As New ListView()
    Private WithEvents contextMenu1 As New ContextMenu()
    Private WithEvents listMenuItem As New MenuItem("List")
    Private WithEvents detailsMenuItem As New MenuItem("Details")

    Public Sub New()

        ' Initialize the shortcut menu. 
        contextMenu1.MenuItems.AddRange(New MenuItem() _
            {Me.listMenuItem, Me.detailsMenuItem})

        ' Initialize the ListView control.
        With Me.listView1
            .BackColor = Color.Black
            .ForeColor = Color.White
            .Dock = DockStyle.Fill
            .View = View.Details
            .FullRowSelect = True
            .OwnerDraw = True
            .ContextMenu = Me.contextMenu1
        End With

        ' Add columns to the ListView control.
        With Me.listView1.Columns
            .Add("Name", 100, HorizontalAlignment.Center)
            .Add("First", 100, HorizontalAlignment.Center)
            .Add("Second", 100, HorizontalAlignment.Center)
            .Add("Third", 100, HorizontalAlignment.Center)
        End With

        ' Create items and add them to the ListView control.
        Dim listViewItem1 As New ListViewItem(New String() _
            {"One", "20", "30", "-40"}, -1)
        Dim listViewItem2 As New ListViewItem(New String() _
            {"Two", "-250", "145", "37"}, -1)
        Dim listViewItem3 As New ListViewItem(New String() _
            {"Three", "200", "800", "-1,001"}, -1)
        Dim listViewItem4 As New ListViewItem(New String() _
            {"Four", "not available", "-2", "100"}, -1)
        Me.listView1.Items.AddRange(New ListViewItem() _
            {listViewItem1, listViewItem2, listViewItem3, listViewItem4})

        ' Initialize the form and add the ListView control to it.
        With Me
            .ClientSize = New Size(450, 150)
            .FormBorderStyle = FormBorderStyle.FixedSingle
            .MaximizeBox = False
            .Text = "ListView OwnerDraw Example"
            .Controls.Add(Me.listView1)
        End With

    End Sub

    ' Clean up any resources being used.        
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            contextMenu1.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub

    <STAThread()> _
    Shared Sub Main()
        Application.Run(New ListViewOwnerDraw())
    End Sub

    ' Sets the ListView control to the List view.
    Private Sub menuItemList_Click(ByVal sender As Object, _
        ByVal e As EventArgs) _
        Handles listMenuItem.Click

        Me.listView1.View = View.List

    End Sub

    ' Sets the ListView control to the Details view.
    Private Sub menuItemDetails_Click(ByVal sender As Object, _
        ByVal e As EventArgs) _
        Handles detailsMenuItem.Click

        Me.listView1.View = View.Details

        ' Reset the tag on each item to re-enable the workaround 
        ' in the MouseMove event handler.
        For Each item As ListViewItem In listView1.Items
            item.Tag = Nothing
        Next

    End Sub

    ' Selects and focuses an item when it is clicked anywhere along 
    ' its width. The click must normally be on the parent item text.
    Private Sub listView1_MouseUp(ByVal sender As Object, _
        ByVal e As MouseEventArgs) _
        Handles listView1.MouseUp

        Dim clickedItem As ListViewItem = Me.listView1.GetItemAt(5, e.Y)
        If (clickedItem IsNot Nothing) Then
            clickedItem.Selected = True
            clickedItem.Focused = True
        End If

    End Sub

    ' Draws the backgrounds for entire ListView items.
    Private Sub listView1_DrawItem(ByVal sender As Object, _
        ByVal e As DrawListViewItemEventArgs) _
        Handles listView1.DrawItem

        If Not (e.State And ListViewItemStates.Selected) = 0 Then

            ' Draw the background for a selected item.
            e.Graphics.FillRectangle(Brushes.Maroon, e.Bounds)
            e.DrawFocusRectangle()

        Else

            ' Draw the background for an unselected item.
            Dim brush As New LinearGradientBrush(e.Bounds, Color.Orange, _
                Color.Maroon, LinearGradientMode.Horizontal)
            Try
                e.Graphics.FillRectangle(brush, e.Bounds)
            Finally
                brush.Dispose()
            End Try

        End If

        ' Draw the item text for views other than the Details view.
        If Not Me.listView1.View = View.Details Then
            e.DrawText()
        End If

    End Sub

    ' Draws subitem text and applies content-based formatting.
    Private Sub listView1_DrawSubItem(ByVal sender As Object, _
        ByVal e As DrawListViewSubItemEventArgs) _
        Handles listView1.DrawSubItem

        Dim flags As TextFormatFlags = TextFormatFlags.Left

        Dim sf As New StringFormat()
        Try

            ' Store the column text alignment, letting it default
            ' to Left if it has not been set to Center or Right.
            Select Case e.Header.TextAlign
                Case HorizontalAlignment.Center
                    sf.Alignment = StringAlignment.Center
                    flags = TextFormatFlags.HorizontalCenter
                Case HorizontalAlignment.Right
                    sf.Alignment = StringAlignment.Far
                    flags = TextFormatFlags.Right
            End Select

            ' Draw the text and background for a subitem with a 
            ' negative value. 
            Dim subItemValue As Double
            If e.ColumnIndex > 0 AndAlso _
                Double.TryParse(e.SubItem.Text, NumberStyles.Currency, _
                NumberFormatInfo.CurrentInfo, subItemValue) AndAlso _
                subItemValue < 0 Then

                ' Unless the item is selected, draw the standard 
                ' background to make it stand out from the gradient.
                If (e.ItemState And ListViewItemStates.Selected) = 0 Then
                    e.DrawBackground()
                End If

                ' Draw the subitem text in red to highlight it. 
                e.Graphics.DrawString(e.SubItem.Text, _
                    Me.listView1.Font, Brushes.Red, e.Bounds, sf)

                Return

            End If

            ' Draw normal text for a subitem with a nonnegative 
            ' or nonnumerical value.
            e.DrawText(flags)

        Finally
            sf.Dispose()
        End Try

    End Sub

    ' Draws column headers.
    Private Sub listView1_DrawColumnHeader(ByVal sender As Object, _
        ByVal e As DrawListViewColumnHeaderEventArgs) _
        Handles listView1.DrawColumnHeader

        Dim sf As New StringFormat()
        Try

            ' Store the column text alignment, letting it default
            ' to Left if it has not been set to Center or Right.
            Select Case e.Header.TextAlign
                Case HorizontalAlignment.Center
                    sf.Alignment = StringAlignment.Center
                Case HorizontalAlignment.Right
                    sf.Alignment = StringAlignment.Far
            End Select

            ' Draw the standard header background.
            e.DrawBackground()

            ' Draw the header text.
            Dim headerFont As New Font("Helvetica", 10, FontStyle.Bold)
            Try
                e.Graphics.DrawString(e.Header.Text, headerFont, _
                    Brushes.Black, e.Bounds, sf)
            Finally
                headerFont.Dispose()
            End Try

        Finally
            sf.Dispose()
        End Try

    End Sub

    ' Forces each row to repaint itself the first time the mouse moves over 
    ' it, compensating for an extra DrawItem event sent by the wrapped 
    ' Win32 control.
    Private Sub listView1_MouseMove(ByVal sender As Object, _
        ByVal e As MouseEventArgs) _
        Handles listView1.MouseMove

        Dim item As ListViewItem = listView1.GetItemAt(e.X, e.Y)
        If item IsNot Nothing AndAlso item.Tag Is Nothing Then
            listView1.Invalidate(item.Bounds)
            item.Tag = "tagged"
        End If

    End Sub

    ' Resets the item tags. 
    Private Sub listView1_Invalidated(ByVal sender As Object, _
        ByVal e As InvalidateEventArgs) Handles listView1.Invalidated

        For Each item As ListViewItem In listView1.Items
            If item Is Nothing Then Return
            item.Tag = Nothing
        Next

    End Sub

    ' Forces the entire control to repaint if a column width is changed.
    Private Sub listView1_ColumnWidthChanged(ByVal sender As Object, _
        ByVal e As ColumnWidthChangedEventArgs) Handles listView1.ColumnWidthChanged

        listView1.Invalidate()

    End Sub

End Class

注解

事件 ListView.DrawSubItem 使你能够自定义 (或所有者绘制) 详细信息视图中控件 ListView 的外观。

当 ListView.DrawSubItem 控件的 属性设置为 且其 ListView.OwnerDrawView 属性Details设置为 true 时，该事件由 ListView 控件引发。 DrawListViewSubItemEventArgs传递给事件处理程序的 包含有关ListViewItem.ListViewSubItem要绘制的 的信息，并且还提供帮助您绘制子项的方法。

ItemState使用 或 Item 属性检索有关要绘制的子项的父项的信息。 若要检索 ListViewItem.ListViewSubItem 自身，请使用 SubItem 属性。 Header使用 属性检索ColumnHeader表示显示子项的列的标题的 。

Graphics使用 属性在 属性指定的Bounds区域内进行实际绘制。 若要绘制不需要自定义的标准 ListView 元素，请使用 DrawBackground、 DrawText和 DrawFocusRectangle 方法。

DrawDefault如果希望操作系统绘制子项，请使用 属性。 如果只想自定义特定子项，这非常有用。

注意

若要避免所有者绘制时图形闪烁的问题，请重写 ListView 控件并将 属性 DoubleBuffered 设置为 true。 当应用程序调用 方法时，此功能仅在 Windows XP 和 Windows Server 2003 系列上 Application.EnableVisualStyles 可用。

构造函数

DrawListViewSubItemEventArgs(Graphics, Rectangle, ListViewItem, ListViewItem+ListViewSubItem, Int32, Int32, ColumnHeader, ListViewItemStates)

初始化 DrawListViewSubItemEventArgs 类的新实例。

属性

Bounds	获取要绘制的 ListViewItem.ListViewSubItem 的大小和位置。
ColumnIndex	获取显示 ListView 的 ListViewItem.ListViewSubItem 列的索引。
DrawDefault	获取或设置一个值，该值指示是否应由操作系统绘制而不是由所有者描述 ListViewItem.ListViewSubItem。
Graphics	获取用于绘制 Graphics 的 ListViewItem.ListViewSubItem。
Header	获取显示 ListView 的 ListViewItem.ListViewSubItem 列的标题。
Item	获取要绘制的 ListViewItem 的父级 ListViewItem.ListViewSubItem。
ItemIndex	获取要绘制的 ListViewItem 的父级 ListViewItem.ListViewSubItem 的索引。
ItemState	获取要绘制的 ListViewItem 的父级 ListViewItem.ListViewSubItem 的当前状态。
SubItem	获取要绘制的 ListViewItem.ListViewSubItem。

方法

DrawBackground()	使用 ListViewItem.ListViewSubItem 的当前背景色绘制它的背景。
DrawFocusRectangle(Rectangle)	如果父级 ListViewItem.ListViewSubItem 具有焦点，则为 ListViewItem 绘制一个聚焦框。
DrawText()	使用 ListViewItem.ListViewSubItem 的当前前景色绘制它的文本。
DrawText(TextFormatFlags)	使用 ListViewItem.ListViewSubItem 的当前前景色以及由指定的 TextFormatFlags 值设置的格式绘制它的文本。
Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetType()	获取当前实例的 Type。 (继承自 Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
ToString()	返回表示当前对象的字符串。 (继承自 Object)

另请参阅

• ListView
• DrawSubItem
• OwnerDraw
• View
• ListViewItem.ListViewSubItem
• View