/*
 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

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'"
 * style="border:15px; float:right; margin: 7px 10px;">
 * 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)
 */
 public Rectangle2D getStringBounds( String str, Graphics context) {
 return font.getStringBounds(str, 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 beginIndex the offset of the beginning of <code>str</code>
 * @param limit the end offset of <code>str</code>
 * @param context the specified <code>Graphics</code> context
 * @return a <code>Rectangle2D</code> that is the bounding box of the
 * specified <code>String</code> in the specified
 * <code>Graphics</code> context.
 * @see java.awt.Font#getStringBounds(String, int, int, FontRenderContext)
 */
 public Rectangle2D getStringBounds( String str,
 int beginIndex, int limit,
 Graphics context) {
 return font.getStringBounds(str, beginIndex, limit,
 myFRC(context));
 }

 /**
 * Returns the bounds of the specified array of characters
 * in the specified <code>Graphics</code> context.
 * The bounds is used to layout the <code>String</code>
 * created with the specified array of characters,
 * <code>beginIndex</code> and <code>limit</code>.
 * <p>Note: The returned bounds is in baseline-relative coordinates
 * (see {@link java.awt.FontMetrics class notes}).
 * @param chars an array of characters
 * @param beginIndex the initial offset of the array of
 * characters
 * @param limit the end offset of the array of characters
 * @param context the specified <code>Graphics</code> context
 * @return a <code>Rectangle2D</code> that is the bounding box of the
 * specified character array in the specified
 * <code>Graphics</code> context.
 * @see java.awt.Font#getStringBounds(char[], int, int, FontRenderContext)
 */
 public Rectangle2D getStringBounds( char [] chars,
 int beginIndex, int limit,
 Graphics context) {
 return font.getStringBounds(chars, beginIndex, limit,
 myFRC(context));
 }

 /**
 * Returns the bounds of the characters indexed in the specified
 * <code>CharacterIterator</code> in the
 * specified <code>Graphics</code> context.
 * <p>Note: The returned bounds is in baseline-relative coordinates
 * (see {@link java.awt.FontMetrics class notes}).
 * @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>Rectangle2D</code> that is the bounding box of the
 * characters indexed in the specified <code>CharacterIterator</code>
 * in the specified <code>Graphics</code> context.
 * @see java.awt.Font#getStringBounds(CharacterIterator, int, int, FontRenderContext)
 */
 public Rectangle2D getStringBounds(CharacterIterator ci,
 int beginIndex, int limit,
 Graphics context) {
 return font.getStringBounds(ci, beginIndex, limit,
 myFRC(context));
 }

 /**
 * Returns the bounds for the character with the maximum bounds
 * in the specified <code>Graphics</code> context.
 * @param context the specified <code>Graphics</code> context
 * @return a <code>Rectangle2D</code> that is the
 * bounding box for the character with the maximum bounds.
 * @see java.awt.Font#getMaxCharBounds(FontRenderContext)
 */
 public Rectangle2D getMaxCharBounds(Graphics context) {
 return font.getMaxCharBounds(myFRC(context));
 }

 private FontRenderContext myFRC(Graphics context) {
 if (context instanceof Graphics2D) {
 return ((Graphics2D)context).getFontRenderContext();
 }
 return DEFAULT_FRC;
 }


 /**
 * Returns a representation of this <code>FontMetrics</code>
 * object's values as a <code>String</code>.
 * @return a <code>String</code> representation of this
 * <code>FontMetrics</code> object.
 * @since JDK1.0.
 */
 public String toString() {
 return getClass().getName() +
 "[font=" + getFont() +
 "ascent=" + getAscent() +
 ", descent=" + getDescent() +
 ", height=" + getHeight() + "]";
 }

 /**
 * Initialize JNI field and method IDs
 */
 private static native void initIDs();
}