[Bug]: Text alignment issues when using different font sizes on the same line

[Tchou]

What happened?

Conky version: 1.21.7
Backend: X11
Font engine: xft

While investigating why conky was truncating its content (last lines of text partially cut), I found out that it behaves randomly when using different font sizes on the same line. Note that even at the same pixelsize, some fonts may be higher than others. Also it is a common use case to have several fonts on the same line (e.g. using a symbolic font for icons and a regular one for text). A simple reproducer is the following one (note the two pixel sizes at the bottom of the config):

conky.config = {
    background = false,
    own_window = true,
    own_window_argb_visual = true,
    own_window_type = 'desktop',
    alignment = 'top_right',
    draw_outline = false,
    draw_shades = false,
    minimum_height = 1,
    minimum_width = 10,
    maximum_width = 4000,
    draw_borders = false,
    border_outer_margin = 0,
    border_inner_margin = 0,
    border_width = 0,
    use_xft = true,
    font = 'Hack:pixelsize=30',
    font0 = 'Helvetica:pixelsize=30'
}
conky.text = [[\
1 ${font}A${font0}B${font}C${font0}D${font}E
2 ${font}A${font0}B${font}C${font0}D${font}E
3 ${font}A${font0}B${font}C${font0}D${font}E
4 ${font}A${font0}B${font}C${font0}D${font}E]]

I expect conky to display 4 lines. Because the fontsizes are different, the text is misaligned and the text height computation is wrong.

If we increase the font0 size a bit, the errors seem to compensate somehow:

 font = 'Hack:pixelsize=30',
 font0 = 'Helvetica:pixelsize=40'

The text is misaligned, but still stays within the computed line height, the the four lines appear. Changing the size so that font is larger is worse:

 font = 'Hack:pixelsize=40',
 font0 = 'Helvetica:pixelsize=30'

I would expect the various texts to be aligned along their baseline.

Version

1.21.7

Which OS/distro are you seeing the problem on?

Ubuntu

Conky config

conky.config = {
    background = false,
    own_window = true,
    own_window_argb_visual = true,
    own_window_type = 'desktop',
    alignment = 'top_right',
    draw_outline = false,
    draw_shades = false,
    minimum_height = 1,
    minimum_width = 10,
    maximum_width = 4000,
    draw_borders = false,
    border_outer_margin = 0,
    border_inner_margin = 0,
    border_width = 0,
    use_xft = true,
    font = 'Hack:pixelsize=30',
    font0 = 'Helvetica:pixelsize=30'
}
conky.text = [[\
1 ${font}A${font0}B${font}C${font0}D${font}E
2 ${font}A${font0}B${font}C${font0}D${font}E
3 ${font}A${font0}B${font}C${font0}D${font}E
4 ${font}A${font0}B${font}C${font0}D${font}E]]

Stack trace

No response

Relevant log output

No response

[Tchou]

To anyone reading this, the link points to a suspicious windows binary.
@brndnmtthws can you delete/hide the above comment ? I have already reported this user to GH.

[brndnmtthws]

To anyone reading this, the link points to a suspicious windows binary. @brndnmtthws can you delete/hide the above comment ? I have already reported this user to GH.

Weird, thanks. Comment deleted and that account has been blocked.