How to do font fallback? For example, a user uses an English font "Arial", and suddenly she types a Chinese character. the character doesn't present in Arial, so we need to find a fallback font that does.
Let's say we find one, but the fallback font has different sizing. How to scale the character to match the other font? What about kerning and other positioning issues?
And also, is your cache ever increasing? Imagine a user zooms in, do you retire those small glyphs?
How to do font fallback? For example, a user uses an English font "Arial", and suddenly she types a Chinese character. the character doesn't present in Arial, so we need to find a fallback font that does.
Let's say we find one, but the fallback font has different sizing. How to scale the character to match the other font? What about kerning and other positioning issues?
And also, is your cache ever increasing? Imagine a user zooms in, do you retire those small glyphs?