ListView.OwnerDraw Vlastnost

public:
 property bool OwnerDraw { bool get(); void set(bool value); };

public bool OwnerDraw { get; set; }

member this.OwnerDraw : bool with get, set

Public Property OwnerDraw As Boolean

Hodnota vlastnosti

true ListView pokud je ovládací prvek nakreslen kódem, který zadáte; false pokud ListView je ovládací prvek nakreslen operačním systémem. Výchozí formát je false.

Příklady

Následující příklad kódu ukazuje, jak poskytnout vlastní výkres pro ovládací prvek ListView . Ovládací ListView prvek v příkladu má pozadí přechodu. Podřízené položky se zápornými hodnotami mají červené popředí a černé pozadí.

Obslužná rutina DrawItem události nakreslí pozadí pro celé položky. Obslužná rutina události DrawSubItem nakreslí textové hodnoty a text i pozadí pro podřízené položky, které mají záporné hodnoty. Obslužná rutina události nakreslí DrawColumnHeader záhlaví jednotlivých sloupců.

Komponenta ContextMenu poskytuje způsob, jak přepínat mezi zobrazením podrobností a zobrazením seznamu. V zobrazení seznamu je vyvolána pouze DrawItem událost. V tomto případě se text i pozadí vykreslí v obslužné rutině DrawItem události.

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

Poznámky

Ovládací ListView prvek je obvykle nakreslen operačním systémem. Pokud chcete přizpůsobit vzhled ListView položek, podřízených položek a záhlaví sloupců, nastavte OwnerDraw vlastnost na true a zadejte obslužnou rutinu pro jednu nebo více následujících událostí: DrawItem, DrawSubItem, DrawColumnHeader. Tomu se říká výkres vlastníka. Když je vlastnost nastavena View na , dojde ke View.Detailsvšem třem událostem, jinak dojde pouze k DrawItem události.

V zobrazení podrobností můžete událost zpracovat DrawItem tak, aby nakreslila prvky společné pro všechny podnabídky, například pozadí, a zpracovat DrawSubItem událost tak, aby nakreslila prvky pro jednotlivé podřízené položky, jako jsou textové hodnoty. Můžete také kreslit všechny položky v ovládacím ListView prvku pomocí pouze jedné z těchto dvou událostí, i když to může být méně výhodné. Pokud chcete nakreslit záhlaví sloupců v zobrazení podrobností, musíte událost zpracovat DrawColumnHeader .

Další informace o zpracování událostí najdete v tématu Zpracování a vyvolávání událostí.

Platí pro

Viz také

• DrawItem
• DrawSubItem
• DrawColumnHeader
• ListViewItem
• ListViewItem.ListViewSubItem
• View
• View