https://bugs.kde.org/show_bug.cgi?id=526707
Bug ID: 526707
Summary: Visual Flicker and Loading Delay
Classification: Applications
Product: okular
Version First unspecified
Reported In:
Platform: Android
OS: Android 16.x
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 196867
--> https://bugs.kde.org/attachment.cgi?id=196867&action=edit
'About' Ppage Screenshot for Android16 for potential, additional context
DESCRIPTION
When paging through documents in Okular Mobile on Android, page turns cause a
noticeable, prolonged screen flicker/blink followed by a delayed render of the
next page. The viewer appears to evict the current page and display an
intermediate blank/loading state rather than buffering adjacent pages.
Steps to Reproduce
1. Open any standard, low-complexity PDF (primarily text, minimal raster
graphics) in Okular Mobile.
2. Swipe horizontally to navigate from one page to the next.
OBSERVED RESULT
The display flashes/blinks with a visible blank/loading frame before the
subsequent page appears.
Page rendering exhibits noticeable latency despite the file having negligible
visual assets.
Document view is constrained to discrete horizontal pagination with no smooth
continuous vertical scroll mode.
Memory lifecycle appears to only cache one page at a time, forcing a complete
reload/render cycle per swipe.
EXPECTED RESULT
Smooth page switching without intermediate blanking or flicker.
Background pre-rendering/caching of adjacent pages (N-1 and N+1) to allow
seamless transitions.
Support for a continuous vertical view mode standard to mobile reading
workflows.
ADDITIONAL INFORMATION
The same PDF documents open instantly and scroll seamlessly without flicker or
render delays in the native Samsung PDF Viewer on the same device.
Tested on high-end hardware (Galaxy S25 Ultra), confirming the behavior stems
from my research dictates is the Qt/Kirigami rendering lifecycle/caching on
Android rather than hardware performance constraints.
SOFTWARE/OS VERSIONS
Operating System (available in the Info Center app, or by running `kinfo` in a
terminal window): Android 16.0
KDE Plasma Version: Could not find in the Android Version
KDE Frameworks Version: 6.30.0
Copied from "Libraries in use" on the "About" page in the app:
Qt Version:
Okular: 26.11.70
Android (16.0)
KDE Frameworks: 6.30.0
Qt: Using 6.11.0 and built against 6.11.0
Build ABI: arm64-little_endian-lp64
Kernel: linux 6.6.98-android15-8-pd6ff1cd-abogkiS938USQSCCZF9-4k
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