- #Java fx listener on resize how to
- #Java fx listener on resize update
You’re trying to update a ListViewĪ lot of people set up their ListView by wrapping a List they are maintaining with FXCollections.ObservableArrayList().
#Java fx listener on resize how to
Here are some scenarios where you might get into that situation and how to fix them. So, if you think you’ve made a change, and you’ve checked that the scene is refreshing using the Scene’s pre-layout pulse listener, chances are JavaFX doesn’t know about your change.
If more than a certain number of grouped nodes are marked, mark the group as dirty. When a node has changed layout or transform properties, it and its children are marked. If a node has changed content (like a text field with changed text), it’s marked to trigger rendering changes. There are some basic rules that govern how JavaFX decides which parts of the scene to refresh. JavaFX doesn’t know about the changes you’ve made Let’s take a look at those situations where JavaFX might not refresh your scene. So unless you’re doing something to stop it, at least once every 60th of a second, JavaFX will check whether your scene needs changing, and make those changes if needed. 
Really worth noting: this happens even when no changes are being made to your scene. I tracked this over 1000 frames and I’ve plotted the refresh rate (how many times it does it per second) against the pulse number. This listener will fire every time JavaFX creates a layout pulse. this goes after you've defined your scene, but before you display your stage this variable needs to go in the Main class, outside of the start() method We can actually test how frequently JavaFX looks at whether it needs to refresh the scene by registering a listener on the scene’s refresh pulse.
You’re preventing JavaFX from checking whether to refresh your scene. JavaFX doesn’t know about the changes you’ve made. What’s causing my scene to hang?Īs a basic rule, there are two reasons that your scene wouldn’t refresh: But, if you’re blocking the UI thread, JavaFX won’t have be able to render the changes until you stop what you’re doing. Changing the scene dimensions might ensure JavaFX knows your scene needs re-rendering. If your scene isn’t refreshing, then forcing it to update will not solve your problem. There are a lot of reasons why the JavaFX scene might not refresh, but I guarantee that if your scene isn’t refreshing it isn’t because JavaFX stopped working, or stopped checking whether your scene has changed. In the background, JavaFX continually refreshes the scene anyway. EfficiencyĪside from making the window flicker frustratingly, forcing JavaFX to regularly recalculate the rendering requirements for a scene is incredibly inefficient. This requires JavaFX to recalculate everything from where to put the window border, to where to put the exit button. Above the Scene, the Window will try to accommodate the changes in the Scene. Recalculating the requirements of the scene does not just impact scene-level objects. Repeatedly doing this at any regular interval threatens the stability of the windowing activities that run in the background. I can’t stress enough that this is incredibly inadvisable. element.getScene().getWindow().setWidth(element.getScene().getWidth() + 0.001) So, if you change something important at the top of the scene graph – like the width of the scene – no matter how small the change, JavaFX will re-calculate the layout and content of the scene graph completely. It uses defined rules to determine which parts of a Scene to re-render.įundamentally, if you change something small, the Toolkit will mark the area around it. The toolkit then renders them in the rendering pipeline. In the background of JavaFX, the quantum toolkit maintains a sister scene graph, which it uses to calculate parts of the UI that need to be altered. In fact, programmers who’ve used Swing may be used to firing data change events as a way to update their view.īut with JavaFX, in almost all cases, this will not solve the problem you’re having and there are different, more stable, ways to ensure your UI updates like you want it to. 
On the face of it, it seems like there are plenty of use cases for forcing a JavaFX scene to refresh. This change forces the background windowing and rendering services to recalculate layout and rendering requirements for the scene graph. The JavaFX scene can be forcibly refreshed by changing the width or height of the Scene by a fractional number of pixels (for example, 0.001). I found out a way to force the Scene to refresh, but in almost every situation it didn’t solve the problem I was having. An awkward TableView that wouldn’t refresh, or the UI hanging unpredictably. When I first started programming with JavaFX, updating the user interface was a constant frustration.
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