[QGIS-Developer] Alternative layer drawing order not honoured in QGIS 3

[Burghardt.Scholle at stadt.wolfsburg.de]

Hi Andreas,

I can confirm your issue. If I change the rendering order in a 2.18 qgs project and open it in 3.0, the checkbox "Control rendering order" is set to “off” and the ordering is “reset” to the rendering order in the “layers” panel.

Regards
Burghardt

Von: QGIS-Developer [mailto:qgis-developer-bounces at lists.osgeo.org] Im Auftrag von Andreas Neumann
Gesendet: Mittwoch, 4. April 2018 11:45
An: QGIS Developers List
Betreff: [QGIS-Developer] Alternative layer drawing order not honoured in QGIS 3


Hi,

I know that probably not many people use the feature of the "alternative drawing order" in QGIS - it is kind of a hidden - not so well-known feature. Normally, QGIS is using the layer rendering order defined in the "Layers" panel. But one can deliberately reorganize the layer rendering order in the separate "Layer Order" panel. This is necessary for more complex cartographic output (e.g. cadastral maps).

I noticed that an existing 2.18 qgs project opened in 3.0 does two bad things:

1. the checkbox "Control rendering order" in the "Layer Order" panel is set to "off" in QGIS 3, whereas it was on in 2.18

2. the ordering in the Layer Order panel is completeley mixed up (not as it was in 2.18).

I think that this a very important issue to fix for any serious cartographic output involving many layers.

My questions:

1. Can others confirm that issue, that the layer drawing order is messed up when opening 2.18 files that had alternative layer orders defined?

2. Who has time and expertise in this code area to fix this issue?

I can provide a Postgis-Dump and a sample project that demonstrates this issue.

See also the screenshot at https://issues.qgis.org/attachments/download/12554/layer_rendering_order_garbled.png showing the issue - on the left is QGIS 2.18 on the right there is QGIS 3.

Issue report at https://issues.qgis.org/issues/18620

Thanks for your replies,
Andreas
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