How can I determine the line-height of a font?

[NathanWailes]

Hi,

I'm trying to use cairocffi to render text to PNGs which I then stitch into a lyrics video that highlights the currently-performed syllable, kind of like karoake. You can see an example of the goal here (this example uses PIL instead of cairocffi): https://www.youtube.com/watch?v=9u9ylseLAfU

The problem with PIL is that if I separately-render two parts of a word so that I can have the parts colored differently, the kerning between the letters is lost.

You can see the previous issues I've created here:

• Pillow - Font spacing changes
• fontforge - How do I reliably get the kerning information into a file?

Anyway, I'm now trying to use cairocffi, but now I'm running into issues because I don't seem to have access to information that PIL provides. For example, I don't see how I can get the height of the text that is (or will be) rendered to the screen, so that I can use that to properly vertically-position the text or limit the height of the image so that I can overlay it on top of the background image I create with PIL.

Any idea how I could get that information?

[liZe]

Any idea how I could get that information?

Yes!

Cairo provides text extents with width, height, and other information. You'll find other useful functions on the same page, and on the text module page.

If you have more specific questions, you should ask Cairo devs using their mailing-list or IRC, they'll probably have more useful answers! CairoCFFI is just a wrapper around Cairo.