Prevent flickers for already loaded images. #325
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* In large SPAs where an image is reused throughout the page, lazyload * has a tendency to "flicker" because of the unnecessary hide/show * cycle. So first, check if an image is already loaded in the cache and * disable any effects (including user specified ones). Otherwise, go on * as before. As a side note, the `effect` API accepts an arbitrary * function, so it's easier to build flicker-resistant animations in, * say, Ember apps. However, a string is still accepted and just * converted to a function.
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Related, this closes #161 |
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Large single-page apps, like Ember, will sometimes rerender the same element with the same image. This can cause lots of flickering with lazyload.
Also, an image reused throughout the page (say, an avatar) fades in every single time, which can make for a jumpy experience (esp. if a rerender is triggered).
Last, the start of the animation is hardwired to
hide(), which unnecessarily causes page reflow issues even when the dimensions are known.To fix this,
settings.effectaccepts a function, which defaults to a noop (preventing flickering for folks without any effect specified), and the effects are never run if the image is already cached. Ifsettings.effectis a string, it gets converted to a function as before, so it should be backwards compatible.For my specific use case, this lets me just use
$el.css({opacity: 0}).animate({opacity: 1});as my effect, which doesn't cause a page reflow or flicker.Tested in Firefox and Chrome.
Easier to see relevant changes with the
?w=1flag.