New Features in Java 2D(TM) Technology

# New Java 2DTM Features in the
JavaTM 2 SDK, v1.4

Documentation Contents

> | New Pipeline Architecture |  | Hardware Acceleration for Offscreen Images
> | Pluggable Image I/O Framework |  | New Java Print Service API
> | Support for additional Image Types |  | Public Bidi Algorithm
> | Font Rasterizer support for TrueType hinting |  | Hinted Lucida Fonts
> | OpenType Font Table Support |  | Support for Numeric Shaping
> | Improved Complex Text Layout Support |  | Complete Porter-Duff Support
> | Support for Checking if Font has a Transform |  | New Equality Methods for FontRenderContext

> New Pipeline Architecture

> The bugtraq reports that correspond to this change are: 4228939 and 4268962

> In the Java 2 SDK, version 1.2 and 1.3, common operations on a `Graphics` object often invalidated the rendering data cached for this `Graphics` object. This invalidation interrupted the rendering process by causing continuous re-creation of rendering information for the `Graphics` object, even for such simple and benign operations as `create()`, `setColor()`, and `translate()`. Because the rendering of Swing hierarchies relies heavily on these common operations, the invalidation and re-creation of rendering data caused poor repaint performance for many Swing applications.

> The new pipeline architecture reduces this performance overhead with several implementation changes that:

> - Improve the way that data is shared by the various rendering pipelines.
> - Reduce the amount of code executed and garbage created when responding to changes in the rendering attributes.
> - Improve the way that various graphics routines are chosen such as the routines that copy pixels from one format and location to another.
> These changes are especially noticeable when the following calls are used frequently, as they are in Swing applications:
> - `getGraphics`, `Graphics.create()` and `Graphics.dispose()`
> - `Graphics.setColor()`, `Graphics.translate`
> - `Graphics.copyArea`, especially when the source and destination regions overlap.
> The runtime footprint should also be improved through better code sharing.

> Other changes in the pipeline architecture have greatly improved the performance of:

> - `draw(Shape)` and `fill(Shape)`, especially when the `Shape` is a `GeneralPath`
> - scaled `drawImage`.
> - Blitting from an offscreen image created with `createImage()` multiple times without any intervening rendering or modifications to that image
> - Remote X11 display over the network of applications that use `createImage()` to create an image buffer for double buffering.
> - Rendering non-opaque text.
> - Systems, such as the SGI Visual 320 workstation, which have display cards that use an RGBx format for pixel storage.
> - Rendering coordinates outside of the range -32768 to 32767 with antialiasing turned off.
> For more information on this feature, see the whitepaper, High Performance Graphics.

> Hardware Acceleration for Offscreen Images

> The bugtraq report that corresponds to this change is: 4330166

> The SDK 1.4 provides access to hardware acceleration for offscreen images, resulting in better performance of rendering to and copying from these images. One problem with hardware-accelerated images is that, on some platforms such as Microsoft Windows, their contents can be lost at any time due to circumstances beyond the application's control. The new `VolatileImage` class allows you to create a hardware-accelerated offscreen image and manage the contents of that image.

> This new API includes:

> - `java.awt.image.VolatileImage`:
>   This class represents an image whose content can be lost at any time, but provides performance benefits. For example, on Microsoft Windows this image can be stored in VRAM and can benefit from hardware acceleration. The class includes methods that you can call to find out if the contents of the image need to be restored.
> - `createVolatileImage(w,h)` in Component.
>   This method creates a `VolatileImage` that is compatible with the `Component`.
> - `createCompatibleVolatileImage(int width, int height)`
>   This method creates a `VolatileImage` that is compatible with the `GraphicsConfiguration`.
> - `GraphicsDevice.getAvailableAcceleratedMemory`
>   This method returns the number of bytes of available accelerated memory. The `VolatileImage.flush` method can be used to release the memory used by an offscreen image.

> For more information on using the `VolatileImage` API, see The `VolatileImage` API User Guide ( PDF)

> Pluggable Image I/O Framework

> The bugtraq report that corresponds to this change is: 4101949

> The JavaTM Image I/O API is an pluggable, extensible framework that supports reading and writing images of various formats and protocols. The API provides this support through plug-ins, most of which will be written by third parties. A conforming implementation will only be required to provide a minimal set of plug-ins, principally for compatibility with previous versions of the Java SDK. An application using this API should be able to read and write images without knowing the image's storage format or the plug-in used to support the format.

> Fundamentally, all image I/O operations consist of reading or writing streams that contain one or more images, one or more preview (thumbnail) images associated with each image, and metadata, which is everything other than pixel data.

> The Java Image I/O API allows applications to:

> - Auto-detect installed plug-ins
> - Choose plug-ins based on format name, file suffix, file contents, or MIME type
> - Access individual images in multi-image files
> - Monitor reading and writing progress
> - Provide progressive updates of images being loaded
> - Read or write only a region of interest of an image
> - Read only selected bands of an image
> - Choose the output size of resolution-independent imagery
> - Retrieve detailed image and stream metadata
> - Work with unknown formats using generic interfaces
> - Work efficiently with both random-access and streaming data sources
> - Transcode between different formats

> See Java Image I/O for more information on the Java Image I/O API.

> New JavaTM Print Service

> The bugtraq reports that corresponds to this change are:
> 4285177 and 4360752

> This API is the product of JSR006, Unified Printing API, and will allow client applications to provide rich access to the capablities of print services available including:

> - Printer browsing and selection
> - Discovery of the capablities of printers
> - Selection of printers for a printer job
> - Specification of a printer job.
> Since all capabilities will be exposed through the API, server applications become first class citizens of this API.

> Server applications can be beneficiaries of the capabilities for spooling documents to print services, whereas previously only graphics calls could be used to generate printer jobs from Java applications.

> See Java Print Service for more information.

> Support for float and double Image Types

> The bugtraq report that corresponds to this change is: 4364491

> Prior to the SDK 1.4, the Java 2D API did not have `DataBuffer` subclasses for float or double sample types. The Java Image I/O API needs these classes to read and write float and double image types.

> The SDK 1.4 contains two new classes to provide float and double image type support: `DataBufferFloat` and `DataBufferDouble`. The `DataBufferFloat` class wraps float arrays of pixels. The `DataBufferDouble` class wraps double arrays of pixels.

> The existing `ComponentColorModel` and `ComponentSampleModel` class implementations have also been updated to support signed short,float, and double data. These classes include definitions of the normalized ranges of component values for the newly-supported data types:

> - For the existing data types, the range remains 0.0 to 1.0.
> - For short data, the values are scaled to between -1.0 and 1.0.
> - For float data, the range is the full range of the float primitive type.
> - For double data, the range is also the range of the float primitive type, since values must be cast to float to interact with the ColorSpace class.
> The `ComponentColorModel` class will not clamp the pixel data. Applications are expected to scale to the appropriate range. Methods are added to the `ColorSpace` class to determine per component minimum and maximum normalized values. Alpha component values must still range from 0.0 to 1.0 normalized.

> The complete additional API is listed below.

> `java.awt.image.ColorModel` includes three new methods to parallel existing methods:

> - `getDataElement(float[] normComponents, int normOffset)`
> - `getDataElements(float[] normComponents, int normOffset, Object obj)`
> - `getNormalizedComponents(Object pixel, float[] normComponents, int normOffset)`
> `java.awt.image.ComponentColorModel` includes a new constructor based on the new datatypes and new methods to override the existing `ColorModel` methods:
> - `ComponentColorModel(ColorSpace colorSpace, boolean hasAlpha, boolean isAlphaPremultiplied, int transparency, int transferType)`
> - `getRed(Object inData)`
> - `getGreen(Object inData)`
> - `getBlue(Object inData)`
> - `getAlpha(Object inData)`
> - `getDataElements(int rgb, Object pixel)`
> - `coerceData(WritableRaster raster, boolean isAlphaPremultiplied)`
> - `createCompatibleWritableRaster(int w, int h)`
> - `createCompatibleSampleModel(int w, int h)`
> `java.awt.image.SampleModel` includes two new methods to accept the new datatypes:
> - `getDataElements(int x, int y, int w, int h, Object obj, DataBuffer data)`
> - `setDataElements(int x, int y, int w, int h, Object obj, DataBuffer data)`
> `java.awt.image.ComponentSampleModel` includes two methods to accept the new datatypes:
> - `createDataBuffer()`
> - `getDataElements(int x, int y, Object obj, DataBuffer data)`
> `java.awt.image.BandedSampleModel` has three methods that were edited to accept the new datatypes:
> - `createDataBuffer()`
> - `getDataElements(int x, int y, Object obj, DataBuffer data)`
> - `setDataElements(int x, int y, Object obj, DataBuffer data)`
> `java.awt.color.ColorSpace` includes two new methods determine per component minimum and maximum normalized values:
> - `getMinValue(int component)`
> - `getMaxValue(int component)`
> `java.awt.color.ICC_ColorSpace` includes new methods override the two new `ColorSpace` methods.

> Public Bidi Algorithm

> The bugtraq report that corresponds to this change is: 4285083

> The Unicode Bidirectional Algorithm analyzes text using the Unicode character properties and determines the direction of runs of the text. The algorithm is necessary to properly display bidirectional text, such as Hebrew and Arabic text, in the correct order.

> The current implementation is all written in the Java programming language, but the SDK 1.4 will include efficient access from native font code so that Hebrew and Arabic text can be more efficiently rendered. The SDK 1.4 will provide access to the native code through the Java Native Interface.

> The new public `Bidi` class implements the Unicode 3.0 Bidi Algorithm and allows access to information on the bidirectional reordering of text so that the mixed, bidirectional text is properly displayed.

> The example BidiSample demonstrates some of the `Bidi` routines.

> Font Rasterizer support for TrueType hinting

> Before this release, the T2K font rasterizer used by Java 2D did not support font-hinting for TrueType fonts. As a result, when TrueType fonts did not always display with a consistent, attractive appearance. For this release, the T2K rasterizer has been modified to use the hints stored in the TrueType fonts.

> By adding this functionality to the T2K rasterizer, dependency on native rasterizers has been greatly reduced. Reducing this dependency results in:

> - Greater portability because hinting of TrueType fonts is performed by the cross-platform T2K rasterizer, not the native rasterizer.
> - More consistent metrics display of TrueType fonts because the same rasterizer is being used for on-screen and off-screen drawing.

> Hinted Lucida Fonts

> The bugtraq report that corresponds to this change is: 4285089

> For the SDK 1.4, the Lucida fonts that are in the Java 2 SDK will be upgraded to contain hints. This will give the Java 2 SDK higher quality fonts that could be used in place of existing fonts or if no other fonts are available. Adding hints to the Lucida fonts also allows the new cross-platform rasterizer to hint the Lucida fonts contained in the SDK, which causes the Lucida fonts to be displayed in a more consistent and attractive manner.

> OpenType Font Table Support

> The bugtraq report that corresponds to this change is: 4285161

> The SDK 1.4 includes a new architecture for providing general OpenType font support. This new architecture provides international character support for contextual scripts like Thai, Indic, Arabic, and Hebrew. It also provides enhanced typographical support for Roman languages.

> Support for Numeric Shaping

> The bugtraq report that corresponds to this change is: 4210199

> Currently, when Java 2D renders numerals surrounded by Arabic text, the numerals have Arabic (roman) shapes, which are the commonly expected numeral shapes in most western countries. However, people in a Hindi locale expect to see Hindi shapes.

> A new attribute, `TextAttribute.NUMERIC_SHAPING`, and a new class, `NumericShaper`, enable you to shape ASCII digits to other Unicode decimal ranges.

> For example, to cause a `TextLayout` instance to convert digits from European to Arabic:

> 1. Create a `NumericShaper` that shapes ARABIC digits:

>    >           Numeric Shaper nS
>    >       	 = NumericShaper.getContextualShaper(NumericShaper.ARABIC)

> 2. Add the `NumericShaper` to an attribute `Map` along with the key value of `TextAttribute.NUMERIC_SHAPING`:

>    >           Map map = new HashMap();
>    >           map.put(TextAttribute.NUMERIC_SHAPING, nS);

> 3. Create a `TextLayout` with the attribute `Map`:

>    >           FontRenderContext frc = ...;
>    >           TextLayout layout = new TextLayout(text, map, frc);

> 4. Render the text:

>    >           layout.draw(g2d, x, y);

> The `NumericShaper` class includes 19 constants representing different Unicode decimal ranges, allowing you to convert to 19 different digit shapes, including Devanagari and Thai.

> Improved Complex-Layout Support in GlyphVector

> Prior to this release, clients could not access glyph-to-character mapping information from `GlyphVector`. Clients can use this information to find out which glyphs in the `GlyphVector` correspond to which characters. This release also defines new methods to get the precise bounds of the `GlyphVector` and of individual glyphs within a `GlyphVector`.

> Note: Although clients can use `GlyphVector` and the glyph-to-character mapping information to implement selection and hit testing, most clients will find TextLayout and the Swing JTextArea and JTextField classes to be more useful and convenient.

> These `GlyphVector` methods are new in the SDK 1.4:

> - `getGlyphCharIndex(int glyphIndex)`
>   Returns the character index of the specified glyph. The character index is the index of the first logical character represented by the glyph.
> - `getGlyphCharIndices(int beginGlyphIndex, int numEntries, int[] codeReturn)`
>   Returns the character indices of the specified glyphs.
> - `getGlyphOutline(int glyphIndex, float x, float y)`
>   Returns a `Shape` whose interior corresponds to the visual representation of the specified glyph within this `GlyphVector`, offset to x, y.
> - `getPixelBounds(FontRenderContext renderFRC, float x, float y)`
>   Returns the pixel bounds of this `GlyphVector` when rendered in a graphics with the given `FontRenderContext` at the given location.
> - `getGlyphPixelBounds(int index, FontRenderContext renderFRC, float x, float y)`
>   Returns the pixel bounds of the glyph at index when this `GlyphVector` is rendered in a `Graphics` with the given `FontRenderContext` at the given location.
> These new `GlyphMetrics` methods deal with transformed fonts:
> - `getAdvanceX()`
>   Returns the x-component of the advance of the glyph.
> - `getAdvanceY`
>   Returns the y-component of the advance of the glyph.
> Complete Porter-Duff Support

> The bugtraq report that corresponds to this change is: 4380232

> The `AlphaComposite` class provides alpha blending capabilities according to modes or rules established by Porter and Duff. Out of the 12 rules that Porter and Duff identified, the `AlphaComposite` API for the SDK, version 1.3 defines and implements only 8 of them:

> - Clear
> - A (Src)
> - A over B (SrcOver)
> - B over A (DstOver)
> - A in B (SrcIn)
> - B in A (DstIn)
> - A held out by B (SrcOut)
> - B held out by A (DstOut)

> For the SDK 1.4, `AlphaComposite` implements the remaining 4 Porter-Duff rules:

> - B (Dst)
> - A atop B (SrcAtop)
> - B atop A (DstAtop)
> - A xor B (Xor)

> Support for Checking if Font has a Transform

> The bugtraq report that corresponds to this change is: 4314043

> As of the SDK 1.2 the `Font` object has a transform attribute that can be accessed with the `Font.getTransform` method. You can perform geometric transformations, such as rotating and shearing, on the `Font` by setting the transform attribute. However, most applications use the Size attribute rather than the transform to control the size and shape of characters. In this case, the transform is a simple identity transform.

> Currently, the only way to determine if the transform is an identity transform is to call `getTransform` and inspect the returned `AffineTransform`. Unfortunately, calling `getTransform` requires the `Font` object to clone the `AffineTransform` because the transform is mutable.

> Two new methods in the SDK 1.4 allow you to check if a `Font` object's transform is an identity tranform without creating a new `AffineTransform`:

> - `java.awt.Font.isTransformed`:
>   Returns true if this `Font` object has a non-identity `AffineTransform` attribute.
> - `java.awt.font.TransformAttribute.isIdentity`:
>   Returns `true` if the wrapped transform is an identity transform.
> New Equality Methods for FontRenderContext

> The bugtraq report that corresponds to this change is: 4328579

> A `FontRenderContext` object encapsulates state about the graphics context and is used by `GlyphVector` and `TextLayout`. Three new methods in `FontRenderContext` allow you to compare the `FontRenderContext` in the `GlyphVector` against the one in the graphics context into which the `GlyphVector` draws:

> - `equals(FontRenderContext)`
> - `equals(Object)`
> - `hashCode()`
> These equals methods also have performance benefits because a client does not have to create an `AffineTransform` to perform an equality test.

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