Best Practices for JavaFX Mobile Applications 3

WARNING: The tips I am giving here are true for the current version of JavaFX Mobile, which is part of the JavaFX 1.1 SDK. In future versions the behavior will change, the
current bad performance of the mentioned artifacts will be optimized away or at least significantly improved. Everything I am writing about here is a snap-shot, nothing should be understood as
final!

Item 3: Use simple shapes instead of images

Item 4: Use small images instead of complex shapes

These two items seem to contradict each other. Unfortunately there is no easy answer available here:  sometimes using shapes is better, sometimes using an image is better. To help making the right decision, here are some points one should consider:

  • Complexity Single basic shapes like rectangles or circles are almost always faster than images. But the higher the number of shapes, which are assembled to get the desired artifact, or the more complex a user-defined path is, the more expensive operations on these shapes are. And the advantage shrinks. Important note: A javafx.text.Text object is a very complex shape.
  • Size The performance of most operations on images behaves quadratic, which means the operations become 4 times as slow if width and height are doubled, 9 times as slow if they are tripled etc. Therefore the bigger an element is, the better is using shapes.
  • Transformations Rotating or scaling does not only look better when using shapes, but it is usually also faster than transforming images. Especially if rotation and scaling are animated, shapes will perform better.
  • Startup time Loading an image and setting up an ImageView is usually slower then setting up shapes.
  • Footprint Static and dynamic footprint is almost always higher when using images.

Important: The variable cache of javafx.scene.Node is currently NOT used in the runtime. Setting it makes no difference!

Links to previous parts:

Item 1: Avoid unnecessary bindings
Item 2: Keep the scenegraph as small as possible