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Cancel Property

Summary
Allow the user to cancel the current operation.
Syntax
C#
C++/CLI
Java
Python
public bool Cancel { get; set; } 
public boolean getCancel() 
public void setCancel(boolean cancel) 
public: 
property bool Cancel { 
   bool get(); 
   void set (    bool ); 
} 
Cancel # get and set (DocumentProgressEventArgs) 

Property Value

true to cancel the current operation; false to continue the current operation.

Remarks

Some of the DocumentWriter operations that use the progress monitor can be lengthy. You can allow the user to cancel the operation by using the DocumentWriter.Progress event to show a progress bar and a cancel button in your application. If the user presses the cancel button, you can set the value of the Cancel property to true to abort the current operation.

Example
C#
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Document.Writer; 
 
 
public void DocumentWriterProgressExample() 
{ 
   // Get the input and output file names to use 
   var inputFileName = Path.Combine(LEAD_VARS.ImagesDir, "test_3.docx"); 
   var outputFileName = Path.Combine(LEAD_VARS.ImagesDir, "test_multipage_DocumentWriter.pdf"); 
 
   // Show the progress dialog 
   using (var dlg = new MyProgressDialog(inputFileName, outputFileName)) 
   { 
      if (dlg.ShowDialog() == DialogResult.OK) 
         Debug.WriteLine("Done!"); 
      else 
         Debug.WriteLine("User has canceled the operation or an error occurred."); 
   } 
} 
 
// Dialog box to show the  
private class MyProgressDialog : Form 
{ 
   // Files 
   private string _inputFileName; 
   private string _outputFileName; 
 
   // The controls on the dialog 
   private Label _descriptionLabel; 
   private ProgressBar _progressBar; 
   private Button _cancelButton; 
 
   // Has the operation been canceled? 
   private bool _isCancelPending; 
   // Is the dialog working? 
   private bool _isWorking; 
 
   public MyProgressDialog(string inputFileName, string outputFileName) 
   { 
      InitializeComponent(); 
 
      _inputFileName = inputFileName; 
      _outputFileName = outputFileName; 
      _isCancelPending = false; 
      _isWorking = true; 
   } 
 
   protected override void OnLoad(EventArgs e) 
   { 
      // To keep the UI functioning, do the conversion in a separate thread 
      BeginInvoke(new MethodInvoker(DoWork)); 
 
      base.OnLoad(e); 
   } 
 
   private void DoWork() 
   { 
      DocumentWriter docWriter; 
      string operation = string.Empty; 
 
      EventHandler<DocumentProgressEventArgs> progressHandler = (object sender, DocumentProgressEventArgs e) => 
      { 
         // Update the description label progress bar 
         _descriptionLabel.Text = operation; 
         _progressBar.Value = e.Percentage; 
 
         // Check if the user clicked the Cancel button, if so, abort the operation 
         if (_isCancelPending) 
            e.Cancel = true; 
 
         Application.DoEvents(); 
      }; 
 
      // Get the number of pages 
      var codecs = new RasterCodecs(); 
      codecs.Options.RasterizeDocument.Load.Resolution = 300; 
      var pageCount = codecs.GetTotalPages(_inputFileName); 
 
      // Create the document writer 
      docWriter = new DocumentWriter(); 
 
      // Create the document 
      operation = "Creating the document..."; 
 
      // Subscribe to the progress event 
      docWriter.Progress += new EventHandler<DocumentProgressEventArgs>(progressHandler); 
      docWriter.BeginDocument(_outputFileName, DocumentFormat.Pdf); 
 
      // Add the pages 
      for (var pageNumber = 1; pageNumber <= pageCount && !_isCancelPending; pageNumber++) 
      { 
         // Load the page as SVG 
         var page = new DocumentWriterSvgPage(); 
         page.SvgDocument = codecs.LoadSvg(_inputFileName, pageNumber, null); 
 
         // Add the page, notice we will not be using image/text feature (the default) 
         operation = string.Format("Adding page {0} of {1}...", pageNumber, pageCount); 
         docWriter.AddPage(page); 
 
         // Delete the SVG 
         page.SvgDocument.Dispose(); 
      } 
 
      // Finally finish writing the PDF file on disk 
      operation = "Finishing the document..."; 
      docWriter.EndDocument(); 
 
      // Remove the progress handler 
      docWriter.Progress -= new EventHandler<DocumentProgressEventArgs>(progressHandler); 
 
      codecs.Dispose(); 
 
      // Set the dialog results based on whether the user has canceled the operation 
      if (_isCancelPending) 
         DialogResult = DialogResult.Cancel; 
      else 
         DialogResult = DialogResult.OK; 
 
      // The dialog can be closed now 
      _isWorking = false; 
 
      // We are done 
      Close(); 
   } 
 
   private void _cancelButton_Click(object sender, EventArgs e) 
   { 
      // Set the isCanceled variable to true, this will break from the 
      // progress callback and closes the dialog 
      _isCancelPending = true; 
   } 
 
   protected override void OnFormClosing(FormClosingEventArgs e) 
   { 
      // Dont allow the form to close while the callback is still working 
      // Instead, cancel the operation 
      if (_isWorking) 
         e.Cancel = true; 
 
      base.OnFormClosing(e); 
   } 
 
   private void InitializeComponent() 
   { 
      // Create the controls in this form, a text label, a progress bar and a cancel button 
      SuspendLayout(); 
 
      // Text label 
      _descriptionLabel = new Label(); 
      _descriptionLabel.Location = new Point(26, 21); 
      _descriptionLabel.Name = "_descriptionLabel"; 
      _descriptionLabel.Size = new Size(367, 23); 
      _descriptionLabel.TabIndex = 0; 
      _descriptionLabel.TextAlign = ContentAlignment.MiddleLeft; 
      _descriptionLabel.Text = "Creating final document..."; 
 
      // Progress bar 
      _progressBar = new ProgressBar(); 
      _progressBar.Location = new Point(27, 47); 
      _progressBar.Name = "_progressBar"; 
      _progressBar.Size = new Size(364, 23); 
      _progressBar.TabIndex = 1; 
 
      // Cancel button 
      _cancelButton = new Button(); 
      _cancelButton.DialogResult = DialogResult.Cancel; 
      _cancelButton.Location = new Point(172, 76); 
      _cancelButton.Name = "_cancelButton"; 
      _cancelButton.Size = new Size(75, 23); 
      _cancelButton.TabIndex = 2; 
      _cancelButton.Text = "Cancel"; 
      _cancelButton.UseVisualStyleBackColor = true; 
      _cancelButton.Click += new System.EventHandler(_cancelButton_Click); 
 
      // Add the controls 
      Controls.Add(_descriptionLabel); 
      Controls.Add(_progressBar); 
      Controls.Add(_cancelButton); 
 
      // Initialize the dialog 
      AutoScaleDimensions = new SizeF(6F, 13F); 
      AutoScaleMode = AutoScaleMode.Font; 
      CancelButton = _cancelButton; 
      ClientSize = new Size(420, 118); 
      FormBorderStyle = FormBorderStyle.FixedDialog; 
      MaximizeBox = false; 
      MinimizeBox = false; 
      Name = "MyProgressDialog"; 
      ShowInTaskbar = false; 
      StartPosition = FormStartPosition.CenterParent; 
      Text = "DocumentWriter Progress Example"; 
 
      ResumeLayout(); 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
} 
Requirements

Target Platforms

Help Version 22.0.2023.3.31
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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.

Leadtools.Document.Writer Assembly

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.