Created attachment 35248 [details]
There are some pictures in the attachment which can explain the problem clearly.
DejaVu Serif fonts are too big in 9 pt in chinese environment. They are higher than Chinese fonts. And my antialias is ture and hintstyle is slight.
However, if I turn hintstyle to middle or full, the problem will go way. But all fonts are ugly when hintstyle is middle or full in my opinion. I like slight. In addition, Sans and Sans Mono are no problem with slight and middle and full hintstyle.
More information is an attachment below.
Reassigning bug to freetype as this is independant of the font, even if the usecase is DejaVu Serif.
Changing Summary from "Serif in 9 pt is too big!!!" to "Latin larger than Chinese with slight hinting at 9pt"
As Denis says: we can't do anything about this:
- we don't have any control over the freetype autohinter so we also don't control how big the fonts are rendered at each size. In fact, Sans, Mono and Serif have exactly the same metrics when it comes to the heights of the letters, it's just the algorithms in freetype that trigger it to be different at one specific setting in your particular version of freetype.
- and even if we did control the autohinter, there's no way for us to make sure that our font works with other fonts well at all sizes. Making it work for this specific font would break it for others. There's something called a BASE table in OpenType to handle mixing different scripts, but it's almost completely unsupported and it probably wouldn't work exactly right anyway at these small sizes where hinting is modifying the height of the glyphs.
The only solution I see is to manually adjust fontconfig parameters so that the font in slight hinting mode gets a size correction, this is, you load it at, say, 9pt but report it as 10pt.
Similar problems exist with other fonts too, for example, think of using Times and Helvetica at the same time, at the same size: They simply don't fit together.
(In reply to comment #1)
> Reassigning bug to freetype as this is independant of the font, even if the
> usecase is DejaVu Serif.
> Changing Summary from "Serif in 9 pt is too big!!!" to "Latin larger than
> Chinese with slight hinting at 9pt"
But the font named Droid Serif work correctly at 9pt and work fine at every sizes. Sigh...