java.awt.peer

Interface ComponentPeer

Known Subinterfaces:
ButtonPeer, CanvasPeer, CheckboxPeer, ChoicePeer, ContainerPeer, DialogPeer, FileDialogPeer, FramePeer, LabelPeer, LightweightPeer, ListPeer, PanelPeer, ScrollbarPeer, ScrollPanePeer, TextAreaPeer, TextComponentPeer, TextFieldPeer, WindowPeer

public interface ComponentPeer

Defines the methods that a component peer is required to implement.

Method Summary

boolean
canDetermineObscurity()
Returns true if this component peer can determine if the component has been obscured, false otherwise.
int
checkImage(Image img, int width, int height, ImageObserver ob)
Returns the construction status of the specified image.
void
coalescePaintEvent(PaintEvent e)
Coalesces the specified paint event.
void
createBuffers(int numBuffers, BufferCapabilities caps)
Create a number of image buffers that implement a buffering strategy according to the given capabilities.
Image
createImage(int width, int height)
Creates an empty image with the specified width and height.
Image
createImage(ImageProducer prod)
Creates an image by starting the specified image producer.
VolatileImage
createVolatileImage(int width, int height)
A convenience method that creates a volatile image.
void
destroyBuffers()
Destroy the resources created by createBuffers.
void
disable()
Disables the component.
void
dispose()
Disposes the component peer.
void
enable()
Enables the component.
void
flip(BufferCapabilities.FlipContents contents)
Perform a page flip, leaving the contents of the back buffer in the specified state.
Image
getBackBuffer()
Return the back buffer of this component.
Rectangle
getBounds()
Get the bounds of this component peer.
ColorModel
getColorModel()
Returns the color model of the component.
FontMetrics
getFontMetrics(Font f)
Returns the font metrics for the specified font.
Graphics
getGraphics()
Returns a Graphics object suitable for drawing on this component.
GraphicsConfiguration
getGraphicsConfiguration()
Get the graphics configuration of the component.
Point
getLocationOnScreen()
Returns the location of this component in screen coordinates.
Dimension
getMinimumSize()
Returns the minimum size for the component.
Dimension
getPreferredSize()
Returns the preferred size for the component.
Toolkit
getToolkit()
Returns the toolkit that created this peer.
void
handleEvent(AWTEvent e)
Handles the given event.
boolean
handlesWheelScrolling()
Returns true, if this component can handle wheel scrolling, false otherwise.
void
hide()
Makes the component invisible.
boolean
isFocusTraversable()
Returns true if the component can receive keyboard input focus.
boolean
isFocusable()
Returns true if the component can receive keyboard input focus.
boolean
isObscured()
Returns true if this component has been obscured, false otherwise.
boolean
isReparentSupported()
Check if this component supports being reparented.
void
layout()
Layout this component peer.
Dimension
minimumSize()
Returns the minimum size for the component.
void
paint(Graphics graphics)
Dimension
preferredSize()
Returns the preferred size for the component.
boolean
prepareImage(Image img, int width, int height, ImageObserver ob)
Prepares an image for rendering on this component.
void
print(Graphics graphics)
void
repaint(long tm, int x, int y, int width, int height)
Repaints the specified rectangle of this component.
void
reparent(ContainerPeer parent)
Reparent this component under another container.
void
requestFocus()
Requests that this component receives the focus.
boolean
requestFocus(Component request, boolean temporary, boolean allowWindowFocus, long time)
Requests that this component receives the focus.
boolean
requestFocus(Component lightweightChild, boolean temporary, boolean focusedWindowChangeAllowed, long time, CausedFocusEvent.Cause cause)
Requests the focus on the component.
void
reshape(int x, int y, int width, int height)
Notifies the peer that the bounds of this component have changed.
void
setBackground(Color color)
Sets the background color of the component.
void
setBounds(int x, int y, int width, int height)
Notifies the peer that the bounds of this component have changed.
void
setBounds(int x, int y, int width, int height, int z)
Set the bounds of this component peer.
void
setCursor(Cursor cursor)
Sets the cursor of the component.
void
setEnabled(boolean enabled)
Sets the enabled/disabled state of this component.
void
setEventMask(long mask)
Part of an older API, no longer needed.
void
setFont(Font font)
Sets the font of the component.
void
setForeground(Color color)
Sets the foreground color of the component.
void
setVisible(boolean visible)
Sets the visibility state of the component.
void
show()
Makes the component visible.
void
updateCursorImmediately()
Updates the cursor.

Method Details

canDetermineObscurity

public boolean canDetermineObscurity()
Returns true if this component peer can determine if the component has been obscured, false otherwise.
Returns:
true if this component peer can determine if the component has been obscured, false otherwise

checkImage

public int checkImage(Image img,
                      int width,
                      int height,
                      ImageObserver ob)
Returns the construction status of the specified image. This is called by Component.checkImage(Image,int,int,ImageObserver).
Parameters:
img - the image
width - the width of the image
height - the height of the image
ob - the image observer to be notified of updates of the status
Returns:
a bitwise ORed set of ImageObserver flags

coalescePaintEvent

public void coalescePaintEvent(PaintEvent e)
Coalesces the specified paint event.
Parameters:
e - the paint event

createBuffers

public void createBuffers(int numBuffers,
                          BufferCapabilities caps)
            throws AWTException
Create a number of image buffers that implement a buffering strategy according to the given capabilities.
Parameters:
numBuffers - the number of buffers
caps - the buffering capabilities
Throws:
AWTException - if the specified buffering strategy is not implemented
Since:
1.2

createImage

public Image createImage(int width,
                         int height)
Creates an empty image with the specified width and height.
Parameters:
width - the width of the image to be created
height - the height of the image to be created
Returns:
the created image

createImage

public Image createImage(ImageProducer prod)
Creates an image by starting the specified image producer. This is called by Component.createImage(ImageProducer).
Parameters:
prod - the image producer to be used to create the image
Returns:
the created image

createVolatileImage

public VolatileImage createVolatileImage(int width,
                                         int height)
A convenience method that creates a volatile image. The volatile image is created on the screen device on which this component is displayed, in the device's current graphics configuration.
Parameters:
width - width of the image
height - height of the image
Since:
1.2
See Also:
VolatileImage

destroyBuffers

public void destroyBuffers()
Destroy the resources created by createBuffers.
Since:
1.2

disable

public void disable()
Disables the component. This is called by Component.disable().

dispose

public void dispose()
Disposes the component peer. This should release all resources held by the peer. This is called when the component is no longer in use.

enable

public void enable()
Enables the component. This is called by Component.enable().

flip

public void flip(BufferCapabilities.FlipContents contents)
Perform a page flip, leaving the contents of the back buffer in the specified state.
Parameters:
contents - the state in which to leave the back buffer
Since:
1.2

getBackBuffer

public Image getBackBuffer()
Return the back buffer of this component.
Returns:
the back buffer of this component.
Since:
1.2

getBounds

public Rectangle getBounds()
Get the bounds of this component peer.
Returns:
component peer bounds
Since:
1.5

getColorModel

public ColorModel getColorModel()
Returns the color model of the component. This is currently not used.
Returns:
the color model of the component

getFontMetrics

public FontMetrics getFontMetrics(Font f)
Returns the font metrics for the specified font. This is called by Component.getFontMetrics(Font).
Parameters:
f - the font for which to query the font metrics
Returns:
the font metrics for the specified font

getGraphics

public Graphics getGraphics()
Returns a Graphics object suitable for drawing on this component. This is called by Component.getGraphics().
Returns:
a graphics object suitable for drawing on this component

getGraphicsConfiguration

public GraphicsConfiguration getGraphicsConfiguration()
Get the graphics configuration of the component. The color model of the component can be derived from the configuration.
Returns:
the graphics configuration of the component

getLocationOnScreen

public Point getLocationOnScreen()
Returns the location of this component in screen coordinates. This is called by Component.getLocationOnScreen().
Returns:
the location of this component in screen coordinates

getMinimumSize

public Dimension getMinimumSize()
Returns the minimum size for the component. This is called by Component.getMinimumSize().
Returns:
the minimum size for the component

getPreferredSize

public Dimension getPreferredSize()
Returns the preferred size for the component. This is called by Component.getPreferredSize().
Returns:
the preferred size for the component

getToolkit

public Toolkit getToolkit()
Returns the toolkit that created this peer.
Returns:
the toolkit that created this peer

handleEvent

public void handleEvent(AWTEvent e)
Handles the given event. This is called from Component.dispatchEvent(AWTEvent) to give the peer a chance to react to events for the component.
Parameters:
e - the event

handlesWheelScrolling

public boolean handlesWheelScrolling()
Returns true, if this component can handle wheel scrolling, false otherwise.
Returns:
true, if this component can handle wheel scrolling, false otherwise

hide

public void hide()
Makes the component invisible. This is called from Component.hide().

isFocusTraversable

public boolean isFocusTraversable()
Returns true if the component can receive keyboard input focus. This is called from Component.isFocusTraversable().

isFocusable

public boolean isFocusable()
Returns true if the component can receive keyboard input focus. This is called from Component.isFocusable().

isObscured

public boolean isObscured()
Returns true if this component has been obscured, false otherwise. This will only work if canDetermineObscurity() also returns true.
Returns:
true if this component has been obscured, false otherwise.

isReparentSupported

public boolean isReparentSupported()
Check if this component supports being reparented.
Returns:
true if this component can be reparented, false otherwise.
Since:
1.5

layout

public void layout()
Layout this component peer.
Since:
1.5

minimumSize

public Dimension minimumSize()
Returns the minimum size for the component. This is called by Component.minimumSize().
Returns:
the minimum size for the component

paint

public void paint(Graphics graphics)

preferredSize

public Dimension preferredSize()
Returns the preferred size for the component. This is called by Component.getPreferredSize().
Returns:
the preferred size for the component

prepareImage

public boolean prepareImage(Image img,
                            int width,
                            int height,
                            ImageObserver ob)
Prepares an image for rendering on this component. This is called by Component.prepareImage(Image,int,int,ImageObserver).
Parameters:
img - the image to prepare
width - the desired width of the rendered image
height - the desired height of the rendered image
ob - the image observer to be notified of updates in the preparation process
Returns:
true if the image has been fully prepared, false otherwise (in which case the image observer receives updates)

print

public void print(Graphics graphics)

repaint

public void repaint(long tm,
                    int x,
                    int y,
                    int width,
                    int height)
Repaints the specified rectangle of this component. This is called from Component.repaint(long,int,int,int,int).
Parameters:
tm - number of milliseconds to wait with repainting
x - the X coordinate of the upper left corner of the damaged rectangle
y - the Y coordinate of the upper left corner of the damaged rectangle
width - the width of the damaged rectangle
height - the height of the damaged rectangle

reparent

public void reparent(ContainerPeer parent)
Reparent this component under another container.
Parameters:
parent -
Since:
1.5

requestFocus

public void requestFocus()
Requests that this component receives the focus. This is called from Component.requestFocus().

requestFocus

public boolean requestFocus(Component request,
                            boolean temporary,
                            boolean allowWindowFocus,
                            long time)
Requests that this component receives the focus. This is called from Component.requestFocus(). This method is only called for heavyweight component's peers. Lightweight components ask their nearest heavyweight component to request focus. It's up to the heavyweight peer to decide if any of it's lightweight descendants are allowed to receive keyboard input focus or not. If the focus request is finally approved, then the peer must post a FOCUS_GAINED event for the requested component.
Parameters:
request - the component for which the focus is requested
temporary - indicates if the focus change is temporary (true) or permanent (false)
allowWindowFocus - indicates if it's allowed to change window focus
time - the timestamp

requestFocus

public boolean requestFocus(Component lightweightChild,
                            boolean temporary,
                            boolean focusedWindowChangeAllowed,
                            long time,
                            CausedFocusEvent.Cause cause)
Requests the focus on the component.

reshape

public void reshape(int x,
                    int y,
                    int width,
                    int height)
Notifies the peer that the bounds of this component have changed. This is called by Component.reshape(int,int,int,int).
Parameters:
x - the X coordinate of the upper left corner of the component
y - the Y coordinate of the upper left corner of the component
width - the width of the component
height - the height of the component

setBackground

public void setBackground(Color color)
Sets the background color of the component. This is called by Component.setBackground(Color).
Parameters:
color - the background color to set

setBounds

public void setBounds(int x,
                      int y,
                      int width,
                      int height)
Notifies the peer that the bounds of this component have changed. This is called by Component.setBounds(int,int,int,int).
Parameters:
x - the X coordinate of the upper left corner of the component
y - the Y coordinate of the upper left corner of the component
width - the width of the component
height - the height of the component

setBounds

public void setBounds(int x,
                      int y,
                      int width,
                      int height,
                      int z)
Set the bounds of this component peer.
Parameters:
x - the new x co-ordinate
y - the new y co-ordinate
width - the new width
height - the new height
z - the new stacking level
Since:
1.5

setCursor

public void setCursor(Cursor cursor)
Sets the cursor of the component. This is called by Component.setCursor(Cursor).

setEnabled

public void setEnabled(boolean enabled)
Sets the enabled/disabled state of this component. This is called by Component.setEnabled(boolean).
Parameters:
enabled - true to enable the component, false to disable it

setEventMask

public void setEventMask(long mask)
Part of an older API, no longer needed.

setFont

public void setFont(Font font)
Sets the font of the component. This is called by Component.setFont(Font).
Parameters:
font - the font to set

setForeground

public void setForeground(Color color)
Sets the foreground color of the component. This is called by Component.setForeground(Color).
Parameters:
color - the foreground color to set

setVisible

public void setVisible(boolean visible)
Sets the visibility state of the component. This is called by Component.setVisible(boolean).
Parameters:
visible - true to make the component visible, false to make it invisible

show

public void show()
Makes the component visible. This is called by Component.show().

updateCursorImmediately

public void updateCursorImmediately()
Updates the cursor.

ComponentPeer.java -- Toplevel component peer Copyright (C) 1999, 2000, 2002 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.