SyntaxEditor - basic questions

Hello, I have more questions. I'm trying to make Comment lines function, similar to VisualStudio. I will paste my code below questions.

1. How to position caret to the end of selection as in regular TextBox? If I programatically change selection, caret stays in original position, expected behavior is to change its position to selection end. I tried to call CaretPosition.MoveToPosition, but it resets selection.

2. How to scroll to caret position? Something like ScrollToCaret() in regular TextBox.

3. How to replace selected text? I did it somehow, but is there any better way? I have problem with that code related to next question. In regular TextBox, I can simply change selected text by txtSource.SelectedText = selText.

4. Why SyntaxEditor handles new lines as CR and not CRLF? We are on Windows, .NET, WinForms, I expected standard Windows new lines. I changed my CommentLines method to split lines by CR character only, but when I prepare new text by StringBuilder.AppendLine, it adds CRLF  to string of course, and when I try to set new selection by new Span created by old selection start and my string length, it selects more characters (if I select 3 lines, it appends 3 more LFs and then string.Length is longer than real span in SyntaxEditor).

So, how to handle selection replacement correctly? This is my code:

			var editor = radSyntaxEditor1.SyntaxEditorElement;

			// if empty selection, set selection to caret position
			if (editor.Selection.IsEmpty)
				editor.Selection.Select(editor.CaretPosition, editor.CaretPosition);

			// extend selection start
			editor.Selection.StartPosition.MoveToLineStart();

			// extend selection end - extend last line if empty or not on first char
			if (editor.Selection.IsEmpty || editor.Selection.EndPosition.ColumnNumber != 0)
				editor.Selection.EndPosition.MoveToLineEnd();

			// extend to start of next line if not on last line
			if (editor.Selection.EndPosition.LineNumber + 1 < editor.Document.CurrentSnapshot.LineCount)
			{
				editor.Selection.EndPosition.MoveLineDown();
				editor.Selection.EndPosition.MoveToLineStart();
			}

			// set caret to selection end
			//editor.CaretPosition.MoveToPosition(editor.Selection.EndPosition);

			// comment lines
			string selText = editor.Selection.GetSelectedText();
			string commentedText = CommentLines(selText);

			// if modified, replace selection
			bool modified = selText != commentedText;
			if (modified)
			{
				var span = editor.Selection.SelectedSpans.First();
				editor.Document.Replace(span, commentedText);
				editor.Selection.Select(new Span(span.Start, commentedText.Length));
			}

			radSyntaxEditor1.Refresh();

        private void radButton1_Click(object sender, EventArgs e)
        {
            var editor = radSyntaxEditor1.SyntaxEditorElement;

			// if empty selection, set selection to caret position
			if (editor.Selection.IsEmpty)
				editor.Selection.Select(editor.CaretPosition, editor.CaretPosition);

			// extend selection start
			editor.Selection.StartPosition.MoveToLineStart();

			// extend selection end - extend last line if empty or not on first char
			if (editor.Selection.IsEmpty || editor.Selection.EndPosition.ColumnNumber != 0)
				editor.Selection.EndPosition.MoveToLineEnd();

			// extend to start of next line if not on last line
			if (editor.Selection.EndPosition.LineNumber + 1 < editor.Document.CurrentSnapshot.LineCount)
			{
				editor.Selection.EndPosition.MoveLineDown();
				editor.Selection.EndPosition.MoveToLineStart();
			}
            CaretPosition start =new CaretPosition( this.radSyntaxEditor1.SyntaxEditorElement.Selection.StartPosition);
            CaretPosition end =new CaretPosition( this.radSyntaxEditor1.SyntaxEditorElement.Selection.EndPosition);
            this.radSyntaxEditor1.SyntaxEditorElement.CaretPosition.MoveToPosition(this.radSyntaxEditor1.SyntaxEditorElement.Selection.EndPosition);
            this.radSyntaxEditor1.SyntaxEditorElement.Selection.Select(start,end);

            this.radSyntaxEditor1.Focus();          
           
        }

2. When the caret position is moved, RadSyntaxEditor automatically scrolls to the caret position. Hence, if you use the above approach from 1. the view will be scrolled to the desired location.

3. Using the selection, you can replace it with any text you need:

            string selText = editor.Selection.GetSelectedText();
            string commentedText = selText.ToUpper(); 

            var span = editor.Selection.SelectedSpans.First();
            editor.Document.Replace(span, commentedText);
            editor.Selection.Select(new Span(span.Start, commentedText.Length));

4. I am not sure what is the exact implementation of the CommentLines method that you have. Could you please elaborate? I believe that the approach for replacing the selection in 3. would fit your requirements. Please give it a try and see whether you have any further questions regarding 4. In case you are still experiencing any further difficulties, it would be greatly appreciated if you can provide more details about the exact goal that you are trying to achieve. Thus, we would get better understanding of the precise case and provide further assistance.

I hope this information helps.

Regards,
Dess | Tech Support Engineer, Principal
Progress Telerik

Hello, I have found next few issues.

1. When zooming, something strange happens with row numbers and its margins, see animation:

2. When user make doubleclick, expected behavior is to select whole word behing cursor as in regular TextBox.  Is this missing in SyntaxEditor?

3. Scrolling by mouse wheel, it scrolls too many lines per mouse wheel step. I have found solution here in forum, but it was on other hand too few, so I multiplied that step by 3. But the best would be if you can modify SyntaxEditor to either make it settable or change it to standard way (3 lines per mouse wheel step). Also that small step doesn't seem to be exactly one line, is it related to changed font size?

4. Replace all function replaces it in whole file, not just in selection.

Hello Marian,

Let me go straight to your questions.

1. I have tested this behavior but wasn't able to reproduce it on my side. I have used the First Look example in our demos. May I ask you to share if you have specified different font for the RadSyntaxEditor? If yes, which one? If not, could it be possible to share a sample project which demonstrates this so that I can debug this on my side?

2. By default when a user double-clicked a word, it will be selected and other equal words will be marked with a border. This is also not reproducible on my end. You can include this in the sample project.

3. You are in the right direction with the mentioned link. The control does not provide out of the box way to manipulate the scroll step. You can use the approach suggested in the forum. The font size will reflect the custom value used for the step. You will need to create additional calculations to scroll 3 rows regardless of the zoom/font size.

4. This is not supported by RadSyntaxEditor, so I have logged a Feature Request in our Feedback Portal to implement such improvement. I have updated your Telerik Points for bringing this to our attention.

Regards,
Dinko
Progress Telerik

Hello,  I have attached my program.

1. I  have custom font, maybe it will be related to this.

2. I couldn't reproduce it too, so sorry, maybe it were not correct doubleclicks, or, I don't know. I tried it in test program and editor, and it works normally, so I don't know what was the problem.

3. Ok. So, that small scrollbar step is one row of standard font, and if I have custom font size, should I calculate also ratio between my font and standard? Btw. what units does SyntaxEditorElement.EditorFontSize use? I expected standard font size in points as in standard WinForms controls.

4. Thanks.

I will repeat question from comments - regular TextBox has CanUndo property, which indicates Undo command is possible and I have used that property for enabling Undo button on toolbar. Is it also somewhere here?

As I wrote in last comment, I successfully migrated my editor to SyntaxEditor, and now it looks much better with coloring, folding, completions etc.

Hi Marian,

Thank you for the provided project. I have tested it on my side but could not observe this behavior. I haven't made any changes to the project except for changing the target framework to 4.8.  Here is the result on my side. Can you share which version of our controls are you using?

The EditorFontSize is set to a custom element RadTextBlock create for the purpose of the control. In your case, the logic for the custom scroll needs to consider the zoom and the fontsize. When the control is zoomed the elements inside are scaled. You can control this by using the ScaleFactor property. Keep in mind that zooming will not change the fontsize.

As for your last question. The Document.History objects expose such property which I think will work for you. Check the following code snippet which demonstrates how to access it.

radSyntaxEditor1.SyntaxEditorElement.Document.History.CanUndo

Regards,
Dinko
Progress Telerik

Hello Dinko,

I use 2022.6.622.40 version. I tried it also in .NET 4.8, behavior is the same. I am sending that project once again, but also with binaries. I compressed it with rar with solid archive option and deleted some unnecessary files from lib directory.

Custom scrolling, I finally solved it. Zoom factor has no effect to scrolling, but line spacing is important. I don't know if it's adjustable, so maybe this code with constants (13 for default font size and 3 for line spacing) isn't generally correct, but it works for my project. Following code is working:

		protected override void OnMouseWheel(MouseEventArgs e)
		{
			System.Reflection.PropertyInfo pi = typeof(SyntaxEditorPresenter).GetProperty("VerticalScrollOffset", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public);

			int defaultFontSize = 13;
			int delta = (int)(3 * (EditorFontSize + 3.0) / (defaultFontSize + 3.0) * this.SyntaxEditorElement.VerticalScrollBar.SmallChange);

			if (e.Delta < 0)
			{
				this.SyntaxEditorElement.VerticalScrollBar.Value += delta;
				pi.SetValue(this.SyntaxEditorElement.EditorPresenter, this.SyntaxEditorElement.VerticalScrollBar.Value);
			}
			else
			{
				this.SyntaxEditorElement.VerticalScrollBar.Value -= delta;
				pi.SetValue(this.SyntaxEditorElement.EditorPresenter, this.SyntaxEditorElement.VerticalScrollBar.Value);
			}
			this.SyntaxEditorElement.EditorPresenter.InvalidateLayout(false);

			//  base.OnMouseWheel(e);
		}

Hello Marian,

I am happy to hear that you were able to create the algorithm for the custom scrolling and thank you for sharing the solution. This way the community can take advantage of it. 

As for the zoom behavior. We don't make any progress here. I still wasn't able to reproduce it. If the same project demonstrates is working at your end and not on mine, this leads me to think that we need to focus on the DPI. Can you share the scaling and the resolution of the monitors which you are using? Just for the test can you run the SyntaxEditor First Look demo inside our Telerik UI for WinForms Demo application to check if this behavior is related to the project or if it is global for your machine.

Regards,
Dinko
Progress Telerik

Hello,

yes. But the best would be, if you can change scroll behavior to this standard behavior in some newer version. This solution works, but it's very dependent on current implementation, if you will change line spacing, make it customizable etc, this will not work correctly anymore.

Zoom... Behavior is the same also in your demo.

I have 1920x1200 resolution with standard DPI, standard fonts, I haven't change anything to something special. I think it was the same also on the production machine, but I am not sure. This is not so problem for me, I think that zoom will be not used often, but if you want to test something, I can do it for solving this problem generally.

Hi Marian,

Thank you for the details.

We are making some progress here. So far we can confirm that it is not related to the custom project. This visual behavior could come from the set-up of the OS. Can you share which windows version is installed on your machine? Also, you can share the culture configuration set on your machine.

Regards,
Dinko
Progress Telerik