Note that you shouldn't use 2) or 3) for non-monospace fonts because of kerning.
font := StandardFonts defaultFont. font widthOfString: 'eT'. "16" font widthOfString: 'Te'. "15" 'eT' inject: 0 into: [ :width :c | width + (font getGlyphWidth: c) ]. "13.416015625" 'Te' inject: 0 into: [ :width :c | width + (font getGlyphWidth: c) ]. "13.416015625" 4) seems fine font := StandardFonts defaultFont. provider := CairoScaledFont fromFreetypeFont: font realFont. width := [ :string | converter := CairoUTF8Converter new. converter convert: string from: 1 to: string size. stringExtents := CairoTextExtents new. provider getExtentsOf: converter buffer into: stringExtents. stringExtents width ]. width value: 'eT'. "12.463638305664063" width value: 'Te'. "12.561752319335938" On Tue, Oct 27, 2015 at 12:27 PM, Yuriy Tymchuk <[email protected]> wrote: > Hi Alex, > > This is indeed a very useful information. You can also put it on > StackOverflow, then it will be Googlable. > > Cheers. > Uko > > > > On 27 Oct 2015, at 12:02, Aliaksei Syrel <[email protected]> wrote: > > Hi > > I'm sending it here so that it doesn't get lost. > > > There are multiple ways to measure string width. In the following examples > performance will be tested measuring 10`000 times the width of the > following string: > > *string := 'abcdefghijklmnopqrstuvwxyz 0123456789!@#$%^&*()_+'.* > > 1) The most straightforward way is to send #widthOfString: to the font. > Time to run gives around 250ms. > http://ws.stfx.eu/2Q5YA9DFTRDR > Resulting value is rounded to integer and seems to be not absolutely > correct and precise. > > 2) More complex way is to go deeper on the level of glyphs and manually > summarise the width of each character in the string sending > #getGlyphWidth: character to the font. Time to run gives around 750ms. > http://ws.stfx.eu/ETBEW1EHAAZ8 > Resulting value is float and looks like correct and precise value. > > 3) Even more complex is to use CairoFontMetricsProvider instead of font's > methods. The same as in 2nd case we measure each character. Time to run > around 350ms. > http://ws.stfx.eu/7I89DMD0ZLM3 > Resulting value is exactly the same as in the 2nd case. With almost equal > performance to 1st it is nice alternative. > > 4) One more way is to let native cairo to calculate everything for us. > Calls happen through nativeboost. Time to run around 120ms. > http://ws.stfx.eu/HYD76OMIOM7L <http://ws.stfx.eu/HYD76OMIOM7L> > As result it returns *CairoTextExtents* which allows to calculate width > and height with one call. > > Cheers, > Alex > > >
