4.5.2.1.28. ProgressBar
The ProgressBar component is designed to display the progress of a long process.
XML name of the component: progressBar
The component is implemented for Web Client and Desktop Client.
Below is an example of the component usage together with the background tasks mechanism:
<progressBar id="progressBar" width="100%"/>@Inject
protected ProgressBar progressBar;
@Inject
protected BackgroundWorker backgroundWorker;
private static final int ITERATIONS = 5;
@Override
public void init(Map<String, Object> params) {
BackgroundTask<Integer, Void> task = new BackgroundTask<Integer, Void>(300, this) {
@Override
public Void run(TaskLifeCycle<Integer> taskLifeCycle) throws Exception {
for (int i = 1; i <= ITERATIONS; i++) {
TimeUnit.SECONDS.sleep(2); // time consuming task
taskLifeCycle.publish(i);
}
return null;
}
@Override
public void progress(List<Integer> changes) {
float lastValue = changes.get(changes.size() - 1);
progressBar.setValue(lastValue / ITERATIONS);
}
};
BackgroundTaskHandler taskHandler = backgroundWorker.handle(task);
taskHandler.execute();
}Here in the BackgroundTask.progress() method, which is executed in UI thread, the ProgressBar component is set to the current value. The component value should be a float number from 0.0 to 1.0.
The changes of the ProgressBar value can be tracked using the ValueChangeListener.
If a running process is unable to send information about the progress, an indeterminate state of the indicator can be displayed. Set the indeterminate to true to show an indeterminate state. Default is false. For example:
<progressBar id="progressBar" width="100%" indeterminate="true"/>By default indeterminate progress bar is displayed as horizontal bar. To make it a spinning wheel instead, set the attribute stylename="indeterminate-circle".
To make the progress bar indicator appear as a dot which progresses over the progress bar track (instead of a growing bar), use the point predefined style:
progressBar.setStyleName(HaloTheme.PROGRESSBAR_POINT);