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How to know which link is "clicked" in the RadLabel_Click Event if it has Multiple HTML A REF tags in the RadLabel Text

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Label

This is a migrated thread and some comments may be shown as answers.

Donald asked on 07 Jun 2011, 07:07 PM

2011-06-08-105448.png

Hi,
I did look at other posts involving creating HTML links in the RadLabel control but they all are navigating to some web page.

I don't know if this is possible but i wanted to "detect" which link is clicked in the RadLabel_Click event and then load some Winforms based on the link.

To make this simple lets say for example, the RadLabel has some HTML text with say 3 link tags.

RadLabel1.Text = "<html><span><a href='??'>Link 1</a>, <a href='??'>Link 2</a>, <a href='??'>Link 3</a> </span></html>"

When user click on "link 1", i would show message box "Link 1" or load Form1, click on Link 2, show message box "Link 2" or load Form2 and so on. I put "??" in the href as am not sure what will go there yet.

Is this possible? I know it can be done with the LinkControl but i really like the HTML formatting available with a RadLabel.

Thanks
Don

Edit:
I do see a "Other" option in the hyperlink type option.(image attached)
Please could you tell me how to use this option? Can i use this option to load winforms?
Thanks..

8 Answers, 1 is accepted

answered on 10 Jun 2011, 11:04 AM

Hi Donald,

Thank you for the question.

Our Html-like feature does not support this functionality out of the box and you can detect the link that the user have pressed after the press action.

Please refer to the code snippet which demonstrates how to detect the pressed link:

this.radLabel1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.radLabel1_MouseDown);

private FormattedText IsMouseOverBlock(FormattedTextBlock textBlock, MouseEventArgs e)

{

Point elementAtPoint = this.radLabel1.LabelElement.PointFromControl(e.Location);

int linesCount = textBlock.Lines.Count;

for (int i = 0; i < linesCount; ++i)

{

TextLine textLine = textBlock.Lines[i];

int textLineCount = textLine.List.Count;

for (int j = 0; j < textLineCount; ++j)

{

FormattedText formattedText = textLine.List[j];

if (!string.IsNullOrEmpty(formattedText.Link) && formattedText.DrawingRectangle.Contains(elementAtPoint))

{

return formattedText;//found link under mouse

}

return null;//notfound

}

private void radLabel1_MouseDown(object sender, MouseEventArgs e)

{

FieldInfo pi = this.radLabel1.LabelElement.Children[2].Children[1].GetType().GetField("textPrimitiveImpl", BindingFlags.Instance | BindingFlags.SetProperty |BindingFlags.NonPublic);

TextPrimitiveHtmlImpl text = (TextPrimitiveHtmlImpl)pi.GetValue(this.radLabel13.LabelElement.Children[2].Children[1]);

FormattedTextBlock textBlock = text.TextBlock;

FormattedText clickedLink = IsMouseOverBlock(textBlock, e);

if (clickedLink != null)

{

MessageBox.Show(clickedLink.Text + " pressed");

}

I hope this helps.

Regards,
Peter
the Telerik team

Q1’11 SP1 of RadControls for WinForms is available for download; also available is the Q2'11 Roadmap for Telerik Windows Forms controls.

answered on 26 May 2014, 09:39 AM

Hello Thomas,

Thank you for writing.

The approach, introduced by Peter for detecting which link is clicked in a HTML-like text formatted RadLabel is still the appropriate way to achieve this requirement. HTML-like Text Formatting is just an advanced text styling mechanism, which can be applied to all Telerik controls for WinForms and their elements and it does not support the mentioned functionality out of the box. If we have more requests for this we will consider it in the future improvement of the HTML-like Text Formatting functionality.

I hope this information helps. Should you have further questions, I would be glad to help.

Regards,
Desislava
Telerik

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answered on 09 Jul 2015, 12:03 AM

I would also like there to be some built-in way to do this. I can somewhat use the code above to detect clicks but it doesn't seem ideal. For example, I can't find a clean way to stop the built-in click behavior. I want to cancel the default action (of doing a Process.Start on the link text) and instead do something else. I've found that I can clear out the LinkText after the control has drawn and then the normal Process.Start won't be called. But then when I clear out the LinkText, then the cursor doesn't turn to a hand when I hover over the link.

Is there some way to be able to cancel the default action but still have everything behave normally? Or better yet, it would be great if this became standard functionality.

answered on 13 Jul 2015, 02:34 PM

Hi Stephen,

Thank you for writing.

The Html-like Text Formatting is basically an advanced styling mechanism which would allow you to easily format your labels using Html tags. As seen from the answers of my colleagues having multiple links in one label and differentiating them in a click event is not supported out of the box.

This functionality, however, can be accomplished. Considering your question, I am not completely sure that I understand it properly. Removing the link text in <a> tag results in an empty link hence the cursor does not turn into a hand. If you would like to override the default implementation of some events you can create a custom RadLabel control and override its input methods, e.g.:

public partial class MyRadLabel : RadLabel

{

public MyRadLabel()

{

InitializeComponent();

}

protected override void OnMouseDown(MouseEventArgs e)

{

//base.OnMouseDown(e);

}

protected override void OnClick(EventArgs e)

{

//base.OnClick(e);

}

Not calling the base implementation will prevent the built-in functionality from executing.

I hope this helps. Should you have further questions please do not hesitate to write back.

Regards,
Hristo Merdjanov
Telerik

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answered on 04 Mar 2018, 12:31 PM

Hi,

I tried to use the same way when Label is placed in Grid. But it doesn/t work

Could you please, look at the code

using System;

using System.Collections.Generic;

using System.Drawing;

using System.Windows.Forms;

using Telerik.WinControls.Primitives;

using Telerik.WinControls.TextPrimitiveUtils;

using Telerik.WinControls.UI;

namespace WindowsFormsApp7

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

var grid = new RadGridView()

{

Dock = DockStyle.Fill,

AutoGenerateColumns = false,

};

grid.AutoGenerateColumns = false;

grid.TableElement.RowHeight = 60;

grid.MasterTemplate.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

// grid.MasterTemplate.AllowAddNewRow = false;

Controls.Add(grid);

var ds = new List<Document>

{

new Document()

{

Name = "<html>Link: <a href='http://google.com'>Google</a></html>"

},

new Document()

{

Name = "<html>Link: <a href='http://microsoft.com'>Microsoft</a><br/>" +

"Second Link: <a href='http://yahoo.com'>Yahoo</a></html>"

},

};

grid.DataSource = ds;

grid.Columns.Add(new GridViewTextBoxColumn("Name")

{

HeaderText = "Name",

DataType = typeof(string),

ReadOnly = true,

Width = 300

});

grid.CellFormatting += (s, e) =>

{

if (e.CellElement.RowInfo is GridViewFilteringRowInfo)

{

return;

}

if (e.CellElement.ColumnInfo.Name == "Name")

{

RadLabelElement label;

if (e.CellElement.Children.Count == 0)

{

label = new RadLabelElement();

e.CellElement.Children.Add(label);

}

else

{

label = e.CellElement.Children[0] as RadLabelElement;

}

try

{

label.Text = ((GridDataCellElement) e.CellElement).Value.ToString();

}

catch (Exception ex)

{

return;

}

label.MouseDown += LabelOnMouseDown;

//e.CellElement.MouseDown += LabelOnMouseDown;

e.CellElement.DrawText = false;

}

};

}

private void LabelOnMouseDown(object sender, MouseEventArgs e)

{

var label = ((RadLabelElement) sender);

//var label = ((GridCellElement)sender).Children[0] as RadLabelElement;

if (label == null)

return;

TextPrimitiveHtmlImpl text = label.LabelText.Impl as TextPrimitiveHtmlImpl;

FormattedTextBlock textBlock = text.TextBlock;

FormattedText clickedLink = IsMouseOverBlock(label, textBlock, e);

if (clickedLink != null)

{

MessageBox.Show(clickedLink.Text + " pressed");

}

private FormattedText IsMouseOverBlock(RadLabelElement label, FormattedTextBlock textBlock, MouseEventArgs e)

{

Point elementAtPoint = label.PointFromControl(e.Location);

int linesCount = textBlock.Lines.Count;

for (int i = 0; i <= linesCount - 1; i++)

{

TextLine textLine = textBlock.Lines[i];

int textLineCount = textLine.List.Count;

for (int j = 0; j <= textLineCount - 1; j++)

{

FormattedText formattedText = textLine.List[j];

if (formattedText.DrawingRectangle.Contains(elementAtPoint))

{

//found link under mouse

return formattedText;

}

return null;

}

public class Document

{

public string Name { get; set; }

}

answered on 05 Mar 2018, 03:18 PM

ClickedLink.gif

Hello, Dmitriy,

Thank you for writing.

When it is placed inside a grid cell, the text is being centered. It is necessary to consider the vertical offset. Here is the modified IsMouseOverBlock method:

private FormattedText IsMouseOverBlock(RadLabelElement label, FormattedTextBlock textBlock, MouseEventArgs e)

{

Point elementAtPoint = label.PointFromControl(e.Location);

int linesCount = textBlock.Lines.Count;

TextPrimitiveHtmlImpl text = label.LabelText.Impl as TextPrimitiveHtmlImpl;

TextParams textParams = new TextParams();

textParams.alignment = ContentAlignment.TopLeft;

textParams.flipText = label.FlipText;

textParams.font = label.Font;

textParams.foreColor = label.ForeColor;

textParams.paintingRectangle = new RectangleF(PointF.Empty, label.Size);

textParams.rightToLeft = label.RightToLeft;

textParams.stretchHorizontally = label.StretchHorizontally;

textParams.text = label.Text;

textParams.textOrientation = label.TextOrientation;

textParams.textWrap = label.TextWrap;

textParams.useCompatibleTextRendering = label.UseCompatibleTextRendering;

textParams.useMnemonic = label.UseMnemonic;

textParams.enabled = label.Enabled;

SizeF size = text.MeasureOverride(new SizeF(float.PositiveInfinity, float.PositiveInfinity), textParams);

elementAtPoint.Offset(0, (int)(grid.TableElement.RowHeight- size.Height) / -2);

for (int i = 0; i <= linesCount - 1; i++)

{

TextLine textLine = textBlock.Lines[i];

int textLineCount = textLine.List.Count;

for (int j = 0; j <= textLineCount - 1; j++)

{

FormattedText formattedText = textLine.List[j];

if (formattedText.DrawingRectangle.Contains(elementAtPoint))

{

//found link under mouse

return formattedText;

}

return null;

}

I hope this information helps. Should you have further questions I would be glad to help.

Regards,
Dess
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