Re: JSUI-MGraphics patch-a-day

Darwin Grosse

Here is the patch for November 10, 2011:

Up to now, all of our drawing has occurred in the paint() method, which is called every time that the component needs to refresh itself. This is fine in many cases, but troubling in some cases:

- If the paint method contains some generative function, you cannot know when the visual is going to be recalculated.

- If your drawing function does *a lot* of stuff, you can find performance starting to suffer.

So what to do? This sketch shows how to draw to an alternative MGraphics instance, save that visual as an Image object, then use that image to redraw the component during a refresh. The performance is very high (in this case, drawing 1000 semi-transparent rectangles) because the drawing is only done when you ask the drawing to be redone.

Very important stuff here. Thanks to JKC for the help with this!


Nov 11, 2011 at 12:37am #214971