Conditional Intelliprompts in SyntaxEditor

Environment

Product Version	Product	Author
2020.2.616	RadSyntaxEditor for WinForms	Desislava Yordanova

Description

RadSyntaxEditor allows you to specify the CompletionInfoCollection and add CompletionInfos to it.

By default, the CodeCompletionCommand is being executed by RadSyntaxEditor when pressing Space + Ctrl keys. It shows the CompletionListWindow. An alternative solution is to display the dialog programmatically by simply calling the SyntaxEditorElement.IntelliPrompts.CompletionListWindow.Show method.

However, the completion items are fixed and the window always shows the same items. A common requirement is to show dynamic items according to the the user's inputs. This tutorial aims to demonstrate a sample approach.

Solution

RadSyntaxEditor handles the user's keyboard input by its SyntaxEditorInputBehavior. You can create a custom behavior and override its ProcessKeyDown method. Thus, you can handle specific keys and execute the desired logic.

The following code snippet demonstrates how to show different suggestions in the CompletionListWindow when Ctrl + Space keys are pressed considering the text just before the caret position:

 public RadForm1()
{
    InitializeComponent();

    this.radSyntaxEditor1.InputHandler = new CustomSyntaxEditorInputBehavior(this.radSyntaxEditor1.SyntaxEditorElement);
}

public class CustomSyntaxEditorInputBehavior : SyntaxEditorInputBehavior
{ 
    public CustomSyntaxEditorInputBehavior(RadSyntaxEditorElement editor) : base(editor)
    {
    }

    public override void ProcessKeyDown(KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Space && e.Control) // default is CodeCompletionCommand
        {
            CaretPosition start = new CaretPosition(this.SyntaxEditor.CaretPosition);
            CaretPosition end = new CaretPosition(start);
            start.MoveToPreviousWord(); 
            string textBeforeCaret = this.SyntaxEditor.GetText(start, end);
            if (textBeforeCaret == "Dock")
            {
                CompletionInfoCollection completionList = new CompletionInfoCollection()
                {
                    new CompletionInfo("Collapsed", "Indicates that the element is collapsed.", null),
                    new CompletionInfo("Hidden", "Indicates that the element is hidden.",null),
                    new CompletionInfo("Visible", "Indicates that the element is visible." ,null),
                };

                this.SyntaxEditor.IntelliPrompts.CompletionListWindow.Presenter.CompletionListItems = completionList;
            }
            else if (textBeforeCaret == "Telerik")
            {
                CompletionInfoCollection completionList = new CompletionInfoCollection()
                {
                    new CompletionInfo("RadGridView", "Grid component", null),
                    new CompletionInfo("RadSyntaxEditor", "Syntax editor",null),
                    new CompletionInfo("RadButton", "Button" ,null),
                };

                this.SyntaxEditor.IntelliPrompts.CompletionListWindow.Presenter.CompletionListItems = completionList;
            }
            base.PerformCodeCompletion(e);
        }
        else
        {
            base.ProcessKeyDown(e);
        }
    } 
}

 Public Sub New()
    InitializeComponent()
    Me.RadSyntaxEditor1.InputHandler = New CustomSyntaxEditorInputBehavior(Me.RadSyntaxEditor1.SyntaxEditorElement)
End Sub

Public Class CustomSyntaxEditorInputBehavior
    Inherits SyntaxEditorInputBehavior

    Public Sub New(ByVal editor As RadSyntaxEditorElement)
        MyBase.New(editor)
    End Sub

    Public Overrides Sub ProcessKeyDown(ByVal e As KeyEventArgs)
        If e.KeyCode = Keys.Space AndAlso e.Control Then
            Dim start As CaretPosition = New CaretPosition(Me.SyntaxEditor.CaretPosition)
            Dim [end] As CaretPosition = New CaretPosition(start)
            start.MoveToPreviousWord()
            Dim textBeforeCaret As String = Me.SyntaxEditor.GetText(start, [end])

            If textBeforeCaret = "Dock" Then
                Dim completionList As CompletionInfoCollection = New CompletionInfoCollection() From {
                    New CompletionInfo("Collapsed", "Indicates that the element is collapsed.", Nothing),
                    New CompletionInfo("Hidden", "Indicates that the element is hidden.", Nothing),
                    New CompletionInfo("Visible", "Indicates that the element is visible.", Nothing)
                }
                Me.SyntaxEditor.IntelliPrompts.CompletionListWindow.Presenter.CompletionListItems = completionList
            ElseIf textBeforeCaret = "Telerik" Then
                Dim completionList As CompletionInfoCollection = New CompletionInfoCollection() From {
                    New CompletionInfo("RadGridView", "Grid component", Nothing),
                    New CompletionInfo("RadSyntaxEditor", "Syntax editor", Nothing),
                    New CompletionInfo("RadButton", "Button", Nothing)
                }
                Me.SyntaxEditor.IntelliPrompts.CompletionListWindow.Presenter.CompletionListItems = completionList
            End If

            MyBase.PerformCodeCompletion(e)
        Else
            MyBase.ProcessKeyDown(e)
        End If
    End Sub
End Class

See Also

• IntelliPrompts