With the release 1.1 of Trident animation library available a couple of weeks ago, it’s time to start the development of version 1.2 (code-named Cookie Jar). The first 1.2dev drop has a few minor API enhancements, as well as a small new demo. This demo is based on the Flash mouse star trailer, and is slightly reminiscent of the Glitzer applet from Paul Schmidinger. Here is a video showing “Star Dust” in action:
The code is quite straightforward (see the test.swing.StarDust class). It has a looping timeline that spawns new stars. At every pulse this timeline checks the current location of the mouse. If the mouse is inside the panel, it creates a new Star object, as well as a matching Timeline object. The paintComponent() method of the panel iterates over all “live” stars and paints them based on their current position, size, rotation, alpha and color.
Here is the relevant code for the spawner timeline:
Timeline spawner = new Timeline();
spawner.addCallback(new UIThreadTimelineCallbackAdapter() {
private float currHue = 0.0f;
@Override
public void onTimelinePulse(float durationFraction,
float timelinePosition) {
Point mouseLoc = MouseInfo.getPointerInfo().getLocation();
SwingUtilities.convertPointFromScreen(mouseLoc, mainPanel);
double currX = mouseLoc.getX();
double currY = mouseLoc.getY();
if ((currX < 0) || (currY < 0) || (currX > mainPanel.getWidth())
|| (currY > mainPanel.getHeight()))
return;
double outerStartSpan = 5;
double outerFinalSpan = 20;
Star star = new Star(currX, currY, outerStartSpan);
Here, we use the MouseInfo class to get the mouse location, and then create a Star object centered at that point. Then, we create a timeline to animate the star location, size, rotation and alpha:
I am thrilled today to announce the availability of the final release for version 1.1 of Trident animation library (code-named Bogeyman). Most of the new functionality in this version was driven by the user feedback, and includes the following:
In addition to the bundled sample applications, Trident has two blueprint projects. These projects show how to use Trident to drive complex animation scenarios in Internet-enabled rich applications that show graphic information on music albums. Project Onyx is the Swing implementation (see detailed walkthroughs), and Project Granite is the SWT implementation (see detailed walkthroughs).
If you have Java 7 installed on your machine, click the button below to launch the WebStart version of Project Onyx:
You are more than welcome to take Trident 1.1 for a ride and report any problems in the project mailing lists, forums or issue tracker.
While Trident requires Java 6 for both the compile and runtime, Emmanuel Bourg has shared his tips on what is required to compile and run version 1.1 of the library under Java 5 and Java 1.4 – complete with a patch for the relevant classes and the build script. While these tips are relevant for the current state of the codebase, Trident core may at any point switch to using Java 6 specific APIs if they are found to be beneficial to the development of the library.
Finally, release 1.1 has one known issue that was found a few hours before the final release was built. As the fix may potentially affect the stability of the library, i have decided to postpone it to the next release. The issue is with running looping timelines on Swing components. If a window hosting such a component is disposed, Trident will continue running the timeline. If the timeline results in updating visual properties of this component (directly or indirectly), the main AWT thread will never shut down – as described in the AWT threading documentation – and the VM will never quit. There are two workaround for this issue in version 1.1:
Use EXIT_ON_CLOSE mode instead of DISPOSE_ON_CLOSE
Override the Component.removeNotify of the relevant component and cancel / abort the timeline
I am excited today to announce the availability of the release candidate for version 1.1 of Trident animation library (code-named Bogeyman). Most of the new functionality in this version was driven by the user feedback, and includes the following:
In addition to the bundled simple applications, Trident has two blueprint projects. These projects show how to use Trident to drive complex animation scenarios in Internet-enabled rich applications that show graphic information on music albums. Project Onyx is the Swing implementation (see detailed walkthroughs), and Project Granite is the SWT implementation (see detailed walkthroughs).
If you have Java 7 installed on your machine, click the button below to launch the WebStart version of Project Onyx:
You are more than welcome to take Trident 1.1RC for a ride and report any problems in the project mailing lists, forums or issue tracker. The final release is scheduled for October 12. Only bugs will be fixed until that date.
Trident animation library for Java applications is nearing release 1.1 (code-named Bogeyman), and it’s time to take a look at the new APIs added in this version. This entry is going to talk about supporting Java UI toolkits.
UI toolkit handlers
Graphical applications are a natural fit for animations, and Trident core has built-in support for Swing and SWT. This support covers threading rules, custom property interpolators and repaint timelines. Application code that needs to support additional Java-based UI toolkits should register a custom UI toolkit handler.
Most modern UI toolkits have threading rules that the applications must respect in order to prevent application freeze and visual artifacts. The threading rules for both Swing and SWT specify that the UI-related operations must be done on a special UI thread, and the methods in the org.pushingpixels.trident.UIToolkitHandler are used to determine the relevance of these threading rules. The UIToolkitHandler interface is illustrated by the core support for SWT:
public class SWTToolkitHandler implements UIToolkitHandler {
@Override
public boolean isHandlerFor(Object mainTimelineObject) {
return (mainTimelineObject instanceof Widget);
}
@Override
public boolean isInReadyState(Object mainTimelineObject) {
return !((Widget) mainTimelineObject).isDisposed();
}
@Override
public void runOnUIThread(Runnable runnable) {
Display.getDefault().asyncExec(runnable);
}
}
This is a very simple implementation of a UI toolkit handler that respects the relevant threading rules:
The isHandlerFor associates this handler with all SWT widgets
The isInReadyState marks disposed widgets to skip the property interpolation / callback invocations
The runOnUIThread runs the UI related logic on the SWT thread
Registering custom UI toolkit handlers
Trident provides two ways to register custom UI toolkit handlers – customization APIs and plugins.
The TridentConfig class has the following APIs to work with UI toolkit handlers:
addUIToolkitHandler(UIToolkitHandler) – registers the UI toolkit handler
removeUIToolkitHandler(UIToolkitHandler) – unregisters the UI toolkit handler
getUIToolkitHandlers() – retrieves an unmodifiable collection of all registered (core and custom) UI toolkit handlers
The UIToolkitHandler entries in the plugin descriptor files allow application code to support additional Java-based UI toolkits. The value associated with this key must be the fully qualified class name of an application class that implements the org.pushingpixels.trident.UIToolkitHandler interface.
Respecting the threading rules
The UIToolkitHandler.isHandlerFor(Object) is used to determine whether the main timeline object is a component / widget for the specific UI toolkit. At runtime, all fields registered with the Timeline.addPropertyToInterpolate methods will be changed on the UI thread using the UIToolkitHandler.runOnUIThread method.
In the simple Swing example that interpolates the foreground color of a button on mouse rollover, the timeline is configured as
Timeline rolloverTimeline = new Timeline(button);
rolloverTimeline.addPropertyToInterpolate("foreground", Color.blue,
Color.red);
If you put a breakpoint in the JComponent.setForeground(Color) – which is called on every timeline pulse – you will see that it is called on the Swing Event Dispatch Thread. Internally, this is what happens:
When the timeline is created, all registered UI toolkit handlers are asked whether they are handlers for the specified object
The org.pushingpixels.trident.swing.SwingToolkitHandler registered in the core library returns true for the button object in its isHandlerFor(Object)
On every timeline pulse, a Runnable object is created internally. The run() method calls the setters for all registered fields – using the PropertyInterpolator.interpolate method of the matching property interpolator
This Runnable is passed to the UIToolkitHandler.runOnUIThread method of the matching UI toolkit handler.
And this is how SwingToolkitHandler.runOnUIThread() is implemented:
@Override
public void runOnUIThread(Runnable runnable) {
if (SwingUtilities.isEventDispatchThread())
runnable.run();
else
SwingUtilities.invokeLater(runnable);
}
Running custom application code on UI thread
The flow described above works for the fields registered with the Timeline.addPropertyToInterpolate methods. What about the custom application callbacks registered with the Timeline.addCallback()? If the callback methods need to respect the UI threading rules of the matching toolkit, the TimelineCallback implementation class needs to be tagged with the org.pushingpixels.trident.callback.RunOnUIThread annotation.
Callback implementations marked with this annotation will have both onTimelineStateChanged and onTimelinePulse invoked on the UI thread, making it safe to query and change the UI. The UIThreadTimelineCallbackAdapter is a core adapter class that is marked with this annotation.
Querying the readiness of the timeline object
The isInReadyState(Object) is the third and final method in the UIToolkitHandler interface. After the specific UI toolkit handler has declared that it will handle the main object of the specific timeline (by returning true from the isHandlerFor(Object) method), it will be used to interpolate the registered fields and run the registered callbacks. However, some UI toolkits may impose additional restrictions on when the UI object is ready to be queried / changed.
For example, once an SWT control is disposed, it will throw an SWTException in the setForeground method. So, if the application code is running a slow animation that changes the foreground color of a button, and the application window containing this button is disposed in the meantime, the call to setForeground should be skipped.
