Canvas Content Shift

Dirk Lemmermann dlemmermann at gmail.com
Mon Apr 10 08:32:30 UTC 2017


HI there,

I was wondering if there is any chance that Java 10 could implement some sort of „content shifting“ for the Canvas API? 

I would love to have this feature for supporting faster horizontal scrolling in my Gantt Chart framework FlexGanttFX. Currently when the user scrolls then the entire content of each canvas in each row of the chart will be redrawn. This could be optimized by only drawing the time range that has been moved into the „viewport“ and by shifting or copying the remaining time range graphics. E.g. the user currently looks at one week and scrolls one day to the right then the data / graphics of 6 days would stay the same and could just be reused. Only one day worth of data would need to be redrawn.

I think in Swing this is comparable with the BLIT_SCROLL_MODE of JViewport.

Dirk



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