FS#12998 - Vertical progress bar (%pb) glitches at the start of a song

Attached to Project: Rockbox
Opened by Guillaume Cocatre-Zilgien (gcocatre) - Tuesday, 16 September 2014, 17:12 GMT
Task Type Bugs
Category Themes
Status Unconfirmed
Assigned To No-one
Operating System All players
Severity Low
Priority Normal
Reported Version Daily build (which?)
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 2
Private No


Consider the following theme markup:


That draws a vertical progress bar that will get filled from bottom to top. When a song starts to play, the progress bar is one pixel high, at the correct position (at the bottom of the viewport). That 1px-high image quickly jumps up one pixel (moves up by one pixel), then comes back down one pixel (at the correct position) whenever the progress percentage is high enough. The progress bar then displays normally and grows as the song is playing. See attached screenshots.

Expected behavior: the position of the progress bar (relative to the viewport) should not change. The bug has been observed in the iPod Classic and Clip Zip sims (builds 1bc89bd and 77bfff5) as well on the actual devices. Inverting the progress bar (with the "invert" parameter) shows the correct behavior (inverted bar with no such glitch).

Affected themes: Ash (iPod Classic), SugarBrown (Clip Zip).
   a.png (4.1 KiB)
   b.png (4.1 KiB)
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Comment by Guillaume Cocatre-Zilgien (gcocatre) - Tuesday, 16 September 2014, 17:15 GMT
Volume and battery bars are affected too (possibly all kinds of bars).
Comment by Dan (TempTest) - Tuesday, 16 September 2014, 17:18 GMT
I have also observed this behaviour (simulator and hardware) on a Sansa Clip Zip using SugarBrown [1] theme. I am not aware of a suitable work around and this appears to be an issue in Rockbox source rather than the theme.