Question

In core Java book it says

The width of the rectangle that the getStringBounds method returns is the horizontal
extent of the string. The height of the rectangle is the sum of ascent, descent, and
leading. The rectangle has its origin at the baseline of the string. The top y -coordinate of the rectangle is negative. Thus, you can obtain string width, height, and
ascent as follows:

double stringWidth = bounds.getWidth();
double stringHeight = bounds.getHeight();
double ascent = -bounds.getY();

What does the author mean when saying that the rectangle has its origin at the baseline of the string, while top y-coordinate is the ascent?

Where does the bounding rectangle of the string start?

with a test string i got the following:

w: 291.0
h: 91.265625
x:0.0
y:-72.38671875
descent: 15.8203125
leading: 3.0585938

That mean the rectangle origin is at the leading not the baseline, am i correct on this?

Answer 1

The math works out:

72.38671875 ascent + 15.8203125 descent + 3.0585938 leading = 91.265625 total height

This tutorial on 2D Text has an image illustrating leading, descent, and ascent.

In your specific case, 72.38671875 is the height of the ascent. That’s measured from the baseline to the top of the tallest glyph. The leading is the space between the bottom of the descender to the top of the next line.

The bounding rectangle is relative to the baseline. The API for FontMetrics.getStringBounds states “The returned bounds is in baseline-relative coordinates”, which explains your results. x will always be 0, and the height of the bounding box will be the ascent plus the descent plus the leading.