Procedura: personalizzare l'aspetto delle righe nel controllo DataGridView di Windows Form
È possibile controllare l'aspetto delle righe DataGridView mediante la gestione di uno degli eventi o entrambi gli eventi DataGridView.RowPrePaint e DataGridView.RowPostPaint. Questi eventi sono stati progettati in modo che l'utente possa disegnare solo ciò che desidera e lasciare che il controllo DataGridView disegni il resto. Ad esempio, se si desidera disegnare uno sfondo personalizzato, è possibile gestire l'evento DataGridView.RowPrePaint e lasciare che le singole celle disegnino il contenuto in primo piano. In alternativa è possibile lasciare che le celle si disegnino da sole e aggiungere il contenuto in primo piano in un gestore per l'evento DataGridView.RowPostPaint. È inoltre possibile disabilitare il disegno delle celle e disegnare tutto personalmente in un gestore dell'evento DataGridView.RowPrePaint.
Nell'esempio di codice seguente i gestori vengono implementati per entrambi gli eventi per fornire uno sfondo con sfumature selezionabili e un contenuto in primo piano personalizzato che occupa più colonne.
Esempio
Imports System
Imports System.Drawing
Imports System.Windows.Forms
Class DataGridViewRowPainting
Inherits Form
Private WithEvents dataGridView1 As New DataGridView()
Private oldRowIndex As Int32 = 0
Private Const CUSTOM_CONTENT_HEIGHT As Int32 = 30
<STAThreadAttribute()> _
Public Shared Sub Main()
Application.Run(New DataGridViewRowPainting())
End Sub 'Main
Public Sub New()
Me.dataGridView1.Dock = DockStyle.Fill
Me.Controls.Add(Me.dataGridView1)
Me.Text = "DataGridView row painting demo"
End Sub 'New
Sub DataGridViewRowPainting_Load(ByVal sender As Object, _
ByVal e As EventArgs) Handles Me.Load
' Set a cell padding to provide space for the top of the focus
' rectangle and for the content that spans multiple columns.
Dim newPadding As New Padding(0, 1, 0, CUSTOM_CONTENT_HEIGHT)
Me.dataGridView1.RowTemplate.DefaultCellStyle.Padding = newPadding
' Set the selection background color to transparent so
' the cell won't paint over the custom selection background.
Me.dataGridView1.RowTemplate.DefaultCellStyle.SelectionBackColor = _
Color.Transparent
' Set the row height to accommodate the normal cell content and the
' content that spans multiple columns.
Me.dataGridView1.RowTemplate.Height += CUSTOM_CONTENT_HEIGHT
' Initialize other DataGridView properties.
Me.dataGridView1.AllowUserToAddRows = False
Me.dataGridView1.EditMode = DataGridViewEditMode.EditOnKeystrokeOrF2
Me.dataGridView1.CellBorderStyle = DataGridViewCellBorderStyle.None
Me.dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect
' Set the column header names.
Me.dataGridView1.ColumnCount = 4
Me.dataGridView1.Columns(0).Name = "Recipe"
Me.dataGridView1.Columns(0).SortMode = _
DataGridViewColumnSortMode.NotSortable
Me.dataGridView1.Columns(1).Name = "Category"
Me.dataGridView1.Columns(2).Name = "Main Ingredients"
Me.dataGridView1.Columns(3).Name = "Rating"
' Hide the column that contains the content that spans
' multiple columns.
Me.dataGridView1.Columns(2).Visible = False
' Populate the rows of the DataGridView.
Dim row1() As String = {"Meatloaf", "Main Dish", _
"1 lb. lean ground beef, 1/2 cup bread crumbs, " + _
"1/4 cup ketchup, 1/3 tsp onion powder, 1 clove of garlic, " + _
"1/2 pack onion soup mix, dash of your favorite BBQ Sauce", "****"}
Dim row2() As String = {"Key Lime Pie", "Dessert", _
"lime juice, whipped cream, eggs, evaporated milk", "****"}
Dim row3() As String = {"Orange-Salsa Pork Chops", "Main Dish", _
"pork chops, salsa, orange juice, pineapple", "****"}
Dim row4() As String = {"Black Bean and Rice Salad", "Salad", _
"black beans, brown rice", "****"}
Dim row5() As String = {"Chocolate Cheesecake", "Dessert", _
"cream cheese, unsweetened chocolate", "***"}
Dim row6() As String = {"Black Bean Dip", "Appetizer", _
"black beans, sour cream, salsa, chips", "***"}
Dim rows() As Object = {row1, row2, row3, row4, row5, row6}
Dim rowArray As String()
For Each rowArray In rows
Me.dataGridView1.Rows.Add(rowArray)
Next rowArray
' Adjust the row heights to accommodate the normal cell content.
Me.dataGridView1.AutoResizeRows( _
DataGridViewAutoSizeRowsMode.AllCellsExceptHeaders)
End Sub 'DataGridViewRowPainting_Load
' Forces the control to repaint itself when the user
' manually changes the width of a column.
Sub dataGridView1_ColumnWidthChanged(ByVal sender As Object, _
ByVal e As DataGridViewColumnEventArgs) _
Handles dataGridView1.ColumnWidthChanged
Me.dataGridView1.Invalidate()
End Sub 'dataGridView1_ColumnWidthChanged
' Forces the row to repaint itself when the user changes the
' current cell. This is necessary to refresh the focus rectangle.
Sub dataGridView1_CurrentCellChanged(ByVal sender As Object, _
ByVal e As EventArgs) Handles dataGridView1.CurrentCellChanged
If oldRowIndex <> -1 Then
Me.dataGridView1.InvalidateRow(oldRowIndex)
End If
oldRowIndex = Me.dataGridView1.CurrentCellAddress.Y
End Sub 'dataGridView1_CurrentCellChanged
' Paints the custom selection background for selected rows.
Sub dataGridView1_RowPrePaint(ByVal sender As Object, _
ByVal e As DataGridViewRowPrePaintEventArgs) _
Handles dataGridView1.RowPrePaint
' Do not automatically paint the focus rectangle.
e.PaintParts = e.PaintParts And Not DataGridViewPaintParts.Focus
' Determine whether the cell should be painted with the
' custom selection background.
If (e.State And DataGridViewElementStates.Selected) = _
DataGridViewElementStates.Selected Then
' Calculate the bounds of the row.
Dim rowBounds As New Rectangle( _
Me.dataGridView1.RowHeadersWidth, e.RowBounds.Top, _
Me.dataGridView1.Columns.GetColumnsWidth( _
DataGridViewElementStates.Visible) - _
Me.dataGridView1.HorizontalScrollingOffset + 1, _
e.RowBounds.Height)
' Paint the custom selection background.
Dim backbrush As New _
System.Drawing.Drawing2D.LinearGradientBrush(rowBounds, _
Me.dataGridView1.DefaultCellStyle.SelectionBackColor, _
e.InheritedRowStyle.ForeColor, _
System.Drawing.Drawing2D.LinearGradientMode.Horizontal)
Try
e.Graphics.FillRectangle(backbrush, rowBounds)
Finally
backbrush.Dispose()
End Try
End If
End Sub 'dataGridView1_RowPrePaint
' Paints the content that spans multiple columns and the focus rectangle.
Sub dataGridView1_RowPostPaint(ByVal sender As Object, _
ByVal e As DataGridViewRowPostPaintEventArgs) _
Handles dataGridView1.RowPostPaint
' Calculate the bounds of the row.
Dim rowBounds As New Rectangle(Me.dataGridView1.RowHeadersWidth, _
e.RowBounds.Top, Me.dataGridView1.Columns.GetColumnsWidth( _
DataGridViewElementStates.Visible) - _
Me.dataGridView1.HorizontalScrollingOffset + 1, e.RowBounds.Height)
Dim forebrush As SolidBrush = Nothing
Try
' Determine the foreground color.
If (e.State And DataGridViewElementStates.Selected) = _
DataGridViewElementStates.Selected Then
forebrush = New SolidBrush(e.InheritedRowStyle.SelectionForeColor)
Else
forebrush = New SolidBrush(e.InheritedRowStyle.ForeColor)
End If
' Get the content that spans multiple columns.
Dim recipe As Object = _
Me.dataGridView1.Rows.SharedRow(e.RowIndex).Cells(2).Value
If (recipe IsNot Nothing) Then
Dim text As String = recipe.ToString()
' Calculate the bounds for the content that spans multiple
' columns, adjusting for the horizontal scrolling position
' and the current row height, and displaying only whole
' lines of text.
Dim textArea As Rectangle = rowBounds
textArea.X -= Me.dataGridView1.HorizontalScrollingOffset
textArea.Width += Me.dataGridView1.HorizontalScrollingOffset
textArea.Y += rowBounds.Height - e.InheritedRowStyle.Padding.Bottom
textArea.Height -= rowBounds.Height - e.InheritedRowStyle.Padding.Bottom
textArea.Height = (textArea.Height \ e.InheritedRowStyle.Font.Height) * _
e.InheritedRowStyle.Font.Height
' Calculate the portion of the text area that needs painting.
Dim clip As RectangleF = textArea
clip.Width -= Me.dataGridView1.RowHeadersWidth + 1 - clip.X
clip.X = Me.dataGridView1.RowHeadersWidth + 1
Dim oldClip As RectangleF = e.Graphics.ClipBounds
e.Graphics.SetClip(clip)
' Draw the content that spans multiple columns.
e.Graphics.DrawString(text, e.InheritedRowStyle.Font, forebrush, _
textArea)
e.Graphics.SetClip(oldClip)
End If
Finally
forebrush.Dispose()
End Try
If Me.dataGridView1.CurrentCellAddress.Y = e.RowIndex Then
' Paint the focus rectangle.
e.DrawFocus(rowBounds, True)
End If
End Sub 'dataGridView1_RowPostPaint
' Adjusts the padding when the user changes the row height so that
' the normal cell content is fully displayed and any extra
' height is used for the content that spans multiple columns.
Sub dataGridView1_RowHeightChanged(ByVal sender As Object, _
ByVal e As DataGridViewRowEventArgs) _
Handles dataGridView1.RowHeightChanged
' Calculate the new height of the normal cell content.
Dim preferredNormalContentHeight As Int32 = _
e.Row.GetPreferredHeight(e.Row.Index, _
DataGridViewAutoSizeRowMode.AllCellsExceptHeader, True) - _
e.Row.DefaultCellStyle.Padding.Bottom()
' Specify a new padding.
Dim newPadding As Padding = e.Row.DefaultCellStyle.Padding
newPadding.Bottom = e.Row.Height - preferredNormalContentHeight
e.Row.DefaultCellStyle.Padding = newPadding
End Sub
End Class 'DataGridViewRowPainting
using System;
using System.Drawing;
using System.Windows.Forms;
class DataGridViewRowPainting : Form
{
private DataGridView dataGridView1 = new DataGridView();
private Int32 oldRowIndex = 0;
private const Int32 CUSTOM_CONTENT_HEIGHT = 30;
[STAThreadAttribute()]
public static void Main()
{
Application.Run(new DataGridViewRowPainting());
}
public DataGridViewRowPainting()
{
this.dataGridView1.Dock = DockStyle.Fill;
this.Controls.Add(this.dataGridView1);
this.Load += new EventHandler(DataGridViewRowPainting_Load);
this.Text = "DataGridView row painting demo";
}
void DataGridViewRowPainting_Load(object sender, EventArgs e)
{
// Set a cell padding to provide space for the top of the focus
// rectangle and for the content that spans multiple columns.
Padding newPadding = new Padding(0, 1, 0, CUSTOM_CONTENT_HEIGHT);
this.dataGridView1.RowTemplate.DefaultCellStyle.Padding = newPadding;
// Set the selection background color to transparent so
// the cell won't paint over the custom selection background.
this.dataGridView1.RowTemplate.DefaultCellStyle.SelectionBackColor =
Color.Transparent;
// Set the row height to accommodate the content that
// spans multiple columns.
this.dataGridView1.RowTemplate.Height += CUSTOM_CONTENT_HEIGHT;
// Initialize other DataGridView properties.
this.dataGridView1.AllowUserToAddRows = false;
this.dataGridView1.EditMode = DataGridViewEditMode.EditOnKeystrokeOrF2;
this.dataGridView1.CellBorderStyle = DataGridViewCellBorderStyle.None;
this.dataGridView1.SelectionMode =
DataGridViewSelectionMode.FullRowSelect;
// Set the column header names.
this.dataGridView1.ColumnCount = 4;
this.dataGridView1.Columns[0].Name = "Recipe";
this.dataGridView1.Columns[0].SortMode =
DataGridViewColumnSortMode.NotSortable;
this.dataGridView1.Columns[1].Name = "Category";
this.dataGridView1.Columns[2].Name = "Main Ingredients";
this.dataGridView1.Columns[3].Name = "Rating";
// Hide the column that contains the content that spans
// multiple columns.
this.dataGridView1.Columns[2].Visible = false;
// Populate the rows of the DataGridView.
string[] row1 = new string[]{"Meatloaf", "Main Dish",
"1 lb. lean ground beef, 1/2 cup bread crumbs, " +
"1/4 cup ketchup, 1/3 tsp onion powder, 1 clove of garlic, " +
"1/2 pack onion soup mix, dash of your favorite BBQ Sauce",
"****"};
string[] row2 = new string[]{"Key Lime Pie", "Dessert",
"lime juice, whipped cream, eggs, evaporated milk", "****"};
string[] row3 = new string[]{"Orange-Salsa Pork Chops",
"Main Dish", "pork chops, salsa, orange juice, pineapple", "****"};
string[] row4 = new string[]{"Black Bean and Rice Salad",
"Salad", "black beans, brown rice", "****"};
string[] row5 = new string[]{"Chocolate Cheesecake",
"Dessert", "cream cheese, unsweetened chocolate", "***"};
string[] row6 = new string[]{"Black Bean Dip", "Appetizer",
"black beans, sour cream, salsa, chips", "***"};
object[] rows = new object[] { row1, row2, row3, row4, row5, row6 };
foreach (string[] rowArray in rows)
{
this.dataGridView1.Rows.Add(rowArray);
}
// Adjust the row heights to accommodate the normal cell content.
this.dataGridView1.AutoResizeRows(
DataGridViewAutoSizeRowsMode.AllCellsExceptHeaders);
// Attach handlers to DataGridView events.
this.dataGridView1.ColumnWidthChanged += new
DataGridViewColumnEventHandler(dataGridView1_ColumnWidthChanged);
this.dataGridView1.RowPrePaint += new
DataGridViewRowPrePaintEventHandler(dataGridView1_RowPrePaint);
this.dataGridView1.RowPostPaint += new
DataGridViewRowPostPaintEventHandler(dataGridView1_RowPostPaint);
this.dataGridView1.CurrentCellChanged += new
EventHandler(dataGridView1_CurrentCellChanged);
this.dataGridView1.RowHeightChanged += new
DataGridViewRowEventHandler(dataGridView1_RowHeightChanged);
}
// Forces the control to repaint itself when the user
// manually changes the width of a column.
void dataGridView1_ColumnWidthChanged(object sender,
DataGridViewColumnEventArgs e)
{
this.dataGridView1.Invalidate();
}
// Forces the row to repaint itself when the user changes the
// current cell. This is necessary to refresh the focus rectangle.
void dataGridView1_CurrentCellChanged(object sender, EventArgs e)
{
if (oldRowIndex != -1)
{
this.dataGridView1.InvalidateRow(oldRowIndex);
}
oldRowIndex = this.dataGridView1.CurrentCellAddress.Y;
}
// Paints the custom selection background for selected rows.
void dataGridView1_RowPrePaint(object sender,
DataGridViewRowPrePaintEventArgs e)
{
// Do not automatically paint the focus rectangle.
e.PaintParts &= ~DataGridViewPaintParts.Focus;
// Determine whether the cell should be painted
// with the custom selection background.
if ((e.State & DataGridViewElementStates.Selected) ==
DataGridViewElementStates.Selected)
{
// Calculate the bounds of the row.
Rectangle rowBounds = new Rectangle(
this.dataGridView1.RowHeadersWidth, e.RowBounds.Top,
this.dataGridView1.Columns.GetColumnsWidth(
DataGridViewElementStates.Visible) -
this.dataGridView1.HorizontalScrollingOffset + 1,
e.RowBounds.Height);
// Paint the custom selection background.
using (Brush backbrush =
new System.Drawing.Drawing2D.LinearGradientBrush(rowBounds,
this.dataGridView1.DefaultCellStyle.SelectionBackColor,
e.InheritedRowStyle.ForeColor,
System.Drawing.Drawing2D.LinearGradientMode.Horizontal))
{
e.Graphics.FillRectangle(backbrush, rowBounds);
}
}
}
// Paints the content that spans multiple columns and the focus rectangle.
void dataGridView1_RowPostPaint(object sender,
DataGridViewRowPostPaintEventArgs e)
{
// Calculate the bounds of the row.
Rectangle rowBounds = new Rectangle(
this.dataGridView1.RowHeadersWidth, e.RowBounds.Top,
this.dataGridView1.Columns.GetColumnsWidth(
DataGridViewElementStates.Visible) -
this.dataGridView1.HorizontalScrollingOffset + 1,
e.RowBounds.Height);
SolidBrush forebrush = null;
try
{
// Determine the foreground color.
if ((e.State & DataGridViewElementStates.Selected) ==
DataGridViewElementStates.Selected)
{
forebrush = new SolidBrush(e.InheritedRowStyle.SelectionForeColor);
}
else
{
forebrush = new SolidBrush(e.InheritedRowStyle.ForeColor);
}
// Get the content that spans multiple columns.
object recipe =
this.dataGridView1.Rows.SharedRow(e.RowIndex).Cells[2].Value;
if (recipe != null)
{
String text = recipe.ToString();
// Calculate the bounds for the content that spans multiple
// columns, adjusting for the horizontal scrolling position
// and the current row height, and displaying only whole
// lines of text.
Rectangle textArea = rowBounds;
textArea.X -= this.dataGridView1.HorizontalScrollingOffset;
textArea.Width += this.dataGridView1.HorizontalScrollingOffset;
textArea.Y += rowBounds.Height - e.InheritedRowStyle.Padding.Bottom;
textArea.Height -= rowBounds.Height -
e.InheritedRowStyle.Padding.Bottom;
textArea.Height = (textArea.Height / e.InheritedRowStyle.Font.Height) *
e.InheritedRowStyle.Font.Height;
// Calculate the portion of the text area that needs painting.
RectangleF clip = textArea;
clip.Width -= this.dataGridView1.RowHeadersWidth + 1 - clip.X;
clip.X = this.dataGridView1.RowHeadersWidth + 1;
RectangleF oldClip = e.Graphics.ClipBounds;
e.Graphics.SetClip(clip);
// Draw the content that spans multiple columns.
e.Graphics.DrawString(
text, e.InheritedRowStyle.Font, forebrush, textArea);
e.Graphics.SetClip(oldClip);
}
}
finally
{
forebrush.Dispose();
}
if (this.dataGridView1.CurrentCellAddress.Y == e.RowIndex)
{
// Paint the focus rectangle.
e.DrawFocus(rowBounds, true);
}
}
// Adjusts the padding when the user changes the row height so that
// the normal cell content is fully displayed and any extra
// height is used for the content that spans multiple columns.
void dataGridView1_RowHeightChanged(object sender,
DataGridViewRowEventArgs e)
{
// Calculate the new height of the normal cell content.
Int32 preferredNormalContentHeight =
e.Row.GetPreferredHeight(e.Row.Index,
DataGridViewAutoSizeRowMode.AllCellsExceptHeader, true) -
e.Row.DefaultCellStyle.Padding.Bottom;
// Specify a new padding.
Padding newPadding = e.Row.DefaultCellStyle.Padding;
newPadding.Bottom = e.Row.Height - preferredNormalContentHeight;
e.Row.DefaultCellStyle.Padding = newPadding;
}
}
Compilazione del codice
L'esempio presenta i seguenti requisiti:
- Riferimenti agli assembly System, System.Drawing e System.Windows.Forms.
Per informazioni sulla compilazione di questo esempio dalla riga di comando per Visual Basic o Visual C#, vedere Building from the Command Line (Visual Basic) o Compilazione dalla riga di comando con csc.exe. È anche possibile compilare questo esempio in Visual Studio incollando il codice in un nuovo progetto. Per ulteriori informazioni, vedere Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio.
Vedere anche
Riferimenti
Concetti
Architettura del controllo DataGridView (Windows Form)