The Graphics class is abstract. It is just a collection of specifications for
low-level drawing methods. The graphics object also contains a reference to the area of ram where the bit image
will be constructed and it also contains the current clipping region. It is used for all types of painting
including placing components, canvas drawing, and laying out text.
The most often use the Graphics object is as a parameter to your paint, paintComponent or print method.
You often cast the abstract Graphics to an actual Graphics2D object to access additional methods. Have a look at the Screws application to understand the basics of drawing.
Learning More
Round Polygons
Graphics has methods drawRoundRect and drawRoundRect to draw rectangles with rounded corners, but there are no built-in
methods to do the same for
arbitrary polygons, including triangles. Here is the code taken from the connectors
downloadable package to do it:
The math behind that program may be a bit baffling. This diagram might help. The techinque for computing the rounding
uses elementary geometry, the pythagorean theorem,
and elementary trigonometry.
Operations on the Entire Image
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Graphics class : available:
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Graphics2D class : available:
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Graphics2D.setTransform : Beware, cascaded transforms are specified in reverse order. : available:
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Graphics2D.addRenderingHints : available:
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setClip class :
Graphics.setClip replaces the clip region.
clip merges/intersecs this clip with the existing clip region. : available:
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Graphics2D.clip :
setClip replaces the clip region.
clip merges/intersecs this clip with the existing clip region. : available:
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Graphics.create : Used to prevent permanently modifying your caller’s
AffineTransform or clip region. : available:
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Area class : Useful to create drop cloths — odd shaped clip regions. : available:
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Composite class : Controls how new painting interacts with what is already painted. : available:
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AlphaComposite class : Controls how new painting interacts with what is already painted. : available:
Lines
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Graphics.drawLine : available:
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BasicStroke class : available:
Rectangles
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Graphics.clearRect : available:
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Graphics.drawRect} : available:
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Graphics.fillRect : available:
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Rectangle class : available:
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RoundRectangle2D.Double : available:
Text
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Graphics.drawString :
the Graphics. drawString method behaves differently from other drawing methods. Usually the x,y is the upper left corner. For drawString, it is the left end of the string baseline. : available:
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FontRenderContext class : available:
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LineMetrics class : available:
Ovals, Ellipse and Circles
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Graphics.drawArc :
Beware. Angles are measured in degrees counter clockwise from 3 o’clock. It does not take start and end angle but start angle and arc size in degrees (end-start). Angles may be negative. : available:
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Graphics.fillArc :
Beware. Angles are measured in degrees counter clockwise from 3 o’clock. It does not take start and end angle but start angle and arc size in degrees (end-start). Angles may be negative. : available:
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Arc2D.Double : available:
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Graphics.fillOval : available:
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Ellipse2D.Double : This is an inner class to describe an ellipse or circle. Note that you specify the upper left corner of the enclosing rectangle, not the centre. : available:
Images
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Graphics.drawImage : available:
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BufferedImage class : available:
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ImageIO class : Used to read and write png, jpg and gif files. : available:
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BufferedImage.getRaster : Used to manipulate individual pixels. : available:
Arbitrary Shapes
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Shape class : Interface you can pass to
draw for drawing arbitrary shape outlines, solids and clip regions. Check out the long list of implementors. : available:
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Path2D.Double :
Path2D is available in Java 1.6+. It replaces the legacy
GeneralPath. : available:
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Graphics2D.draw(Shape) : Draw a line around an arbitrary shape. : available:
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Graphics.drawPolygon : Draws outline of a closed polygon. : available:
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Graphics.drawPolyline : Draws open polygon, series of line segments. : available:
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Polygon class : available:
punctuation 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z (all)
©1996-2012 Roedy Green, Canadian Mind Products
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