CODEWITHSUNDEEP
javafx
interestedparty333
interestedparty333

Reputation: 2536

Extend a class to have my custom class rendered as part of the Node graph?

In JavaFX, once I have a Scene, Pane, and/or Canvas setup and have my Node graph setup, how do I add my own custom components? I've already added them to the Node graph, but they're not being rendered, because they neither inherit from a particular node nor implement the particular method necessary to have their rendering method called. There isn't much complexity involved in drawing these components -- it's about twenty calls of drawRectangle etc..

If I recall correctly, in Swing, I had each component implement a version of draw, and draw was called automatically as part of the framework. But I haven't found the equivalent mechanism in JavaFX yet.

Upvotes: 0

Views: 387

Answers (2)

interestedparty333
interestedparty333

Reputation: 2536

I needed to pass in the Pane that I'm using for drawing into the constructor of my "custom class." The custom class then adds the necessary shapes to the provided pane. I assume I'll also need to keep track of those shapes as a data member of the custom class and remove/replace them when the custom class needs a new visual representation.

See Fedor Losev's answer below for a more complete list of options. E.g., I could have used a Canvas instead of a Pane.

Upvotes: 0

Fedor Losev
Fedor Losev

Reputation: 3322

JavaFX doesn't have "ondraw" in the usual sense, because components are usually composed and rendered on GPU.

There are multiple ways to create custom drawing, depending on your needs and requirements.

You can merely use Canvas for simple drawing, pretty clear described in official tutorial . This is the simplest way for complex drawings and probably it is what you are looking for. Add canvas node to the scene and draw on it. You can encapsulate the logic by extending Canvas or a container component that will contain Canvas (or by presenter etc. if you employ some kind of MVP/MVC).

Another way is just to compose from existing visual components e.g. shapes and images, for example by extending or preparing a Pane or other container and adding children components.

Yet another is to prepare a bitmap with custom drawing and use Image component, you can use Swing or other APIs to draw a bitmap in advance and use it for rendering. In general this is similar to using canvas but more complex, unless you see clear benefits or have particular reasons, canvas is preferred.

Last way is to implement custom scene Node with complete rendering, I would not go into detail and advice against it; it is relatively complex, will use non-public APIs, probably would not be compatible between JDK releases and is useful only for very special needs.

Note, if you are creating a custom reusable library component, you probably will need to dive into the topic of skinning and component lifecycle.

Upvotes: 2

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