Sets the resolution for the fontmap.
This is a scale factor between points specified in a `PangoFontDescription` and Cairo units. The default value is 96, meaning that a 10 point font will be 13 units high. (10 * 96. / 72. = 13.3).
| this |
a `PangoCairoFontMap` |
| dpi |
the resolution in "dots per inch". (Physical inches aren't actually involved; the terminology is conventional.) |