I wrote a bit about "jank" in JUCE

[sudara]

@Mrugalla

you can always just setBufferedImage(true) on a component in order to make it bypass all its automatic repaint calls, except for the ones apearing at the end of resized(). because then you can really surgically define when to repaint stuff manually

Ahh, true, I totally ignored this. I was under the impression a component’s cachedImage invalidates on any repaint() call. So for example, my CaretComponent calls setVisible on itself, which calls repaint on itself, which calls repaint on the TextEditor, which calls repaint on the Form its in… so all of those components would have their cache invalidated. So, I don’t think it would rescue me from “jank” caused by repaint calls (which are everywhere!).

Actually, maybe like others, I’m generally unclear about the “good” setBufferedToImage use cases.

The docs are a bit murky, but reading the code it seems that cachedImage->paint is only ever called in paintWithinParentContext which is called from paintComponentAndChildren (which recursively goes through the hierarchy top down painting children)

So if I’m understanding correctly, setBufferedToImage would be better named cacheComponentAndChildrenUntilRepaint — the cache is only used when the component’s parent is painting and is calling paintComponentAndChildren (opposite direction of what’s happening with the caret example).

@ImJimmi

Text is one place where it is almost always faster to render from an image, so that might improve the case of the caret in the text editor.

Oooh, this makes sense!