1. 程式人生 > >Henry手記:WinForm Datagrid結構剖析(三)類程式碼

Henry手記:WinForm Datagrid結構剖析(三)類程式碼

-------------------X類的程式碼X---------------------<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Option Strict On

Option Explicit On

Imports System.Collections

Imports System.ComponentModel

Imports System.Drawing

Imports System.Windows.Forms

Imports System.Data

Public

Class DataGridComboBox

‘與DataGridTextBox類相類似地定義一個在下拉框列類中使用的ComboBox

Inherits ComboBox

Public Sub New()

MyBase.New()

End Sub

Public isInEditOrNavigateMode As Boolean = True

End Class

Public Class DataGridComboBoxColumn

Inherits DataGridColumnStyle

' 與使用者介面相關的變數

Private xMargin As Integer = 2

Private

yMargin As Integer = 1

Private Combo As DataGridComboBox

Private _DisplayMember As String

Private _ValueMember As String

' 用於跟蹤編輯狀態變化的變數

Private OldVal As String = String.Empty

Private InEdit As Boolean = False

'建構函式 – 例項的DisplayMember, ValueMember值為由父類傳來的integer型別的值

Public Sub New(ByRef DataSource As

DataTable, _

ByVal DisplayMember As Integer, _

ByVal ValueMember As Integer)

Combo = New DataGridComboBox()

_DisplayMember = DataSource.Columns.Item(index:=DisplayMember).ToString

_ValueMember = DataSource.Columns.Item(index:=ValueMember).ToString

With Combo

.Visible = False

.DataSource = DataSource

.DisplayMember = _DisplayMember

.ValueMember = _ValueMember

End With

End Sub

'建構函式– 例項的DisplayMember, ValueMember 是String型別的值

Public Sub New(ByRef DataSource As DataTable, _

ByVal DisplayMember As String, _

ByVal ValueMember As String)

Combo = New DataGridComboBox()

With Combo

.Visible = False

.DataSource = DataSource

.DisplayMember = DisplayMember

.ValueMember = ValueMember

End With

End Sub

'------------------------------------------------------

'從 DataGridColumnStyle類繼承下來的方法

'------------------------------------------------------

' 焦點離開combobox格後的改變

Protected Overloads Overrides Sub Abort(ByVal RowNum As Integer)

Debug.WriteLine("Abort()")

RollBack()

HideComboBox()

EndEdit()

End Sub

' 接受改變

Protected Overloads Overrides Function Commit(ByVal DataSource As CurrencyManager, _

ByVal RowNum As Integer) As Boolean

HideComboBox()

If Not InEdit Then

Return True

End If

Try

Dim Value As Object = Combo.SelectedValue

If NullText.Equals(Value) Then

Value = Convert.DBNull

End If

SetColumnValueAtRow(DataSource, RowNum, Value)

Catch e As Exception

RollBack()

Return False

End Try

EndEdit()

Return True

End Function

' 移開聚焦

Protected Overloads Overrides Sub ConcedeFocus()

Combo.Visible = False

End Sub

' 編輯單元格

Protected Overloads Overrides Sub Edit(ByVal Source As CurrencyManager, _

ByVal Rownum As Integer, _

ByVal Bounds As Rectangle, _

ByVal [ReadOnly] As Boolean, _

ByVal InstantText As String, _

ByVal CellIsVisible As Boolean)

Combo.Text = String.Empty

Dim OriginalBounds As Rectangle = Bounds

OldVal = Combo.Text

If CellIsVisible Then

Bounds.Offset(xMargin, yMargin)

Bounds.Width -= xMargin * 2

Bounds.Height -= yMargin

Combo.Bounds = Bounds

Combo.Visible = True

Else

Combo.Bounds = OriginalBounds

Combo.Visible = False

End If

Combo.SelectedValue = GetText(GetColumnValueAtRow(Source, Rownum))

If Not InstantText Is Nothing Then

Combo.SelectedValue = InstantText

End If

Combo.RightToLeft = Me.DataGridTableStyle.DataGrid.RightToLeft

Combo.Focus()

If InstantText Is Nothing Then

Combo.SelectAll()

Else

Dim [End] As Integer = Combo.Text.Length

Combo.Select([End], 0)

End If

If Combo.Visible Then

DataGridTableStyle.DataGrid.Invalidate(OriginalBounds)

End If

InEdit = True

End Sub

Protected Overloads Overrides Function GetMinimumHeight() As Integer

' 設定combobox的最小高度

Return Combo.PreferredHeight + yMargin

End Function

Protected Overloads Overrides Function GetPreferredHeight(ByVal g As Graphics, _

ByVal Value As Object) As Integer

Debug.WriteLine("GetPreferredHeight()")

Dim NewLineIndex As Integer = 0

Dim NewLines As Integer = 0

Dim ValueString As String = Me.GetText(Value)

Do

While NewLineIndex <> -1

NewLineIndex = ValueString.IndexOf("r/n", NewLineIndex + 1)

NewLines += 1

End While

Loop

Return FontHeight * NewLines + yMargin

End Function

Protected Overloads Overrides Function GetPreferredSize(ByVal g As Graphics, _

ByVal Value As Object) As Size

Dim Extents As Size = Size.Ceiling(g.MeasureString(GetText(Value), _

Me.DataGridTableStyle.DataGrid.Font))

Extents.Width += xMargin * 2 + DataGridTableGridLineWidth

Extents.Height += yMargin

Return Extents

End Function

Protected Overloads Overrides Sub Paint(ByVal g As Graphics, _

ByVal Bounds As Rectangle, _

ByVal Source As CurrencyManager, _

ByVal RowNum As Integer)

Paint(g, Bounds, Source, RowNum, False)

End Sub

Protected Overloads Overrides Sub Paint(ByVal g As Graphics, _

ByVal Bounds As Rectangle, _

ByVal Source As CurrencyManager, _

ByVal RowNum As Integer, _

ByVal AlignToRight As Boolean)

Dim Text As String = GetText(GetColumnValueAtRow(Source, RowNum))

PaintText(g, Bounds, Text, AlignToRight)

End Sub

Protected Overloads Sub Paint(ByVal g As Graphics, _

ByVal Bounds As Rectangle, _

ByVal Source As CurrencyManager, _

ByVal RowNum As Integer, _

ByVal BackBrush As Brush, _

ByVal ForeBrush As Brush, _

ByVal AlignToRight As Boolean)

Dim Text As String = GetText(GetColumnValueAtRow(Source, RowNum))

PaintText(g, Bounds, Text, BackBrush, ForeBrush, AlignToRight)

End Sub

Protected Overloads Overrides Sub SetDataGridInColumn(ByVal Value As DataGrid)

MyBase.SetDataGridInColumn(Value)

If Not (Combo.Parent Is Value) Then

If Not (Combo.Parent Is Nothing) Then

Combo.Parent.Controls.Remove(Combo)

End If

End If

If Not (Value Is Nothing) Then Value.Controls.Add(Combo)

End Sub

Protected Overloads Overrides Sub UpdateUI(ByVal Source As CurrencyManager, _

Val RowNum As Integer, ByVal InstantText As String)

Combo.Text = GetText(GetColumnValueAtRow(Source, RowNum))

If Not (InstantText Is Nothing) Then

Combo.Text = InstantText

End If

End Sub

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