CenteredImageSpan.java 文件源码

@Override
public int getSize(Paint paint, CharSequence text,
                   int start, int end,
                   Paint.FontMetricsInt fm) {
    Drawable d = getCachedDrawable();
    Rect rect = d.getBounds();

    if (fm != null) {
        // Centers the text with the ImageSpan
        if ((rect.bottom - (fm.descent - fm.ascent)) >= 0) {
            // Stores the initial descent and computes the margin available
            initialDescent = fm.descent;
            extraSpace = rect.bottom - (fm.descent - fm.ascent);
        }

        fm.descent = extraSpace / 2 + initialDescent;
        fm.bottom = fm.descent;

        fm.ascent = -rect.bottom + fm.descent;
        fm.top = fm.ascent;
    }

    return rect.right;
}