QGIS: Changing labeling color within label

Question

I have a point layer in QGIS that looks like the following picture:

Content of the Dicke Auf field :

BS 4/ DPM 4
Ansatzhöhe: 275.96
UK Auffüllung: 274.71
Dicke Auffüllung: 1.3
OK Sand: 274.62
Grundwasser: 271,26

Now I'd like to change the color of the different labels individually (e.g. OK Sand = red, Grundwasser = blue). Is that possible?

I already tried the editor, but I only managed to change the entire label:

if ("Dicke Auf"  >=  '0,5','cyan','red')

Answer 1

Labeling in different colors is possible with html-formatted labels, introduced in QGIS 3.28. See here for some use cases.

Check the box Allow html formatting in the Text tab of label settings. Then insert a html code in the value field. Use format() function, define the styles you want using placeholders like %1, then add the text content you want to have formatted this way.

Here is an example of the syntax to use to have the first line with the content of field_1 in blue, on the next line field_2 in red:

format(
  '<span style="color:blue"> <p> %1 </p> </span> <br>
   <span style="color:red"> %2 </span>',
  field_1,
  field_2
)

or, with the same result, simply concatenating the different elements:

'<span style="color:blue"><p>'  ||  field_1  || '</p></span>'  || 
'<span style="color:red">'  ||  field_2  || '</span><br>'

You can also mix this to get different font sizes, bold/strong, italic etc. like this:

'<span style="color:blue"><p style="font-size: 40pt"; ><strong>'  ||  field_1  || '</strong></p></span>'  || 
'<span style="color:red"><p style="font-size: 30pt"><i>'  ||  field_2  || '</i></p></span>'  || 
'<span style="color:green"><p style="font-size: 20pt">'  ||  field3 || '</p></span>'