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Java 2D is an API for drawing two-dimensional graphics using the Java programming language. Every Java 2D drawing operation can ultimately be treated as filling a shape using a paint and compositing the result onto the screen.
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Java 2D is an API for drawing two-dimensional graphics using the Java programming language. Every Java 2D drawing operation can ultimately be treated as filling a shape using a paint and compositing the result onto the screen.
The Java 2D API and its documentation are available for download as a part of JDK 6. Java 2D API classes are organised into the following packages in JDK 6:
java.awt The main package for the Java Abstract Window Toolkit. java.awt.geom The Java standard library of two dimensional geometric shapes such as lines, ellipses, and quadrilaterals. java.awt.font The library for manipulating glyphs in Java. java.awt.color The library dealing with the many different ways that color can be represented. java.awt.image The library for manipulating graphical images. java.awt.print The library of tools for writing to paper.These objects are a necessary part of every Java 2D drawing operation.
A shape in Java 2D is a boundary which defines an inside and an outside. Pixels inside the shape are affected by the drawing operation, those outside are not.
Trying to fill a straight line segment will result in no pixels being affected, as such a shape does not contain any pixels itself. Instead, a thin rectangle must be used so that the shape contains some pixels.
A paint generates the colors to be used for each pixel of the fill operation. The simplest paint is java.awt.Color , which generates the same color for all pixels. More complicated paints may produce gradients, images, or indeed any combination of colors. Filling a circular shape using the color yellow results in a solid yellow circle, while filling the same circular shape using a paint that generates an image produces a circular cutout of the image.
During any drawing operation, there is a source (the pixels being produced by the paint) and a destination (the pixels already onscreen). Normally, the source pixels simply overwrite the destination pixels, but the composite allows this behavior to be changed.
The composite, given the source and destination pixels, produces the final result that ultimately ends up onscreen. The most common composite is java.awt.AlphaComposite , which can treat the pixels being drawn as partially transparent, so that the destination pixels show through to some degree.
To fill a shape, the first step is to identify which pixels fall inside the shape. These pixels will be affected by the fill operation. Pixels that are partially inside and partially outside the shape may be affected to a lesser degree if anti-aliasing is enabled.
The paint is then asked to generate a color for each of the pixels to be painted. In the common case of a solid-color fill, each pixel will be set to the same color.
The composite takes the pixels generated by the paint and combines them with the pixels already onscreen to produce the final result.
These objects can be viewed as performing their duties in terms of the simpler objects described above.
Every Java 2D operation is subject to a transform, so that shapes may be translated, rotated, sheared, and scaled as they are drawn. The active transform is most often the identity transform, which does nothing.
Filling using a transform can be viewed as simply creating a new, transformed shape and then filling that shape.
In addition to the fill operation, Java 2D provides a draw operation. While fill draws the interior of a shape, draw draws its outline. The outline can be as simple as a thin line, or as complicated as a dashed line with each dash having rounded edges.
The object responsible for generating the outline is the stroke. Given an input shape, the stroke produces a new shape representing its outline. For instance, an infinitely thin line segment (with no interior) might be stroked into a one-pixel-wide rectangle.
A draw operation can therefore be described as creating a new, stroked object and then filling that object.
Technically speaking, the stroke is only required to accept an input shape and produce a new shape. The stroke implementation provided with Java 2D implements the outline rules described above, but a custom-written stroke could produce any shape it wished.
Conceptually, drawing a straight black line in Java 2D can be thought of as creating a line segment, transforming it according to the current transform, stroking it to create a thin rectangle, querying this shape to compute the pixels being affected, generating the pixels using java.awt.Color.BLACK , and then compositing the results onto the screen.
However, performing this entire sequence of steps for each drawing operation would be very inefficient. Java 2D therefore optimizes common drawing operations so that many of these steps can be skipped. If the paint is a simple solid color, for instance, there is no need to actually command it to generate a list of colors to be painted. Likewise, if the default fully opaque composite is in use, actually asking it to perform the compositing operation is unnecessary and would waste effort.
Java 2D performs the minimum amount of work necessary to make it seem as if it is performing all of these steps for each operation, therefore retaining both great flexibility and high performance.
For simplicity, the textual examples provided in this article have assumed that the screen is the destination device. However, the destination can be anything, such as a printer, memory image, or even an object which accepts Java 2D graphics commands and translates them into vector graphic image files.
Since Java SE 6, Java2D and OpenGL have become interoperable, allowing, for example, the drawing of animated 3D graphics instead of icons on a Button (see JOGL).
In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate passes or layers and then combine the resulting 2D images into a single, final image called the composite. Compositing is used extensively in film when combining computer-rendered image elements with live footage. Alpha blending is also used in 2D computer graphics to put rasterized foreground elements over a background.
Flood fill, also called seed fill, is a flooding algorithm that determines and alters the area connected to a given node in a multi-dimensional array with some matching attribute. It is used in the "bucket" fill tool of paint programs to fill connected, similarly-colored areas with a different color, and in games such as Go and Minesweeper for determining which pieces are cleared. A variant called boundary fill uses the same algorithms but is defined as the area connected to a given node that does not have a particular attribute.
SVG is an XML-based vector image format for defining two-dimensional graphics, having support for interactivity and animation. The SVG specification is an open standard developed by the World Wide Web Consortium since 1999.
2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them. It may refer to the branch of computer science that comprises such techniques or to the models themselves.
A blitter is a circuit, sometimes as a coprocessor or a logic block on a microprocessor, dedicated to the rapid movement and modification of data within a computer's memory. A blitter can copy large quantities of data from one memory area to another relatively quickly, and in parallel with the CPU, while freeing up the CPU's more complex capabilities for other operations. A typical use for a blitter is the movement of a bitmap, such as windows and icons in a graphical user interface or images and backgrounds in a 2D video game. The name comes from the bit blit operation of the 1973 Xerox Alto, which stands for bit-block transfer. A blit operation is more than a memory copy, because it can involve data that's not byte aligned, handling transparent pixels, and various ways of combining the source and destination data.
Bit blit is a data operation commonly used in computer graphics in which several bitmaps are combined into one using a boolean function.
QuickDraw was the 2D graphics library and associated application programming interface (API) which is a core part of classic Mac OS. It was initially written by Bill Atkinson and Andy Hertzfeld. QuickDraw still existed as part of the libraries of macOS, but had been largely superseded by the more modern Quartz graphics system. In Mac OS X Tiger, QuickDraw has been officially deprecated. In Mac OS X Leopard applications using QuickDraw cannot make use of the added 64-bit support. In OS X Mountain Lion, QuickDraw header support was removed from the operating system. Applications using QuickDraw still ran under OS X Mountain Lion to macOS High Sierra; however, the current versions of Xcode and the macOS SDK do not contain the header files to compile such programmes.
Ray casting is the methodological basis for 3D CAD/CAM solid modeling and image rendering. It is essentially the same as ray tracing for computer graphics where virtual light rays are "cast" or "traced" on their path from the focal point of a camera through each pixel in the camera sensor to determine what is visible along the ray in the 3D scene. The term "Ray Casting" was introduced by Scott Roth while at the General Motors Research Labs from 1978–1980. His paper, "Ray Casting for Modeling Solids", describes modeled solid objects by combining primitive solids, such as blocks and cylinders, using the set operators union (+), intersection (&), and difference (-). The general idea of using these binary operators for solid modeling is largely due to Voelcker and Requicha's geometric modelling group at the University of Rochester. See solid modeling for a broad overview of solid modeling methods. This figure on the right shows a U-Joint modeled from cylinders and blocks in a binary tree using Roth's ray casting system in 1979.
Transparency in computer graphics is possible in a number of file formats. The term "transparency" is used in various ways by different people, but at its simplest there is "full transparency" i.e. something that is completely invisible. Only part of a graphic should be fully transparent, or there would be nothing to see. More complex is "partial transparency" or "translucency" where the effect is achieved that a graphic is partially transparent in the same way as colored glass. Since ultimately a printed page or computer or television screen can only be one color at a point, partial transparency is always simulated at some level by mixing colors. There are many different ways to mix colors, so in some cases transparency is ambiguous.
A computer font is implemented as a digital data file containing a set of graphically related glyphs. A computer font is designed and created using a font editor. A computer font specifically designed for the computer screen, and not for printing, is a screen font.
Digital illustration or computer illustration is the use of digital tools to produce images under the direct manipulation of the artist, usually through a pointing device such as a graphics tablet or, less commonly, a mouse. It is distinguished from computer-generated art, which is produced by a computer using mathematical models created by the artist. It is also distinct from digital manipulation of photographs, in that it is an original construction "from scratch". Photographic elements such as background or texture may be incorporated into such works, but they are not necessarily the primary basis.
Real-time computer graphics or real-time rendering is the sub-field of computer graphics focused on producing and analyzing images in real time. The term can refer to anything from rendering an application's graphical user interface (GUI) to real-time image analysis, but is most often used in reference to interactive 3D computer graphics, typically using a graphics processing unit (GPU). One example of this concept is a video game that rapidly renders changing 3D environments to produce an illusion of motion.
Clipping, in the context of computer graphics, is a method to selectively enable or disable rendering operations within a defined region of interest. Mathematically, clipping can be described using the terminology of constructive geometry. A rendering algorithm only draws pixels in the intersection between the clip region and the scene model. Lines and surfaces outside the view volume are removed.
In computer graphics, image tracing, raster-to-vector conversion or raster vectorization is the conversion of raster graphics into vector graphics.
The canvas element is part of HTML5 and allows for dynamic, scriptable rendering of 2D shapes and bitmap images. It is a low level, procedural model that updates a bitmap. HTML5 Canvas also helps in making 2D games.
Java AWT Native Interface (JAWT) is an interface for the Java programming language that enables rendering libraries compiled to native code to draw directly to a Java Abstract Window Toolkit (AWT) Canvas object drawing surface.
3D computer graphics, sometimes called CGI, 3-D-CGI or three-dimensional computer graphics, are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering digital images.
The Abstract Window Toolkit (AWT) is Java's original platform-dependent windowing, graphics, and user-interface widget toolkit, preceding Swing. The AWT is part of the Java Foundation Classes (JFC) — the standard API for providing a graphical user interface (GUI) for a Java program. AWT is also the GUI toolkit for a number of Java ME profiles. For example, Connected Device Configuration profiles require Java runtimes on mobile telephones to support the Abstract Window Toolkit.
2D to 3D video conversion is the process of transforming 2D ("flat") film to 3D form, which in almost all cases is stereo, so it is the process of creating imagery for each eye from one 2D image.
This is a glossary of terms relating to computer graphics.