[Bug]: LWC 3.7.0 and QGIS 3.34 raster - symbology

[josemvm]

What is the bug?

qgis desktop 3.22.16

LWC 3.6.8

===========
qgis desktop 3.28.13

LWC 3.7.0

Steps to reproduce the issue

.

Versions

Versions :

• Lizmap Web Client : 3.7.0
• Lizmap plugin : 4.1.1
• QGIS Desktop : 3.28.13
• QGIS Server : 3.28.13
• Py-QGIS-Server : not used
• QGIS Server plugin atlasprint : 3.3.2
• QGIS Server plugin lizmap_server : 2.8.1
• QGIS Server plugin wfsOutputExtension : 1.8.0

List of safeguards :

• Mode : normal
• Allow parent folder : no
• Prevent other drive : no
• Prevent PG service : no
• Prevent PG Auth DB : no
• Force PG user&pass : no
• Prevent ECW : no

Check Lizmap plugin

• I have done the step just before in the Lizmap QGIS desktop plugin before opening this ticket. Otherwise, my ticket is not considered valid and might get closed.

Operating system

Ubuntu 22.04

Browsers

Firefox

Browsers version

Firefox 120.0.1

Relevant log output

No response

[josemvm]

in case of linear interpolation, not for discrete or exact interpolation

[Gustry]

Similar to qgis/QGIS#55651 ?

[josemvm]

no, only in case of linear interpolation type not for discrete or exact interpolation type

[Antoviscomi]

@josemvm in my LWC 3.7 the color ramp it's not rendered (there isn't a ramp in legend) as in screenshot below

respect to QGIS

in LWC 3.6.9 it seems compressed as in screenshot below

so I confirm the Issue

[josemvm]

@Antoviscomi thanks
maybe a qgis server bug...

[Gustry]

Lizmap is taking the JSON legend from QGIS Server, as you can see in the ticket I mentioned earlier.
You can open your "developer tools" (F12), check the request made to QGIS server GetLegendGraphic and check the content of the JSON response. It's in the webbrowser.

[josemvm]

@Gustry the url from lizmap doesn´t contain the GetLegendGraphic
myhost/index.php/lizmap/service?repository=ma&project=PIAAC-AC&REQUEST=GetMap&SERVICE=WMS&VERSION=1.3.0&FORMAT=image%2Fpng&STYLES=default&TRANSPARENT=true&LAYERS=lst_inv_ac&DPI=96&WIDTH=2080&HEIGHT=475&CRS=EPSG%3A3763&BBOX=-253278.93184485074%2C-179934.01850668347%2C297055.50215735065%2C-54256.68381868075&ts=1707138769681

i can replace the request for myhost/index.php/lizmap/service?repository=ma&project=PIAAC-AC&REQUEST=GetLegendGraphic&FORMAT=image&&SERVICE=WMS&VERSION=1.3.0&FORMAT=image%2Fpng&STYLES=default&TRANSPARENT=true&LAYERS=lst_inv_ac&DPI=96&WIDTH=2080&HEIGHT=475&CRS=EPSG%3A3763&BBOX=-253278.93184485074%2C-179934.01850668347%2C297055.50215735065%2C-54256.68381868075&ts=1707138769681

and get:

[Gustry]

This a GetLegendGraphic as a picture.
Now, Lizmap use the GetLegendGraphic as JSON, to be able to have a checkbox

[Antoviscomi]

@Gustry here in LWC 3.6.9 the request is:

http://myhost/webgis/index.php/lizmap/service?repository=tempor&project=ProvaFiles&SERVICE=WMS&VERSION=1.3.0&REQUEST=GetLegendGraphic&LAYER=orto2008&STYLE=predefinito&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&FORMAT=image%2Fpng&TRANSPARENT=TRUE&WIDTH=150&LAYERFONTSIZE=0&ITEMFONTSIZE=9&SYMBOLSPACE=1&ICONLABELSPACE=2&DPI=96&RULELABEL=AUTO&LAYERSPACE=0&LAYERFONTBOLD=FALSE&LAYERTITLE=FALSE&SCALE=75000

and this it's the result

in 3.7 there is not a similar request in browser's 'developer tools'

[Gustry]

in 3.7 there is not a similar request in browser's 'developer tools'

There is, check my screenshot, it's a POST request. There must be a GetLegendGraphic request ... it's the only way to ask QGIS server for the legend.

[Antoviscomi]

@Gustry there is not a request GetLegendGraphic on mine that's all

[Antoviscomi]

only in Payload it is, and no response in LWC 3.7
repository=tempor&project=ProvaFiles&SERVICE=WMS&REQUEST=GetLegendGraphic&VERSION=1.3.0&FORMAT=application%2Fjson&LAYER=edificicetraro_ctr%2Cterritori_boschi_foreste%2Corto2008&STYLES=predefinito%2Cpredefinito%2Cpredefinito

[Gustry]

there is not a request GetLegendGraphic on mine that's all

In your screenshot, it's the last one. Click one it, you will see in the Request tab, then open the "Response tab" and paste the content here

[Antoviscomi]

@Gustry
this is the response

{
    "nodes": [
        {
            "symbols": [
                {
                    "title": "Band 1"
                },
                {
                    "title": ""
                }
            ],
            "title": "Temperatura Massima (\u00b0C)",
            "type": "layer",
            "name": "orto2008",
            "layerName": "Temperatura Massima (\u00b0C)"
        }
    ],
    "title": ""
}

[Gustry]

There isn't any icon key in the JSON.

This JSON is generated by QGIS Server, it's a graphical legend in JSON format.

This issue must be reported in QGIS. When QGIS will be fixed, it's high probability that the icon will be displayed in Lizmap Web Client then.

[Antoviscomi]

@Gustry why in LWC 3.6.9 it works? There is not the same request?

[Gustry]

• Before 3.7 : you can see your URL you have provided : FORMAT=image/png, QGIS server must give back to Lizmap Web Client a PNG file
• Now with 3.7, you can see FORMAT=application/json, QGIS server must give back a JSON representation of the legend.

So the bug is quite similar to qgis/QGIS#55651 as I mentioned before. QGIS server is skipping some layers in the JSON representation.

[nboisteault]

@Gustry So we could use the FORMAT=image/png request for raster layers?

[josemvm]

@Gustry So we could use the FORMAT=image/png request for raster layers?

@Gustry is it possible fix it with the workaround above? this is a little annoying... in production environment

thanks

[Gustry]

Yes @josemvm I know this issue, it's unfortunate and I understand...
But there is nothing I can do here, I'm doing the same answer as on #4328 (comment)
Feel free to contact us.

[Gustry]

Given the work in 3liz/qgis-lizmap-server-plugin#77 we could notice that rendering the raster legend with QGIS < 3.34 is broken.

Supporting raster legend 3.7 will only work at least with QGIS 3.34.

@josemvm which version are you using ?
@Antoviscomi We can see your request that this is a QGIS Server < 3.34

[josemvm]

hi @Gustry i'am using qgis server 3.28

[Gustry]

???

@josemvm We understand when there is a minimum of text and also when there is a single ?. It looks like #4377

this is a little annoying... in production environment

This is annoying as well to read, when we are spending so many "unpaid" time trying to make an opensource product.

[Antoviscomi]

@Gustry the above request was february 5 dated, now I'm on 3.36 version of QGisServer but I've not looked at this issue anymore, so I cannot tell It's yet here. I can test it asap if needed

@Gustry this is the request from LWC 3.7.7 on QGISServer 3.36.2

{
    "nodes": [
        {
            "symbols": [
                {
                    "title": "Band 1: Red (Red)"
                },
                { 
                    "icon": "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",
                    "max": 255,
                    "min": 0,
                    "title": ""
                }
            ],
            "title": "550041_ORTO",
            "type": "layer",
            "name": "l_550041_ORTO",
            "layerName": "550041_ORTO"
        }
    ],
    "title": ""
}

and this is the result on LWC 3.7.7 Canvas and TOC

the legend is now visible but however it seems a little bit small

[Gustry]

Thanks for checking @Antoviscomi

[Antoviscomi]

It's a pleasure @Gustry

[josemvm]

@Gustry i'm sorry, you are right but i had no intention of hurting anyone or devaluing your work or project

[gioman]

and this is the result on LWC 3.7.7 Canvas and TOC

the legend is now visible but however it seems a little bit small

Doesn't this mean that the reported issue is fixed (meaning also that QGIS 3.34 is necessary?)?

[Gustry]

Using QGIS 3.34 is indeed better, but the image provided by QGIS server is too small.
Definitely do not use QGIS < 3.34 for raster symbology.

[Antoviscomi]

@Gustry @gioman in 3.36 version it's small also, so I think it's better to try to adjust the served image dimension before to render it in legend (i.e. managing it with a zoom control?)

[Antoviscomi]

The default values of height and width are 16 px, if its possible to change it only for raster legend, i .e. via bootstrap or via script, the image become as large as we need (this as workaround).
in the belowe screenshots I've symply altered theese values in legend style to h = 75 px and W = 35 px

[gioman]

Using QGIS 3.34 is indeed better, but the image provided by QGIS server is too small.

@Gustry any reason why QGIS server returns (on purpose?) such small raster legend?

[Gustry]

I don't know. Maybe first developed for vector purpose/testing ?

According to the PR I made, the GetLegendGraphic JSON was working nicely on QGIS 3.16. Then with LTR 3.22 and 3.28, the JSON was broken, and then on 3.34, the JSON output is back, so no a lot of users on QGIS 3.22 and 3.28 it seems.

[gioman]

I don't know. Maybe first developed for vector purpose/testing ?

According to the PR I made, the GetLegendGraphic JSON was working nicely on QGIS 3.16. Then with LTR 3.22 and 3.28, the JSON was broken, and then on 3.34, the JSON output is back, so no a lot of users on QGIS 3.22 and 3.28 it seems.

@Gustry not sure I follow: what would be the ideal fix here, patch QGIS Server to generate raster legends with a more reasonable size?

[josemvm]

According to the PR I made, the GetLegendGraphic JSON was working nicely on QGIS 3.16. Then with LTR 3.22 and 3.28, the JSON was broken, and then on 3.34, the JSON output is back, so no a lot of users on QGIS 3.22 and 3.28 it seems.

@Gustry according to my latest experiences, I think the problem lies on LWC and not on qgis server.
i have tested on qgis server 3.28 and LWC 3.6.14-pre and this last version of LWC can render the raster symbology perfectly:

[josemvm]

ok, sorry...

This a GetLegendGraphic as a picture.
Now, Lizmap use the GetLegendGraphic as JSON, to be able to have a checkbox

[Gustry]

i have tested on qgis server 3.28 and LWC 3.6.14-pre

@josemvm Before LWC 3.7, whatever the version of QGIS server, the format is PNG #4036 (comment)

[josemvm]

@josemvm Before LWC 3.7, whatever the version of QGIS server, the format is PNG #4036 (comment)

@Gustry 3.22(.16)

[Gustry]

@josemvm "Whatever" means "regardless" ;-)
It doesn't matter the version of QGIS server used, only LWC version, requesting the legend in JSON format.

@Gustry not sure I follow: what would be the ideal fix here, patch QGIS Server to generate raster legends with a more reasonable size?

@gioman Yes, being able to set the size of the picture would be better, or at least increase it by default, like the rendering in QGIS Desktop.

Doing the tip of @Antoviscomi works, but with text/fonts, this can lead to "transformed vertically" text

[Antoviscomi]

Doing the tip of @Antoviscomi works, but with text/fonts, this can lead to "transformed vertically" text

@Gustry i meanth that the 'zoom/size' control should acts on the png part only of raster legend served by QGIS Server, obviously if is possible to manage it separately from text part, so that the text part will not deformed

[gioman]

@gioman Yes, being able to set the size of the picture would be better, or at least increase it by default, like the rendering in QGIS Desktop.

@Gustry so this is the ideal solution you are looking for, correct?

[gioman]

Doing the tip of @Antoviscomi works, but with text/fonts, this can lead to "transformed vertically" text

I'm not sure I understand how the workaround works.

[Antoviscomi]

I'm not sure I understand how the workaround works

@gioman I suggest to add a size control in LWC that allow to manage the height/width of png legend served by QGIS server (now the default size readed by LWC is 16x16px, that seems very small) so a control (hardcoded in LWC css i.e.) should permit to well adapts these dimensions

[josemvm]

@josemvm Before LWC 3.7, whatever the version of QGIS server, the format is PNG https://github.com/3liz/lizmap-web-client/>issues/4036#issuecomment-1927391719

@Gustry i misinterpreted your affirmation
thanks

[josemvm]

maybe an option in the lizmap plugin to GetLegendGraphic as a picture/png, only for lwc 3.7 (?)

[Gustry]

Thanks @Antoviscomi for the correction, indeed, way better !

@josemvm yes, we have talked about that internally. It might be needed maybe for some rendering engine, for like proportional circle. Feel free to contact us.

[Antoviscomi]

@Gustry @gioman @josemvm

setting

height: 'auto;

in map.css at

lizmap-treeview img.legend{
    height: 16px;
    width: 16px;
}

the png raster legend it seems to works as expetted

[Gustry]

Thanks @Antoviscomi for the fix
Fixed in next 3.7 and 3.8