/*
 * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
 * 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,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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.
     */
    private static class KeyReference extends SoftReference
        implements DisposerRecord, Disposer.PollDisposable {

        static ReferenceQueue queue = Disposer.getQueue();

        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
Font.  The advance is the
distance from the leftmost point to the rightmost point on the
character's baseline.  Note that the advance of a
String is not necessarily the sum of the advances
of its characters.
Returns:
   an array storing the advance widths of the
                characters in the Font
                described by this FontMetrics object./**
     * 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.
     */
    // More efficient than base class implementation - reuses existing cache
    public int[] getWidths() {
        int[] widths = new int[256];
        for (char ch = 0 ; ch < 256 ; ch++) {
            float w = advCache[ch];
            if (w == UNKNOWN_WIDTH) {
                w = advCache[ch] = handleCharWidth(ch);
            }
            widths[ch] = (int) (0.5 + w);
        }
        return widths;
    }

    public int getMaxAdvance() {
        return (int)(0.99f + this.maxAdvance);
    }

  /*
   * Returns the typographic ascent of the font. This is the maximum distance
   * glyphs in this font extend above the base line (measured in typographic
   * units).
   */
    public int getAscent() {
        return (int)(roundingUpValue + this.ascent);
    }

  /*
   * Returns the typographic descent of the font. This is the maximum distance
   * glyphs in this font extend below the base line.
   */
    public int getDescent() {
        return (int)(roundingUpValue + this.descent);
    }

    public int getLeading() {
        // nb this ensures the sum of the results of the public methods
        // for leading, ascent & descent sum to height.
        // if the calculations in any other methods change this needs
        // to be changed too.
        // the 0.95 value used here and in the other methods allows some
        // tiny fraction of leeway before rouding up. A higher value (0.99)
        // caused some excessive rounding up.
        return
            (int)(roundingUpValue + descent + leading) -
            (int)(roundingUpValue + descent);
    }

    // height is calculated as the sum of two separately rounded up values
    // because typically clients use ascent to determine the y location to
    // pass to drawString etc and we need to ensure that the height has enough
    // space below the baseline to fully contain any descender.
    public int getHeight() {

        if (height < 0) {
            height = getAscent() + (int)(roundingUpValue + descent + leading);
        }
        return height;
    }
}