Vorgehensweise: Deaktivieren von Schaltflächen in einer Schaltflächenspalte im DataGridView-Steuerelement von Windows Forms
Das DataGridView-Steuerelement enthält die DataGridViewButtonCell-Klasse, über die Zellen mit einer schaltflächenähnlichen Benutzeroberfläche angezeigt werden können. DataGridViewButtonCell bietet jedoch keine Möglichkeit, die Darstellung der in der Zelle angezeigten Schaltfläche zu deaktivieren.
Im folgenden Codebeispiel wird veranschaulicht, wie die DataGridViewButtonCell-Klasse angepasst wird, um Schaltflächen anzuzeigen, die deaktiviert angezeigt werden können. Im Beispiel wird der neue Zellentyp DataGridViewDisableButtonCell definiert, der aus DataGridViewButtonCell abgeleitet wird. Dieser Zellentyp stellt eine neue Enabled-Eigenschaft bereit, die auf false festgelegt werden kann, um eine deaktivierte Schaltfläche in der Zelle zu zeichnen. Im Beispiel wird auch der neue Spaltentyp DataGridViewDisableButtonColumn definiert, der DataGridViewDisableButtonCell-Objekte anzeigt. Zur Veranschaulichung dieses neuen Zellen- und Spaltentyps wird durch den aktuellen Wert jeder DataGridViewCheckBoxCell im übergeordneten DataGridView bestimmt, ob die Enabled-Eigenschaft der DataGridViewDisableButtonCell in derselben Zeile gleich true oder gleich false ist.
Hinweis
Wenn Sie aus DataGridViewCell oder DataGridViewColumn ableiten und der abgeleiteten Klasse neue Eigenschaften hinzufügen, müssen Sie die Clone-Methode überschreiben, damit die neuen Eigenschaften bei Klonvorgängen kopiert werden. Außerdem sollten Sie die Clone-Methode der Basisklasse aufrufen, damit die Eigenschaften der Basisklasse in die neue Zelle oder Spalte kopiert werden.
Beispiel
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;
class Form1 : Form
{
private DataGridView dataGridView1 = new DataGridView();
[STAThread]
public static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}
public Form1()
{
this.AutoSize = true;
this.Load += new EventHandler(Form1_Load);
}
public void Form1_Load(object sender, EventArgs e)
{
DataGridViewCheckBoxColumn column0 =
new DataGridViewCheckBoxColumn();
DataGridViewDisableButtonColumn column1 =
new DataGridViewDisableButtonColumn();
column0.Name = "CheckBoxes";
column1.Name = "Buttons";
dataGridView1.Columns.Add(column0);
dataGridView1.Columns.Add(column1);
dataGridView1.RowCount = 8;
dataGridView1.AutoSize = true;
dataGridView1.AllowUserToAddRows = false;
dataGridView1.ColumnHeadersDefaultCellStyle.Alignment =
DataGridViewContentAlignment.MiddleCenter;
// Set the text for each button.
for (int i = 0; i < dataGridView1.RowCount; i++)
{
dataGridView1.Rows[i].Cells["Buttons"].Value =
"Button " + i.ToString();
}
dataGridView1.CellValueChanged +=
new DataGridViewCellEventHandler(dataGridView1_CellValueChanged);
dataGridView1.CurrentCellDirtyStateChanged +=
new EventHandler(dataGridView1_CurrentCellDirtyStateChanged);
dataGridView1.CellClick +=
new DataGridViewCellEventHandler(dataGridView1_CellClick);
this.Controls.Add(dataGridView1);
}
// This event handler manually raises the CellValueChanged event
// by calling the CommitEdit method.
void dataGridView1_CurrentCellDirtyStateChanged(object sender,
EventArgs e)
{
if (dataGridView1.IsCurrentCellDirty)
{
dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit);
}
}
// If a check box cell is clicked, this event handler disables
// or enables the button in the same row as the clicked cell.
public void dataGridView1_CellValueChanged(object sender,
DataGridViewCellEventArgs e)
{
if (dataGridView1.Columns[e.ColumnIndex].Name == "CheckBoxes")
{
DataGridViewDisableButtonCell buttonCell =
(DataGridViewDisableButtonCell)dataGridView1.
Rows[e.RowIndex].Cells["Buttons"];
DataGridViewCheckBoxCell checkCell =
(DataGridViewCheckBoxCell)dataGridView1.
Rows[e.RowIndex].Cells["CheckBoxes"];
buttonCell.Enabled = !(Boolean)checkCell.Value;
dataGridView1.Invalidate();
}
}
// If the user clicks on an enabled button cell, this event handler
// reports that the button is enabled.
void dataGridView1_CellClick(object sender,
DataGridViewCellEventArgs e)
{
if (dataGridView1.Columns[e.ColumnIndex].Name == "Buttons")
{
DataGridViewDisableButtonCell buttonCell =
(DataGridViewDisableButtonCell)dataGridView1.
Rows[e.RowIndex].Cells["Buttons"];
if (buttonCell.Enabled)
{
MessageBox.Show(dataGridView1.Rows[e.RowIndex].
Cells[e.ColumnIndex].Value.ToString() +
" is enabled");
}
}
}
}
public class DataGridViewDisableButtonColumn : DataGridViewButtonColumn
{
public DataGridViewDisableButtonColumn()
{
this.CellTemplate = new DataGridViewDisableButtonCell();
}
}
public class DataGridViewDisableButtonCell : DataGridViewButtonCell
{
private bool enabledValue;
public bool Enabled
{
get
{
return enabledValue;
}
set
{
enabledValue = value;
}
}
// Override the Clone method so that the Enabled property is copied.
public override object Clone()
{
DataGridViewDisableButtonCell cell =
(DataGridViewDisableButtonCell)base.Clone();
cell.Enabled = this.Enabled;
return cell;
}
// By default, enable the button cell.
public DataGridViewDisableButtonCell()
{
this.enabledValue = true;
}
protected override void Paint(Graphics graphics,
Rectangle clipBounds, Rectangle cellBounds, int rowIndex,
DataGridViewElementStates elementState, object value,
object formattedValue, string errorText,
DataGridViewCellStyle cellStyle,
DataGridViewAdvancedBorderStyle advancedBorderStyle,
DataGridViewPaintParts paintParts)
{
// The button cell is disabled, so paint the border,
// background, and disabled button for the cell.
if (!this.enabledValue)
{
// Draw the cell background, if specified.
if ((paintParts & DataGridViewPaintParts.Background) ==
DataGridViewPaintParts.Background)
{
SolidBrush cellBackground =
new SolidBrush(cellStyle.BackColor);
graphics.FillRectangle(cellBackground, cellBounds);
cellBackground.Dispose();
}
// Draw the cell borders, if specified.
if ((paintParts & DataGridViewPaintParts.Border) ==
DataGridViewPaintParts.Border)
{
PaintBorder(graphics, clipBounds, cellBounds, cellStyle,
advancedBorderStyle);
}
// Calculate the area in which to draw the button.
Rectangle buttonArea = cellBounds;
Rectangle buttonAdjustment =
this.BorderWidths(advancedBorderStyle);
buttonArea.X += buttonAdjustment.X;
buttonArea.Y += buttonAdjustment.Y;
buttonArea.Height -= buttonAdjustment.Height;
buttonArea.Width -= buttonAdjustment.Width;
// Draw the disabled button.
ButtonRenderer.DrawButton(graphics, buttonArea,
PushButtonState.Disabled);
// Draw the disabled button text.
if (this.FormattedValue is String)
{
TextRenderer.DrawText(graphics,
(string)this.FormattedValue,
this.DataGridView.Font,
buttonArea, SystemColors.GrayText);
}
}
else
{
// The button cell is enabled, so let the base class
// handle the painting.
base.Paint(graphics, clipBounds, cellBounds, rowIndex,
elementState, value, formattedValue, errorText,
cellStyle, advancedBorderStyle, paintParts);
}
}
}
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Windows.Forms.VisualStyles
Class Form1
Inherits Form
Private WithEvents dataGridView1 As New DataGridView()
<STAThread()> _
Public Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
Public Sub New()
Me.AutoSize = True
End Sub
Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) _
Handles Me.Load
Dim column0 As New DataGridViewCheckBoxColumn()
Dim column1 As New DataGridViewDisableButtonColumn()
column0.Name = "CheckBoxes"
column1.Name = "Buttons"
dataGridView1.Columns.Add(column0)
dataGridView1.Columns.Add(column1)
dataGridView1.RowCount = 8
dataGridView1.AutoSize = True
dataGridView1.AllowUserToAddRows = False
dataGridView1.ColumnHeadersDefaultCellStyle.Alignment = _
DataGridViewContentAlignment.MiddleCenter
' Set the text for each button.
Dim i As Integer
For i = 0 To dataGridView1.RowCount - 1
dataGridView1.Rows(i).Cells("Buttons").Value = _
"Button " + i.ToString()
Next i
Me.Controls.Add(dataGridView1)
End Sub
' This event handler manually raises the CellValueChanged event
' by calling the CommitEdit method.
Sub dataGridView1_CurrentCellDirtyStateChanged( _
ByVal sender As Object, ByVal e As EventArgs) _
Handles dataGridView1.CurrentCellDirtyStateChanged
If dataGridView1.IsCurrentCellDirty Then
dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit)
End If
End Sub
' If a check box cell is clicked, this event handler disables
' or enables the button in the same row as the clicked cell.
Public Sub dataGridView1_CellValueChanged(ByVal sender As Object, _
ByVal e As DataGridViewCellEventArgs) _
Handles dataGridView1.CellValueChanged
If dataGridView1.Columns(e.ColumnIndex).Name = "CheckBoxes" Then
Dim buttonCell As DataGridViewDisableButtonCell = _
CType(dataGridView1.Rows(e.RowIndex).Cells("Buttons"), _
DataGridViewDisableButtonCell)
Dim checkCell As DataGridViewCheckBoxCell = _
CType(dataGridView1.Rows(e.RowIndex).Cells("CheckBoxes"), _
DataGridViewCheckBoxCell)
buttonCell.Enabled = Not CType(checkCell.Value, [Boolean])
dataGridView1.Invalidate()
End If
End Sub
' If the user clicks on an enabled button cell, this event handler
' reports that the button is enabled.
Sub dataGridView1_CellClick(ByVal sender As Object, _
ByVal e As DataGridViewCellEventArgs) _
Handles dataGridView1.CellClick
If dataGridView1.Columns(e.ColumnIndex).Name = "Buttons" Then
Dim buttonCell As DataGridViewDisableButtonCell = _
CType(dataGridView1.Rows(e.RowIndex).Cells("Buttons"), _
DataGridViewDisableButtonCell)
If buttonCell.Enabled Then
MsgBox(dataGridView1.Rows(e.RowIndex). _
Cells(e.ColumnIndex).Value.ToString() + _
" is enabled")
End If
End If
End Sub
End Class
Public Class DataGridViewDisableButtonColumn
Inherits DataGridViewButtonColumn
Public Sub New()
Me.CellTemplate = New DataGridViewDisableButtonCell()
End Sub
End Class
Public Class DataGridViewDisableButtonCell
Inherits DataGridViewButtonCell
Private enabledValue As Boolean
Public Property Enabled() As Boolean
Get
Return enabledValue
End Get
Set(ByVal value As Boolean)
enabledValue = value
End Set
End Property
' Override the Clone method so that the Enabled property is copied.
Public Overrides Function Clone() As Object
Dim Cell As DataGridViewDisableButtonCell = _
CType(MyBase.Clone(), DataGridViewDisableButtonCell)
Cell.Enabled = Me.Enabled
Return Cell
End Function
' By default, enable the button cell.
Public Sub New()
Me.enabledValue = True
End Sub
Protected Overrides Sub Paint(ByVal graphics As Graphics, _
ByVal clipBounds As Rectangle, ByVal cellBounds As Rectangle, _
ByVal rowIndex As Integer, _
ByVal elementState As DataGridViewElementStates, _
ByVal value As Object, ByVal formattedValue As Object, _
ByVal errorText As String, _
ByVal cellStyle As DataGridViewCellStyle, _
ByVal advancedBorderStyle As DataGridViewAdvancedBorderStyle, _
ByVal paintParts As DataGridViewPaintParts)
' The button cell is disabled, so paint the border,
' background, and disabled button for the cell.
If Not Me.enabledValue Then
' Draw the background of the cell, if specified.
If (paintParts And DataGridViewPaintParts.Background) = _
DataGridViewPaintParts.Background Then
Dim cellBackground As New SolidBrush(cellStyle.BackColor)
graphics.FillRectangle(cellBackground, cellBounds)
cellBackground.Dispose()
End If
' Draw the cell borders, if specified.
If (paintParts And DataGridViewPaintParts.Border) = _
DataGridViewPaintParts.Border Then
PaintBorder(graphics, clipBounds, cellBounds, cellStyle, _
advancedBorderStyle)
End If
' Calculate the area in which to draw the button.
Dim buttonArea As Rectangle = cellBounds
Dim buttonAdjustment As Rectangle = _
Me.BorderWidths(advancedBorderStyle)
buttonArea.X += buttonAdjustment.X
buttonArea.Y += buttonAdjustment.Y
buttonArea.Height -= buttonAdjustment.Height
buttonArea.Width -= buttonAdjustment.Width
' Draw the disabled button.
ButtonRenderer.DrawButton(graphics, buttonArea, _
PushButtonState.Disabled)
' Draw the disabled button text.
If TypeOf Me.FormattedValue Is String Then
TextRenderer.DrawText(graphics, CStr(Me.FormattedValue), _
Me.DataGridView.Font, buttonArea, SystemColors.GrayText)
End If
Else
' The button cell is enabled, so let the base class
' handle the painting.
MyBase.Paint(graphics, clipBounds, cellBounds, rowIndex, _
elementState, value, formattedValue, errorText, _
cellStyle, advancedBorderStyle, paintParts)
End If
End Sub
End Class
Kompilieren des Codes
Für dieses Beispiel benötigen Sie Folgendes:
- Verweise auf die Assemblys "System", "System.Drawing", "System.Windows.Forms" und "System.Windows.Forms.VisualStyles".
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