raster export (save as...) not working if QGIS locale uses commas as decimal separator

[gioman]

QGIS master Ubuntu 20.04

*) in QGIS properties > general set a locale to language that uses the comma as a decimal separator (pt_PT in my case)

*) add a raster layer

*) right click the raster layer > export > save as...

*) set the export properties and try to set a HxV resolution to a decimal value > QGIS allows to enter the only the comma as a separator

*) click "ok" >

Cannot write raster. Error code: data source creation
Cannot create new dataset  /tmp/test.tif:
Attempt to create 0x0 dataset is illegal,sizes must be larger than zero.

*) works ok if resolution is set to values with no decimals

I am pretty sure to have seen this (QGIS not letting use the point as a separator in case the QGIS locale uses the comma) in other parts of QGIS but I don't recall where right now.

[agiudiceandrea]

It seems the same occurs in the Extent box with a Locale with the comma as a decimal separator:

and in the No data values box, where it is possible to enter a comma as decimal separator but the values will not be used (the value range set will not be nodata in the exported raster layer), while using the point as a decimal separator the values will be used.

[agiudiceandrea]

I think the issue is caused by the use of QDoubleValidator with QLineEdit widgets and then to use toDouble() and QString::number(), which are not Locale aware, instead of QLocate().toDouble() and QLocale().toString() or the new QgsDoubleValidator.
Similar issues in other part of the code have been fixed by @SebastienPeillet and @elpaso.
See e.g. #33859, #37136 and #8358

[gioman]

Please note that the same error message is returned if the "resolution" fields are left empty (if the layer being exported is a WMS this fields are empty by default), regardless of the QGIS locale. This was not the case in the past see #29891 (comment) I suggest to not enable the "ok" button unless the resolution fields are filled.

[SrNetoChan]

What doyou think it should be the expected behaviour, should the user be allowed to input either points or commas in the text widgets?

[SrNetoChan]

@gioman I have created a regression test case to verify the locale comma related problems in the raster dialog:

https://qgis.tenant.kiwitcms.org/case/42/

We should run those on all platforms when the fix is merged into master.

[gioman]

We should run those on all platforms when the fix is merged into master.

@SrNetoChan thanks, agree!