Wednesday, May 01, 2013

Simpler way to create fonts

Just a quick note about the new and simpler way to create fonts in wxWidgets 2.9: in addition to a multitude of wxFont constructors taking various font attributes, such as size, style, weight, face name and so on, there is now another constructor, taking a single wxFontInfo object that combines all of them together and allows to use the named parameter idiom for the font creation.

It may seem non-obvious how can adding another constructor help with the problem of having too many constructors, so here is a quick example to show how it does: suppose you want to create an underlined, 12 point version of "Courier" font. Here is how you'd do it currently:

wxFont f(12, wxFONTFAMILY_DEFAULT, wxFONTSTYLE_NORMAL, wxFONTWEIGHT_NORMAL, true, "Courier");
And here is how you'd do it with the new constructor:
wxFont f(wxFontInfo(12).Underlined().FaceName("Courier"));

Hopefully the advantages from the point of view of the library user are clear:

  • You don't need to specify the default parameters such as wxFONTFAMILY_DEFAULT, that you don't care about.
  • Each font attribute is clearly written out, while the meaning of true (which meant that the font should be underlined, by the way) was hardly obvious in the first form.
  • You can specify the parameters in any order instead of having to check the documentation every time.
  • Last and really least but still: you can create strike-through fonts (notice that they are only supported under MSW and GTK currently) using the new constructor using the natural Strikethrough() syntax, while this wasn't supported at all with the old constructor.
From our, i.e. developers, point of view, there is one extra important advantage, related to the last point: if support for a new wxFont attribute is added later, this way of creating fonts will be easy to extend to support it.

So my advice is to use wxFontInfo in all the new code using wxWidgets 2.9. The old constructors are not going anywhere and can still be used (except for the one taking int flags which was added for 2.9.4 and now removed to avoid ambiguities with the other existing constructors), but there is no reason to prefer them to the new one.

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