jj2000.disp
Class ImgScrollPane.ImageScrollDisplay

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.Canvas
              |
              +--jj2000.disp.ImgScrollPane.ImageScrollDisplay

All Implemented Interfaces:

javax.accessibility.Accessible, java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable

Enclosing class:

ImgScrollPane

private class ImgScrollPane.ImageScrollDisplay

extends java.awt.Canvas

This class implements the component that displays the currently viewable image portion inside the ImgScrollPane. It handles the necessary erasing, zooming and panning.

NOTE: extending 'Canvas' instead of 'Component' solves the flickering problem of lightweight components which are in heavyweight containers.

Nested Class Summary

Nested classes inherited from class java.awt.Canvas

java.awt.Canvas.AccessibleAWTCanvas

Nested classes inherited from class java.awt.Component

java.awt.Component.AccessibleAWTComponent, java.awt.Component.BltBufferStrategy, java.awt.Component.FlipBufferStrategy

Field Summary

(package private) java.awt.Dimension	dim The preferred size for this component
(package private) int	dimFlags The image dimension flags, as in ImageObserver.
(package private) boolean	erase If the current graphics context should be erased prior to drawing the image.
(package private) java.awt.Image	img The image to be displayed
(package private) java.awt.Dimension	imgDim The image dimensions, without any scaling.
(package private) java.awt.Point	lastUpdateOffset The last offset used in update().

Fields inherited from class java.awt.Canvas

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

private

ImgScrollPane.ImageScrollDisplay()

Method Summary

(package private) boolean	calcDim() Calculates the image display dimensions according to the zoom and image size.
java.awt.Dimension	getMaximumSize() Returns the maximum size for this component, which is infinite.
java.awt.Dimension	getMinimumSize() Returns the minimum size for this component, which is (0,0).
java.awt.Dimension	getPreferredSize() Returns the preferred size for this component, which is the image display size, if known, the previous image display size, if any, or the size specified at the constructor.
boolean	imageUpdate(java.awt.Image img, int infoflags, int x, int y, int w, int h) Monitors the image rendering for dimensions and calls the superclass' 'imageUpdate()' method.
void	paint(java.awt.Graphics g) Paints the image, if any, on the graphics context by calling update().
(package private) void	setImage(java.awt.Image img) Sets the image to display in this component.
void	update(java.awt.Graphics g) Updates the component by drawing the relevant part of the image that fits within the Graphics clipping area of 'g'.

Methods inherited from class java.awt.Canvas

addNotify, createBufferStrategy, createBufferStrategy, getAccessibleContext, getBufferStrategy

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, paramString, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, validate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

img

java.awt.Image img

The image to be displayed

dim

java.awt.Dimension dim

The preferred size for this component

erase

boolean erase

If the current graphics context should be erased prior to drawing the image. Set when the image and/or zoom factor is changed.

imgDim

java.awt.Dimension imgDim

The image dimensions, without any scaling. Set as soon as they are known.

dimFlags

int dimFlags

The image dimension flags, as in ImageObserver. The ImageObserver.WIDTH and ImageObserver.HEIGHT flags are set whenever the dimension is stored in imgDim. They are reset whenever the image changes.

lastUpdateOffset

java.awt.Point lastUpdateOffset

The last offset used in update().

Constructor Detail

ImgScrollPane.ImageScrollDisplay

private ImgScrollPane.ImageScrollDisplay()

Method Detail

setImage

void setImage(java.awt.Image img)

Sets the image to display in this component. If the image is not ready for display it will be prepared in the current thread. The current zoom factor applies.

If the image is not ready for display (i.e. it has not been rendered at its natural size) it will be rendered in the current thread, if not being already rendered in another one. This means that the current thread can block until the image is ready.

If the image is rendered incrementally (it depends on the underlying 'ImageProducer') it will be displayed in that way if the incremental display is set for the Component class. See the 'imageUpdate()' method of the 'Component' class.

If the image is the same as the current one nothing is done.

Parameters:

img - The image to display.

See Also:

Component.imageUpdate(java.awt.Image, int, int, int, int, int)

getMinimumSize

public java.awt.Dimension getMinimumSize()

Returns the minimum size for this component, which is (0,0).

Overrides:

getMinimumSize in class java.awt.Component

Returns:

The minimum size

getMaximumSize

public java.awt.Dimension getMaximumSize()

Returns the maximum size for this component, which is infinite.

Overrides:

getMaximumSize in class java.awt.Component

Returns:

The maximum size

getPreferredSize

public java.awt.Dimension getPreferredSize()

Returns the preferred size for this component, which is the image display size, if known, the previous image display size, if any, or the size specified at the constructor.

Overrides:

getPreferredSize in class java.awt.Component

Returns:

The preferred size for this component.

imageUpdate

public boolean imageUpdate(java.awt.Image img,
                           int infoflags,
                           int x,
                           int y,
                           int w,
                           int h)

Monitors the image rendering for dimensions and calls the superclass' 'imageUpdate()' method. If the display size of the image is not yet known and the image dimensions are obtained, then the scrollbars' values are set. If 'img' is not the current image to display nothing is done and 'false' is returned indicating that nothing more is necessary for it.

Specified by:

imageUpdate in interface java.awt.image.ImageObserver

Overrides:

imageUpdate in class java.awt.Component

See Also:

ImageObserver.imageUpdate(java.awt.Image, int, int, int, int, int), Component.imageUpdate(java.awt.Image, int, int, int, int, int)

paint

public void paint(java.awt.Graphics g)

Paints the image, if any, on the graphics context by calling update().

Overrides:

paint in class java.awt.Canvas

Parameters:

g - The graphics context to paint on.

update

public void update(java.awt.Graphics g)

Updates the component by drawing the relevant part of the image that fits within the Graphics clipping area of 'g'. If the image is not already being prepared for rendering or is not already rendered this method does not start it. This is to avoid blocking the AWT threads for rendering the image. The image rendering is started by the 'setImage()' method.

Overrides:

update in class java.awt.Canvas

Parameters:

g - The graphics context where to draw

See Also:

setImage(java.awt.Image)

calcDim

boolean calcDim()

Calculates the image display dimensions according to the zoom and image size. The dimensions are stored in 'dim'.

Returns:

True if the dimensions could be calculated, false if not (i.e. not enough info is available).