Module java.desktop
Package java.awt.font

Class FontRenderContext

java.lang.Object
java.awt.font.FontRenderContext
public class FontRenderContext extends Object
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 Also:

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    FontRenderContext()
    Constructs a new FontRenderContext object.
     
    FontRenderContext(AffineTransform tx, boolean isAntiAliased, boolean usesFractionalMetrics)
    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.
     
    FontRenderContext(AffineTransform tx, Object aaHint, Object fmHint)
    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.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    equals(FontRenderContext rhs)
    Return true if rhs has the same transform, antialiasing, and fractional metrics values as this.
    boolean
    equals(Object obj)
    Return true if obj is an instance of FontRenderContext and has the same transform, antialiasing, and fractional metrics values as this.
    Object
    getAntiAliasingHint()
    Return the text anti-aliasing rendering mode hint used in this FontRenderContext.
    Object
    getFractionalMetricsHint()
    Return the text fractional metrics rendering mode hint used in this FontRenderContext.
    AffineTransform
    getTransform()
    Gets the transform that is used to scale typographical points to pixels in this FontRenderContext.
    int
    getTransformType()
    Returns the integer type of the affine transform for this FontRenderContext as specified by AffineTransform.getType()
    int
    hashCode()
    Return a hashcode for this FontRenderContext.
    boolean
    isAntiAliased()
    Returns a boolean which indicates whether or not some form of antialiasing is specified by this FontRenderContext.
    boolean
    isTransformed()
    Indicates whether or not this FontRenderContext object measures text in a transformed render context.
    boolean
    usesFractionalMetrics()
    Returns a boolean which whether text fractional metrics mode is used in this FontRenderContext.

    Methods declared in class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • FontRenderContext

      protected FontRenderContext()
      Constructs a new FontRenderContext object.

    • FontRenderContext

      public FontRenderContext(AffineTransform tx, boolean isAntiAliased, boolean usesFractionalMetrics)
      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).

      Parameters:
      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.

    • FontRenderContext

      public FontRenderContext(AffineTransform tx, Object aaHint, Object fmHint)
      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.
      Parameters:
      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:
      IllegalArgumentException - if the hints are not one of the legal values.
      Since:
      1.6

  • Method Details

    • isTransformed

      public boolean isTransformed()
      Indicates whether or not this FontRenderContext object measures text in a transformed render context.
      Returns:
      true if this FontRenderContext object has a non-identity AffineTransform attribute. false otherwise.
      Since:
      1.6
      See Also:

    • getTransformType

      public int getTransformType()
      Returns the integer type of the affine transform for this FontRenderContext as specified by AffineTransform.getType()
      Returns:
      the type of the transform.
      Since:
      1.6
      See Also:

    • getTransform

      public AffineTransform getTransform()
      Gets the transform that is used to scale typographical points to pixels in this FontRenderContext.
      Returns:
      the AffineTransform of this FontRenderContext.
      See Also:

    • isAntiAliased

      public boolean isAntiAliased()
      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.
      Returns:
      true, if text is anti-aliased in this FontRenderContext; false otherwise.
      See Also:

    • usesFractionalMetrics

      public boolean usesFractionalMetrics()
      Returns a boolean which whether text fractional metrics mode is used in this FontRenderContext. Call getFractionalMetricsHint() to obtain the corresponding rendering hint value.
      Returns:
      true, if layout should be performed with fractional metrics; false otherwise. in this FontRenderContext.
      See Also:

    • getAntiAliasingHint

      public Object getAntiAliasingHint()
      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

    • getFractionalMetricsHint

      public Object getFractionalMetricsHint()
      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

    • equals

      public boolean equals(Object obj)
      Return true if obj is an instance of FontRenderContext and has the same transform, antialiasing, and fractional metrics values as this.
      Overrides:
      equals in class Object
      Parameters:
      obj - the object to test for equality
      Returns:
      true if the specified object is equal to this FontRenderContext; false otherwise.
      See Also:

    • equals

      public boolean equals(FontRenderContext rhs)
      Return true if rhs has the same transform, antialiasing, and fractional metrics values as this.
      Parameters:
      rhs - the FontRenderContext to test for equality
      Returns:
      true if rhs is equal to this FontRenderContext; false otherwise.
      Since:
      1.4

    • hashCode

      public int hashCode()
      Return a hashcode for this FontRenderContext.
      Overrides:
      hashCode in class Object
      Returns:
      a hash code value for this object.
      See Also: