DurianSwt: Reactive utilities and fluent builders for SWT

Infrastructure

• ControlWrapper - create custom widgets which properly encapsulate their base control.
• Coat - a functional interface for populating an empty Composite.
• CoatMux - a mechanism for layering and swapping Coats.
• SwtExec - an ExecutorService which executes on the SWT thread.
• SwtExec.Guarded - an ExecutorService which is tied to the lifetime of an SWT widget. Say goodbye to SWTException: Widget is disposed forever! It can also subscribe to any kind of observable (Guava's ListenableFuture or RxJava's Observable), see DurianRx for more info.

SwtExec.async().guardOn(textBox).subscribe(serverResponse, txt -> {
  textBox.setText(txt);
});

Fluent builders

• Layouts - all the layouts you'll need in SWT

void textOkCanel(Composite cmp) {
  Layouts.setGrid(cmp).numColumns(3);

  // instructions fill the full width
  Text text = new Text(cmp, SWT.WRAP);
  Layouts.setGridData(text).horizontalSpan(3).grabAll();

  // right-justified ok / cancel buttons
  Layouts.newGridPlaceholder(cmp).grabHorizontal();
  Button btnOk = new Button(cmp, SWT.PUSH);
  Layouts.setGridData(btn).widthHint(SwtMisc.defaultButtonWidth());
  Button btnCancel = new Button(cmp, SWT.PUSH);
  Layouts.setGridData(btn).widthHint(SwtMisc.defaultButtonWidth());
}

• Shells - dialogs without boilerplate

Shells.builder(SWT.DIALOG_TRIM, this::textOkCanel)
  .setTitle("Confirm operation")
  .setSize(SwtMisc.defaultDialogWidth(), 0) // set the width, pack height to fit contents
  .openOnDisplayBlocking();

• Actions - builder and one-liner: Actions.create("Redo", this::redo);

• LabelProviders - builder and one-liner: LabelProviders.createWithText(Person::getName)

• ColumnFormat and ColumnViewerFormat - tables and trees without boilerplate

ColumnViewerFormat<Person> format = ColumnViewerFormat.builder();
format.setStyle(SWT.SINGLE | SWT.FULL_SELECTION);
format.addColumn().setText("First").setLabelProviderText(Person::getFirstName);
format.addColumn().setText("Last").setLabelProviderText(Person::getLastName);
format.addColumn().setText("Age").setLabelProviderText(p -> Integer.toString(p.getAge())).setLayoutPixel(3 * SwtMisc.systemFontWidth());
TableViewer table = format.buildTable(parent);
TreeViewer tree = format.buildTree(parent);

Resource management

• OnePerWidget - a cache tied to the lifetime of an SWT Widget.
• ColorPool - a pool of colors tied to the lifetime of a widget. ColorPool.forWidget(widget).getColor(rgbValue)
• ImageDescriptors - use ImageDescriptors with proper resource sharing. ImageDescriptors.set(btn, imageDescriptor)

Interactive testing

Ideally, all UI code would have fully automated UI testing, but such tests are time-consuming to write, so they often just don't get written at all. InteractiveTest bridges the gap by making it easy to write user-in-the-loop guided tests. Furthermore, these tests can even be run in a headless enviroment on a CI server, where the test UI will be opened, then automatically closed after a timeout. This ensures that the tests are all in working order and ready for a human tester to do final validation.

From ViewerMiscTest.java:

String message = StringPrinter.buildStringFromLines(
  "- The table and the tree should keep their selection in sync.",
  "- The table and the tree should not allow multi-selection.",
  "- The categories in the tree should not be selectable.");
InteractiveTest.testCoat(message, cmp -> {
  TableAndTree tableAndTree = new TableAndTree(cmp, SWT.SINGLE);

  // get the selection of the tree
  RxBox<Optional<TreeNode<String>>> treeSelection = ViewerMisc.<TreeNode<String>> singleSelection(tableAndTree.tree)
      // only names can be selected - not categories
      .enforce(opt -> opt.map(val -> isName(val) ? val : null));

  // sync the tree and the table
  RxOptional<TreeNode<String>> tableSelection = ViewerMisc.singleSelection(tableAndTree.table);
  Rx.subscribe(treeSelection, tableSelection::set);
  Rx.subscribe(tableSelection, treeSelection::set);
});

Miscellaneous stuff

• SwtMisc - useful static methods.
  • blockForError, blockForSuccess, blockForQuestion, etc. - opens a dialog and blocks for the user's response, can be called from any thread.
  • loopUntil, loopUntilDisposed, loopUntilGet - spins the SWT display loop until some condition is satisfied.
  • systemFontHeight/Width, scaleByFont, scaleByFontHeight - resolution-independent sizes.
  • treeDefControl, treeDefComposite - a TreeDef for traversing UI elements.
  • setEnabledDeep - sets the enabled status of every child, grandchild, etc. of the given composite.
• SwtRx - methods for converting SWT events and models to RxJava Observables.
• SwtDebug - utilities for debugging SWT events.
• OS, Arch, and SwtPlatform - detect things about the running system, and manipulate the SWT jars for build tools.
  • These do not require SWT or JFace, so you can add DurianSwt to your gradle or maven dependencies without needing to also figure out the SWT messiness.
  • You can also just copy-paste these straight into your own code - they have no external dependencies.

String installerExtension = OS.getNative().winMacLinux("exe","dmg","sh");
String helperBinary = "driver_" + Arch.getNative().x86x64("", "_64") + ".dll";
String swtJarName = "org.eclipse.swt." + SwtPlatform.getRunning();

• ViewerMisc - useful static methods for JFace viewers.
  • singleSelection, multiSelection - returns an RxBox for listening to and setting the selection of a viewer.
  • setTreeContentProvider, setLazyTreeContentProvider - uses a TreeDef to provide the content of a TreeViewer.

Requirements

Durian requires:

• Java 8
• Durian and DurianRx
• Guava and RxJava
• SWT and JFace from Eclipse 4.4+
  • SWT and JFace are not included in the Maven POM, but everything else is.

Acknowledgements

• Thanks to David Karnok for contributing an SwtScheduler that honors the Scheduler/Worker contracts.
• Thanks to Moritz Post for his fluent layout idea.
• Formatted by spotless, as such.
• Bugs found by findbugs, as such.
• OSGi metadata generated by JRuyi's [osgibnd-gradle-plugin] (https://github.com/jruyi/osgibnd-gradle-plugin), which leverages Peter Kriens' bnd.
• Scripts in the .ci folder are inspired by Ben Limmer's work.
• Built by gradle.
• Tested by junit.
• Maintained by DiffPlug.