/*
* @(#)FontRenderContext.java 1.36 06/04/07
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
/*
* @author Charlton Innovations, Inc.
*/
package java.awt.font;
import java.awt.RenderingHints;
import static java.awt.RenderingHints.*;
import java.awt.geom.AffineTransform;
/**
* The <code>FontRenderContext</code> 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</code> are
* obtained from a {@link java.awt.Graphics2D Graphics2D} object. A
* <code>FontRenderContext</code> which is directly constructed will
* most likely not represent any actual graphics device, and may lead
* to unexpected or incorrect results.
* <p>
* @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 <code>FontRenderContext</code>
* object.
*
*/
protected FontRenderContext() {
aaHintValue = VALUE_TEXT_ANTIALIAS_DEFAULT;
fmHintValue = VALUE_FRACTIONALMETRICS_DEFAULT;
defaulting = true;
}
/**
* Constructs a <code>FontRenderContext</code> object from an
* optional {@link AffineTransform} and two <code>boolean</code>
* values that determine if the newly constructed object has
* anti-aliasing or fractional metrics.
* In each case the boolean values <CODE>true</CODE> and <CODE>false</CODE>
* correspond to the rendering hint values <CODE>ON</CODE> and
* <CODE>OFF</CODE> 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</code>. 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 <code>FontRenderContext</code> object from an
* optional {@link AffineTransform} and two <code>Object</code>
* 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</code>. If null, an
* identity tranform 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</code>.
* {@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</code>
* @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 <code>FontRenderContext</code> object
* measures text in a transformed render context.
* @return <code>true</code> if this <code>FontRenderContext</code>
* object has a non-identity AffineTransform attribute.
* <code>false</code> 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
* <code>FontRenderContext</code> 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 <code>FontRenderContext</code>.
* @return the <code>AffineTransform</code> of this
* <code>FontRenderContext</code>.
* @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 <code>FontRenderContext</code>.
* Call {@link #getAntiAliasingHint() getAntiAliasingHint()}
* for the specific rendering hint value.
* @return <code>true</code>, if text is anti-aliased in this
* <code>FontRenderContext</code>; <code>false</code> 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 <code>FontRenderContext</code>.
* Call {@link #getFractionalMetricsHint() getFractionalMetricsHint()}
* to obtain the corresponding rendering hint value.
* @return <code>true</code>, if layout should be performed with
* fractional metrics; <code>false</code> otherwise.
* in this <code>FontRenderContext</code>.
* @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
* <code>FontRenderContext</code>.
* 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</code>.
* @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
* <code>FontRenderContext</code>.
* 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</code>.
* @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.
* @param obj the object to test for equality
* @return <code>true</code> if the specified object is equal to
* this <code>FontRenderContext</code>; <code>false</code>
* 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.
* @param rhs the <code>FontRenderContext</code> to test for equality
* @return <code>true</code> if <code>rhs</code> is equal to
* this <code>FontRenderContext</code>; <code>false</code>
* 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.
*/
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;
}
}
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