Class ncsa.horizon.awt.ImageCanvas 
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Class ncsa.horizon.awt.ImageCanvas 

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Canvas
                   |
                   +----ncsa.horizon.awt.ImageCanvas
public class ImageCanvas
extends Canvas
implements ImageObserver, Cloneable
A Canvas object for displaying images. Features include

Variable Index

o doclear
o mode
o msgfont
o offscreen
o size
o SIZE_IMAGE_CENTER
Trim the image to the Canvas size (centered)
o SIZE_IMAGE_FIT
Fit the image to the Canvas size (default)
o SIZE_IMAGE_FLUSH
Scale the image to the Canvas size (centered)
o SIZE_IMAGE_SCALE
Scale the image to the Canvas size (centered)
o SIZE_IMAGE_TRUNCATE
Trim the image to the Canvas size (flush top/left)
o tracker
o view

Constructor Index

o ImageCanvas()
o ImageCanvas(Dimension)
o ImageCanvas(int, int)

Method Index

o clear()
clear the canvas.
o clone()
make a copy of this canvas in an efficient manner
o displayImage(Image)
o imageUpdate(Image, int, int, int, int, int)
o isLoading()
indicate whether there is an image being loaded at this time
o offpaint(Graphics)
paint the image with a double-buffering technique.
o paint(Graphics)
this calls tryPaint(Graphics)
o paintMessage(Graphics, String)
print a message on the canvas.
o preferredSize()
o setMode(int)
Set the display mode for sizing or trimming the viewable image.
o setPreferredSize(Dimension)
o setPreferredSize(int, int)
o tryPaint(Graphics)
like paint() except that it returns a boolean indicating whether it was successful in painting the image onto the canvas
o update(Graphics)
calls offpaint()
o viewSize()
determine the dimesions necessary to fit the current image into the display canvas (while preserving the aspect ratio.)
o viewSize(int, int)
determine the dimesions necessary to fit an image of width wd and height ht into the display canvas (while preserving the aspect ratio).

Variables

o SIZE_IMAGE_FIT 
  public final static int SIZE_IMAGE_FIT
Fit the image to the Canvas size (default)
o SIZE_IMAGE_CENTER 
  public final static int SIZE_IMAGE_CENTER
Trim the image to the Canvas size (centered)
o SIZE_IMAGE_TRUNCATE 
  public final static int SIZE_IMAGE_TRUNCATE
Trim the image to the Canvas size (flush top/left)
o SIZE_IMAGE_SCALE 
  public final static int SIZE_IMAGE_SCALE
Scale the image to the Canvas size (centered)
o SIZE_IMAGE_FLUSH 
  public final static int SIZE_IMAGE_FLUSH
Scale the image to the Canvas size (centered)
o view 
  protected Image view
o mode 
  protected int mode
o offscreen 
  protected Image offscreen
o tracker 
  protected MediaTracker tracker
o msgfont 
  protected static Font msgfont
o doclear 
  protected boolean doclear
o size 
  protected Dimension size

Constructors

o ImageCanvas 
  public ImageCanvas()
o ImageCanvas 
  public ImageCanvas(int w,
                     int h)
o ImageCanvas 
  public ImageCanvas(Dimension sz)

Methods

o preferredSize 
  public Dimension preferredSize()
Overrides:
preferredSize in class Component
o setPreferredSize 
  public void setPreferredSize(int w,
                               int h)
o setPreferredSize 
  public void setPreferredSize(Dimension sz)
o displayImage 
  public void displayImage(Image im)
o clear 
  public synchronized void clear()
clear the canvas. This method also releases references to images being displayed
o offpaint 
  protected void offpaint(Graphics g)
paint the image with a double-buffering technique. This method first creates an offscreen Image, paints the real image to it (via tryPaint()), and then paints that copy to the canvas.
o paint 
  public void paint(Graphics g)
this calls tryPaint(Graphics)
Overrides:
paint in class Canvas
o paintMessage 
  protected void paintMessage(Graphics g,
                              String msg)
print a message on the canvas. Message is placed over a white rectangle to that it can be seen.
o imageUpdate 
  public boolean imageUpdate(Image img,
                             int flags,
                             int x,
                             int y,
                             int width,
                             int height)
Overrides:
imageUpdate in class Component
o tryPaint 
  protected boolean tryPaint(Graphics g)
like paint() except that it returns a boolean indicating whether it was successful in painting the image onto the canvas
o update 
  public void update(Graphics g)
calls offpaint()
Overrides:
update in class Component
o viewSize 
  public Dimension viewSize(int wd,
                            int ht)
determine the dimesions necessary to fit an image of width wd and height ht into the display canvas (while preserving the aspect ratio). An input dimension < 0 means use the corresponding dimension of the current image being displayed.
o viewSize 
  public Dimension viewSize()
determine the dimesions necessary to fit the current image into the display canvas (while preserving the aspect ratio.)
o isLoading 
  public boolean isLoading()
indicate whether there is an image being loaded at this time
o clone 
  public synchronized Object clone()
make a copy of this canvas in an efficient manner
Overrides:
clone in class Object
o setMode 
  public void setMode(int _mode)
Set the display mode for sizing or trimming the viewable image.
Parameters:
_mode - The mode to use. Valid modes are SIZE_IMAGE_FIT, SIZE_IMAGE_CENTER, and SIZE_IMAGE_TRUNCATE. 
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