Zoom tool UI: large scale jumps from small mouse movement (hand tremor)

[qgib]

Author Name: Garth Fletcher (@fgfletcher)
Original Redmine Issue: 18376
Affected QGIS version: 3.0.0
Redmine category:osx_ui

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When clicking on the map with the zoom (magnifying glass) tools the slightest inadvertent movement of the mouse while pressed causes the scale factor to jump - e.g., from 1:1,000 to 1:1,000,000 (zoom out tool) or to 1:10 (zoom in tool).

Apparently the smallest movement is interpreted as a request to adjust scale. This is much too "sensitive" and frequently results in large scale jumps from very small hand trembles.

This could be avoided by requiring some minimum movement size (perhaps 10x10 pixels) before interpreting the movement as a request to rescale rather than just a normal zoom in or out command.

This was reported (#25898) for QGIS 2.18.15 but that ticket was closed with comment "This is fixed for 3.0 - a 2.18 fix is not possible...".

However the issue has not been fixed in 3.0. (3.0.0-Girona from MacPorts 2018_03_06).

PS the addition of the Option key to toggle zoom direction is very nice - thanks!

[qgib]

Author Name: Giovanni Manghi (@gioman)

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End of life notice: QGIS 2.18 LTR

Source:
http://blog.qgis.org/2019/03/09/end-of-life-notice-qgis-2-18-ltr/

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• resolution was changed from to end of life
• status_id was changed from Open to Closed

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• resolution was changed from end of life to
• status_id was changed from Closed to Open

[Pedro-Murteira]

@fgfletcher I can't seem to replicate this, what I mean is that the scale doesn't change drastically when the mouse movement is minimal, it requires a bit more than a slight movement to drastically change the scale. (QGIS 3.16.14 and 3.22.1.)

[fgfletcher]

Yes, it has been fixed, at least since 3.18.3 and continues to be OK through 3.23.0 nightly.

The motion required is greater than 1/8" on screen, which is fine.
Previously an inadvertent 1 pixel motion was enough - which was very irritating.

The selection rectangle starts to draw before the threshold is reached, It might be nice, though not necessary, if the rectangle drawing only occurred after the threshold was reached; i.e., linking the decision to draw a selection rectangle to the decision about whether a normal zoom or a zoom to expand the selected area to full screen. However, that might conflict with the desire to select very small areas with other tools, so probably not worth doing.