I am using ImageToVTKImageFilter to convert ITKImage to VTKImage with the following code:
typedef itk::ImageToVTKImageFilter ConverterType;
typename ConverterType::Pointer converter = ConverterType::New();
converter->SetInput(image);
converter->Update();
converter->UpdateOutputInformation();
The Update() function is a blocking call that takes 2-3 seconds to complete. During this time, my Qt UI freezes because Update() blocks the main thread responsible for UI rendering.
To address this, I tried moving the Update() call to a separate thread using QThread and also attempted to trigger Update() with a timer. Unfortunately, both methods not worked out.
Has anyone encountered a similar issue or have recommendations for avoiding UI thread blocking? I want the image conversion to occur asynchronously without freezing the UI. Any assistance would be greatly appreciated!
Hello,
I imagine you want to animate some kind of progress bar or some other visual feedback to the user the process is going on. In my program I do this during a large data file load, in the client code:
// data load takes place in another thread, so we can show and update a progress bar
//////////////////////////////////
QProgressDialog progressDialog;
progressDialog.show();
progressDialog.setLabelText("Loading and parsing " + _path + "...");
progressDialog.setMinimum(0);
progressDialog.setValue(0);
progressDialog.setMaximum(getFileSize() / 100); // see DataLoader::doLoad(). Dividing
// by 100 allows a max value of ~400GB
// when converting from long to int
QThread *thread = new QThread(); // does it need to set parent (a QObject)?
DataLoader *dl = new DataLoader(file, _data, data_line_count, _dataPageFirstLine,
_dataPageLastLine); // Do not set a parent. The object
// cannot be moved if it has a
// parent.
dl->moveToThread(thread);
dl->connect(thread, SIGNAL(finished()), dl, SLOT(deleteLater()));
dl->connect(thread, SIGNAL(started()), dl, SLOT(doLoad()));
dl->connect(dl, SIGNAL(progress(int)), &progressDialog, SLOT(setValue(int)));
thread->start();
/////////////////////////////////
// wait for the data load to finish
// not very beautiful, but simple and effective
while (!dl->isFinished()) {
thread->wait(200); // reduces cpu usage, refreshes at each 500 milliseconds
QCoreApplication::processEvents(); // let Qt repaint widgets
}
The DataLoader class is here: gammaray/domain/auxiliary/dataloader.h at master · PauloCarvalhoRJ/gammaray · GitHub and gammaray/domain/auxiliary/dataloader.cpp at master · PauloCarvalhoRJ/gammaray · GitHub . I think you can taylor the code to suit your need.
I hope this helps,
PC