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appendix H
java.awt.peer
Package Reference
CONTENTS
The java.awt.peer package
is interesting because it contains no classes. Every object defined
within the java.awt.peer
package is an interface. By examining the contents of the classes
in the java.awt package,
you will find that all the GUI components in that package implement
the interfaces found in the java.awt.peer
package. Nearly all the methods defined in the java.awt.peer
interfaces are friendly methods, meaning that they can
only be accessed from within java.awt
package classes.
Extends: ComponentPeer
The ButtonPeer interface
extends interface java.awt.peer.ComponentPeer.
The ButtonPeer interface
provides the basic structure required for button component functionality.
setLabel
void setLabel(String label)
The setLabel method
should set the displayed label for the button using the specified
label string.
Parameters: label-a
string that will be displayed as the button's label.
Extends: ComponentPeer
The CanvasPeer interface
extends interface java.awt.peer.ComponentPeer.
The CanvasPeer interface
provides the basic structure required for canvas component functionality.
Extends: MenuItemPeer
The CheckboxMenuItemPeer
interface extends interface java.awt.peer.MenuItemPeer.
The CheckboxMenuItemPeer
interface provides the basic structure required for check box
menu item component functionality.
setState
void setState(boolean t)
The setState method
sets the checked state of a check box menu item.
Parameters: t-a
boolean value that will be true
if the check box is to be checked, false
if not.
Extends: ComponentPeer
The CheckboxPeer interface
extends interface java.awt.peer.ComponentPeer.
The CheckboxPeer interface
provides the basic structure required for check box component
functionality.
setState
void setState(boolean state)
The setState method
sets the checked state of a check box.
Parameters: t-a
boolean value that will be true
if the check box is to be checked, false
if not.
setCheckboxGroup
void setCheckboxGroup(CheckboxGroup g)
The setCheckboxGroup method
should set which check box group the check box belongs to, using
the specified check box group.
Parameters: g-a
CheckboxGroup object that
this check box will be a member of.
setLabel
void setLabel(String label)
The setLabel method
should set the displayed label for the check box using the specified
label string.
Parameters: label-a
String that will be displayed
as the check box's label.
Extends: ComponentPeer
The ChoicePeer interface
extends interface java.awt.peer.ComponentPeer.
The ChoicePeer interface
provides the basic structure required for Choice
component functionality.
addItem
void addItem(String item, int index)
The addItem method
adds the specified item to the choice list at the specified list
index.
Parameters: item-a
string value representing the item to be added to the choice list.
Parameters: index-the
integer index into the choice list where the item parameter is
to be added.
select
void select(int index)
The select method
selects the choice list item at the specified index.
Parameters: index-the
index into the choice list to be selected.
The ComponentPeer interface
extends class java.lang.Object.
The ComponentPeer interface
provides the basic structure required for component functionality.
show
void show()
The show method
should be implemented to make the Component
object visible.
hide
void hide()
The hide method
should hide the component so that is not visible.
enable
void enable()
The enable method
should enable the component so that it can be selected by the
user.
disable
void disable()
The disable method
should disable the component (gray it out, and so on) so that
it cannot be selected by the user.
paint
void paint(Graphics g)
The paint method
should display the component using the specified Graphics
context.
Parameters: g-a
Graphics object used for
drawing purposes.
repaint
void repaint(long tm, int x, int y, int
width, int height)
The repaint method
repaints a part of the component at some specified time in the
Qfuture.
Parameters:
tm-maximum time in milliseconds
before the update.
x-the x coordinate of the
component's bounding rectangle to repaint.
y-the y coordinate of the
component's bounding rectangle to repaint.
width-the width of the component's
bounding rectangle to repaint.
height-the height of the
component's bounding rectangle to repaint.
print
void print(Graphics g)
The print method
should print the component using the specified Graphics
object.
Parameters: g-a
Graphics object used for
drawing purposes.
reshape
void reshape(int x, int y, int width,
int height)
The reshape method
reshapes the component to the specified bounding rectangle.
Parameters:
x-the x coordinate of the
component's new bounding rectangle.
y-the y coordinate of the
component's new bounding rectangle.
width-the width of the component's
new bounding rectangle.
height-the height of the
component's new bounding rectangle.
handleEvent
boolean handleEvent(Event e)
The handleEvent method
should handle the specified event for the component.
Parameters: e-an
Event object encapsulating
some system event.
minimumSize
Dimension minimumSize()
The minimumSize method
returns the minimum size allowable for the component.
Returns: A Dimension
object containing the component's minimum size.
preferredSize
Dimension preferredSize()
The preferredSize method
returns the preferred size allowable for the component.
Returns: A Dimension
object containing the component's preferred size.
getColorModel
ColorModel getColorModel()
The getColorModel method
returns the color model used for this component.
Returns: A ColorModel
object that contains the component's color model information.
getToolkit
Toolkit getToolkit()
The getToolkit method
returns the component's managing tool kit.
Returns: A Toolkit
object.
getGraphics
Graphics getGraphics()
The getGraphics method
returns a Graphics context
for the component.
Returns: A Graphics
object used for drawing purposes.
getFontMetrics
FontMetrics getFontMetrics(Font font)
The getFontMetrics method
returns the font metrics information for the specified Font.
Parameters: font-a
Font object.
Returns: A FontMetrics
object containing metrics information on the specified font.
dispose
void dispose()
The dispose method
disposes of a component's resources and the component itself.
setForeground
void setForeground(Color c)
The setForeground method
sets the foreground color for the component using the specified
color.
Parameters: c-a
Color object specifying which
color to use for the foreground color.
setBackground
void setBackground(Color c)
The setBackground method
sets the background color for the component using the specified
color.
Parameters: c-a
Color object specifying which
color to use for the background color.
setFont
void setFont(Font f)
The setFont method
sets the font to use for this component using the specified font.
Parameters: f-a
Font object specifying which
font to use for the component.
requestFocus
void requestFocus()
The requestFocus method
requests the input focus for the component.
nextFocus
void nextFocus()
The nextFocus method
shifts the focus to the next component on the screen.
createImage
Image createImage(ImageProducer producer)
The createImage method
creates an Image object using
the specified ImageProducer
interface.
Parameters: producer-an
ImageProducer derived object
used to produce an image.
Returns: An Image
object.
createImage
Image createImage(int width, int height)
This createImage method
creates an image for offscreen use using the specified sizes.
Parameters:
width-the width of
the image to be created.
height-the height of the
image to be created.
Returns: An Image
object.
prepareImage
boolean prepareImage(Image img, int w,
int h, ImageObserver o)
The prepareImage method
prepares the image for rendering on this component using the specified
parameters.
Parameters:
img-an Image
object to be rendered.
w-the width of the rectangle
to render the image in.
h-the height of the rectangle
to render the image in.
o-the image observer used
to monitor the image rendering.
Returns: A boolean value that is true if the image
was rendered successfully, false if not.
checkImage
int checkImage(Image img, int w, int
h, ImageObserver o)
The checkImage method
returns the status of a scaled rendering of a specified Image.
Parameters:
img-an Image
object to be rendered.
w-the width of the rectangle
to render the image in.
h-the height of the rectangle
to render the image in.
o-the image observer used
to monitor the image rendering.
Returns: An integer value containing the boolean
OR of the image observer status flags.
Extends: ComponentPeer
The ContainerPeer interface
extends interface java.awt.peer.ComponentPeer.
The ContainerPeer interface
provides the basic structure required for container component
functionality.
insets
Insets insets()
The insets method
returns an Insets object
representing the insets of the container.
Returns: An Insets
object.
Extends: WindowPeer
The DialogPeer interface
extends interface java.awt.peer.WindowPeer.
The DialogPeer interface
provides the basic structure required for dialog box component
functionality.
setTitle
void setTitle(String title)
The setTitle method
sets the title to be displayed on the dialog's title bar.
Parameters: title-a
string value that will be used as the dialog's title.
setResizable
void setResizable(boolean resizeable)
The setResizable method
determines the dialog's resize state.
Parameters: resizeable-a
boolean value that is true
if the dialog can be resized, false
if not.
Extends: DialogPeer
The FileDialogPeer interface
extends interface java.awt.peer.DialogPeer.
The FileDialogPeer interface
provides the basic structure required for file selection dialog
component func-tionality.
setFile
void setFile(String file)
The setFile method
sets the filename to be displayed in the file dialog.
Parameters: file-a
string value representing a filename.
setDirectory
void setDirectory(String dir)
The setDirectory method
sets the directory to be selected in the file dialog.
Parameters: dir-a
string value representing the directory name.
setFilenameFilter
void setFilenameFilter(FilenameFilter
filter)
The setFilenameFilter()
sets the filter to be used in the file dialog.
Parameters: filter-a
FilenameFilter object used
to filter filenames.
Extends: WindowPeer
The FramePeer interface extends
interface java.awt.peer.WindowPeer.
The FramePeer interface provides
the basic structure required for frame component functionality.
setTitle
void setTitle(String title)
The setTitle method
sets the title of the frame to the specified title string.
Parameters: title-a
string value representing the frame's title.
setIconImage
void setIconImage(Image im)
The setIconImage method
sets the image to be used when the frame is iconized.
Parameters: im-an
Image object.
setMenuBar
void setMenuBar(MenuBar mb)
The setMenuBar method
sets the menu bar to be used for the frame.
Parameters: mb-A
MenuBar object.
setResizable
void setResizable(boolean resizeable)
The setResizable method
determines the resize state of the frame.
Parameters: resizeable-a
boolean value that is true
if the frame can be resized, false
if not.
setCursor
void setCursor(int cursorType)
The setCursor method
sets the cursor type for the frame.
Parameters: cursorType-an
integer value representing the cursor type.
Extends: ComponentPeer
The LabelPeer interface extends
interface java.awt.peer.ComponentPeer.
The LabelPeer interface provides
the basic structure required for label component functionality.
setText
void setText(String label)
The setText method
sets the text to be displayed on the label.
Parameters: label-a
string value that is used as the label string.
setAlignment
void setAlignment(int alignment)
The setAlignment method
sets the alignment type of the label.
Parameters: alignment-an
integer value that determines the alignment of the label (LEFT,
RIGHT, or CENTER).
Extends: ComponentPeer
The ListPeer interface extends
interface java.awt.peer.ComponentPeer.
The ListPeer interface provides
the basic structure required for list component functionality.
getSelectedIndexes
int[] getSelectedIndexes()
The getSelectedIndexes method
returns an array containing the selected indexes in the list.
Returns: An integer array containing the indexes
that are currently selected in the list.
void addItem(String item, int index)
The addItem method
adds a String item at the
specified index.
Parameters:
item-a string value to be
added to the list.
index-an integer value representing
the index into the list.
delItems
void delItems(int start, int end)
The delItems method
deletes a range of values from the list using the specified range
values.
Parameters:
start-an integer value marking
the start of the deletion range.
end-an integer value marking
the end of the deletion range.
clear
void clear()
The clear method
clears all elements from the list.
select
void select(int index)
This select method
selects the specified index.
Parameters: index-an
integer value specifying the item in the list to be selected.
deselect
void deselect(int index)
The deselect method
deselects an item within the list.
Parameters: index-an
integer value specifying the item in the list to be deselected.
makeVisible
void makeVisible(int index)
The makeVisible method
forces the list to scroll, if necessary, so that the specified
index will be made visible to the user.
Parameters: index-an
integer value representing the index to be made visible.
setMultipleSelections
void setMultipleSelections(boolean v)
The setMultipleSelections
method specifies whether the list should allow multiple
selections or not.
Parameters: v-a
boolean value that is true
if multiple selections are to be allowed, false
if not.
preferredSize
Dimension preferredSize(int v)
The preferredSize method
sets the preferred size for a list of the specified number of
items.
Parameters: v-an
integer value specifying the number of items within the list.
Returns: A Dimension
object containing the preferred size of the list.
minimumSize
Dimension minimumSize(int v)
The minimumSize method
sets the minimum size for a list of the specified number of items.
Parameters: v-an
integer value specifying the number of items within the list.
Returns: A Dimension
object containing the minimum size of the list.
Extends: MenuComponentPeer
The MenuBarPeer interface
extends interface java.awt.peer.MenuComponentPeer.
The MenuBarPeer interface
provides the basic structure required for menu bar component functionality.
addMenu
void addMenu(Menu m)
The addMenu method
adds the specified Menu to
the menu bar.
Parameters: m-the
Menu object to be added to
the menu bar.
delMenu
void delMenu(int index)
The delMenu method
deletes the menu at the specified index from the menu bar.
Parameters: index-an
integer value representing the index to be deleted from the menu
bar.
addHelpMenu
void addHelpMenu(Menu m)
The addHelpMenu
adds a help menu to the menu bar.
Parameters: m-the
Menu object to be added to
the menu bar.
Extends: MenuComponentPeer
The MenuComponentPeer interface
extends interface java.awt.peer.MenuComponentPeer.
The MenuComponentPeer interface
provides the basic structure required for menu component functionality.
dispose
void dispose()
The dispose method
disposes of a MenuComponent's
allocated resources.
Extends: MenuComponentPeer
The MenuItemPeer interface
extends interface java.awt.peer.MenuComponentPeer.
The MenuItemPeer interface
provides the basic structure required for menu item component
functionality.
setLabel
void setLabel(String label)
The setLabel method
sets the label string that will be displayed on the menu item.
Parameters: label-a
string value that will be displayed as the menu item's label.
enable
void enable()
The enable method
enables the menu item for user selection.
disable
void disable()
The disable method
disables the menu item for user selection.
Extends: MenuItemPeer
The MenuPeer interface extends
interface java.awt.peer.MenuItemPeer.
The MenuPeer interface provides
the basic structure required for menu component functionality.
addSeparator
void addSeparator()
The addSeparator method
adds a separator element to the menu. A separator is an item like
a line that cannot be selected by the user and that will not trigger
a menu selection event.
addItem
void addItem(MenuItem item)
The addItem method
adds a menu item to the menu.
Parameters: item-a
MenuItem object.
delItem
void delItem(int index)
The delItem method
deletes the menu item at the specified index.
Parameters: index-an
integer value representing the index on the menu to be deleted.
Extends: ContainerPeer
The PanelPeer interface extends
interface java.awt.peer.ContainerPeer.
The PanelPeer interface provides
the basic structure required for panel component functionality.
Extends: ComponentPeer
The ScrollbarPeer interface
extends interface java.awt.peer.ComponentPeer.
The ScrollbarPeer interface
provides the basic structure required for scrollbar component
functionality.
setValue
void setValue(int value)
The setValue method
sets the value of the scrollbar.
Parameters: value-an
integer value representing the value (position) of the scrollbar.
setValues
void setValues(int value, int visible,
int minimum, int maximum)
The setValues method sets the specified properties
of the scrollbar.
Parameters:
value-the new value of the
scrollbar.
visible-the number of units
to be displayed by the scrollbar.
Parameters:
minimum-the minimum value
of the scrollbar.
maximum-the maximum value
of the scrollbar.
setLineIncrement
void setLineIncrement(int l)
The setLineIncrement method
sets the increment value represented by a user clicking on a scrollbar
line up/down widget.
Parameters: l-an
integer value representing the line increment value.
setPageIncrement
void setPageIncrement(int l)
The setPageIncrement method
sets the increment value represented by a user clicking on a scrollbar
page up/down widget.
Parameters: l-an
integer value representing the page increment value.
Extends: TextComponentPeer
The TextAreaPeer interface
extends interface java.awt.peer.TextAreaPeer.
The TextAreaPeer interface
provides the basic structure required for text area component
functionality.
insertText
void insertText(String txt, int pos)
The insertText method
inserts the specified text at the specified position within the
text area.
Parameters:
txt-a string value representing
the text to be inserted.
pos-an integer value representing
the position within the text area to insert the text at.
replaceText
void replaceText(String txt, int start,
int end)
The replaceText
method replaces text at the specified positions with the new text.
Parameters:
txt-a string value representing
the text to be inserted into the text area.
start-an integer value containing
the start position of the text to be replaced.
end-an integer value containing
the end position of the text to be replaced.
preferredSize
Dimension preferredSize(int rows, int
cols)
The preferredSize method
returns the preferred size of a text area of the specified dimensions.
Parameters:
rows-the number of rows in
the text area.
cols-the number of columns
in the text area.
Returns: A Dimension
object containing the preferred size of the text area.
minimumSize
Dimension minimumSize(int rows, int cols)
The minimumSize method
returns the minimum size of a text area of the specified dimensions.
Parameters:
rows-the number of rows in
the text area.
cols-the number of columns
in the text area.
Returns: A Dimension
object containing the minimum size of the text area.
Extends: ComponentPeer
The TextComponentPeer interface
extends interface java.awt.peer.ComponentPeer.
The TextComponentPeer interface
provides the basic structure required for text component functionality.
setEditable
void setEditable(boolean editable)
The setEditable method
is used to set the text component's editable state.
Parameters: A boolean value that is true
if the text can be edited, false
if not.
getText
String getText()
The getText method
returns the text component's displayed text.
Returns: A string value representing the text contained
in the text component.
setText
void setText(String l)
The setText method
sets the text to be displayed in the text component.
Parameters: l-a
string value to be displayed by the text component.
getSelectionStart
int getSelectionStart()
The getSelectionStart method
returns the position of the first selected character in the text
component.
Returns: An integer value specifying the position
of the first selected character in the text component.
getSelectionEnd
int getSelectionEnd()
The getSelectionEnd method
returns the position of the last selected character in the text
component.
Returns: An integer value specifying the position
of the last selected character in the text component.
select
void select(int selStart, int selEnd)
The select method
selects the specified text within the TextComponent.
Parameters:
selStart-an integer value
representing the starting character to be selected.
selEnd-an integer value representing
the ending character to be selected.
Extends: TextComponentPeer
The TextFieldPeer interface
extends class java.lang.Object.
The TextFieldPeer interface
provides the basic structure required for text field component
functionality.
setEchoCharacter
void setEchoCharacter(char c)
The setEchoCharacter method
sets the echo character to be echoed to the screen as the user
types.
Parameters: c-a
character value to be displayed no matter what character the user
types.
preferredSize
Dimension preferredSize(int cols)
The preferredSize method
returns the preferred size of the text field based on the specified
number of characters.
Parameters: cols-an
integer value containing the number of characters in the text
field.
Returns: A Dimension
object containing the preferred size of the text field.
minimumSize
Dimension minimumSize(int cols)
The minimumSize method
returns the minimum size of the text field based on the specified
number of characters.
Parameters: cols-an
integer value containing the number of characters in the text
field.
Returns: A Dimension
object containing the minimum size of the text field.
Extends: ContainerPeer
The WindowPeer interface
extends interface java.awt.peer.ContainerPeer.
The WindowPeer interface
provides the basic structure required for window component functionality.
toFront
void toFront()
The toFront method
moves the window to the front of the display.
toBack
void toBack()
The toBack method
moves the window to the back of the display.
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