/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * 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

 * published by the Free Software Foundation.  Oracle designates this

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

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.font;

import java.lang.ref.ReferenceQueue;

import java.lang.ref.SoftReference;

import java.awt.FontMetrics;

import java.awt.Font;

import java.awt.GraphicsEnvironment;

import java.awt.geom.AffineTransform;

import java.awt.geom.NoninvertibleTransformException;

import java.awt.font.FontRenderContext;

import java.awt.font.TextLayout;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.util.concurrent.ConcurrentHashMap;

import sun.java2d.Disposer;

import sun.java2d.DisposerRecord;

/*

 * This class provides a summary of the glyph measurements  for a Font

 * and a set of hints that guide their display.  It provides more metrics

 * information for the Font than the java.awt.FontMetrics class. There

 * is also some redundancy with that class.

 * <p>

 * The design metrics for a Font are obtained from Font.getDesignMetrics().

 * The FontDesignMetrics object returned will be independent of the

 * point size of the Font.

 * Most users are familiar with the idea of using <i>point size</i> to

 * specify the size of glyphs in a font. This point size defines a

 * measurement between the baseline of one line to the baseline of the

 * following line in a single spaced text document. The point size is

 * based on <i>typographic points</i>, approximately 1/72 of an inch.

 * <p>

 * The Java2D API adopts the convention that one point is equivalent

 * to one unit in user coordinates.  When using a normalized transform

 * for converting user space coordinates to device space coordinates (see

 * GraphicsConfiguration.getDefaultTransform() and

 * GraphicsConfiguration.getNormalizingTransform()), 72 user space units

 * equal 1 inch in device space.  In this case one point is 1/72 of an inch.

 * <p>

 * The FontDesignMetrics class expresses font metrics in terms of arbitrary

 * <i>typographic units</i> (not points) chosen by the font supplier

 * and used in the underlying platform font representations.  These units are

 * defined by dividing the em-square into a grid.  The em-sqaure is the

 * theoretical square whose dimensions are the full body height of the

 * font.  A typographic unit is the smallest measurable unit in the

 * em-square.  The number of units-per-em is determined by the font

 * designer.  The greater the units-per-em, the greater the precision

 * in metrics.  For example, Type 1 fonts divide the em-square into a

 * 1000 x 1000 grid, while TrueType fonts typically use a 2048 x 2048

 * grid.  The scale of these units can be obtained by calling

 * getUnitsPerEm().

 * <p>

 * Typographic units are relative -- their absolute size changes as the

 * size of the of the em-square changes.  An em-square is 9 points high

 * in a 9-point font.  Because typographic units are relative to the

 * em-square, a given location on a glyph will have the same coordinates

 * in typographic units regardless of the point size.

 * <p>

 * Converting typographic units to pixels requires computing pixels-per-em

 * (ppem).  This can be computed as:

 * <pre>

         ppem = device_resolution * (inches-per-point) * pointSize

 * </pre>

 * where device resolution could be measured in pixels/inch and the point

 * size of a font is effectively points/em.  Using a normalized transform

 * from user space to device space (see above), results in 1/72 inch/point.

 * In this case, ppem is equal to the point size on a 72 dpi monitor, so

 * that an N point font displays N pixels high.  In general,

 * <pre>

        pixel_units = typographic_units * (ppem / units_per_em)

 * </pre>

 * @see java.awt.Font

 * @see java.awt.GraphicsConfiguration#getDefaultTransform

 * @see java.awt.GraphicsConfiguration#getNormalizingTransform

 */

public final class FontDesignMetrics extends FontMetrics {

    static final long serialVersionUID = 4480069578560887773L;

    private static final float UNKNOWN_WIDTH = -1;

    private static final int CURRENT_VERSION = 1;

    // height, ascent, descent, leading are reported to the client

    // as an integer this value is added to the true fp value to

    // obtain a value which is usually going to result in a round up

    // to the next integer except for very marginal cases.

    private static float roundingUpValue = 0.95f;

    // These fields are all part of the old serialization representation

    private Font  font;

    private float ascent;

    private float descent;

    private float leading;

    private float maxAdvance;

    private double[] matrix;

    private int[] cache; // now unused, still here only for serialization

    // End legacy serialization fields

    private int serVersion = 0;  // If 1 in readObject, these fields are on the input stream:

    private boolean isAntiAliased;

    private boolean usesFractionalMetrics;

    private AffineTransform frcTx;

    private transient float[] advCache; // transient since values could change across runtimes

    private transient int height = -1;

    private transient FontRenderContext frc;

    private transient double[] devmatrix = null;

    private transient FontStrike fontStrike;

    private static FontRenderContext DEFAULT_FRC = null;

    private static FontRenderContext getDefaultFrc() {

        if (DEFAULT_FRC == null) {

            AffineTransform tx;

            if (GraphicsEnvironment.isHeadless()) {

                tx = new AffineTransform();

            } else {

                tx =  GraphicsEnvironment

                    .getLocalGraphicsEnvironment()

                    .getDefaultScreenDevice()

                    .getDefaultConfiguration()

                    .getDefaultTransform();

            }

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

        }

        return DEFAULT_FRC;

    }

    /* Strongly cache up to 5 most recently requested FontMetrics objects,

     * and softly cache as many as GC allows. In practice this means we

     * should keep references around until memory gets low.

     * We key the cache either by a Font or a combination of the Font and

     * and FRC. A lot of callers use only the font so although there's code

     * duplication, we allow just a font to be a key implying a default FRC.

     * Also we put the references on a queue so that if they do get nulled

     * out we can clear the keys from the table.

     */

        implements DisposerRecord, Disposer.PollDisposable {

        Object key;

        KeyReference(Object key, Object value) {

            super(value, queue);

            this.key = key;

            Disposer.addReference(this, this);

        }

        /* It is possible that since this reference object has been

         * enqueued, that a new metrics has been put into the table

         * for the same key value. So we'll test to see if the table maps

         * to THIS reference. If its a new one, we'll leave it alone.

         * It is possible that a new entry comes in after our test, but

         * it is unlikely and if this were a problem we would need to

         * synchronize all 'put' and 'remove' accesses to the cache which

         * I would prefer not to do.

         */

        public void dispose() {

            if (metricsCache.get(key) == this) {

                metricsCache.remove(key);

            }

        }

    }

    private static class MetricsKey {

        Font font;

        FontRenderContext frc;

        int hash;

        MetricsKey() {

        }

        MetricsKey(Font font, FontRenderContext frc) {

            init(font, frc);

        }

        void init(Font font, FontRenderContext frc) {

            this.font = font;

            this.frc = frc;

            this.hash = font.hashCode() + frc.hashCode();

        }

        public boolean equals(Object key) {

            if (!(key instanceof MetricsKey)) {

                return false;

            }

            return

                font.equals(((MetricsKey)key).font) &&

                frc.equals(((MetricsKey)key).frc);

        }

        public int hashCode() {

            return hash;

        }

        /* Synchronize access to this on the class */

        static final MetricsKey key = new MetricsKey();

    }

    /* All accesses to a CHM do not in general need to be synchronized,

     * as incomplete operations on another thread would just lead to

     * harmless cache misses.

     */

    private static final ConcurrentHashMap<Object, KeyReference>

        metricsCache = new ConcurrentHashMap<Object, KeyReference>();

    private static final int MAXRECENT = 5;

    private static final FontDesignMetrics[]

        recentMetrics = new FontDesignMetrics[MAXRECENT];

    private static int recentIndex = 0;

    public static FontDesignMetrics getMetrics(Font font) {

        return getMetrics(font, getDefaultFrc());

     }

    public static FontDesignMetrics getMetrics(Font font,

                                               FontRenderContext frc) {

        /* When using alternate composites, can't cache based just on

         * the java.awt.Font. Since this is rarely used and we can still

         * cache the physical fonts, its not a problem to just return a

         * new instance in this case.

         * Note that currently Swing native L&F composites are not handled

         * by this code as they use the metrics of the physical anyway.

         */

        SunFontManager fm = SunFontManager.getInstance();

        if (fm.maybeUsingAlternateCompositeFonts() &&

            FontUtilities.getFont2D(font) instanceof CompositeFont) {

            return new FontDesignMetrics(font, frc);

        }

        FontDesignMetrics m = null;

        KeyReference r;

        /* There are 2 possible keys used to perform lookups in metricsCache.

         * If the FRC is set to all defaults, we just use the font as the key.

         * If the FRC is non-default in any way, we construct a hybrid key

         * that combines the font and FRC.

         */

        boolean usefontkey = frc.equals(getDefaultFrc());

        if (usefontkey) {

            r = metricsCache.get(font);

        } else /* use hybrid key */ {

            // NB synchronization is not needed here because of updates to

            // the metrics cache but is needed for the shared key.

            synchronized (MetricsKey.class) {

                MetricsKey.key.init(font, frc);

                r = metricsCache.get(MetricsKey.key);

            }

        }

        if (r != null) {

            m = (FontDesignMetrics)r.get();

        }

        if (m == null) {

            /* either there was no reference, or it was cleared. Need a new

             * metrics instance. The key to use in the map is a new

             * MetricsKey instance when we've determined the FRC is

             * non-default. Its constructed from local vars so we are

             * thread-safe - no need to worry about the shared key changing.

             */

            m = new FontDesignMetrics(font, frc);

            if (usefontkey) {

                metricsCache.put(font, new KeyReference(font, m));

            } else /* use hybrid key */ {

                MetricsKey newKey = new MetricsKey(font, frc);

                metricsCache.put(newKey, new KeyReference(newKey, m));

            }

        }

        /* Here's where we keep the recent metrics */

        for (int i=0; i<recentMetrics.length; i++) {

            if (recentMetrics[i]==m) {

                return m;

            }

        }

        synchronized (recentMetrics) {

            recentMetrics[recentIndex++] = m;

            if (recentIndex == MAXRECENT) {

                recentIndex = 0;

            }

        }

        return m;

    }

  /*

   * Constructs a new FontDesignMetrics object for the given Font.

   * Its private to enable caching - call getMetrics() instead.

   * @param font a Font object.

   */

    private FontDesignMetrics(Font font) {

        this(font, getDefaultFrc());

    }

    /* private to enable caching - call getMetrics() instead. */

    private FontDesignMetrics(Font font, FontRenderContext frc) {

      super(font);

      this.font = font;

      this.frc = frc;

      this.isAntiAliased = frc.isAntiAliased();

      this.usesFractionalMetrics = frc.usesFractionalMetrics();

      frcTx = frc.getTransform();

      matrix = new double[4];

      initMatrixAndMetrics();

      initAdvCache();

    }

    private void initMatrixAndMetrics() {

        Font2D font2D = FontUtilities.getFont2D(font);

        fontStrike = font2D.getStrike(font, frc);

        StrikeMetrics metrics = fontStrike.getFontMetrics();

        this.ascent = metrics.getAscent();

        this.descent = metrics.getDescent();

        this.leading = metrics.getLeading();

        this.maxAdvance = metrics.getMaxAdvance();

        devmatrix = new double[4];

        frcTx.getMatrix(devmatrix);

    }

    private void initAdvCache() {

        advCache = new float[256];

        // 0 is a valid metric so force it to -1

        for (int i = 0; i < 256; i++) {

            advCache[i] = UNKNOWN_WIDTH;

        }

    }

    private void readObject(ObjectInputStream in) throws IOException,

                                                  ClassNotFoundException {

        in.defaultReadObject();

        if (serVersion != CURRENT_VERSION) {

            frc = getDefaultFrc();

            isAntiAliased = frc.isAntiAliased();

            usesFractionalMetrics = frc.usesFractionalMetrics();

            frcTx = frc.getTransform();

        }

        else {

            frc = new FontRenderContext(frcTx, isAntiAliased, usesFractionalMetrics);

        }

        // when deserialized, members are set to their default values for their type--

        // not to the values assigned during initialization before the constructor

        // body!

        height = -1;

        cache = null;

        initMatrixAndMetrics();

        initAdvCache();

    }

    private void writeObject(ObjectOutputStream out) throws IOException {

        cache = new int[256];

        for (int i=0; i < 256; i++) {

            cache[i] = -1;

        }

        serVersion = CURRENT_VERSION;

        out.defaultWriteObject();

        cache = null;

    }

    private float handleCharWidth(int ch) {

        return fontStrike.getCodePointAdvance(ch); // x-component of result only

    }

    // Uses advCache to get character width

    // It is incorrect to call this method for ch > 255

    private float getLatinCharWidth(char ch) {

        float w = advCache[ch];

        if (w == UNKNOWN_WIDTH) {

            w = handleCharWidth(ch);

            advCache[ch] = w;

        }

        return w;

    }

    /* Override of FontMetrics.getFontRenderContext() */

    public FontRenderContext getFontRenderContext() {

        return frc;

    }

    public int charWidth(char ch) {

        // default metrics for compatibility with legacy code

        float w;

        if (ch < 0x100) {

            w = getLatinCharWidth(ch);

        }

        else {

            w = handleCharWidth(ch);

        }

        return (int)(0.5 + w);

    }

    public int charWidth(int ch) {

        if (!Character.isValidCodePoint(ch)) {

            ch = 0xffff;

        }

        float w = handleCharWidth(ch);

        return (int)(0.5 + w);

    }

    public int stringWidth(String str) {

        float width = 0;

        if (font.hasLayoutAttributes()) {

            /* TextLayout throws IAE for null, so throw NPE explicitly */

            if (str == null) {

                throw new NullPointerException("str is null");

            }

            if (str.length() == 0) {

                return 0;

            }

            width = new TextLayout(str, font, frc).getAdvance();

        } else {

            int length = str.length();

            for (int i=0; i < length; i++) {

                char ch = str.charAt(i);

                if (ch < 0x100) {

                    width += getLatinCharWidth(ch);

                } else if (FontUtilities.isNonSimpleChar(ch)) {

                    width = new TextLayout(str, font, frc).getAdvance();

                    break;

                } else {

                    width += handleCharWidth(ch);

                }

            }

        }

        return (int) (0.5 + width);

    }

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

        float width = 0;

        if (font.hasLayoutAttributes()) {

            if (len == 0) {

                return 0;

            }

            String str = new String(data, off, len);

            width = new TextLayout(str, font, frc).getAdvance();

        } else {

            /* Explicit test needed to satisfy superclass spec */

            if (len < 0) {

                throw new IndexOutOfBoundsException("len="+len);

            }

            int limit = off + len;

            for (int i=off; i < limit; i++) {

                char ch = data[i];

                if (ch < 0x100) {

                    width += getLatinCharWidth(ch);

                } else if (FontUtilities.isNonSimpleChar(ch)) {

                    String str = new String(data, off, len);

                    width = new TextLayout(str, font, frc).getAdvance();

                    break;

                } else {

                    width += handleCharWidth(ch);

                }

            }

        }

        return (int) (0.5 + width);

    }

    /**

     * 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