Bug 480036

SUMMARY
Moving from Okular 22.12.3 to 23.03.8 using CTRL + Mouse  wheel scroll to zoom in or out no longer follows the preset zoom percentages (100; 150; 200; 400; ...; 10,000), but zoom in is always +24 % and zoom out is always -24 % of the *current* value.


STEPS TO REPRODUCE
1. Use any okular version after 22.12.3
2. Hold CTRL + Scroll to zoom
3. Get very uneven zoom percentages after multiple zoom ins and outs

OBSERVED RESULT
Having the uneven zoom percentages (triple zoom in from 100 % zooms in consecutive +24 % of the current value, resulting in 190,7 % zoom) causes severe performance drops at high zoom levels. Rendering at high zoom levels takes many seconds (tested on multiple systems, high-end Hardware suffers just the same), but using the CTRL + "+ key" results in the usual steps (...2,500 %; 5,000 %; 10,000 %) renders the content nearly instantly. The relative to current value zoom levels also skip the [Fit Page] and [Fit Width] levels of zoom.

Since it is always + or - 24% of the current value, it is impossible to return to the "original" zoom level when alternating zooming in and out, ultimately one gets a reduced zoom level. For example, starting at 100 % and zooming in and out 30 times in a row lands you at 41.1 % zoom level.

EXPECTED RESULT
Using CTRL + Mouse Wheel to zoom should jump between the preset zoom levels (100, 125, 150, 200, 400,...) the same way when using CTRL + "+ key", as it was behaving up until Okular version 22.12.3.

SOFTWARE/OS VERSIONS
Arch Linux, Kernel-Version: 6.7.0-arch3-1
KDE Frameworks Version: 5.114.0
Qt Version:  5.15.12 (built against 5.15.12)

ADDITIONAL INFORMATION
Checking the dates of the releases between the Okular versions 22.12.3 and 23.03.8 the only two commits mentioning any changes to zoom or scroll in this timeframe are 30969b49 (Feb. 20th, 2023) and 0b25a83c (Feb 20th, 2023).