layer should not get the "show" checkbox disabled based on visiblity slider state

[aseerel4c26]

Michael, while you're at it: The automatic "hide" feature of a layer is breaking my GUI expectations (which is most striking if you use the new mouse wheel slider movement - ticket #13703 ).

Steps:

1. scroll muuuuch to lower the Opacity of a layer until the slider is at the lowest position
2. (the layer automatically gets the "show" checkbox disabled)
3. scroll in the opposite direction to increase the Opacity again (undo your action in 1.)

Expected: layer gets visible again since you have undone your movement
Actual: the layer stays inactive and you need to check the box (which you've never enabled)

I guess it is this bit (and could not find a comment why it is there) (source):

if (getRealValue() <= 0.001 && !getValueIsAdjusting()) {
	                setVisibleFlag(false);

Is there a reason for this feature? I would suggest to not automatically disable the "show" checkbox based on slider action. Thank you! :)

[michael2402]

The feature is there because of historical reasons. The visible boolean flag was there first, the slider came afterwards.

I don't even think that the visible flag is required any more. We could remove it and define a layer to be visible if it's visibility is not 0. The main reason I see is the visibility toggle button: It needs to know the old opacity.

The problem is that users may not really know what happens if they set the visibility to 0 - the layer is still marked as visible but they don't see anything.

[aseerel4c26]

Thanks for the explanation.

I do not think that "users may not really know ..." is a problem. The user is using the slider actively to lower the opacity, so it should be obvious what the slider does. By the way: even with the current setup users "users may not really know ..." why a layer is not visible despite the "show" checkbox being ticked: imagine the user setting a opacity of 0.05. That's not really visible, but the "show" checkbox may still be enabled.

In addition: Currently I see the "visible" control at two places. The eye symbol in the layers and the checkbox in the visibility control popup. I do not think that we need an additional checkbox there.

Maybe someone else could share their thoughts!

[aseerel4c26]

I did a test with a user who never used JOSM before (only saw me using it sometimes). I showed him JOSM's slippy map, the layer list, the function of the eye icon (on/off of the layer) and the sliders (I moved the opacity slider around a bit and showed the effect on the map). He told me "ahh, this is like GIMP!" I asked the person to close his eyes. Then I set the opacity slider to a very low value (but not 0) making the map invisible. I asked the person to open eyes and asked: "why can't I see the map? What's wrong?" The user had a short look at the eye icon and then opened the visibility popup. Then he moved the opacity slider back up and told me "there it is!". This only took some seconds in total.

Taken into account that the opacity change is only valid for the layer's lifetime, I think the additional checkbox (compare with JOSM version 7000 below) in the popup and any automatic visibility status changes (which are based on the opacity slider) are superfluous.

Have a nice day!

[aseerel4c26]

screenshot of josm 7000

[aseerel4c26]

fixed in the meantime (except the duplicated visibility box - different, not that clear issue) - see #13703

[michael2402]

About the duplicated visibility box: Try toggeling the visibility of a whole bunch of layers. You can simply select using shift and then use that visibility box. I used it some times when working with many layers.