Esempio di editor di tipi dell'interfaccia utente di Windows Form

Nell'esempio di codice seguente sono contenuti due diversi editor di tipi dell'interfaccia utente per due proprietà del controllo FlashTrackBar descritto in Esempio di controllo Windows Form. Per scaricare il codice sorgente, vedere Guida rapida a Windows.

FlashTrackBarValueEditor viene applicato alla proprietà Value e illustra quanto elencato di seguito.

• Come FlashTrackBarValueEditor estende la classe System.Drawing.Design.UITypeEditor.
• Come eseguire l'override del metodo EditValue per impostare le proprietà dell'editor.
• Come eseguire l'override del metodo GetEditStyle per specificare lo stile dell'editor.

Nel secondo esempio, denominato FlashTrackBarDarkenByEditor, FlashTrackBarValueEditor viene esteso ed viene eseguito l'override di un metodo di supporto per impostare le proprietà. FlashTrackBarDarkenByEditor viene applicato alla proprietà DarkenBy di FlashTrackBar.

Nota   È necessario compilare questi esempi (FlashTrackBarUITypeEditor e FlashTrackBarDarkenByEditor) unitamente al controllo FlashTrackBar descritto in Esempio di controllo Windows Form. Per ulteriori informazioni su come generare gli esempi, vedere l'esempio CustomUITypeEditor in Esempi di .NET - Windows Form: Creazione di controlli.

Imports System
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Drawing.Design
Imports System.Windows.Forms
Imports System.Diagnostics
Imports System.Windows.Forms.ComponentModel
Imports System.Windows.Forms.Design

Namespace Microsoft.Samples.WindowsForms.VB.FlashTrackBar

    Public Class FlashTrackBarValueEditor
        Inherits UITypeEditor

        Private edSvc As IWindowsFormsEditorService


        Overridable Protected Sub SetEditorProps(editingInstance As FlashTrackBar, editor As FlashTrackBar)
            editor.ShowValue = true
            editor.StartColor = Color.Navy
            editor.EndColor = Color.White
            editor.ForeColor = Color.White
            editor.Min = editingInstance.Min
            editor.Max = editingInstance.Max
        End Sub

        Overrides OverLoads Public Function EditValue(context As ITypeDescriptorContext, provider As IServiceProvider, value As object) As Object

            If (Not (context Is Nothing) And Not (context.Instance Is Nothing) And Not (provider Is Nothing)) Then

                edSvc = CType(provider.GetService(GetType(IWindowsFormsEditorService)), IWindowsFormsEditorService)

                If Not (edSvc Is Nothing) Then

                    Dim trackBar As FlashTrackBar = New FlashTrackBar()
                    AddHandler trackBar.ValueChanged, AddressOf Me.ValueChanged
                    SetEditorProps(CType(context.Instance, FlashTrackBar), TrackBar)

                    Dim asInt As Boolean = True

                    If (TypeOf value Is Integer) Then
                        trackBar.Value = CInt(value)
                    ElseIf (TypeOf value Is System.Byte) Then
                        asInt = False
                        trackBar.Value = CType(value, Byte)
                    End If

                    edSvc.DropDownControl(trackBar)

                    If (asInt) Then
                        value = trackBar.Value
                    Else
                        value = CType(trackBar.Value, Byte)
                    End If

                End If

            End If

            Return value

         End Function

        Overrides OverLoads Public Function GetEditStyle(context As ITypeDescriptorContext) As UITypeEditorEditStyle
            If (Not (context Is Nothing) And Not (context.Instance Is Nothing)) Then
                Return UITypeEditorEditStyle.DropDown
            End If
            Return MyBase.GetEditStyle(context)
        End Function

        private Sub ValueChanged(sender As object, e As EventArgs)
            If Not (edSvc Is Nothing) Then
                edSvc.CloseDropDown()
            End If
        End Sub

    End Class

End Namespace
[C#]
namespace Microsoft.Samples.WindowsForms.Cs.FlashTrackBar {
    using System;
    using System.ComponentModel;
    using System.ComponentModel.Design;
    using System.Diagnostics;
    using System.Drawing;
    using System.Drawing.Drawing2D;
    using System.Drawing.Design;
    using System.Windows.Forms;
    using System.Windows.Forms.ComponentModel;
    using System.Windows.Forms.Design;

    public class FlashTrackBarValueEditor : System.Drawing.Design.UITypeEditor {

        private IWindowsFormsEditorService edSvc = null;

        protected virtual void SetEditorProps(FlashTrackBar editingInstance, FlashTrackBar editor) {
            editor.ShowValue = true;
            editor.StartColor = Color.Navy;
            editor.EndColor = Color.White;
            editor.ForeColor = Color.White;
            editor.Min = editingInstance.Min;
            editor.Max = editingInstance.Max;
        }

        public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value) {

            if (context != null
                && context.Instance != null
                && provider != null) {

                edSvc = (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));

                if (edSvc != null) {
                    FlashTrackBar trackBar = new FlashTrackBar();
                    trackBar.ValueChanged += new EventHandler(this.ValueChanged);
                    SetEditorProps((FlashTrackBar)context.Instance, trackBar);
                    bool asInt = true;
                    if (value is int) {
                        trackBar.Value = (int)value;
                    }
                    else if (value is byte) {
                        asInt = false;
                        trackBar.Value = (byte)value;
                    }
                    edSvc.DropDownControl(trackBar);
                    if (asInt) {
                        value = trackBar.Value;
                    }
                    else {
                        value = (byte)trackBar.Value;
                    }
                }
            }

            return value;
        }

        public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context) {
            if (context != null && context.Instance != null) {
                return UITypeEditorEditStyle.DropDown;
            }
            return base.GetEditStyle(context);
        }

        private void ValueChanged(object sender, EventArgs e) {
            if (edSvc != null) {
                edSvc.CloseDropDown();
            }
        }
    }
}

Nel seguente esempio di codice viene mostrato l'editor di tipi dell'interfaccia utente per la proprietà DarkenBy del controllo FlashTrackBar. Questo editor estende FlashTrackBarValueEditor implementato nell'esempio precedente.

Imports System
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Drawing.Design
Imports System.Windows.Forms
Imports System.Diagnostics

Namespace Microsoft.Samples.WindowsForms.VB.FlashTrackBar 

   Public Class FlashTrackBarDarkenByEditor 
        Inherits FlashTrackBarValueEditor 
   
       Overrides Protected Sub SetEditorProps(editingInstance As FlashTrackBar, editor As FlashTrackBar) 
           MyBase.SetEditorProps(editingInstance, editor)
           editor.Min = 0
           editor.Max = System.Byte.MaxValue
       End Sub
   
   End Class
   
End Namespace
[C#]
namespace Microsoft.Samples.WindowsForms.Cs.FlashTrackBar {
   using System;
   using System.ComponentModel;
   using System.ComponentModel.Design;
   using System.Diagnostics;
   using System.Drawing;
   using System.Drawing.Drawing2D;
   using System.Drawing.Design;
   using System.Windows.Forms;
   using System.Windows.Forms.ComponentModel;
   using System.Windows.Forms.Design;

   public class FlashTrackBarDarkenByEditor : FlashTrackBarValueEditor {
       protected override void SetEditorProps(FlashTrackBar editingInstance, FlashTrackBar editor) {
           base.SetEditorProps(editingInstance, editor);
           editor.Min = 0;
           editor.Max = byte.MaxValue;
       }
   }
}

Vedere anche

Implementazione di un editor di tipi con interfaccia utente | Supporto in fase di progettazione per Windows Form