Page thumbnails pinch to zoom - Multiple selection lost

[Loki@99]

Hi,

There's an issue with page thumbnails pinch to zoom gesture feature.

Steps to reproduce
1. Open a PDF with many pages
2. Select some pages
2. Perform a pinch to zoom action in thumbnails panel with finger on touchscreen
You may need to perform a pinch in and out gesture many times cause sometimes the first pinch doesn't trigger the bug

Issue
Selection lost

GIF - Pages 3838, 3839, 3840 selection lost after pinch zoom gesture performed with finger on touchscreen
No mouse or touchpad involved in the action. The mouse pointer you see is due to the GIF recorder (Licecap)

issue.gif

Thanks for investigating,

[Daniel - PDF-XChange]

Hello, Loki@99

I'm sorry to say that this looks to be a "user error" situation, I have spent the past 20 minutes zooming in and out on the thumbnails, putting the tablet down and picking it back to up try other angles, focusing on pinching over the selected pages, over the non-selected pages, and spreading my fingers apart over both sections, even using my non-dominant hand, and could not reproduce the issue.

The only cases of de-selection, were caused by a clear mis-press elsewhere in the thumbnails pane.

Kind regards,

[Loki@99]

Hi Daniel,

I'm sorry to say that this looks to be a "user error" situation.

Thanks for trying.

I thought the same before but it's certainly not a "user error".

It's a random bug but I just noticed that in order to reproduce it, you have to keep your finger spread after the pinch out action and keep them close to screen. I'm not sure though.

I'll add further details if I find something.

[Daniel - PDF-XChange]

Hello, Loki@99

If you are keeping your fingers close to the screen, it is very likely you are tapping it again, even the lightest tap is enough for modern capacitive touch screens. It is also worth noting capacitive touch devices are very sensitive to environmental conditions. In some cases, this can cause a screen to be sensitive enough that it responds to the faintest touch which you could not perceive yourself.

It may help to setup a screen recording with some exaggerated "click" animation, which will showcase there is a click happening on the unwanted selection action. This is not something our software is able to do on its own, we only listen for the touch handling events, and interpret them as they come. A click occurring here to change the selection, means either a case of either user error, or excessive hardware sensitivity, before we are involved at all.

Kind regards,