How do I implement a progress bar in C

Question

How do I implement a progress bar and backgroundworker for database calls in C    I do have some methods that deal with large amounts of data  They are relatively long running operations  so I want to implement a progress bar to let the user know that something is actually happening   I thought of using progress bar or status strip label  but since there is a single UI thread  the thread where the database-dealing methods are executed  UI controls are not updated  making the progress bar or status strip label are useless to me   I ve already seen some examples  but they deal with for-loops  ex   for int i   0  i  lt  count  i           System Threading Thread Sleep 70              do analysis         bgWorker ReportProgress  100   i    count      private void bgWorker ProgressChanged object sender  ProgressChangedEventArgs e        progressBar Value   Math Min e ProgressPercentage  100       I m looking for better examples

User · Answer

This will Helpfull Easy to implement 100  tested   for int i 1 i lt linecount i       progressBar1 Value   i   progressBar1 Maximum   linecount     show process bar counts  LabelTotal Text   i ToString       of     linecount    show number of count in lable  int presentage    i   100    linecount   LabelPresentage Text   presentage ToString             show precentage in lable  Application DoEvents    keep form active in every loop

User · Answer

When you perform operations on Background thread and you want to update UI  you can not call or set anything from background thread  In case of WPF you need Dispatcher BeginInvoke and in case of WinForms you need Invoke method   WPF      assuming  this  is the window containing your progress bar      following code runs in background worker thread    for int i 0 i lt count i          DoSomething        this Dispatcher BeginInvoke  Action delegate             this progressBar Value    int   100 i  count               WinForms      assuming  this  is the window containing your progress bar      following code runs in background worker thread    for int i 0 i lt count i          DoSomething        this Invoke delegate             this progressBar Value    int   100 i  count               for WinForms delegate may require some casting or you may need little help there  dont remember the exact syntax now

User · Answer

Some people may not like it  but this is what I do   private void StartBackgroundWork         if  Application RenderWithVisualStyles          progressBar Style   ProgressBarStyle Marquee      else           progressBar Style   ProgressBarStyle Continuous          progressBar Maximum   100          progressBar Value   0          timer Enabled   true            backgroundWorker RunWorkerAsync       private void timer Tick object sender  EventArgs e        if  progressBar Value  lt  progressBar Maximum          progressBar Increment 5       else         progressBar Value   progressBar Minimum      The Marquee style requires VisualStyles to be enabled  but it continuously scrolls on its own without needing to be updated   I use that for database operations that don t report their progress

User · Answer

The idea behind reporting progress with the background worker is through sending a  percent completed  event  You are yourself responsible for determining somehow  how much  work has been completed  Unfortunately this is often the most difficult part   In your case  the bulk of the work is database-related  There is to my knowledge no way to get progress information from the DB directly  What you can try to do however  is split up the work dynamically  E g   if you need to read a lot of data  a naive way to implement this could be     Determine how many rows are to be retrieved  SELECT COUNT    FROM      Divide the actual reading in smaller chunks  reporting progress every time one chunk is completed   for  int i   0  i  lt  count  i          bgWorker ReportProgress  100   i    count               read data for step i

User · Answer

I have not compiled this as it is meant for a proof of concept   This is how I have implemented a Progress bar for database access in the past  This example shows access to a SQLite database using the System Data SQLite module  private void backgroundWorker1 DoWork object sender  DoWorkEventArgs e              Get the BackgroundWorker that raised this event      BackgroundWorker worker   sender as BackgroundWorker      using SQLiteConnection cnn   new SQLiteConnection  Data Source MyDatabase db                  cnn Open            int TotalQuerySize   GetQueryCount  Query   cnn      This needs to be implemented and is not shown in example         using  SQLiteCommand cmd   cnn CreateCommand                          cmd CommandText    Query is here               using SQLiteDataReader reader   cmd ExecuteReader                                  int i   0                  while reader Read                                             Access the database data using the reader     Each  Read   provides the next Row                     if worker WorkerReportsProgress  worker ReportProgress   i   100  TotalQuerySize                                                     private void backgroundWorker1 ProgressChanged object sender  ProgressChangedEventArgs e        this progressBar1 Value   e ProgressPercentage     private void backgroundWorker1 RunWorkerCompleted object sender  RunWorkerCompletedEventArgs e           Notify someone that the database access is finished   Do stuff to clean up if needed        This could be a good time to hide  clear or do somthign to the progress bar    public void AcessMySQLiteDatabase         BackgroundWorker backgroundWorker1   new BackgroundWorker        backgroundWorker1 DoWork             new DoWorkEventHandler backgroundWorker1 DoWork       backgroundWorker1 RunWorkerCompleted             new RunWorkerCompletedEventHandler      backgroundWorker1 RunWorkerCompleted       backgroundWorker1 ProgressChanged             new ProgressChangedEventHandler      backgroundWorker1 ProgressChanged

User · Answer

If you can t know the progress you should not fake it by abusing a progress bar  instead just display some sort of busy icon like en wikipedia org wiki Throbber Spinning wheel  Show it when starting the task and hide it when it s finished  That would make for a more  honest  GUI

[c#] How do I implement a progress bar in C#?

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