Java 2D - Frequently Asked Questions

System Properties for Java 2D^TM Technology

• What release you are running (we are constantly improving our hardware acceleration renderers, so each release has more to offer)
• What OS you are running (our story on Windows is different from our story on Linux which is again different from our story on Solaris ... and the Apple folks have their own story for their platform)
• What kind of hardware you have (your graphics card capabilities can be the single most important factor in enabling Java2D hardware acceleration).

• All of the articles listed for the "hardware acceleration" Q&A above
• The gamers on http://javagaming.org are highly sensitive to performance and that web site has several good discussions about performance issues.

-Dsun.java2d.trace=[log[,timestamp]],[count],[out:<filename>],[help],[verbose]

System Properties for Java 2D^TM Technology

   BufferedImage createResizedCopy(Image originalImage, 
                                int scaledWidth, int scaledHeight, 
                                boolean preserveAlpha)
{
    int imageType = preserveAlpha ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
    BufferedImage scaledBI = new BufferedImage(scaledWidth, scaledHeight, imageType);
    Graphics2D g = scaledBI.createGraphics();
    if (preserveAlpha) {
       g.setComposite(AlphaComposite.Src);
    }
    g.drawImage(originalImage, 0, 0, scaledWidth, scaledHeight, null); 
    g.dispose();
    return scaledBI;
}

Class RenderingHints

g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_[NEAREST_NEIGHBOR BILINEAR BICUBIC]); 

BufferedImage

-Djava.awt.headless=true

http://www.realvnc.com

http://www.x.org

• Antialiased and sub-pixel (aka LCD) text display
• Transformed text
• Text as shapes that can be filled with colours, gradient paints etc.
• Rendering complex text scripts (eg Indic), Bidi text etc
• APIs to locate and use platform fonts
• APIs to directly load and register fonts from files and network resources.

• java.awt.Graphics2D.drawString() draws a String of text using the current font and other rendering attributes. This is the most
• java.awt.font.TextLayout object allows you to implement text editing yourself: it includes mixed styles, BIDI text layout, carets, highlighting, hit testing and many other features.
• java.awt.font.GlyphVector can be used to accomplish GlyphVectorGlyphMetrics
• Using Swing text components : since Swing is based upon Java 2D JTextField, JTextArea, and JEditorPane, which supports editing and multiple fonts and styles, all utilise the above Java 2D APIs. Many developers will therefore not directly use the 2D text APIs but will use the UI-oriented Swing interfaces.

TrueType

TrueType

java.awt.GraphicsEnvironment.getAvailableFontFamilyNames()java.awt.GraphicsEnvironment.getAllFonts()getAvailableFontFamilyNames()Font

• If you ship a private JRE with your application you can copy your fonts to $JAVAHOME/jre/lib/fonts since they will be available only to java applications executed by that JRE and will be visible via Java's font enumeration APIs.
• You may also load custom fonts dynamically - by using java.awt.Font.createFont() to instantiate your fonts from files or network streams.

createFont()FontFont.deriveFont()Font.createFont()

GraphicsEnvironment.registerFont()Font.createFont()

• The DPI reported by platform APIs likely has no correspondence to the true DPI
• Its unlikely that Java 2D's default matches the platform default.

java.awt.Toolkit.getScreenResolution()

Font.canDisplay()

http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6274842

java -Dawt.useSystemAAFontSettings=lcd

• "false" corresponds to disabling font smoothing on the desktop.
• "on" corresponds to Gnome Best shapes/Best contrast (no equivalent Windows desktop setting)
• "gasp" corresponds to Windows "Standard" font smoothing [see note (*) below] (no equivalent Gnome desktop setting)
• "lcd" corresponds to Gnome's "subpixel smoothing" and Windows "ClearType"

TrueType

Fontmetricsjava.awt.Graphics.getFontMetrics(Font)FontRenderContext

FontMetrics

Fontmetricsjava.awt.Graphics.getFontMetrics(Font)FontRenderContext

Logical bounds are the most commonly used and include the ascent, descent, leading and advance of the text. They are useful to position the text correctly, particularly when appending one string after another or for multiple lines of text but they very likely will not enclose the rendered image. Particular examples of this may be glyphs which extend a pixel to the left of the "origin" at which it is drawn. "W" is a particular example - the leftmost long diagonal may extend to the left of the rendering origin. Glyphs in italic fonts are may commonly extend further to the right than the overall "advance" of the text may indicate. These two issues may lead to text being clipped on the left or the right if placed in a tight area measured using the advance of the string. Adding a couple of pixels of padding at each end is probably the simplest workaround for this. Similarly large descenders, or diacritics that are used in European languages may extend beyond the reported descent or ascent. If used to create a tight bounding box for a label for example this may clip at the bottom or top. Extra padding is again the simplest solution. To get the logical bounds of a String one may use any of following methods as appropriate :

* Font.getStringBounds(...)
* TextLayout.getAscent()
* TextLayout.getDescent()
* TextLayout.getLeading()
* TextLayout.getAdvance()
* GlyphVector.getLogicalBounds(...)
 

 

 

  * GlyphVector.getVisualBounds(...)
  * TextLayout.getBounds()
 

TextLayout.getBounds()
 

FontRenderContext
 

  * GlyphVector.getPixelBounds(...)
  * TextLayout.getPixelBounds(...) (new in Java SE 6)
 

TextLayout.getPixelBounds(...)

1.1 (aka AWT) printing - java.awt.PrintJob

• A UI component-oriented printing API
• Can print only the 1.1 "Graphics" API, not "Graphics2D" extensions

2D printing - java.awt.print.PrinterJob

• A more flexible API for printing documents
• Can print all of Java 2D.
• Callback printing model
• Integrates with javax.print

Java Printing Service - javax.print packages

• Adds discovery of printers and capabilities
• Adds ability to specify job behaviour through attributes
• Adds ability to install custom print services

PrinterJob

• "how can I print all a JTable?"
• "how can I just ask Swing to print the contents of a text component (rather than

Class JTable

Printing using non opaque colours, gradient paints, and custom paints

• the application printing code could avoid using these.
• the application could render a selected area which uses these to an offscreen opaque BufferedImage and then draw that BufferedImage to the printer graphics.
• the application could lower the device resolution of the print job which may be higher than needed, using the PrinterResolution attribute.

Printing Text on Solaris with non-Postscript standard fonts

Java Homepage

PrintService

Networking
/Domain Sockets;/
CUPS now supports the much faster UNIX  domain sockets for local printing

• localhost:631 via a TCP/IP socket connection - this is the same as in
• a unix domain socket at /var/run/cups/cups.sock

  http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6500903

• Edit the cups configuration file, usually /etc/cups/cupsd.conf, and locate

  # Listen /var/run/cups/cups.sock

• Ensure the line to listen on TCP/IP port 631 is present and UNcommented :
• Finally save the file and restart cups

sh /etc/init.d/cups restart
 
cd /usr/lib
ln -s libcups.so.2 libcups.so    

• paint, which represents the color or pattern rendered to the destination for the text and shape draw and fill methods.
• stroke, which describes the line style of the outline of shapes which are rendered using the shape draw (but not fill) methods.
• font, which is the font of the text to be rendered in the text draw methods.
• rendering hint, which suggests optional algorithms for how a primitive should be rendered, such as whether a faster or more accurate algorithm should be used.
• transform, which represents the mapping from user space to device space and additional coordinate transforms, such as rotate and scale, to be applied to all primitives.
• composite, which defines how the paint colors should replace or be mixed or blended with the colors already in the destination for all primitives.
• clip, which identifies a subset of the pixels in the destination which are allowed to be changed. Pixels which fall outside the clip should never be modified by any primitive.

In addition to these classes that allow you to create common shapes, the Java 2D API provides two other classes that allow you to define odd shapes: GeneralPath and Area. Shapes created with GeneralPath must be created segment by segment, but this means that you can combine straight lines and curved lines into a single shape. The Area class supports constructive area geometry, which allows you to combine two shapes to create another shape, either by adding or intersecting the shapes, subtracting one shape from another, or by subtracting the intersection of the shapes.

You can also create a Shape object from a String by calling getOutline on a TextLayout object. After creating the Shape, you can perform operations such as filling and transforming on the Shape.

For more information on working with shapes in Java 2D, see the 2D Graphics tutorial.

GeneralPath

To perform transformations, use these steps:

Use getTransform to get the current transform:

<blockquote>AffineTransform aT = g2.getTransform();

Use the transform, translate, scale, shear, or rotate methods to concatenate a transform:

<blockquote>g2.transform(...);

Perform the rendering:

<blockquote>g2.draw(...);

Restore the original transform using setTransform:

<blockquote>g2.setTransform(aT);