c# - Proper way to sync a wpf progress bar with function from a library -

so have function (from library) works big word files. can't make changes on function. while processing, want show progress bar, because either way app looks frozen , users not aware it's working. i'm using worker this:

private void btnclick(object sender, routedeventargs e) {      backgroundworker worker = new backgroundworker();     worker.runworkercompleted += worker_runworkercompleted;     worker.workerreportsprogress = true;     worker.dowork += worker_doconvertone;     worker.progresschanged += worker_progresschanged;     worker.runworkerasync(); }  private void worker_doconvertone(object sender, doworkeventargs e) {     var worker = sender backgroundworker;         //the progress bar filled on 20%         worker.reportprogress(0);         worker.reportprogress(10);         worker.reportprogress(20);          //processing         mylonglastingfunction(bigwordfile);          //the progress bas full         worker.reportprogress(100, "done processing."); }  private void worker_runworkercompleted(object sender, runworkercompletedeventargs e) {     messagebox.show("converting finished!");     testprogressbar.value = 0;     progresstextblock.text = ""; }  private void worker_progresschanged(object sender, progresschangedeventargs e) {     testprogressbar.value = e.progresspercentage;     progresstextblock.text = (string)e.userstate; } 

it's doing work, it's workaround , want know if there proper way solve problem. in advance. :)

i take question altering mylonglastingfunction not possible give periodic updates on progress, , ability not exist in function.

for these scenarios when duration of task cannot determined progress bar dependency property isindeterminate="true" accepted way give information user. animates progress bar scrolling continuously.

xaml

   <progressbar margin="10" isindeterminate="true" /> 

i prefer animated moving dots seen on windows phone. example has been implemented here.

if not require next best method estimate total time, , subdividing time dispatchtimer give periodic event increment progress bar. has 2 problems of either finishing before reaching 100% (not bad thing) or reaching 100% , getting stuck there actual time longer estimate. second undesired effect make application inactive again.