Definition
HTML Standard defines TextMetrics
[Exposed=(Window,Worker)]
interface TextMetrics {
// x-direction
readonly attribute double width; // advance width
readonly attribute double actualBoundingBoxLeft;
readonly attribute double actualBoundingBoxRight;
// y-direction
readonly attribute double fontBoundingBoxAscent;
readonly attribute double fontBoundingBoxDescent;
readonly attribute double actualBoundingBoxAscent;
readonly attribute double actualBoundingBoxDescent;
readonly attribute double emHeightAscent;
readonly attribute double emHeightDescent;
readonly attribute double hangingBaseline;
readonly attribute double alphabeticBaseline;
readonly attribute double ideographicBaseline;
};