imagingbook.common.image.ImageGraphics

All Implemented Interfaces:: AutoCloseable

public class ImageGraphics extends Object implements AutoCloseable

This class defines functionality for drawing anti-aliased "pixel" graphics in images of type ByteProcessor, ShortProcessor or ColorProcessor (there is no support for FloatProcessor). It uses the capabilities of AWT's Graphics2D class by drawing to a BufferedImage, which is a copy of the original image. After performing the drawing operations the BufferedImage is copied back to the original. Thus all operations possible on a Graphics2D instance are available, including the drawing of Shape objects with floating-point coordinates, arbitrary strokes and anti-aliasing, which is not available with ImageJ's built-in graphics operations (for class ImageProcessor).

Since drawing involves copying the image multiple times, graphic operations should be grouped for efficiency reasons. Here is an example for the intended form of use:

 ImageProcessor ip = ... ;   // some ByteProcessor, ShortProcessor or ColorProcessor
 try (ImageGraphics ig = new ImageGraphics(ip)) {
        ig.setColor(255);
        ig.setLineWidth(1.0);
        ig.drawLine(40, 100.5, 250, 101.5);
        ig.drawOval(230.6, 165.2, 150, 150);
        ...
 }

Note the use of double coordinates throughout. The original image (ip in the above example) is automatically updated at the end of the try() ... clause (by ImageGraphics implementing the AutoCloseable interface). The getGraphics2D() method exposes the underlying Graphics2D instance of the ImageGraphics object, which can then be used to perform arbitrary AWT graphic operations. Thus, the above example could alternatively be implemented as follows:

 ImageProcessor ip = ... ;   // some ByteProcessor, ShortProcessor or ColorProcessor
 try (ImageGraphics ig = new ImageGraphics(ip)) {
        Graphics2D g2 = ig.getGraphics2D();
        g2.setColor(Color.white);
        g2.setStroke(new BasicStroke(1.0f));
        g2.draw(new Line2D.Double(40, 100.5, 250, 101.5));
        g2.draw(new Ellipse2D.Double(230.6, 165.2, 150, 150));
        ...
 }

This class also defines several convenience methods for drawing shapes with floating-point (double) coordinates, as well as for setting colors and stroke parameters. If intermediate updates are needed (e.g., for animations), the update() method can be invoked any time.

Version:

2020-01-07

See Also:

Constructor Summary

Constructors

Constructor

Description

ImageGraphics(ImageProcessor ip)

Constructor.

ImageGraphics(ImageProcessor ip, Color color, BasicStroke stroke)

Constructor.
Method Summary

Modifier and Type

Method

Description

void

close()

void

drawLine(double x1, double y1, double x2, double y2)

Draws a straight line segment specified with double coordinate values (convenience method).

void

drawOval(double x, double y, double w, double h)

Draws an ellipse specified with double coordinate values (convenience method).

void

drawPolygon(Point2D... points)

Draws a closed polygon specified by a sequence of Point2D objects with arbitrary coordinate values (convenience method).

void

drawRectangle(double x, double y, double w, double h)

Draws a rectangle specified with double coordinate values (convenience method).

Graphics2D

getGraphics2D()

Returns the underlying Graphics2D object, which can be used to perform arbitrary graphics operations.

void

setAntialiasing(boolean onoff)

Turn anti-aliasing on/off for this ImageGraphics instance (turned on by default).

void

setColor(int gray)

Sets this graphics context's current color to the specified (gray) color, with RGB = (gray, gray, gray).

void

setColor(Color color)

Sets this graphics context's current color to the specified color.

void

setEndCapButt()

Sets the end cap style of the current stroke to "BUTT".

void

setEndCapRound()

Sets the end cap style of the current stroke to "ROUND".

void

setEndCapSquare()

Sets the end cap style of the current stroke to "SQUARE".

void

setLineJoinBevel()

Sets the line segment join style of the current stroke to "BEVEL".

void

setLineJoinMiter()

Sets the line segment join style of the current stroke to "MITER".

void

setLineJoinRound()

Sets the line segment join style of the current stroke to "ROUND".

void

setLineWidth(double width)

Sets the line width of the current stroke.

void

setStroke(BasicStroke stroke)

Sets the stroke to be used for all subsequent graphics operations.

void

update()

Forces the image to be updated by copying the (modified) BufferedImage back to the input image.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details
- ImageGraphics
  
  public ImageGraphics(ImageProcessor ip)
  
  Constructor. The supplied image must be of type ByteProcessor, ShortProcessor or ColorProcessor. An IllegalArgumentException is thrown for images of type FloatProcessor.
  
  Parameters:
  
  ip - image to draw on
- ImageGraphics
  
  public ImageGraphics(ImageProcessor ip, Color color, BasicStroke stroke)
  
  Constructor. The supplied image must be of type ByteProcessor, ShortProcessor or ColorProcessor. An IllegalArgumentException is thrown for images of type FloatProcessor.
  
  Parameters:
  
  ip - image to draw on
  
  color - the initial drawing color
  
  stroke - the initial stroke
Method Details
- setAntialiasing
  
  public void setAntialiasing(boolean onoff)
  
  Turn anti-aliasing on/off for this ImageGraphics instance (turned on by default). The new setting will only affect subsequent graphics operations.
  
  Parameters:
  
  onoff - set true to turn on
- getGraphics2D
  
  public Graphics2D getGraphics2D()
  
  Returns the underlying Graphics2D object, which can be used to perform arbitrary graphics operations.
  
  Returns:
  
  the Graphics2D object
- update
  
  public void update()
  
  Forces the image to be updated by copying the (modified) BufferedImage back to the input image. There is usually no need to call this (expensive) method explicitly. It is called automatically and only once at end of the try() ... clause, as described in the ImageGraphics class documentation above.
- close
  
  public void close()
  
  Specified by:
  
  close in interface AutoCloseable
- drawLine
  
  public void drawLine(double x1, double y1, double x2, double y2)
  
  Draws a straight line segment specified with double coordinate values (convenience method).
  Parameters:
  
  x1 - x-coordinate of start point
  
  y1 - y-coordinate of start point
  
  x2 - x-coordinate of end point
  
  y2 - y-coordinate of end point
  
  See Also:
  
  Line2D
- drawOval
  
  public void drawOval(double x, double y, double w, double h)
  
  Draws an ellipse specified with double coordinate values (convenience method).
  Parameters:
  
  x - x-coordinate of the upper-left corner of the framing rectangle
  
  y - y-coordinate of the upper-left corner of the framing rectangle
  
  w - width
  
  h - height
  
  See Also:
  
  Ellipse2D
- drawRectangle
  
  public void drawRectangle(double x, double y, double w, double h)
  
  Draws a rectangle specified with double coordinate values (convenience method).
  Parameters:
  
  x - x-coordinate of the upper-left corner
  
  y - y-coordinate of the upper-left corner
  
  w - width
  
  h - height
  
  See Also:
  
  Rectangle2D
- drawPolygon
  
  public void drawPolygon(Point2D... points)
  
  Draws a closed polygon specified by a sequence of Point2D objects with arbitrary coordinate values (convenience method). Note that the the polygon is automatically closed, i.e., N+1 segments are drawn if the number of given points is N.
  Parameters:
  
  points - a sequence of 2D points
  
  See Also:
  
  Path2D
- setColor
  
  public void setColor(Color color)
  
  Sets this graphics context's current color to the specified color. All subsequent graphics operations using this graphics context use this specified color.
  Parameters:
  
  color - the new rendering color
  
  See Also:
  
  Graphics.setColor(java.awt.Color)
- setColor
  
  public void setColor(int gray)
  
  Sets this graphics context's current color to the specified (gray) color, with RGB = (gray, gray, gray).
  
  Parameters:
  
  gray - the gray value
- setStroke
  
  public void setStroke(BasicStroke stroke)
  
  Sets the stroke to be used for all subsequent graphics operations.
  Parameters:
  
  stroke - a BasicStroke instance
  
  See Also:
  
  BasicStroke
- setLineWidth
  
  public void setLineWidth(double width)
  
  Sets the line width of the current stroke. All other stroke properties remain unchanged.
  Parameters:
  
  width - the line width
  
  See Also:
  
  BasicStroke
- setEndCapButt
  
  public void setEndCapButt()
  
  Sets the end cap style of the current stroke to "BUTT". All other stroke properties remain unchanged.
  See Also:
  
  BasicStroke
- setEndCapRound
  
  public void setEndCapRound()
  
  Sets the end cap style of the current stroke to "ROUND". All other stroke properties remain unchanged.
  See Also:
  
  BasicStroke
- setEndCapSquare
  
  public void setEndCapSquare()
  
  Sets the end cap style of the current stroke to "SQUARE". All other stroke properties remain unchanged.
  See Also:
  
  BasicStroke
- setLineJoinBevel
  
  public void setLineJoinBevel()
  
  Sets the line segment join style of the current stroke to "BEVEL". All other stroke properties remain unchanged.
  See Also:
  
  BasicStroke
- setLineJoinMiter
  
  public void setLineJoinMiter()
  
  Sets the line segment join style of the current stroke to "MITER". All other stroke properties remain unchanged.
  See Also:
  
  BasicStroke
- setLineJoinRound
  
  public void setLineJoinRound()
  
  Sets the line segment join style of the current stroke to "ROUND". All other stroke properties remain unchanged.
  See Also:
  
  BasicStroke

Class ImageGraphics

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Details

ImageGraphics

ImageGraphics

Method Details

setAntialiasing

getGraphics2D

update

close

drawLine

drawOval

drawRectangle

drawPolygon

setColor

setColor

setStroke

setLineWidth

setEndCapButt

setEndCapRound

setEndCapSquare

setLineJoinBevel

setLineJoinMiter

setLineJoinRound