方法 : オーナー描画リスト ボックスを作成する

更新 : 2007 年 11 月

.NET Compact Framework を使用してオーナー描画リスト ボックスを作成できますが、.NET Framework で作成する場合ほど簡単ではありません。.NET Compact Framework では、DrawModeDrawItem、およびリスト ボックスやその他のコントロールの描画メンバがサポートされていませんが、それらの機能はプログラミングできます。この例では、オーナー描画リスト ボックスを作成するためのカスタム コントロールを定義し、フォントを選択するためのリスト ボックスとしてそのコントロールを実装します。

このサンプルには、基本クラス OwnerDrawnListBox が含まれています。FontListBox はこのクラスから派生します。OwnerDrawnListBox クラスの主な機能は以下のとおりです。

  • リスト ボックスを構築するための、垂直スクロール バー、アイテム格納用の配列、およびビットマップを指定します。

  • アイテムの高さプロパティを設定し、コントロールの高さを指定して、描画されるアイテムの個数を決定します。

  • SelectedIndex プロパティを指定します。このプロパティで、現在のスクロール バーで選択されているアイテム、アイテムの高さ、およびマウス ポインタの座標を判断します。

  • SelectedIndexChanged イベントを指定します。

  • アイテムが必ず表示されるようにします。

  • 不要な場合、スクロール バーを削除します。

  • 上方向キーおよび下方向キーによる、キーボード操作を指定します。

FontListBox クラスは、OwnerDrawnListBox を継承します。このクラスに実装されている機能および使用されている手法は次のとおりです。

  • アイテムの適切な高さを決定します。

  • オーバーライドした OnPaint メソッドを使用して、アイテムを描画します。選択されているアイテムは強調表示して描画します。ちらつきを抑えるために、このメソッドは、コントロール全体の描画が終わるまでコントロールを表示しません。

  • SelectedFaceName プロパティを指定します。このプロパティには選択されたフォントの名前が入ります。

DrawFontList フォームは次の処理を行います。

  • 新しい FontListBox インスタンスを作成し、コントロールのコレクションに追加します。

  • SelectedIndexChanged イベント用のイベント ハンドラを追加します。

  • フォントの一覧を使用して FontListBox を作成します。

  • 選択されたフォントのサンプルを表示するためのラベルを指定します。

オーナー描画リスト ボックスを作成するには

  1. カスタム コントロール クラス OwnerDrawnListBox をプロジェクトに追加します。

    ' Base custom control for DrawFontList
    Class OwnerDrawnListBox
        Inherits Control
        Private Const SCROLL_WIDTH As Integer = 20
        Private itemH As Integer = -1
        Private selIndex As Integer = -1
    
        Private offScreenBitmap As Bitmap
        Private vs As VScrollBar
        Private itemsAList As ArrayList
    
    
        Public Sub New()
            Me.vs = New VScrollBar
            Me.vs.Parent = Me
            Me.vs.Visible = False
            Me.vs.SmallChange = 1
            AddHandler Me.vs.ValueChanged, AddressOf Me.ScrollValueChanged
    
            Me.itemsAList = New ArrayList
        End Sub
    
    
        Public ReadOnly Property Items() As ArrayList
            Get
                Return Me.itemsAList
            End Get
        End Property
    
    
        Protected ReadOnly Property OffScreen() As Bitmap
            Get
                Return Me.offScreenBitmap
            End Get
        End Property
    
    
        Protected ReadOnly Property VScrollBar() As VScrollBar
            Get
                Return Me.vs
            End Get
        End Property
    
        Friend Event SelectedIndexChanged As EventHandler
    
    
        Protected Overridable Sub OnSelectedIndexChanged(ByVal e As EventArgs)
            RaiseEvent SelectedIndexChanged(Me, e)
        End Sub
    
        Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
            Me.SelectedIndex = Me.vs.Value + e.Y / Me.ItemHeight
    
            ' Invalidate the control so we can draw the item as selected.
            Me.Refresh()
        End Sub
    
        ' Get or set index of selected item.
        Public Property SelectedIndex() As Integer
            Get
                Return Me.selIndex
            End Get
    
            Set(ByVal Value As Integer)
                Me.selIndex = Value
    
                RaiseEvent SelectedIndexChanged(Me, Nothing)
            End Set
        End Property
    
    
        Protected Sub ScrollValueChanged(ByVal o As Object, ByVal e As EventArgs)
            Me.Refresh()
        End Sub
    
    
        Protected Overridable Property ItemHeight() As Integer
            Get
                Return Me.itemH
            End Get
    
            Set(ByVal Value As Integer)
                Me.itemH = Value
            End Set
        End Property
    
    
        ' If the requested index is before the first visible index then set the
        ' first item to be the requested index. If it is after the last visible
        ' index, then set the last visible index to be the requested index.
        Public Sub EnsureVisible(ByVal index As Integer)
            If index < Me.vs.Value Then
                Me.vs.Value = index
                Me.Refresh()
            ElseIf index >= Me.vs.Value + Me.DrawCount Then
                Me.vs.Value = index - Me.DrawCount + 1
                Me.Refresh()
            End If
        End Sub
    
    
        ' Need to set focus to the control when it 
        ' is clicked so that keyboard events occur.
        Protected Overrides Sub OnClick(ByVal e As EventArgs)
            Me.Focus()
            MyBase.OnClick(e)
        End Sub
    
        ' Selected item moves when you use the keyboard up/down keys.
        Protected Overrides Sub OnKeyDown(ByVal e As KeyEventArgs)
            Select Case e.KeyCode
                Case Keys.Down
                    If Me.SelectedIndex < Me.vs.Maximum Then
                        Me.SelectedIndex = Me.SelectedIndex + 1
                        EnsureVisible(Me.SelectedIndex + 1)
                        Me.Refresh()
                    End If
                Case Keys.Up
                    If Me.SelectedIndex > Me.vs.Minimum Then
                        Me.SelectedIndex = Me.SelectedIndex - 1
                        EnsureVisible(Me.SelectedIndex - 1)
                        Me.Refresh()
                    End If
                Case Keys.PageDown
                    Me.SelectedIndex = Math.Min(Me.vs.Maximum, Me.SelectedIndex + Me.DrawCount)
                    EnsureVisible(Me.SelectedIndex)
                    Me.Refresh()
                Case Keys.PageUp
                    Me.SelectedIndex = Math.Max(Me.vs.Minimum, Me.SelectedIndex - Me.DrawCount)
                    EnsureVisible(Me.SelectedIndex)
                    Me.Refresh()
                Case Keys.Home
                    Me.SelectedIndex = 0
                    EnsureVisible(Me.SelectedIndex)
                    Me.Refresh()
                Case Keys.End
                    Me.SelectedIndex = Me.itemsAList.Count - 1
                    EnsureVisible(Me.SelectedIndex)
                    Me.Refresh()
            End Select
    
            MyBase.OnKeyDown(e)
        End Sub
    
        ' Calculate how many items we can draw given the height of the control.
        Protected ReadOnly Property DrawCount() As Integer
            Get
                If Me.vs.Value + Me.vs.LargeChange > Me.vs.Maximum Then
                    Return Me.vs.Maximum - Me.vs.Value + 1
                Else
                    Return Me.vs.LargeChange
                End If
            End Get
        End Property
    
        Protected Overrides Sub OnResize(ByVal e As EventArgs)
            Dim viewableItemCount As Integer = Me.ClientSize.Height / Me.ItemHeight
    
            Me.vs.Bounds = New Rectangle(Me.ClientSize.Width - SCROLL_WIDTH, 0, SCROLL_WIDTH, Me.ClientSize.Height)
    
    
            ' Determine if scrollbars are needed
            If Me.itemsAList.Count > viewableItemCount Then
                Me.vs.Visible = True
                Me.vs.LargeChange = viewableItemCount
                Me.offScreenBitmap = New Bitmap(Me.ClientSize.Width - SCROLL_WIDTH - 1, Me.ClientSize.Height - 2)
            Else
                Me.vs.Visible = False
                Me.vs.LargeChange = Me.itemsAList.Count
                Me.offScreenBitmap = New Bitmap(Me.ClientSize.Width - 1, Me.ClientSize.Height - 2)
            End If
    
            Me.vs.Maximum = Me.itemsAList.Count - 1
        End Sub
    End Class
    
    // Base custom control for DrawFontList
    class OwnerDrawnListBox : Control
    {
        const int SCROLL_WIDTH = 20;
        int itemHeight         = -1;
        int selectedIndex      = -1;
    
        Bitmap offScreen;
        VScrollBar vs;
        ArrayList items;
    
        public OwnerDrawnListBox()
        {
            this.vs = new VScrollBar();
            this.vs.Parent      = this;
            this.vs.Visible     = false;
            this.vs.SmallChange = 1;
            this.vs.ValueChanged += new EventHandler(this.ScrollValueChanged);
    
            this.items = new ArrayList();
        }
    
        public ArrayList Items
        {
            get
            {
                return this.items;
            }
        }
    
        protected Bitmap OffScreen
        {
            get
            {
                return this.offScreen;
            }
        }
    
        protected VScrollBar VScrollBar
        {
            get
            {
                return this.vs;
            }
        }
    
        public event EventHandler SelectedIndexChanged;
    
        // Raise the SelectedIndexChanged event
        protected virtual void OnSelectedIndexChanged(EventArgs e)
        {
            if(this.SelectedIndexChanged != null)
                this.SelectedIndexChanged(this, e);
        }
    
        protected override void OnMouseDown(MouseEventArgs e)
        {
            this.SelectedIndex = this.vs.Value + (e.Y / this.ItemHeight);
    
            // Invalidate the control so we can draw the item as selected.
            this.Refresh();
        }
    
        // Get or set index of selected item.
        public int SelectedIndex
        {
            get
            {
                return this.selectedIndex;
            }
    
            set
            {
                this.selectedIndex = value;
    
                if (this.SelectedIndexChanged != null)
                    this.SelectedIndexChanged(this, EventArgs.Empty);
    
            }
        }
    
        protected void ScrollValueChanged(object o, EventArgs e)
        {
            this.Refresh();
        }
    
        protected virtual int ItemHeight
        {
            get
            {
                return this.itemHeight;
            }
    
            set
            {
                this.itemHeight = value;
            }
        }
    
        // If the requested index is before the first visible index then set the
        // first item to be the requested index. If it is after the last visible
        // index, then set the last visible index to be the requested index.
        public void EnsureVisible(int index)
        {
            if(index < this.vs.Value)
            {
                this.vs.Value = index;
                this.Refresh();
            }
            else if(index >= this.vs.Value + this.DrawCount)
            {
                this.vs.Value = index - this.DrawCount + 1;
                this.Refresh();
            }
        }
    
    
        // Need to set focus to the control when it
        // is clicked so that keyboard events occur.
        protected override void OnClick(EventArgs e)
        {
            this.Focus();
            base.OnClick(e);
        }
    
        // Selected item moves when you use the keyboard up/down keys.
        protected override void OnKeyDown(KeyEventArgs e)
        {
            switch(e.KeyCode)
            {
                case Keys.Down:
                    if(this.SelectedIndex < this.vs.Maximum)
                    {
                        EnsureVisible(++this.SelectedIndex);
                        this.Refresh();
                    }
                    break;
                case Keys.Up:
                    if(this.SelectedIndex > this.vs.Minimum)
                    {
                        EnsureVisible(--this.SelectedIndex);
                        this.Refresh();
                    }
                    break;
                case Keys.PageDown:
                    this.SelectedIndex = Math.Min(this.vs.Maximum, this.SelectedIndex + this.DrawCount);
                    EnsureVisible(this.SelectedIndex);
                    this.Refresh();
                    break;
                case Keys.PageUp:
                    this.SelectedIndex = Math.Max(this.vs.Minimum, this.SelectedIndex - this.DrawCount);
                    EnsureVisible(this.SelectedIndex);
                    this.Refresh();
                    break;
                case Keys.Home:
                    this.SelectedIndex = 0;
                    EnsureVisible(this.SelectedIndex);
                    this.Refresh();
                    break;
                case Keys.End:
                    this.SelectedIndex = this.items.Count - 1;
                    EnsureVisible(this.SelectedIndex);
                    this.Refresh();
                    break;
            }
    
            base.OnKeyDown(e);
        }
    
        // Calculate how many items we can draw given the height of the control.
        protected int DrawCount
        {
            get
            {
                if(this.vs.Value + this.vs.LargeChange > this.vs.Maximum)
                    return this.vs.Maximum - this.vs.Value + 1;
                else
                    return this.vs.LargeChange;
            }
        }
    
        protected override void OnResize(EventArgs e)
        {
            int viewableItemCount = this.ClientSize.Height / this.ItemHeight;
    
            this.vs.Bounds = new Rectangle(this.ClientSize.Width - SCROLL_WIDTH,
                0,
                SCROLL_WIDTH,
                this.ClientSize.Height);
    
    
            // Determine if scrollbars are needed
            if(this.items.Count > viewableItemCount)
            {
                this.vs.Visible = true;
                this.vs.LargeChange = viewableItemCount;
                this.offScreen = new Bitmap(this.ClientSize.Width - SCROLL_WIDTH - 1, this.ClientSize.Height - 2);
            }
            else
            {
                this.vs.Visible = false;
                this.vs.LargeChange = this.items.Count;
                this.offScreen = new Bitmap(this.ClientSize.Width - 1, this.ClientSize.Height - 2);
            }
    
            this.vs.Maximum = this.items.Count - 1;
        }
    }
    
  2. FontListBox クラスをプロジェクトに追加します。このクラスは、OwnerDrawnListBox を実装したクラスです。

    ' Derive an implementation of the
    ' OwnerDrawnListBox class
    Class FontListBox
        Inherits OwnerDrawnListBox
        Private Const FONT_SIZE As Integer = 10
        Private Const DRAW_OFFSET As Integer = 5
    
    
        Public Sub New()
    
            ' Determine what the item height should be
            ' by adding 30% padding after measuring
            ' the letter A with the selected font.
            Dim g As Graphics = Me.CreateGraphics()
            Me.ItemHeight = Fix(g.MeasureString("A", Me.Font).Height * 1.3)
            g.Dispose()
        End Sub
    
        ' Return the name of the selected font.
        Public ReadOnly Property SelectedFaceName() As String
            Get
                Return CStr(Me.Items(Me.SelectedIndex))
            End Get
        End Property
    
    
        ' Determine what the text color should be
        ' for the selected item drawn as highlighted
        Function CalcTextColor(ByVal backgroundColor As Color) As Color
            If backgroundColor.Equals(Color.Empty) Then
                Return Color.Black
            End If
            Dim sum As Integer = backgroundColor.R + backgroundColor.G + backgroundColor.B
    
            If sum > 256 Then
                Return Color.Black
            Else
                Return Color.White
            End If
        End Function
    
        Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
            Dim font As Font
            Dim fontColor As Color
    
            ' The base class contains a bitmap, offScreen, for constructing
            ' the control and is rendered when all items are populated.
            ' This technique prevents flicker.
            Dim gOffScreen As Graphics = Graphics.FromImage(Me.OffScreen)
            gOffScreen.FillRectangle(New SolidBrush(Me.BackColor), Me.ClientRectangle)
    
            Dim itemTop As Integer = 0
    
            ' Draw the fonts in the list.
            Dim n As Integer
            For n = Me.VScrollBar.Value To (Me.VScrollBar.Value + DrawCount) - 1
                ' If the font name contains "dings" it needs to be displayed
                ' in the list box with a readable font with the default font.
                If CStr(Me.Items(n)).ToLower().IndexOf("dings") <> -1 Then
                    font = New Font(Me.Font.Name, FONT_SIZE, FontStyle.Regular)
                Else
                    font = New Font(CStr(Me.Items(n)), FONT_SIZE, FontStyle.Regular)
                End If
                ' Draw the selected item to appear highlighted
                If n = Me.SelectedIndex Then
                    gOffScreen.FillRectangle(New SolidBrush(SystemColors.Highlight), 1, itemTop + 1, Me.ClientSize.Width - IIf(Me.VScrollBar.Visible, Me.VScrollBar.Width, 2), Me.ItemHeight)
                    ' If the scroll bar is visible, subtract the scrollbar width
                    ' otherwise subtract 2 for the width of the rectangle
                    fontColor = CalcTextColor(SystemColors.Highlight)
                Else
                    fontColor = Me.ForeColor
                End If
                ' Draw the item
                gOffScreen.DrawString(CStr(Me.Items(n)), font, New SolidBrush(fontColor), DRAW_OFFSET, itemTop)
                itemTop += Me.ItemHeight
            Next n
    
            ' Draw the list box
            e.Graphics.DrawImage(Me.OffScreen, 1, 1)
    
            gOffScreen.Dispose()
        End Sub
    
    
        ' Draws the external border around the control.
        Protected Overrides Sub OnPaintBackground(ByVal e As PaintEventArgs)
            e.Graphics.DrawRectangle(New Pen(Color.Black), 0, 0, Me.ClientSize.Width - 1, Me.ClientSize.Height - 1)
        End Sub
    End Class
    
    // Derive an implementation of the
    // OwnerDrawnListBox class
    class FontListBox : OwnerDrawnListBox
    {
        const int FONT_SIZE    = 10;
        const int DRAW_OFFSET  = 5;
    
        public FontListBox()
        {
    
            // Determine what the item height should be
            // by adding 30% padding after measuring
            // the letter A with the selected font.
            Graphics g = this.CreateGraphics();
            this.ItemHeight = (int)(g.MeasureString("A", this.Font).Height * 1.3);
            g.Dispose();
        }
    
        // Return the name of the selected font.
        public string SelectedFaceName
        {
            get
            {
                return (string)this.Items[this.SelectedIndex];
            }
        }
    
        // Determine what the text color should be
        // for the selected item drawn as highlighted
        Color CalcTextColor(Color backgroundColor)
        {
            if(backgroundColor.Equals(Color.Empty))
                return Color.Black;
    
            int sum = backgroundColor.R + backgroundColor.G + backgroundColor.B;
    
            if(sum > 256)
                return Color.Black;
            else
                return Color.White;
        }
    
        protected override void OnPaint(PaintEventArgs e)
        {
            Font font;
            Color fontColor;
    
            // The base class contains a bitmap, offScreen, for constructing
            // the control and is rendered when all items are populated.
            // This technique prevents flicker.
            Graphics gOffScreen = Graphics.FromImage(this.OffScreen);
            gOffScreen.FillRectangle(new SolidBrush(this.BackColor), this.ClientRectangle);
    
            int itemTop = 0;
    
            // Draw the fonts in the list.
            for(int n = this.VScrollBar.Value; n < this.VScrollBar.Value + DrawCount; n++)
            {
                // If the font name contains "dings" it needs to be displayed
                // in the list box with a readable font with the default font.
                if(((string)this.Items[n]).ToLower().IndexOf("dings") != -1)
                    font = new Font(this.Font.Name, FONT_SIZE, FontStyle.Regular);
                else
                    font = new Font((string)this.Items[n], FONT_SIZE, FontStyle.Regular);
    
                // Draw the selected item to appear highlighted
                if(n == this.SelectedIndex)
                {
                    gOffScreen.FillRectangle(new SolidBrush(SystemColors.Highlight),
                        1,
                        itemTop + 1,
                        // If the scroll bar is visible, subtract the scrollbar width
                        // otherwise subtract 2 for the width of the rectangle
                        this.ClientSize.Width - (this.VScrollBar.Visible ? this.VScrollBar.Width : 2),
                        this.ItemHeight);
                    fontColor = CalcTextColor(SystemColors.Highlight);
                }
                else
                    fontColor = this.ForeColor;
    
                // Draw the item
                gOffScreen.DrawString((string)this.Items[n], font, new SolidBrush(fontColor), DRAW_OFFSET, itemTop);
                itemTop += this.ItemHeight;
            }
    
            // Draw the list box
            e.Graphics.DrawImage(this.OffScreen, 1, 1);
    
            gOffScreen.Dispose();
        }
    
        // Draws the external border around the control.
    
        protected override void OnPaintBackground(PaintEventArgs e)
        {
            e.Graphics.DrawRectangle(new Pen(Color.Black), 0, 0, this.ClientSize.Width - 1, this.ClientSize.Height - 1);
        }
    }
    
  3. フォームに Label コントロールを 2 つ追加し、descLabel および sampleLabel という名前を付けます。後の方のラベルに FontListBox で選択したフォントのサンプル文字が表示されます。

  4. フォームに FontListBox のインスタンスを作成します。

  5. フォームの Load イベントのコンストラクタに、次のコードを追加します。

    ' Create a new instance of FontListBox.
    myListBox.Parent = Me
    
    ' Configure the event handler for the SelectedIndexChanged event. 
    AddHandler myListBox.SelectedIndexChanged, AddressOf Me.SelectedIndexChanged
    
    ' Draw the bounds of the FontListBox.
    myListBox.Bounds = New Rectangle(5, 5, 150, 100)
    
    ' Add fonts to list, repeat the list 4 times
    ' so that the scroll bar can be demonstrated.
    Dim n As Integer
    For n = 0 To 3
        myListBox.Items.Add("Bookdings")
        myListBox.Items.Add("Courier New")
        myListBox.Items.Add("Frutiger Linotype")
        myListBox.Items.Add("Tahoma")
    Next n
    
    
    ' Labels to show the selected font from the list box. Assumes
    ' instances of these labels have been declared for the form.
    descLabel.Parent = Me
    descLabel.Text = "Font Sample:"
    descLabel.Bounds = New Rectangle(10, myListBox.Bottom + 20, Me.ClientSize.Width - 10, 30)
    
    ' Assumes an instance sampleLabel is declared for the form.
    sampleLabel.Parent = Me
    sampleLabel.Bounds = New Rectangle(10, descLabel.Bottom, Me.ClientSize.Width - 10, 30)
    sampleLabel.Text = "AaBbCc 123"
    
    // Create a new instance of FontListBox.
    box = new FontListBox();
    box.Parent = this;
    
    // Configure the event handler for the SelectedIndexChanged event.
    box.SelectedIndexChanged += new EventHandler(this.SelectedIndexChanged);
    
    // Draw the bounds of the FontListBox.
    box.Bounds = new Rectangle(5, 5, 150, 100);
    
    // Add fonts to list, repeat the list 4 times
    // so that the scroll bar can be demonstrated.
    for(int n = 0; n < 4; n++)
    {
        box.Items.Add("Bookdings");
        box.Items.Add("Courier New");
        box.Items.Add("Frutiger Linotype");
        box.Items.Add("Tahoma");
    }
    
    
    // Labels to show the selected font and a sample.
    Label desc = new Label();
    desc.Parent = this;
    desc.Text = "Font Sample:";
    desc.Bounds = new Rectangle(10, box.Bottom + 20, this.ClientSize.Width - 10, 30);
    
    sample = new Label();
    sample.Parent = this;
    sample.Bounds = new Rectangle(10, desc.Bottom, this.ClientSize.Width - 10, 30);
    sample.Text = "AaBbCc 123";
    
  6. FontListBox コントロールの SelectedChangedEvent イベント用のコードを追加します。このコードでは、選択されたフォントで sampleLabel コントロールに文字を表示します。

    ' Event handler for SelectedIndexChanged to
    ' display a sample of the selected font.
    
    ' Assumes that an instace of myListBox has been declared for the form.
    Friend Sub SelectedIndexChanged(ByVal o As Object, ByVal e As EventArgs)
        sampleLabel.Font = New Font(myListBox.SelectedFaceName, 12, FontStyle.Regular)
    End Sub
    
    // Event handler for SelectedIndexChanged to
    // display a sample of the selected font.
    private void SelectedIndexChanged(object o, EventArgs e)
    {
        sample.Font = new Font(box.SelectedFaceName, 12, FontStyle.Regular);
    }
    

コードのコンパイル方法

この例では、次の名前空間への参照が必要です。

参照

概念

カスタム コントロールの開発

.NET Compact Framework に関する「方法」トピック