Using font family multiple times results in default font

[saschagehlich]

Issue or Feature

When registering multiple font files with the same font family, but different styles (like in examples/font.js), the default font is used instead of the given font files. When using different font family names for every font file, it works.

Right now, examples/font.js creates this image:

As you can see, the Pfennig font is not used at all.

Changing the font definitions like this (and changing the font property on the rendering context accordingly):

Canvas.registerFont(fontFile('Pfennig.ttf'), {family: 'Pfennig'})
Canvas.registerFont(fontFile('PfennigBold.ttf'), {family: 'PfennigBold', weight: 'bold'})
Canvas.registerFont(fontFile('PfennigItalic.ttf'), {family: 'PfennigItalic', style: 'italic'})
Canvas.registerFont(fontFile('PfennigBoldItalic.ttf'), {family: 'PfennigBoldItalic', weight: 'bold', style: 'italic'})

This results in:

Your Environment

• Version of node-canvas (e.g. 1.4.0): 2.0.0-alpha.3
• Environment (e.g. node 4.2.0 on Mac OS X 10.8): node 7.9.0 on macOS 10.12.6

[chearon]

Spent an hour trying to figure out why, and then I remembered that I already know why.

The three consecutive registerFont calls basically add 3 PangoFontDescriptions to an internal list held in node-canvas. When you set ctx.font = "pfennigFont" it finds 3 matches, and joins the real font names with commas before it sends the font query to Pango. So what gets sent to the OS in this case would be {family: "Pfennig, Pfennig, Pfennig"}.

That's a totally valid query, and it works on Linux and Windows. But this bug in Pango causes the bug you're seeing. See my comment on the original Canvas.registerFont PR here. I submitted a patch to Pango here but they haven't said anything, I'll see if I can ping Behdad or someone else, but in the meantime I could probably update the code so that it doesn't send duplicate font names, which would also fix it.

[saschagehlich]

Thanks a lot for investigating @chearon!

[chearon]

No problem, thanks for reporting. I plan on making a PR soon. This should work out-of-the-box on macOS.

[pravdomil]

see
https://gitlab.gnome.org/GNOME/pango/merge_requests/4

[LinusU]

Should be fixed in pango 1.42.3? Could someone confirm?

[chearon]

Yep, fixed in exactly that version.