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 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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 */

package java.awt;

import java.awt.Graphics2D;

import java.awt.font.FontRenderContext;

import java.awt.font.LineMetrics;

import java.awt.geom.Rectangle2D;

import java.text.CharacterIterator;

/**

 * The <code>FontMetrics</code> class defines a font metrics object, which

 * encapsulates information about the rendering of a particular font on a

 * particular screen.

 * <p>

 * <b>Note to subclassers</b>: Since many of these methods form closed,

 * mutually recursive loops, you must take care that you implement

 * at least one of the methods in each such loop to prevent

 * infinite recursion when your subclass is used.

 * In particular, the following is the minimal suggested set of methods

 * to override in order to ensure correctness and prevent infinite

 * recursion (though other subsets are equally feasible):

 * <ul>

 * <li>{@link #getAscent()}

 * <li>{@link #getLeading()}

 * <li>{@link #getMaxAdvance()}

 * <li>{@link #charWidth(char)}

 * <li>{@link #charsWidth(char[], int, int)}

 * </ul>

 * <p>

 * <img src="doc-files/FontMetrics-1.gif" alt="The letter 'p' showing its 'reference point'" border=15 align

 * ALIGN=right HSPACE=10 VSPACE=7>

 * Note that the implementations of these methods are

 * inefficient, so they are usually overridden with more efficient

 * toolkit-specific implementations.

 * <p>

 * When an application asks to place a character at the position

 * (<i>x</i>,&nbsp;<i>y</i>), the character is placed so that its

 * reference point (shown as the dot in the accompanying image) is

 * put at that position. The reference point specifies a horizontal

 * line called the <i>baseline</i> of the character. In normal

 * printing, the baselines of characters should align.

 * <p>

 * In addition, every character in a font has an <i>ascent</i>, a

 * <i>descent</i>, and an <i>advance width</i>. The ascent is the

 * amount by which the character ascends above the baseline. The

 * descent is the amount by which the character descends below the

 * baseline. The advance width indicates the position at which AWT

 * should place the next character.

 * <p>

 * An array of characters or a string can also have an ascent, a

 * descent, and an advance width. The ascent of the array is the

 * maximum ascent of any character in the array. The descent is the

 * maximum descent of any character in the array. The advance width

 * is the sum of the advance widths of each of the characters in the

 * character array.  The advance of a <code>String</code> is the

 * distance along the baseline of the <code>String</code>.  This

 * distance is the width that should be used for centering or

 * right-aligning the <code>String</code>.

 * <p>Note that the advance of a <code>String</code> is not necessarily

 * the sum of the advances of its characters measured in isolation

 * because the width of a character can vary depending on its context.

 * For example, in Arabic text, the shape of a character can change

 * in order to connect to other characters.  Also, in some scripts,

 * certain character sequences can be represented by a single shape,

 * called a <em>ligature</em>.  Measuring characters individually does

 * not account for these transformations.

 * <p>Font metrics are baseline-relative, meaning that they are

 * generally independent of the rotation applied to the font (modulo

 * possible grid hinting effects).  See {@link java.awt.Font Font}.

 *

 * @author      Jim Graham

 * @see         java.awt.Font

 * @since       JDK1.0

 */

public abstract class FontMetrics implements java.io.Serializable {

    static {

        /* ensure that the necessary native libraries are loaded */

        Toolkit.loadLibraries();

        if (!GraphicsEnvironment.isHeadless()) {

            initIDs();

        }

    }

    private static final FontRenderContext

        DEFAULT_FRC = new FontRenderContext(null, false, false);

    /**

     * The actual {@link Font} from which the font metrics are

     * created.

     * This cannot be null.

     *

     * @serial

     * @see #getFont()

     */

    protected Font font;

    /*

     * JDK 1.1 serialVersionUID

     */

    private static final long serialVersionUID = 1681126225205050147L;

    /**

     * Creates a new <code>FontMetrics</code> object for finding out

     * height and width information about the specified <code>Font</code>

     * and specific character glyphs in that <code>Font</code>.

     * @param     font the <code>Font</code>

     * @see       java.awt.Font

     */

    protected FontMetrics(Font font) {

        this.font = font;

    }

    /**

     * Gets the <code>Font</code> described by this

     * <code>FontMetrics</code> object.

     * @return    the <code>Font</code> described by this

     * <code>FontMetrics</code> object.

     */

    public Font getFont() {

        return font;

    }

    /**

     * Gets the <code>FontRenderContext</code> used by this

     * <code>FontMetrics</code> object to measure text.

     * <p>

     * Note that methods in this class which take a <code>Graphics</code>

     * parameter measure text using the <code>FontRenderContext</code>

     * of that <code>Graphics</code> object, and not this

     * <code>FontRenderContext</code>

     * @return    the <code>FontRenderContext</code> used by this

     * <code>FontMetrics</code> object.

     * @since 1.6

     */

    public FontRenderContext getFontRenderContext() {

        return DEFAULT_FRC;

    }

    /**

     * Determines the <em>standard leading</em> of the

     * <code>Font</code> described by this <code>FontMetrics</code>

     * object.  The standard leading, or

     * interline spacing, is the logical amount of space to be reserved

     * between the descent of one line of text and the ascent of the next

     * line. The height metric is calculated to include this extra space.

     * @return    the standard leading of the <code>Font</code>.

     * @see   #getHeight()

     * @see   #getAscent()

     * @see   #getDescent()

     */

    public int getLeading() {

        return 0;

    }

    /**

     * Determines the <em>font ascent</em> of the <code>Font</code>

     * described by this <code>FontMetrics</code> object. The font ascent

     * is the distance from the font's baseline to the top of most

     * alphanumeric characters. Some characters in the <code>Font</code>

     * might extend above the font ascent line.

     * @return     the font ascent of the <code>Font</code>.

     * @see        #getMaxAscent()

     */

    public int getAscent() {

        return font.getSize();

    }

    /**

     * Determines the <em>font descent</em> of the <code>Font</code>

     * described by this

     * <code>FontMetrics</code> object. The font descent is the distance

     * from the font's baseline to the bottom of most alphanumeric

     * characters with descenders. Some characters in the

     * <code>Font</code> might extend

     * below the font descent line.

     * @return     the font descent of the <code>Font</code>.

     * @see        #getMaxDescent()

     */

    public int getDescent() {

        return 0;

    }

    /**

     * Gets the standard height of a line of text in this font.  This

     * is the distance between the baseline of adjacent lines of text.

     * It is the sum of the leading + ascent + descent. Due to rounding

     * this may not be the same as getAscent() + getDescent() + getLeading().

     * There is no guarantee that lines of text spaced at this distance are

     * disjoint; such lines may overlap if some characters overshoot

     * either the standard ascent or the standard descent metric.

     * @return    the standard height of the font.

     * @see       #getLeading()

     * @see       #getAscent()

     * @see       #getDescent()

     */

    public int getHeight() {

        return getLeading() + getAscent() + getDescent();

    }

    /**

     * Determines the maximum ascent of the <code>Font</code>

     * described by this <code>FontMetrics</code> object.  No character

     * extends further above the font's baseline than this height.

     * @return    the maximum ascent of any character in the

     * <code>Font</code>.

     * @see       #getAscent()

     */

    public int getMaxAscent() {

        return getAscent();

    }

    /**

     * Determines the maximum descent of the <code>Font</code>

     * described by this <code>FontMetrics</code> object.  No character

     * extends further below the font's baseline than this height.

     * @return    the maximum descent of any character in the

     * <code>Font</code>.

     * @see       #getDescent()

     */

    public int getMaxDescent() {

        return getDescent();

    }

    /**

     * For backward compatibility only.

     * @return    the maximum descent of any character in the

     * <code>Font</code>.

     * @see #getMaxDescent()

     * @deprecated As of JDK version 1.1.1,

     * replaced by <code>getMaxDescent()</code>.

     */

    @Deprecated

    public int getMaxDecent() {

        return getMaxDescent();

    }

    /**

     * Gets the maximum advance width of any character in this

     * <code>Font</code>.  The advance is the

     * distance from the leftmost point to the rightmost point on the

     * string's baseline.  The advance of a <code>String</code> is

     * not necessarily the sum of the advances of its characters.

     * @return    the maximum advance width of any character

     *            in the <code>Font</code>, or <code>-1</code> if the

     *            maximum advance width is not known.

     */

    public int getMaxAdvance() {

        return -1;

    }

    /**

     * Returns the advance width of the specified character in this

     * <code>Font</code>.  The advance is the

     * distance from the leftmost point to the rightmost point on the

     * character's baseline.  Note that the advance of a

     * <code>String</code> is not necessarily the sum of the advances

     * of its characters.

     *

     * <p>This method doesn't validate the specified character to be a

     * valid Unicode code point. The caller must validate the

     * character value using {@link

     * java.lang.Character#isValidCodePoint(int)

     * Character.isValidCodePoint} if necessary.

     *

     * @param codePoint the character (Unicode code point) to be measured

     * @return    the advance width of the specified character

     *            in the <code>Font</code> described by this

     *            <code>FontMetrics</code> object.

     * @see   #charsWidth(char[], int, int)

     * @see   #stringWidth(String)

     */

    public int charWidth(int codePoint) {

        if (!Character.isValidCodePoint(codePoint)) {

            codePoint = 0xffff; // substitute missing glyph width

        }

        if (codePoint < 256) {

            return getWidths()[codePoint];

        } else {

            char[] buffer = new char[2];

            int len = Character.toChars(codePoint, buffer, 0);

            return charsWidth(buffer, 0, len);

        }

    }

    /**

     * Returns the advance width of the specified character in this

     * <code>Font</code>.  The advance is the

     * distance from the leftmost point to the rightmost point on the

     * character's baseline.  Note that the advance of a

     * <code>String</code> is not necessarily the sum of the advances

     * of its characters.

     *

     * <p><b>Note:</b> This method cannot handle <a

     * href="../lang/Character.html#supplementary"> supplementary

     * characters</a>. To support all Unicode characters, including

     * supplementary characters, use the {@link #charWidth(int)} method.

     *

     * @param ch the character to be measured

     * @return     the advance width of the specified character

     *                  in the <code>Font</code> described by this

     *                  <code>FontMetrics</code> object.

     * @see        #charsWidth(char[], int, int)

     * @see        #stringWidth(String)

     */

    public int charWidth(char ch) {

        if (ch < 256) {

            return getWidths()[ch];

        }

        char data[] = {ch};

        return charsWidth(data, 0, 1);

    }

    /**

     * Returns the total advance width for showing the specified

     * <code>String</code> in this <code>Font</code>.  The advance

     * is the distance from the leftmost point to the rightmost point

     * on the string's baseline.

     * <p>

     * Note that the advance of a <code>String</code> is

     * not necessarily the sum of the advances of its characters.

     * @param str the <code>String</code> to be measured

     * @return    the advance width of the specified <code>String</code>

     *                  in the <code>Font</code> described by this

     *                  <code>FontMetrics</code>.

     * @throws NullPointerException if str is null.

     * @see       #bytesWidth(byte[], int, int)

     * @see       #charsWidth(char[], int, int)

     * @see       #getStringBounds(String, Graphics)

     */

    public int stringWidth(String str) {

        int len = str.length();

        char data[] = new char[len];

        str.getChars(0, len, data, 0);

        return charsWidth(data, 0, len);

    }

    /**

     * Returns the total advance width for showing the specified array

     * of characters in this <code>Font</code>.  The advance is the

     * distance from the leftmost point to the rightmost point on the

     * string's baseline.  The advance of a <code>String</code>

     * is not necessarily the sum of the advances of its characters.

     * This is equivalent to measuring a <code>String</code> of the

     * characters in the specified range.

     * @param data the array of characters to be measured

     * @param off the start offset of the characters in the array

     * @param len the number of characters to be measured from the array

     * @return    the advance width of the subarray of the specified

     *               <code>char</code> array in the font described by

     *               this <code>FontMetrics</code> object.

     * @throws    NullPointerException if <code>data</code> is null.

     * @throws    IndexOutOfBoundsException if the <code>off</code>

     *            and <code>len</code> arguments index characters outside

     *            the bounds of the <code>data</code> array.

     * @see       #charWidth(int)

     * @see       #charWidth(char)

     * @see       #bytesWidth(byte[], int, int)

     * @see       #stringWidth(String)

     */

    public int charsWidth(char data[], int off, int len) {

        return stringWidth(new String(data, off, len));

    }

    /**

     * Returns the total advance width for showing the specified array

     * of bytes in this <code>Font</code>.  The advance is the

     * distance from the leftmost point to the rightmost point on the

     * string's baseline.  The advance of a <code>String</code>

     * is not necessarily the sum of the advances of its characters.

     * This is equivalent to measuring a <code>String</code> of the

     * characters in the specified range.

     * @param data the array of bytes to be measured

     * @param off the start offset of the bytes in the array

     * @param len the number of bytes to be measured from the array

     * @return    the advance width of the subarray of the specified

     *               <code>byte</code> array in the <code>Font</code>

     *                  described by

     *               this <code>FontMetrics</code> object.

     * @throws    NullPointerException if <code>data</code> is null.

     * @throws    IndexOutOfBoundsException if the <code>off</code>

     *            and <code>len</code> arguments index bytes outside

     *            the bounds of the <code>data</code> array.

     * @see       #charsWidth(char[], int, int)

     * @see       #stringWidth(String)

     */

    public int bytesWidth(byte data[], int off, int len) {

        return stringWidth(new String(data, 0, off, len));

    }

    /**

     * Gets the advance widths of the first 256 characters in the

     * <code>Font</code>.  The advance is the

     * distance from the leftmost point to the rightmost point on the

     * character's baseline.  Note that the advance of a

     * <code>String</code> is not necessarily the sum of the advances

     * of its characters.

     * @return    an array storing the advance widths of the

     *                 characters in the <code>Font</code>

     *                 described by this <code>FontMetrics</code> object.

     */

    public int[] getWidths() {

        int widths[] = new int[256];

        for (char ch = 0 ; ch < 256 ; ch++) {

            widths[ch] = charWidth(ch);

        }

        return widths;

    }

    /**

     * Checks to see if the <code>Font</code> has uniform line metrics.  A

     * composite font may consist of several different fonts to cover

     * various character sets.  In such cases, the

     * <code>FontLineMetrics</code> objects are not uniform.

     * Different fonts may have a different ascent, descent, metrics and

     * so on.  This information is sometimes necessary for line

     * measuring and line breaking.

     * @return <code>true</code> if the font has uniform line metrics;

     * <code>false</code> otherwise.

     * @see java.awt.Font#hasUniformLineMetrics()

     */

    public boolean hasUniformLineMetrics() {

        return font.hasUniformLineMetrics();

    }

    /**

     * Returns the {@link LineMetrics} object for the specified

     * <code>String</code> in the specified {@link Graphics} context.

     * @param str the specified <code>String</code>

     * @param context the specified <code>Graphics</code> context

     * @return a <code>LineMetrics</code> object created with the

     * specified <code>String</code> and <code>Graphics</code> context.

     * @see java.awt.Font#getLineMetrics(String, FontRenderContext)

     */

    public LineMetrics getLineMetrics( String str, Graphics context) {

        return font.getLineMetrics(str, myFRC(context));

    }

    /**

     * Returns the {@link LineMetrics} object for the specified

     * <code>String</code> in the specified {@link Graphics} context.

     * @param str the specified <code>String</code>

     * @param beginIndex the initial offset of <code>str</code>

     * @param limit the end offset of <code>str</code>

     * @param context the specified <code>Graphics</code> context

     * @return a <code>LineMetrics</code> object created with the

     * specified <code>String</code> and <code>Graphics</code> context.

     * @see java.awt.Font#getLineMetrics(String, int, int, FontRenderContext)

     */

    public LineMetrics getLineMetrics( String str,

                                            int beginIndex, int limit,

                                            Graphics context) {

        return font.getLineMetrics(str, beginIndex, limit, myFRC(context));

    }

    /**

     * Returns the {@link LineMetrics} object for the specified

     * character array in the specified {@link Graphics} context.

     * @param chars the specified character array

     * @param beginIndex the initial offset of <code>chars</code>

     * @param limit the end offset of <code>chars</code>

     * @param context the specified <code>Graphics</code> context

     * @return a <code>LineMetrics</code> object created with the

     * specified character array and <code>Graphics</code> context.

     * @see java.awt.Font#getLineMetrics(char[], int, int, FontRenderContext)

     */

    public LineMetrics getLineMetrics(char [] chars,

                                            int beginIndex, int limit,

                                            Graphics context) {

        return font.getLineMetrics(

                                chars, beginIndex, limit, myFRC(context));

    }

    /**

     * Returns the {@link LineMetrics} object for the specified

     * {@link CharacterIterator} in the specified {@link Graphics}

     * context.

     * @param ci the specified <code>CharacterIterator</code>

     * @param beginIndex the initial offset in <code>ci</code>

     * @param limit the end index of <code>ci</code>

     * @param context the specified <code>Graphics</code> context

     * @return a <code>LineMetrics</code> object created with the

     * specified arguments.

     * @see java.awt.Font#getLineMetrics(CharacterIterator, int, int, FontRenderContext)

     */

    public LineMetrics getLineMetrics(CharacterIterator ci,

                                            int beginIndex, int limit,

                                            Graphics context) {

        return font.getLineMetrics(ci, beginIndex, limit, myFRC(context));

    }

    /**

     * Returns the bounds of the specified <code>String</code> in the

     * specified <code>Graphics</code> context.  The bounds is used

     * to layout the <code>String</code>.

     * <p>Note: The returned bounds is in baseline-relative coordinates

     * (see {@link java.awt.FontMetrics class notes}).

     * @param str the specified <code>String</code>

     * @param context the specified <code>Graphics</code> context

     * @return a {@link Rectangle2D} that is the bounding box of the

     * specified <code>String</code> in the specified

     * <code>Graphics</code> context.

     * @see java.awt.Font#getStringBounds(String, FontRenderContext)