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/*
 * @author Charlton Innovations, Inc.
 */

package java.awt.font;

import java.awt.RenderingHints;
import static java.awt.RenderingHints.*;
import java.awt.geom.AffineTransform;


 The FontRenderContext class is a container for the information needed to correctly measure text. The measurement of text can vary because of rules that map outlines to pixels, and rendering hints provided by an application. 

  One such piece of information is a transform that scales
  typographical points to pixels. (A point is defined to be exactly 1/72
  of an inch, which is slightly different than
  the traditional mechanical measurement of a point.)  A character that
  is rendered at 12pt on a 600dpi device might have a different size
  than the same character rendered at 12pt on a 72dpi device because of
  such factors as rounding to pixel boundaries and hints that the font
  designer may have specified.
  

  Anti-aliasing and Fractional-metrics specified by an application can also
  affect the size of a character because of rounding to pixel
  boundaries.
  
 Typically, instances of FontRenderContext are obtained from a Graphics2D object. A FontRenderContext which is directly constructed will most likely not represent any actual graphics device, and may lead to unexpected or incorrect results. @see java.awt.RenderingHints#KEY_TEXT_ANTIALIASING @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS @see java.awt.Graphics2D#getFontRenderContext() @see java.awt.font.LineMetrics 
/**
*   The {@code FontRenderContext} class is a container for the
*   information needed to correctly measure text.  The measurement of text
*   can vary because of rules that map outlines to pixels, and rendering
*   hints provided by an application.
*   <p>
*   One such piece of information is a transform that scales
*   typographical points to pixels. (A point is defined to be exactly 1/72
*   of an inch, which is slightly different than
*   the traditional mechanical measurement of a point.)  A character that
*   is rendered at 12pt on a 600dpi device might have a different size
*   than the same character rendered at 12pt on a 72dpi device because of
*   such factors as rounding to pixel boundaries and hints that the font
*   designer may have specified.
*   <p>
*   Anti-aliasing and Fractional-metrics specified by an application can also
*   affect the size of a character because of rounding to pixel
*   boundaries.
*   <p>
*   Typically, instances of {@code FontRenderContext} are
*   obtained from a {@link java.awt.Graphics2D Graphics2D} object.  A
*   {@code FontRenderContext} which is directly constructed will
*   most likely not represent any actual graphics device, and may lead
*   to unexpected or incorrect results.
*   @see java.awt.RenderingHints#KEY_TEXT_ANTIALIASING
*   @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS
*   @see java.awt.Graphics2D#getFontRenderContext()
*   @see java.awt.font.LineMetrics
*/

public class FontRenderContext {
    private transient AffineTransform tx;
    private transient Object aaHintValue;
    private transient Object fmHintValue;
    private transient boolean defaulting;

    
Constructs a new FontRenderContext object. 
/**
     * Constructs a new {@code FontRenderContext}
     * object.
     *
     */
    protected FontRenderContext() {
        aaHintValue = VALUE_TEXT_ANTIALIAS_DEFAULT;
        fmHintValue = VALUE_FRACTIONALMETRICS_DEFAULT;
        defaulting = true;
    }

    
Constructs a FontRenderContext object from an optional AffineTransform and two boolean values that determine if the newly constructed object has anti-aliasing or fractional metrics. In each case the boolean values true and false correspond to the rendering hint values ON and OFF respectively. 
 To specify other hint values, use the constructor which specifies the rendering hint values as parameters : FontRenderContext(AffineTransform, Object, Object). 
Params:
  • tx – the transform which is used to scale typographical points to pixels in this FontRenderContext. If null, an identity transform is used.
  • isAntiAliased – determines if the newly constructed object
has anti-aliasing.
  • usesFractionalMetrics – determines if the newly constructed
object has fractional metrics.
/**
     * Constructs a {@code FontRenderContext} object from an
     * optional {@link AffineTransform} and two {@code boolean}
     * values that determine if the newly constructed object has
     * anti-aliasing or fractional metrics.
     * In each case the boolean values {@code true} and {@code false}
     * correspond to the rendering hint values {@code ON} and
     * {@code OFF} respectively.
     * <p>
     * To specify other hint values, use the constructor which
     * specifies the rendering hint values as parameters :
     * {@link #FontRenderContext(AffineTransform, Object, Object)}.
     * @param tx the transform which is used to scale typographical points
     * to pixels in this {@code FontRenderContext}.  If null, an
     * identity transform is used.
     * @param isAntiAliased determines if the newly constructed object
     * has anti-aliasing.
     * @param usesFractionalMetrics determines if the newly constructed
     * object has fractional metrics.
     */
    public FontRenderContext(AffineTransform tx,
                            boolean isAntiAliased,
                            boolean usesFractionalMetrics) {
        if (tx != null && !tx.isIdentity()) {
            this.tx = new AffineTransform(tx);
        }
        if (isAntiAliased) {
            aaHintValue = VALUE_TEXT_ANTIALIAS_ON;
        } else {
            aaHintValue = VALUE_TEXT_ANTIALIAS_OFF;
        }
        if (usesFractionalMetrics) {
            fmHintValue = VALUE_FRACTIONALMETRICS_ON;
        } else {
            fmHintValue = VALUE_FRACTIONALMETRICS_OFF;
        }
    }

    
Constructs a FontRenderContext object from an optional AffineTransform and two Object values that determine if the newly constructed object has anti-aliasing or fractional metrics. 
Params:
  • tx – the transform which is used to scale typographical points to pixels in this FontRenderContext. If null, an identity transform is used.
  • aaHint – - one of the text antialiasing rendering hint values defined in java.awt.RenderingHints. Any other value will throw IllegalArgumentException. VALUE_TEXT_ANTIALIAS_DEFAULT may be specified, in which case the mode used is implementation dependent.
  • fmHint – - one of the text fractional rendering hint values defined in java.awt.RenderingHints. VALUE_FRACTIONALMETRICS_DEFAULT may be specified, in which case the mode used is implementation dependent. Any other value will throw IllegalArgumentException
Throws:
Since:1.6
/**
     * Constructs a {@code FontRenderContext} object from an
     * optional {@link AffineTransform} and two {@code Object}
     * values that determine if the newly constructed object has
     * anti-aliasing or fractional metrics.
     * @param tx the transform which is used to scale typographical points
     * to pixels in this {@code FontRenderContext}.  If null, an
     * identity transform is used.
     * @param aaHint - one of the text antialiasing rendering hint values
     * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
     * Any other value will throw {@code IllegalArgumentException}.
     * {@link java.awt.RenderingHints#VALUE_TEXT_ANTIALIAS_DEFAULT VALUE_TEXT_ANTIALIAS_DEFAULT}
     * may be specified, in which case the mode used is implementation
     * dependent.
     * @param fmHint - one of the text fractional rendering hint values defined
     * in {@link java.awt.RenderingHints java.awt.RenderingHints}.
     * {@link java.awt.RenderingHints#VALUE_FRACTIONALMETRICS_DEFAULT VALUE_FRACTIONALMETRICS_DEFAULT}
     * may be specified, in which case the mode used is implementation
     * dependent.
     * Any other value will throw {@code IllegalArgumentException}
     * @throws IllegalArgumentException if the hints are not one of the
     * legal values.
     * @since 1.6
     */
    public FontRenderContext(AffineTransform tx, Object aaHint, Object fmHint){
        if (tx != null && !tx.isIdentity()) {
            this.tx = new AffineTransform(tx);
        }
        try {
            if (KEY_TEXT_ANTIALIASING.isCompatibleValue(aaHint)) {
                aaHintValue = aaHint;
            } else {
                throw new IllegalArgumentException("AA hint:" + aaHint);
            }
        } catch (Exception e) {
            throw new IllegalArgumentException("AA hint:" +aaHint);
        }
        try {
            if (KEY_FRACTIONALMETRICS.isCompatibleValue(fmHint)) {
                fmHintValue = fmHint;
            } else {
                throw new IllegalArgumentException("FM hint:" + fmHint);
            }
        } catch (Exception e) {
            throw new IllegalArgumentException("FM hint:" +fmHint);
        }
    }

    
Indicates whether or not this FontRenderContext object measures text in a transformed render context. 
See Also:
Returns: true if this FontRenderContext object has a non-identity AffineTransform attribute. false otherwise.
Since:  1.6
/**
     * Indicates whether or not this {@code FontRenderContext} object
     * measures text in a transformed render context.
     * @return  {@code true} if this {@code FontRenderContext}
     *          object has a non-identity AffineTransform attribute.
     *          {@code false} otherwise.
     * @see     java.awt.font.FontRenderContext#getTransform
     * @since   1.6
     */
    public boolean isTransformed() {
        if (!defaulting) {
            return tx != null;
        } else {
            return !getTransform().isIdentity();
        }
    }

    
Returns the integer type of the affine transform for this FontRenderContext as specified by AffineTransform.getType() 
See Also:
Returns:the type of the transform.
Since:1.6
/**
     * Returns the integer type of the affine transform for this
     * {@code FontRenderContext} as specified by
     * {@link java.awt.geom.AffineTransform#getType()}
     * @return the type of the transform.
     * @see AffineTransform
     * @since 1.6
     */
    public int getTransformType() {
        if (!defaulting) {
            if (tx == null) {
                return AffineTransform.TYPE_IDENTITY;
            } else {
                return tx.getType();
            }
        } else {
            return getTransform().getType();
        }
    }

    
 Gets the transform that is used to scale typographical points to pixels in this FontRenderContext. @return the AffineTransform of this FontRenderContext. @see AffineTransform 
/**
    *   Gets the transform that is used to scale typographical points
    *   to pixels in this {@code FontRenderContext}.
    *   @return the {@code AffineTransform} of this
    *    {@code FontRenderContext}.
    *   @see AffineTransform
    */
    public AffineTransform getTransform() {
        return (tx == null) ? new AffineTransform() : new AffineTransform(tx);
    }

    
Returns a boolean which indicates whether or not some form of antialiasing is specified by this FontRenderContext. Call getAntiAliasingHint() for the specific rendering hint value. @return true, if text is anti-aliased in this FontRenderContext; false otherwise. @see java.awt.RenderingHints#KEY_TEXT_ANTIALIASING @see #FontRenderContext(AffineTransform,boolean,boolean) @see #FontRenderContext(AffineTransform,Object,Object) 
/**
    * Returns a boolean which indicates whether or not some form of
    * antialiasing is specified by this {@code FontRenderContext}.
    * Call {@link #getAntiAliasingHint() getAntiAliasingHint()}
    * for the specific rendering hint value.
    *   @return    {@code true}, if text is anti-aliased in this
    *   {@code FontRenderContext}; {@code false} otherwise.
    *   @see        java.awt.RenderingHints#KEY_TEXT_ANTIALIASING
    *   @see #FontRenderContext(AffineTransform,boolean,boolean)
    *   @see #FontRenderContext(AffineTransform,Object,Object)
    */
    public boolean isAntiAliased() {
        return !(aaHintValue == VALUE_TEXT_ANTIALIAS_OFF ||
                 aaHintValue == VALUE_TEXT_ANTIALIAS_DEFAULT);
    }

    
Returns a boolean which whether text fractional metrics mode is used in this FontRenderContext. Call getFractionalMetricsHint() to obtain the corresponding rendering hint value. @return true, if layout should be performed with fractional metrics; false otherwise. in this FontRenderContext. @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS @see #FontRenderContext(AffineTransform,boolean,boolean) @see #FontRenderContext(AffineTransform,Object,Object) 
/**
    * Returns a boolean which whether text fractional metrics mode
    * is used in this {@code FontRenderContext}.
    * Call {@link #getFractionalMetricsHint() getFractionalMetricsHint()}
    * to obtain the corresponding rendering hint value.
    *   @return    {@code true}, if layout should be performed with
    *   fractional metrics; {@code false} otherwise.
    *               in this {@code FontRenderContext}.
    *   @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS
    *   @see #FontRenderContext(AffineTransform,boolean,boolean)
    *   @see #FontRenderContext(AffineTransform,Object,Object)
    */
    public boolean usesFractionalMetrics() {
        return !(fmHintValue == VALUE_FRACTIONALMETRICS_OFF ||
                 fmHintValue == VALUE_FRACTIONALMETRICS_DEFAULT);
    }

    
Return the text anti-aliasing rendering mode hint used in this FontRenderContext. This will be one of the text antialiasing rendering hint values defined in java.awt.RenderingHints. 
Returns: text anti-aliasing rendering mode hint used in this FontRenderContext.
Since:1.6
/**
     * Return the text anti-aliasing rendering mode hint used in this
     * {@code FontRenderContext}.
     * This will be one of the text antialiasing rendering hint values
     * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
     * @return  text anti-aliasing rendering mode hint used in this
     * {@code FontRenderContext}.
     * @since 1.6
     */
    public Object getAntiAliasingHint() {
        if (defaulting) {
            if (isAntiAliased()) {
                 return VALUE_TEXT_ANTIALIAS_ON;
            } else {
                return VALUE_TEXT_ANTIALIAS_OFF;
            }
        }
        return aaHintValue;
    }

    
Return the text fractional metrics rendering mode hint used in this FontRenderContext. This will be one of the text fractional metrics rendering hint values defined in java.awt.RenderingHints. 
Returns:the text fractional metrics rendering mode hint used in this FontRenderContext.
Since:1.6
/**
     * Return the text fractional metrics rendering mode hint used in this
     * {@code FontRenderContext}.
     * This will be one of the text fractional metrics rendering hint values
     * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
     * @return the text fractional metrics rendering mode hint used in this
     * {@code FontRenderContext}.
     * @since 1.6
     */
    public Object getFractionalMetricsHint() {
        if (defaulting) {
            if (usesFractionalMetrics()) {
                 return VALUE_FRACTIONALMETRICS_ON;
            } else {
                return VALUE_FRACTIONALMETRICS_OFF;
            }
        }
        return fmHintValue;
    }

    
Return true if obj is an instance of FontRenderContext and has the same
transform, antialiasing, and fractional metrics values as this.

Params:
  • obj – the object to test for equality
Returns:true if the specified object is equal to this FontRenderContext; false otherwise.
/**
     * Return true if obj is an instance of FontRenderContext and has the same
     * transform, antialiasing, and fractional metrics values as this.
     * @param obj the object to test for equality
     * @return {@code true} if the specified object is equal to
     *         this {@code FontRenderContext}; {@code false}
     *         otherwise.
     */
    public boolean equals(Object obj) {
        try {
            return equals((FontRenderContext)obj);
        }
        catch (ClassCastException e) {
            return false;
        }
    }

    
Return true if rhs has the same transform, antialiasing,
and fractional metrics values as this.

Params:
  • rhs – the FontRenderContext to test for equality
Returns:true if rhs is equal to this FontRenderContext; false otherwise.
Since:1.4
/**
     * Return true if rhs has the same transform, antialiasing,
     * and fractional metrics values as this.
     * @param rhs the {@code FontRenderContext} to test for equality
     * @return {@code true} if {@code rhs} is equal to
     *         this {@code FontRenderContext}; {@code false}
     *         otherwise.
     * @since 1.4
     */
    public boolean equals(FontRenderContext rhs) {
        if (this == rhs) {
            return true;
        }
        if (rhs == null) {
            return false;
        }

        /* if neither instance is a subclass, reference values directly. */
        if (!rhs.defaulting && !defaulting) {
            if (rhs.aaHintValue == aaHintValue &&
                rhs.fmHintValue == fmHintValue) {

                return tx == null ? rhs.tx == null : tx.equals(rhs.tx);
            }
            return false;
        } else {
            return
                rhs.getAntiAliasingHint() == getAntiAliasingHint() &&
                rhs.getFractionalMetricsHint() == getFractionalMetricsHint() &&
                rhs.getTransform().equals(getTransform());
        }
    }

    
Return a hashcode for this FontRenderContext.

/**
     * Return a hashcode for this FontRenderContext.
     */
    public int hashCode() {
        int hash = tx == null ? 0 : tx.hashCode();
        /* SunHints value objects have identity hashcode, so we can rely on
         * this to ensure that two equal FRC's have the same hashcode.
         */
        if (defaulting) {
            hash += getAntiAliasingHint().hashCode();
            hash += getFractionalMetricsHint().hashCode();
        } else {
            hash += aaHintValue.hashCode();
            hash += fmHintValue.hashCode();
        }
        return hash;
    }
}