Viewport scrolling performance

[Alex Ryzhov <ar...@gmail.com>]

Hi,

I noticed a significant downgrade in performance after migrating my custom
component that uses a ScrollPane from Swing to Pivot. After some profiling I
discovered that the reason for performance downgrade is the scroll mode: the
Swing version sets scroll mode to BACKINGSTORE_SCROLL_MODE, but Pivot's
viewport uses an equivalent of BLIT_SCROLL_MODE.

My component uses scaled images which cannot be correctly rendered
partially, so the entire scaled image is redrawn every time the viewport
changes which happens dozens of times when the user scrolls by dragging the
scroller. think that user experience would be significantly improved with an
algorithm that proactively drew the contents of the viewport in an offscreen
buffer when the user scrolls in a given direction, which is closer to
BACKINGSTORE_SCROLL_MODE. I mean, my iPhone scrolls better :)

Thanks,
Alex

Re: Viewport scrolling performance

[Greg Brown <gk...@verizon.net>]

> My component uses scaled images which cannot be correctly rendered partially, so the entire scaled image is redrawn every time the viewport changes which happens dozens of times when the user scrolls by dragging the scroller. think that user experience would be significantly improved with an algorithm that proactively drew the contents of the viewport in an offscreen buffer when the user scrolls in a given direction, which is closer to BACKINGSTORE_SCROLL_MODE. I mean, my iPhone scrolls better :) 

Agreed:

https://issues.apache.org/jira/browse/PIVOT-454