How to get ascender/descender and x height for a g

问题:

I need to get a ascender/descender and x-height..

By using following code I can find the descender and the total height:

descender_height = paint.descent();
total_height = descender_height - paint.ascent();
//ascender = ?; is this always equal to descender height?
//x_height = ?; total_height - 2*descender_height ?

Thanks

回答1:

I would think the ascender and descender height would typically be the same, but I wouldn't depend on it for every font. I don't really see a direct way to get to the x-height, but a trick you could use would be something like the below. Also, for the total height, are you talking about the absolute distance from the highest ascender to the lowest descender? I've also included something for that below. I haven't tested these myself, but it should work (but let me know if I'm misinterpreting something you've said):

// Assuming TextPaint/Paint tp;
Rect bounds;

// this will just retrieve the bounding rect for 'x'
tp.getTextBounds("x", 0, 1, bounds);
int xHeight = bounds.height();

Paint.FontMetrics metrics = tp.getFontMetrics();
int totalHeight = metrics.top - metrics.bottom;

回答2:

This is what worked for me:

Paint.FontMetrics fm = paint.getFontMetrics();
int totalHeight = (int)(fm.bottom - fm.top + .5f);