Font.java 文件源码

/**
 * Returns the logical bounds of the specified array of characters
 * in the specified <code>FontRenderContext</code>.  The logical
 * bounds contains the origin, ascent, advance, and height, which
 * includes the leading.  The logical bounds does not always enclose
 * all the text.  For example, in some languages and in some fonts,
 * accent marks can be positioned above the ascent or below the
 * descent.  To obtain a visual bounding box, which encloses all the
 * text, use the {@link TextLayout#getBounds() getBounds} method of
 * <code>TextLayout</code>.
 * <p>Note: The returned bounds is in baseline-relative coordinates
 * (see {@link java.awt.Font class notes}).
 * @param chars an array of characters
 * @param beginIndex the initial offset in the array of
 * characters
 * @param limit the end offset in the array of characters
 * @param frc the specified <code>FontRenderContext</code>
 * @return a <code>Rectangle2D</code> that is the bounding box of the
 * specified array of characters in the specified
 * <code>FontRenderContext</code>.
 * @throws IndexOutOfBoundsException if <code>beginIndex</code> is
 *         less than zero, or <code>limit</code> is greater than the
 *         length of <code>chars</code>, or <code>beginIndex</code>
 *         is greater than <code>limit</code>.
 * @see FontRenderContext
 * @see Font#createGlyphVector
 * @since 1.2
 */
public Rectangle2D getStringBounds(char [] chars,
                                int beginIndex, int limit,
                                   FontRenderContext frc) {
    if (beginIndex < 0) {
        throw new IndexOutOfBoundsException("beginIndex: " + beginIndex);
    }
    if (limit > chars.length) {
        throw new IndexOutOfBoundsException("limit: " + limit);
    }
    if (beginIndex > limit) {
        throw new IndexOutOfBoundsException("range length: " +
                                            (limit - beginIndex));
    }

    // this code should be in textlayout
    // quick check for simple text, assume GV ok to use if simple

    boolean simple = values == null ||
        (values.getKerning() == 0 && values.getLigatures() == 0 &&
          values.getBaselineTransform() == null);
    if (simple) {
        simple = ! FontUtilities.isComplexText(chars, beginIndex, limit);
    }

    if (simple) {
        GlyphVector gv = new StandardGlyphVector(this, chars, beginIndex,
                                                 limit - beginIndex, frc);
        return gv.getLogicalBounds();
    } else {
        // need char array constructor on textlayout
        String str = new String(chars, beginIndex, limit - beginIndex);
        TextLayout tl = new TextLayout(str, this, frc);
        return new Rectangle2D.Float(0, -tl.getAscent(), tl.getAdvance(),
                                     tl.getAscent() + tl.getDescent() +
                                     tl.getLeading());
    }
}