Class ImageLabel

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Canvas
                   |
                   +----ImageLabel

public class ImageLabel

extends Canvas

By default, with FlowLayout the ImageLabel takes its minimum size (just enclosing the image). The default with BorderLayout is to expand to fill the region in width (North/South), height (East/West) or both (Center). This is the same behavior as with the builtin Label class. If you give an explicit resize or reshape call before adding the ImageLabel to the Container, this size will override the defaults.

Here is an example of its use:

public class ShowImages extends Applet {
  private ImageLabel image1, image2;
  public void init() {
    image1 = new ImageLabel(getCodeBase(),
                            "some-image.gif");
    image2 = new ImageLabel(getCodeBase(),
                            "other-image.jpg");
    add(image1);
    add(image2);
  }
}

Version:

1.0 (1997)

Author:

Marty Hall (hall@apl.jhu.edu)

See Also:

Icon, ImageButton

ImageLabel()

Create an ImageLabel with the default image.

ImageLabel(Image)

Create an ImageLabel using the image specified.

ImageLabel(String)

Create an ImageLabel using the image at URL specified by the string.

ImageLabel(URL)

Create an ImageLabel using the image at URL specified.

ImageLabel(URL, String)

Create an ImageLabel using the image in the file in the specified directory.

centerAt(int, int)

Moves the image so that it is centered at the specified location, as opposed to the move method of Component which places the top left corner at the specified location.

debug(String)

Calls System.out.println if the debug variable is true; does nothing otherwise.

drawRect(Graphics, int, int, int, int, int, Color)

Draws a rectangle with the specified OUTSIDE left, top, width, and height.

getBorder()

Gets the border width.

getBorderColor()

Gets the border color.

getDefaultImageString()

Returns the string representing the URL that will be used if none is supplied in the constructor.

getHeight()

Gets the height (image height plus 2x border).

getImage()

The Image associated with the ImageLabel.

getImageString()

Returns the string representing the URL of image.

getWidth()

Gets the width (image width plus twice border).

hasExplicitSize()

Has the ImageLabel been given an explicit size? This is used to decide if the image should be stretched or not.

inside(int, int)

Determines if the x and y (in the ImageLabel's own coordinate system) is inside the ImageLabel.

isDebugging()

Is the debugging flag set?

minimumSize()

Used by layout managers to calculate the smallest size allocated for the Component.

paint(Graphics)

Draws the image.

preferredSize()

Used by layout managers to calculate the usual size allocated for the Component.

reshape(int, int, int, int)

Resizes the ImageLabel.

resize(int, int)

Resizes the ImageLabel.

setBorder(int)

Sets the border thickness.

setBorderColor(Color)

Sets the border color.

setDefaultImageString(String)

Sets the string representing the URL that will be used if none is supplied in the constructor.

setIsDebugging(boolean)

Set the debugging flag.

waitForImage(boolean)

Makes sure that the Image associated with the Canvas is done loading before returning, since loadImage spins off a separate thread to do the loading.

  public ImageLabel()

Create an ImageLabel with the default image.

See Also:

getDefaultImageString, setDefaultImageString

  public ImageLabel(String imageURLString)

Create an ImageLabel using the image at URL specified by the string.

Parameters:

imageURLString - A String specifying the URL of the image.

  public ImageLabel(URL imageURL)

Create an ImageLabel using the image at URL specified.

Parameters:

imageURL - The URL of the image.

  public ImageLabel(URL imageDirectory,
                    String file)

Create an ImageLabel using the image in the file in the specified directory.

Parameters:

imageDirectory - Directory containing image

file - Filename of image

  public ImageLabel(Image image)

Create an ImageLabel using the image specified. The other constructors eventually call this one, but you may want to call it directly if you already have an image (e.g. created via createImage).

Parameters:

image - The image

  public void waitForImage(boolean doLayout)

Makes sure that the Image associated with the Canvas is done loading before returning, since loadImage spins off a separate thread to do the loading. Once you get around to drawing the image, this will make sure it is loaded, waiting if not. The user does not need to call this at all, but if several ImageLabels are used in the same Container, this can cause several repeated layouts, so users might want to explicitly call this themselves before adding the ImageLabel to the Container. Another alternative is to start asynchronous loading by calling prepareImage on the ImageLabel's image (see getImage).

Parameters:

doLayout - Determines if the Container should be re-laid out after you are finished waiting. This should be true when called from user functions, but is set to false when called from preferredSize to avoid an infinite loop. This is needed when using BorderLayout, which calls preferredSize before calling paint.

  public void centerAt(int x,
                       int y)

Moves the image so that it is centered at the specified location, as opposed to the move method of Component which places the top left corner at the specified location.

Note: The effects of this could be undone by the LayoutManager of the parent Container, if it is using one. So this is normally only used in conjunction with a null LayoutManager.

Parameters:

x - The X coord of center of the image (in parent's coordinate system)

y - The Y coord of center of the image (in parent's coordinate system)

See Also:

move

  public synchronized boolean inside(int x,
                                     int y)

Determines if the x and y (in the ImageLabel's own coordinate system) is inside the ImageLabel. Put here because Netscape 2.02 has a bug in which it doesn't process inside() and locate() tests correctly.

Overrides:

inside in class Component

  public void paint(Graphics g)

Draws the image. If you override this in a subclass, be sure to call super.paint.

Overrides:

paint in class Canvas

  public Dimension preferredSize()

Used by layout managers to calculate the usual size allocated for the Component. Since some layout managers (e.g. BorderLayout) may call this before paint is called, you need to make sure that the image is done loading, which will force a resize, which determines the values returned.

Overrides:

preferredSize in class Component

  public Dimension minimumSize()

Used by layout managers to calculate the smallest size allocated for the Component. Since some layout managers (e.g. BorderLayout) may call this before paint is called, you need to make sure that the image is done loading, which will force a resize, which determines the values returned.

Overrides:

minimumSize in class Component

  public void resize(int width,
                     int height)

Resizes the ImageLabel. If you don't resize the label explicitly, then what happens depends on the layout manager. With FlowLayout, as with FlowLayout for Labels, the ImageLabel takes its minimum size, just enclosing the image. With BorderLayout, as with BorderLayout for Labels, the ImageLabel is expanded to fill the section. Stretching GIF/JPG files does not always result in clear looking images. So just as with builtin Labels and Buttons, don't use FlowLayout if you don't want the Buttons to get resized. If you don't use any LayoutManager, then the ImageLabel will also just fit the image.

Note that if you resize explicitly, you must do it before the ImageLabel is added to the Container. In such a case, the explicit size overrides the image dimensions.

Overrides:

resize in class Component

See Also:

reshape

  public void reshape(int x,
                      int y,
                      int width,
                      int height)

Resizes the ImageLabel. If you don't resize the label explicitly, then what happens depends on the layout manager. With FlowLayout, as with FlowLayout for Labels, the ImageLabel takes its minimum size, just enclosing the image. With BorderLayout, as with BorderLayout for Labels, the ImageLabel is expanded to fill the section. Stretching GIF/JPG files does not always result in clear looking images. So just as with builtin Labels and Buttons, don't use FlowLayout if you don't want the Buttons to get resized. If you don't use any LayoutManager, then the ImageLabel will also just fit the image.

Note that if you resize explicitly, you must do it before the ImageLabel is added to the Container. In such a case, the explicit size overrides the image dimensions.

Overrides:

reshape in class Component

See Also:

resize

  protected void drawRect(Graphics g,
                          int left,
                          int top,
                          int width,
                          int height,
                          int lineThickness,
                          Color rectangleColor)

Draws a rectangle with the specified OUTSIDE left, top, width, and height. Used to draw the border.

  protected void debug(String message)

Calls System.out.println if the debug variable is true; does nothing otherwise.

Parameters:

message - The String to be printed.

  public Image getImage()

The Image associated with the ImageLabel.

  public int getBorder()

Gets the border width.

  public void setBorder(int border)

Sets the border thickness.

  public Color getBorderColor()

Gets the border color.

  public void setBorderColor(Color borderColor)

Sets the border color.

  public int getWidth()

Gets the width (image width plus twice border).

  public int getHeight()

Gets the height (image height plus 2x border).

  protected boolean hasExplicitSize()

Has the ImageLabel been given an explicit size? This is used to decide if the image should be stretched or not. This will be true if you call resize or reshape on the ImageLabel before adding it to a Container. It will be false otherwise.

  public static String getDefaultImageString()

Returns the string representing the URL that will be used if none is supplied in the constructor.

  public static void setDefaultImageString(String file)

Sets the string representing the URL that will be used if none is supplied in the constructor. Note that this is static, so is shared by all ImageLabels. Using this might be convenient in testing, but "real" applications should avoid it.

  protected String getImageString()

Returns the string representing the URL of image.

  public boolean isDebugging()

Is the debugging flag set?

  public void setIsDebugging(boolean debug)

Set the debugging flag. Verbose messages will be printed to System.out if this is true.