java.awt.FontMetrics Maven / Gradle / Ivy

Neither this file nor any files generated from it describe a complete specification, and they may only be used as described below. For example, no permission is given for you to incorporate this file, in whole or in part, in an implementation of a Java specification.

Sun Microsystems Inc. owns the copyright in this file and it is provided to you for informative, as opposed to normative, use. The file and any files generated from it may be used to generate other informative documentation, such as a unified set of documents of API signatures for a platform that includes technologies expressed as Java APIs. The file may also be used to produce "compilation stubs," which allow applications to be compiled and validated for such platforms.

Any work generated from this file, such as unified javadocs or compiled stub files, must be accompanied by this notice in its entirety.

This work corresponds to the API signatures of JSR 217: Personal Basis Profile 1.1. In the event of a discrepency between this work and the JSR 217 specification, which is available at http://www.jcp.org/en/jsr/detail?id=217, the latter takes precedence. */ 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 FontMetrics class defines a font metrics object, which * encapsulates information about the rendering of a particular font on a * particular screen. *

* Note to subclassers: 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): *

*
• {@link #getAscent()} *
• {@link #getLeading()} *
• {@link #getMaxAdvance()} *
• {@link #charWidth(char)} *
• {@link #charsWidth(char[], int, int)} *

* * Note that the implementations of these methods are * inefficient, so they are usually overridden with more efficient * toolkit-specific implementations. *

* When an application asks AWT to place a character at the position * (x, y), 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 baseline of the character. In normal * printing, the baselines of characters should align. *

* In addition, every character in a font has an ascent, a * descent, and an advance width. 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. *

* 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 String is the * distance along the baseline of the String. This * distance is the width that should be used for centering or * right-aligning the String. * Note that the advance of a String 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 ligature. Measuring characters individually does * not account for these transformations. * * @version 1.49 01/23/03 * @author Jim Graham * @see java.awt.Font * @since JDK1.0 */ public abstract class FontMetrics implements java.io.Serializable { /** * 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 FontMetrics object for finding out * height and width information about the specified Font * and specific character glyphs in that Font. * @param font the Font * @see java.awt.Font */ protected FontMetrics(Font font) { } /** * Gets the Font described by this * FontMetrics object. * @return the Font described by this * FontMetrics object. */ public Font getFont() { return null; } /** * Determines the standard leading of the * Font described by this FontMetrics * 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 Font. * @see #getHeight() * @see #getAscent() * @see #getDescent() */ public int getLeading() { return 0; } /** * Determines the font ascent of the Font * described by this FontMetrics object. The font ascent * is the distance from the font's baseline to the top of most * alphanumeric characters. Some characters in the Font * might extend above the font ascent line. * @return the font ascent of the Font. * @see #getMaxAscent() */ public int getAscent() { return 0; } /** * Determines the font descent of the Font * described by this * FontMetrics 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 * Font might extend * below the font descent line. * @return the font descent of the Font. * @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 0; } /** * Determines the maximum ascent of the Font * described by this FontMetrics object. No character * extends further above the font's baseline than this height. * @return the maximum ascent of any character in the * Font. * @see #getAscent() */ public int getMaxAscent() { return 0; } /** * Determines the maximum descent of the Font * described by this FontMetrics object. No character * extends further below the font's baseline than this height. * @return the maximum descent of any character in the * Font. * @see #getDescent() */ public int getMaxDescent() { return 0; } // /** // * For backward compatibility only. // * @return the maximum descent of any character in the // * Font. // * @see #getMaxDescent() // * @deprecated As of JDK version 1.1.1, // * replaced by getMaxDescent(). // */ // public int getMaxDecent() { return 0; } /** * Gets the maximum advance width of any character in this * Font. The advance is the * distance from the leftmost point to the rightmost point on the * string's baseline. The advance of a String is * not necessarily the sum of the advances of its characters. * @return the maximum advance width of any character * in the Font, or -1 if the * maximum advance width is not known. */ public int getMaxAdvance() { return 0; } /** * Returns the advance width of the specified character in this * 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. * @param ch the character to be measured * @return the advance width of the specified char * in the Font described by this * FontMetrics object. * @see #charsWidth(char[], int, int) * @see #stringWidth(String) */ public int charWidth(int ch) { return 0; } /** * Returns the advance width of the specified character in this * 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. * @param ch the character to be measured * @return the advance width of the specified char * in the Font described by this * FontMetrics object. * @see #charsWidth(char[], int, int) * @see #stringWidth(String) */ public int charWidth(char ch) { return 0; } // PBP/PP /** * Returns the total advance width for showing the specified * String in this Font. The advance * is the distance from the leftmost point to the rightmost point * on the string's baseline. *

* Note that the total advance width returned from this method * does not take into account the rendering context. Therefore, * the anti-aliasing and fractional metrics hints can affect the * value of the advance. The advance of a String is * not necessarily the sum of the advances of its characters. *