GCanvas

java.lang.Object
- java.awt.Component
- - java.awt.Container
  - - javax.swing.JComponent
    - - acm.graphics.GCanvas

All Implemented Interfaces:

GCanvasInterface, GContainer, ImageObserver, MenuContainer, Serializable, Iterable<GObject>
```
public class GCanvas
extends JComponent
implements GCanvasInterface, GContainer, Iterable<GObject>
```
The GCanvas class is a lightweight component that also serves as a container for graphical objects. As such, this class provides the link between graphical objects and the window system. Conceptually, the GCanvas provides a background canvas to which other graphical objects can be added.

See Also:

Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from class javax.swing.JComponent
  JComponent.AccessibleJComponent
- Nested classes/interfaces inherited from class java.awt.Container
  Container.AccessibleAWTContainer
- Nested classes/interfaces inherited from class java.awt.Component
  Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy

Field Summary
- Fields inherited from class javax.swing.JComponent
  listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW
- Fields inherited from class java.awt.Component
  accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
- Fields inherited from interface acm.graphics.GContainer
  BACK_TO_FRONT, FRONT_TO_BACK
- Fields inherited from interface java.awt.image.ImageObserver
  ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

Constructors
Constructor and Description

GCanvas()
Creates a new GCanvas that contains no objects.

Constructors
Constructor and Description
`GCanvas()` Creates a new `GCanvas` that contains no objects.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Component`	`add(Component comp)` Adds the component to this canvas without changing its location.
`void`	`add(Component comp, double x, double y)` Adds the component to this canvas and sets its location to the point (`x`, `y`).
`void`	`add(Component comp, GPoint pt)` Adds the component to this canvas and sets its location to the specified point.
`void`	`add(GObject gobj)` Adds the graphical object to this canvas.
`void`	`add(GObject gobj, double x, double y)` Adds the graphical object to this canvas and sets its location to the point (`x`, `y`).
`void`	`add(GObject gobj, GPoint pt)` Adds the graphical object to this canvas and sets its location to the specified point.
`void`	`clear()` Removes all graphical objects from this canvas.
`protected void`	`conditionalRepaint()` Repaints the canvas if auto-repaint is in effect.
`void`	`diff(File file)` Compares the pixels of this canvas to the image stored in the given file.
`void`	`diff(File file, boolean ignoreWindowSize)` Compares the pixels of this canvas to the image stored in the given file.
`void`	`diff(String file)` Compares the pixels of this canvas to the image stored in the given file.
`void`	`diff(String file, boolean ignoreWindowSize)` Compares the pixels of this canvas to the image stored in the given file.
`protected void`	`dispatchMouseEvent(MouseEvent e)` Dispatches this mouse event to the uppermost graphical object for which the active point is within the object bounds.
`void`	`draw(Shape paramShape)` Draws an outlined version of the given shape.
`void`	`drawArc(double paramDouble1, double paramDouble2, double paramDouble3, double paramDouble4, double paramDouble5, double paramDouble6)` Draws an outlined arc with the given coordinates.
`void`	`drawLine(double paramDouble1, double paramDouble2, double paramDouble3, double paramDouble4)` Draws a line with the given endpoint coordinates.
`void`	`drawOval(double paramDouble1, double paramDouble2, double paramDouble3, double paramDouble4)` Draws an outlined oval with the given coordinates.
`GPoint`	`drawPolarLine(double x0, double y0, double r, double theta)` Draws a line with the given polar coordinates, returning its starting endpoint.
`GPoint`	`drawPolarLine(GPoint p0, double r, double theta)` Draws a line with the given polar coordinates, returning its starting endpoint.
`void`	`drawRect(double paramDouble1, double paramDouble2, double paramDouble3, double paramDouble4)` Draws an outlined rectangle with the given coordinates.
`void`	`fill(Shape paramShape)` Draws a filled version of the given shape.
`void`	`fillArc(double paramDouble1, double paramDouble2, double paramDouble3, double paramDouble4, double paramDouble5, double paramDouble6)` Draws a filled arc with the given coordinates.
`void`	`fillOval(double paramDouble1, double paramDouble2, double paramDouble3, double paramDouble4)` Draws a filled oval with the given coordinates.
`void`	`fillRect(double paramDouble1, double paramDouble2, double paramDouble3, double paramDouble4)` Draws a filled rectangle with the given coordinates.
`boolean`	`getAutoRepaintFlag()` Returns the current setting of the auto-repaint flag as described in `setAutoRepaintFlag`.
`<T extends GObject> T`	`getElement(int index)` Returns the graphical object at the specified index, numbering from back to front in the the z dimension.
`<T extends GObject> T`	`getElementAt(double... coords)` This version of getElementAt accepts a variable number of coordinate pairs (in x1, y1, x2, y2, x3, y3, ...
`<T extends GObject> T`	`getElementAt(double x, double y)` Returns the topmost graphical object that contains the point (`x`, `y`), or `null` if no such object exists.
`<T extends GObject> T`	`getElementAt(GPoint pt)` Returns the topmost graphical object that contains the specified point, or `null` if no such object exists.
`int`	`getElementCount()` Returns the number of graphical objects stored in this `GCanvas`.
`boolean`	`getNativeArcFlag()` Returns the current setting of the native-arc flag as described in `setNativeArcFlag`.
`Graphics2D`	`getOSG()` Returns the graphical pen for drawing on this canvas.
`String`	`getPixelsAsString()` Returns a Base64-encoded representation of the pixel data of this image.
`int`	`getRGB(int x, int y)` Returns the RGB color stored at the given (x, y) pixel, or 0 if that pixel falls outside the bounds of this canvas.
`boolean`	`hasElementAt(double... coords)` Returns true if a graphical object exists that touches any of the given (x, y) pixel positions, or false if no such object exists.
`boolean`	`hasElementAt(double x, double y)` Returns true if a graphical object exists that touches the given (x, y) pixel position, or false if no such object exists.
`boolean`	`inBounds(int x, int y)` Whether the given (x, y) point falls within the bounds of this canvas, from (0, 0) ..
`boolean`	`isAntiAliasing()` Sets whether this canvas uses anti-aliasing, which is smoothing and blending of neighboring pixels.
`Iterator<GObject>`	`iterator()` Returns an `Iterator` that cycles through the elements within this container in the default direction, which is from back to front.
`Iterator<GObject>`	`iterator(int direction)` Returns an `Iterator` that cycles through the elements within this container in the specified direction, which must be one of the constants `GContainer.FRONT_TO_BACK` or `GContainer.BACK_TO_FRONT`.
`void`	`paintComponent(Graphics g)` Paints the canvas.
`void`	`remove(Component comp)` Removes the component from the canvas.
`void`	`remove(double x, double y)` Removes the top-most graphical object at the given (x, y) position from this container.
`void`	`remove(GObject gobj)` Removes a graphical object from this `GCanvas`.
`void`	`remove(GPoint pt)` Removes the top-most graphical object at the given (x, y) position from this container.
`void`	`removeAll()` Removes all graphical objects from this `GCanvas`.
`void`	`removeAll(double... coords)` Removes all graphical objects at the given (x, y) positions from this container.
`void`	`removeAll(double x, double y)` Removes all graphical objects at the given (x, y) position from this container.
`void`	`removeAll(GPoint pt)` Removes all graphical objects at the given (x, y) position from this container.
`void`	`save(File file)` Writes the contents of the canvas to the given file.
`void`	`save(String filename)` Writes the contents of the canvas to the given file.
`protected void`	`sendBackward(GObject gobj)` Implements the `sendBackward` function from the `GContainer` interface.
`protected void`	`sendForward(GObject gobj)` Implements the `sendForward` function from the `GContainer` interface.
`protected void`	`sendToBack(GObject gobj)` Implements the `sendToBack` function from the `GContainer` interface.
`protected void`	`sendToFront(GObject gobj)` Implements the `sendToFront` function from the `GContainer` interface.
`void`	`setAntiAliasing(boolean antialias)` Sets whether this canvas uses anti-aliasing, which is smoothing and blending of neighboring pixels.
`void`	`setAutoRepaintFlag(boolean state)` Changes the setting of the auto-repaint flag.
`void`	`setBackground(Color color)`
`void`	`setBorder(Color color)` Sets this canvas to use a border of the given color, 1px thick.
`void`	`setBorder(Color color, int thickness)` Sets this canvas to use a border of the given color and number of pixels thick.
`void`	`setColor(Color color)`
`void`	`setColor(int paramInt)`
`void`	`setForeground(Color color)`
`void`	`setForeground(int paramInt)`
`void`	`setNativeArcFlag(boolean state)` Sets whether the redering code for `GArc` and `GOval` should use Java arcs.
`void`	`setOpaque(boolean flag)` Sets a flag indicating whether this canvas is opaque, which means that it obscures anything behind it.
`void`	`setPixelsFromString(String base64)`
`void`	`setRGB(int x, int y, int rgb)`
`void`	`setRGB(int x, int y, int rgb, boolean repaint)`
`void`	`setShowPixelGrid(boolean show)` Sets whether to display information on this canvas about the current pixel where the mouse pointer is resting.
`void`	`setShowPixelInfo(boolean show)` Sets whether to display information on this canvas about the current pixel where the mouse pointer is resting.
`void`	`showDiffDialog()` Pops up a dialog box to compare the contents of this canvas to an expected image file.
`void`	`showDiffDialog(File directory)` Pops up a dialog box to compare the contents of this canvas to an expected image file.
`void`	`showDiffDialog(String directory)` Pops up a dialog box to compare the contents of this canvas to an expected image file.
`File`	`showSaveDialog()` Pops up a dialog box to save the contents of this canvas to a file.
`File`	`showSaveDialog(File directory)` Pops up a dialog box to save the contents of this canvas to a file.
`File`	`showSaveDialog(String directory)` Pops up a dialog box to save the contents of this canvas to a file.
`BufferedImage`	`toImage()` Returns the pixel contents of this canvas as a BufferedImage.
`BufferedImage`	`toImage(int width, int height)` Returns the pixel contents of this canvas as a BufferedImage of the given size.
`protected void`	`updateEnabledList()` Reconstructs the enabledList list in the correct order.

Methods inherited from class javax.swing.JComponent
addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBaseline, getBaselineResizeBehavior, getBorder, getBounds, getClientProperty, getComponentGraphics, getComponentPopupMenu, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getFontMetrics, getGraphics, getHeight, getInheritsPopupMenu, getInputMap, getInputMap, getInputVerifier, getInsets, getInsets, getListeners, getLocation, getMaximumSize, getMinimumSize, getNextFocusableComponent, getPopupLocation, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getUIClassID, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, hide, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isOptimizedDrawingEnabled, isPaintingForPrint, isPaintingOrigin, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paint, paintBorder, paintChildren, paintImmediately, paintImmediately, paramString, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processKeyBinding, processKeyEvent, processMouseEvent, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, removeVetoableChangeListener, repaint, repaint, requestDefaultFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, resetKeyboardActions, reshape, revalidate, scrollRectToVisible, setActionMap, setAlignmentX, setAlignmentY, setAutoscrolls, setBorder, setComponentPopupMenu, setDebugGraphicsOptions, setDefaultLocale, setDoubleBuffered, setEnabled, setFocusTraversalKeys, setFont, setInheritsPopupMenu, setInputMap, setInputVerifier, setMaximumSize, setMinimumSize, setNextFocusableComponent, setPreferredSize, setRequestFocusEnabled, setToolTipText, setTransferHandler, setUI, setVerifyInputWhenFocusTarget, setVisible, unregisterKeyboardAction, update, updateUI

Methods inherited from class java.awt.Container
add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getLayout, getMousePosition, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, printComponents, processContainerEvent, processEvent, remove, removeContainerListener, setComponentZOrder, setFocusCycleRoot, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setLayout, transferFocusDownCycle, validate, validateTree

Methods inherited from class java.awt.Component
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, createImage, createImage, createVolatileImage, createVolatileImage, disableEvents, dispatchEvent, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAccessibleContext, getBackground, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getForeground, getGraphicsConfiguration, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getToolkit, getTreeLock, gotFocus, handleEvent, hasFocus, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface acm.graphics.GCanvasInterface
getBackground, getFont, getHeight, getSize, getWidth, repaint, setFont, setSize

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Constructor Detail
  - GCanvas
```
public GCanvas()
```
    Creates a new GCanvas that contains no objects.
    
    Usage:
    
    GCanvas gc = new GCanvas();
- Method Detail
  - add
```
public Component add(Component comp)
```
    Adds the component to this canvas without changing its location. If the component has no size, its size is set to its preferred size. The return type is Component to match the method in the Container class, but the result is typically ignored.
    
    Overrides:
    
    add in class Container
    
    Parameters:
    
    comp - The component to add
    
    Usage:
    
    gc.add(comp);
  - add
```
public final void add(Component comp,
                      double x,
                      double y)
```
    Adds the component to this canvas and sets its location to the point (x, y).
    
    Specified by:
    
    add in interface GCanvasInterface
    
    Parameters:
    
    comp - The component to add
    
    x - The new x-coordinate for the object
    
    y - The new y-coordinate for the object
    
    Usage:
    
    gc.add(comp, x, y);
  - add
```
public final void add(Component comp,
                      GPoint pt)
```
    Adds the component to this canvas and sets its location to the specified point.
    
    Specified by:
    
    add in interface GCanvasInterface
    
    Parameters:
    
    comp - The component to add
    
    pt - A GPoint object giving the coordinates of the point
    
    Usage:
    
    gc.add(comp, pt);
  - add
```
public void add(GObject gobj)
```
    Adds the graphical object to this canvas.
    
    Specified by:
    
    add in interface GCanvasInterface
    
    Specified by:
    
    add in interface GContainer
    
    Parameters:
    
    gobj - The graphical object to add
    
    Usage:
    
    gc.add(gobj);
  - add
```
public final void add(GObject gobj,
                      double x,
                      double y)
```
    Adds the graphical object to this canvas and sets its location to the point (x, y).
    
    Specified by:
    
    add in interface GCanvasInterface
    
    Specified by:
    
    add in interface GContainer
    
    Parameters:
    
    gobj - The graphical object to add
    
    x - The new x-coordinate for the object
    
    y - The new y-coordinate for the object
    
    Usage:
    
    gc.add(gobj, x, y);
  - add
```
public final void add(GObject gobj,
                      GPoint pt)
```
    Adds the graphical object to this canvas and sets its location to the specified point.
    
    Specified by:
    
    add in interface GCanvasInterface
    
    Specified by:
    
    add in interface GContainer
    
    Parameters:
    
    gobj - The graphical object to add
    
    pt - A GPoint object giving the coordinates of the point
    
    Usage:
    
    gc.add(gobj, pt);
  - clear
```
public void clear()
```
    Removes all graphical objects from this canvas.
    
    Specified by:
    
    clear in interface GCanvasInterface
  - conditionalRepaint
```
protected void conditionalRepaint()
```
    Repaints the canvas if auto-repaint is in effect. This method is called only by the repaint method in GObject and is not accessible outside the package.
    
    Usage:
    
    gc.conditionalRepaint();
    
    Noshow:
  - diff
```
public void diff(File file)
```
    Compares the pixels of this canvas to the image stored in the given file.
  - diff
```
public void diff(File file,
                 boolean ignoreWindowSize)
```
    Compares the pixels of this canvas to the image stored in the given file. If ignoreWindowSize is true, allows the two windows' sizes to differ as long as they don't have any different drawn shapes between them.
  - diff
```
public void diff(String file)
```
    Compares the pixels of this canvas to the image stored in the given file.
  - diff
```
public void diff(String file,
                 boolean ignoreWindowSize)
```
    Compares the pixels of this canvas to the image stored in the given file. If ignoreWindowSize is true, allows the two windows' sizes to differ as long as they don't have any different drawn shapes between them.
  - dispatchMouseEvent
```
protected void dispatchMouseEvent(MouseEvent e)
```
    Dispatches this mouse event to the uppermost graphical object for which the active point is within the object bounds.
    
    Parameters:
    
    e - The event that triggered this response
    
    Usage:
    
    gc.dispatchMouseEvent(MouseEvent e);
    
    Noshow:
  - draw
```
public void draw(Shape paramShape)
```
    Draws an outlined version of the given shape.
  - drawArc
```
public void drawArc(double paramDouble1,
                    double paramDouble2,
                    double paramDouble3,
                    double paramDouble4,
                    double paramDouble5,
                    double paramDouble6)
```
    Draws an outlined arc with the given coordinates.
  - drawLine
```
public void drawLine(double paramDouble1,
                     double paramDouble2,
                     double paramDouble3,
                     double paramDouble4)
```
    Draws a line with the given endpoint coordinates.
  - drawOval
```
public void drawOval(double paramDouble1,
                     double paramDouble2,
                     double paramDouble3,
                     double paramDouble4)
```
    Draws an outlined oval with the given coordinates.
  - drawPolarLine
```
public GPoint drawPolarLine(double x0,
                            double y0,
                            double r,
                            double theta)
```
    Draws a line with the given polar coordinates, returning its starting endpoint.
  - drawPolarLine
```
public GPoint drawPolarLine(GPoint p0,
                            double r,
                            double theta)
```
    Draws a line with the given polar coordinates, returning its starting endpoint.
  - drawRect
```
public void drawRect(double paramDouble1,
                     double paramDouble2,
                     double paramDouble3,
                     double paramDouble4)
```
    Draws an outlined rectangle with the given coordinates.
  - fill
```
public void fill(Shape paramShape)
```
    Draws a filled version of the given shape.
  - fillArc
```
public void fillArc(double paramDouble1,
                    double paramDouble2,
                    double paramDouble3,
                    double paramDouble4,
                    double paramDouble5,
                    double paramDouble6)
```
    Draws a filled arc with the given coordinates.
  - fillOval
```
public void fillOval(double paramDouble1,
                     double paramDouble2,
                     double paramDouble3,
                     double paramDouble4)
```
    Draws a filled oval with the given coordinates.
  - fillRect
```
public void fillRect(double paramDouble1,
                     double paramDouble2,
                     double paramDouble3,
                     double paramDouble4)
```
    Draws a filled rectangle with the given coordinates.
  - getAutoRepaintFlag
```
public boolean getAutoRepaintFlag()
```
    Returns the current setting of the auto-repaint flag as described in setAutoRepaintFlag.
    
    Returns:
    
    true if auto-repaint mode is enabled, and false otherwise
    
    Usage:
    
    if (gc.getAutoRepaintFlag()) . . .
  - getElement
```
public <T extends GObject> T getElement(int index)
```
    Returns the graphical object at the specified index, numbering from back to front in the the z dimension.
    
    Specified by:
    
    getElement in interface GCanvasInterface
    
    Specified by:
    
    getElement in interface GContainer
    
    Parameters:
    
    index - The index of the component to return
    
    Returns:
    
    The graphical object at the specified index
    
    Usage:
    
    GObject gobj = gc.getElement(index);
  - getElementAt
```
public <T extends GObject> T getElementAt(double x,
                                          double y)
```
    Returns the topmost graphical object that contains the point (x, y), or null if no such object exists.
    
    Specified by:
    
    getElementAt in interface GCanvasInterface
    
    Specified by:
    
    getElementAt in interface GContainer
    
    Parameters:
    
    x - The x-coordinate of the point being tested
    
    y - The y-coordinate of the point being tested
    
    Returns:
    
    The graphical object at the specified location, or null if no such object exists
    
    Usage:
    
    GObject gobj = gc.getElementAt(x, y);
  - getElementAt
```
public <T extends GObject> T getElementAt(double... coords)
```
    This version of getElementAt accepts a variable number of coordinate pairs (in x1, y1, x2, y2, x3, y3, ... order) and will return the topmost graphical objectfound at any of these pairs. The pairs are checked in the order they are passed. If no graphical object is found at any of these coordinate pairs, null is returned.
    
    Specified by:
    
    getElementAt in interface GCanvasInterface
  - getElementAt
```
public final <T extends GObject> T getElementAt(GPoint pt)
```
    Returns the topmost graphical object that contains the specified point, or null if no such object exists.
    
    Specified by:
    
    getElementAt in interface GCanvasInterface
    
    Specified by:
    
    getElementAt in interface GContainer
    
    Parameters:
    
    pt - The coordinates being tested
    
    Returns:
    
    The graphical object at the specified location, or null if no such object exists
    
    Usage:
    
    GObject gobj = gc.getElementAt(pt);
  - getElementCount
```
public int getElementCount()
```
    Returns the number of graphical objects stored in this GCanvas.
    
    Specified by:
    
    getElementCount in interface GCanvasInterface
    
    Specified by:
    
    getElementCount in interface GContainer
    
    Returns:
    
    The number of graphical objects in this GCanvas
    
    Usage:
    
    int n = gc.getElementCount();
  - getNativeArcFlag
```
public boolean getNativeArcFlag()
```
    Returns the current setting of the native-arc flag as described in setNativeArcFlag.
    
    Returns:
    
    true if native arcs are enabled, and false otherwise
    
    Usage:
    
    if (gc.getNativeArcFlag()) . . .
  - getOSG
```
public Graphics2D getOSG()
```
    Returns the graphical pen for drawing on this canvas.
  - getPixelsAsString
```
public String getPixelsAsString()
```
    Returns a Base64-encoded representation of the pixel data of this image.
  - getRGB
```
public int getRGB(int x,
                  int y)
```
    Returns the RGB color stored at the given (x, y) pixel, or 0 if that pixel falls outside the bounds of this canvas.
  - hasElementAt
```
public boolean hasElementAt(double x,
                            double y)
```
    Returns true if a graphical object exists that touches the given (x, y) pixel position, or false if no such object exists.
    
    Specified by:
    
    hasElementAt in interface GCanvasInterface
  - hasElementAt
```
public boolean hasElementAt(double... coords)
```
    Returns true if a graphical object exists that touches any of the given (x, y) pixel positions, or false if no such object exists. This method accepts a variable number of coordinate pairs (in x1, y1, x2, y2, x3, y3, ... order). The pairs are checked in the order they are passed.
    
    Specified by:
    
    hasElementAt in interface GCanvasInterface
  - inBounds
```
public boolean inBounds(int x,
                        int y)
```
    Whether the given (x, y) point falls within the bounds of this canvas, from (0, 0) .. (width-1, height-1) inclusive.
  - isAntiAliasing
```
public boolean isAntiAliasing()
```
    Sets whether this canvas uses anti-aliasing, which is smoothing and blending of neighboring pixels. Default true.
    
    Specified by:
    
    isAntiAliasing in interface GCanvasInterface
  - iterator
```
public Iterator<GObject> iterator()
```
    Returns an Iterator that cycles through the elements within this container in the default direction, which is from back to front. You can also run the iterator in the opposite direction by using the iterator(direction) form of this method.
    
    Specified by:
    
    iterator in interface GCanvasInterface
    
    Specified by:
    
    iterator in interface Iterable<GObject>
    
    Returns:
    
    An Iterator ranging over the elements of the container from back to front
    
    Usage:
    
    Iterator i = gc.iterator();
  - iterator
```
public Iterator<GObject> iterator(int direction)
```
    Returns an Iterator that cycles through the elements within this container in the specified direction, which must be one of the constants GContainer.FRONT_TO_BACK or GContainer.BACK_TO_FRONT.
```
      for (Iterator<GObject> i = gc.iterator(direction); i.hasNext(); )
 
```
    Specified by:
    
    iterator in interface GCanvasInterface
    
    Returns:
    
    An Iterator ranging over the elements of the container in the specified direction
    
    Usage:
    
    Iterator i = gc.iterator(direction);
  - paintComponent
```
public void paintComponent(Graphics g)
```
    Paints the canvas. This method is not ordinarily called by clients.
    
    Overrides:
    
    paintComponent in class JComponent
    
    Parameters:
    
    g - The graphics context into which the canvas is painted
    
    Usage:
    
    gc.paintComponent(g);
    
    Noshow:
  - remove
```
public void remove(Component comp)
```
    Removes the component from the canvas.
    
    Overrides:
    
    remove in class Container
    
    Parameters:
    
    comp - The component to remove
    
    Usage:
    
    gc.remove(comp);
  - remove
```
public void remove(double x,
                   double y)
```
    Removes the top-most graphical object at the given (x, y) position from this container. If no graphical object is located at that position, does nothing.
    
    Specified by:
    
    remove in interface GCanvasInterface
    
    Usage:
    
    gc.remove(x, y);
  - remove
```
public void remove(GObject gobj)
```
    Removes a graphical object from this GCanvas.
    
    Specified by:
    
    remove in interface GCanvasInterface
    
    Specified by:
    
    remove in interface GContainer
    
    Parameters:
    
    gobj - The graphical object to remove
    
    Usage:
    
    gc.remove(gobj);
  - remove
```
public void remove(GPoint pt)
```
    Removes the top-most graphical object at the given (x, y) position from this container. If no graphical object is located at that position, does nothing.
    
    Specified by:
    
    remove in interface GCanvasInterface
    
    Usage:
    
    gc.remove(pt);
  - removeAll
```
public void removeAll()
```
    Removes all graphical objects from this GCanvas.
    
    Specified by:
    
    removeAll in interface GCanvasInterface
    
    Specified by:
    
    removeAll in interface GContainer
    
    Overrides:
    
    removeAll in class Container
    
    Usage:
    
    gc.removeAll();
  - removeAll
```
public void removeAll(double x,
                      double y)
```
    Removes all graphical objects at the given (x, y) position from this container. If no graphical objects are located at that position, does nothing.
    
    Specified by:
    
    removeAll in interface GCanvasInterface
    
    Usage:
    
    gc.removeAll(x, y);
  - removeAll
```
public void removeAll(double... coords)
```
    Removes all graphical objects at the given (x, y) positions from this container. If no graphical objects are located at that position, does nothing.
    
    Specified by:
    
    removeAll in interface GCanvasInterface
    
    Usage:
    
    gc.removeAll(x1, y1, x2, y2, ...);
  - removeAll
```
public void removeAll(GPoint pt)
```
    Removes all graphical objects at the given (x, y) position from this container. If no graphical objects are located at that position, does nothing.
    
    Specified by:
    
    removeAll in interface GCanvasInterface
    
    Usage:
    
    gc.removeAll(pt);
  - save
```
public void save(File file)
```
    Writes the contents of the canvas to the given file.
  - save
```
public void save(String filename)
```
    Writes the contents of the canvas to the given file.
  - sendBackward
```
protected void sendBackward(GObject gobj)
```
    Implements the sendBackward function from the GContainer interface. Clients should not be calling this method, but the semantics of interfaces forces it to be exported.
    
    Noshow:
  - sendForward
```
protected void sendForward(GObject gobj)
```
    Implements the sendForward function from the GContainer interface. Clients should not be calling this method, but the semantics of interfaces forces it to be exported.
    
    Noshow:
  - sendToBack
```
protected void sendToBack(GObject gobj)
```
    Implements the sendToBack function from the GContainer interface. Clients should not be calling this method, but the semantics of interfaces forces it to be exported.
    
    Noshow:
  - sendToFront
```
protected void sendToFront(GObject gobj)
```
    Implements the sendToFront function from the GContainer interface. Clients should not be calling this method, but the semantics of interfaces forces it to be exported.
    
    Noshow:
  - setAntiAliasing
```
public void setAntiAliasing(boolean antialias)
```
    Sets whether this canvas uses anti-aliasing, which is smoothing and blending of neighboring pixels. Default true.
    
    Specified by:
    
    setAntiAliasing in interface GCanvasInterface
  - setAutoRepaintFlag
```
public void setAutoRepaintFlag(boolean state)
```
    Changes the setting of the auto-repaint flag. By default, any change to a graphical object contained in this canvas automatically triggers a repaint of the canvas as a whole. While this behavior makes it much easier to use the package, it has the disadvantage that repaint requests come much more frequently than necessary. You can disable this feature by calling setAutoRepaintFlag(false), but you must then make explicit calls to repaint() whenever you want to update the display. The advantage of this model is that you can then make many different changes and have them all appear at once with a single repaint call.
    
    Parameters:
    
    state - true to enable auto-repaint mode, and false to disable it
    
    Usage:
    
    gc.setAutoRepaintFlag(state);
  - setBackground
```
public void setBackground(Color color)
```
    Specified by:
    
    setBackground in interface GCanvasInterface
    
    Overrides:
    
    setBackground in class JComponent
  - setBorder
```
public void setBorder(Color color)
```
    Sets this canvas to use a border of the given color, 1px thick.
  - setBorder
```
public void setBorder(Color color,
                      int thickness)
```
    Sets this canvas to use a border of the given color and number of pixels thick.
  - setColor
```
public void setColor(Color color)
```
  - setColor
```
public void setColor(int paramInt)
```
  - setForeground
```
public void setForeground(Color color)
```
    Overrides:
    
    setForeground in class JComponent
  - setForeground
```
public void setForeground(int paramInt)
```
  - setNativeArcFlag
```
public void setNativeArcFlag(boolean state)
```
    Sets whether the redering code for GArc and GOval should use Java arcs. By default, arcs and ovals are rendered using polygons and polylines to ensure that the same set of pixels is covered by the fill and frame. If this value is set to true, the renderers will use the native arc code, which is more efficient but less accurate.
    
    Parameters:
    
    state - true to enable native arcs, false to use polygons
    
    Usage:
    
    gc.setNativeArcFlag(state);
  - setOpaque
```
public void setOpaque(boolean flag)
```
    Sets a flag indicating whether this canvas is opaque, which means that it obscures anything behind it. Setting this flag to false makes the GCanvas transparent, so that any other lightweight components behind it show through.
    
    Overrides:
    
    setOpaque in class JComponent
    
    Parameters:
    
    flag - true to make this canvas opaque, and false to make it transparent
    
    Usage:
    
    gc.setOpaque(flag);
    
    Noshow:
  - setPixelsFromString
```
public void setPixelsFromString(String base64)
```
  - setRGB
```
public void setRGB(int x,
                   int y,
                   int rgb)
```
  - setRGB
```
public void setRGB(int x,
                   int y,
                   int rgb,
                   boolean repaint)
```
  - setShowPixelGrid
```
public void setShowPixelGrid(boolean show)
```
    Sets whether to display information on this canvas about the current pixel where the mouse pointer is resting. Displays the current pixel's (x, y) coordinate and color.
  - setShowPixelInfo
```
public void setShowPixelInfo(boolean show)
```
    Sets whether to display information on this canvas about the current pixel where the mouse pointer is resting. Displays the current pixel's (x, y) coordinate and color.
    
    Specified by:
    
    setShowPixelInfo in interface GCanvasInterface
  - showDiffDialog
```
public void showDiffDialog()
```
    Pops up a dialog box to compare the contents of this canvas to an expected image file.
  - showDiffDialog
```
public void showDiffDialog(File directory)
```
    Pops up a dialog box to compare the contents of this canvas to an expected image file. Starts the dialog box pointed at the given directory.
  - showDiffDialog
```
public void showDiffDialog(String directory)
```
    Pops up a dialog box to compare the contents of this canvas to an expected image file. Starts the dialog box pointed at the given directory.
  - showSaveDialog
```
public File showSaveDialog()
```
    Pops up a dialog box to save the contents of this canvas to a file. Returns the file saved to, or null if none.
  - showSaveDialog
```
public File showSaveDialog(File directory)
```
    Pops up a dialog box to save the contents of this canvas to a file. Starts the dialog box pointed at the given directory. Returns the file saved to, or null if none.
  - showSaveDialog
```
public File showSaveDialog(String directory)
```
    Pops up a dialog box to save the contents of this canvas to a file. Starts the dialog box pointed at the given directory. Returns the file saved to, or null if none.
  - toImage
```
public BufferedImage toImage()
```
    Returns the pixel contents of this canvas as a BufferedImage.
    
    Specified by:
    
    toImage in interface GCanvasInterface
  - toImage
```
public BufferedImage toImage(int width,
                             int height)
```
    Returns the pixel contents of this canvas as a BufferedImage of the given size.
  - updateEnabledList
```
protected void updateEnabledList()
```
    Reconstructs the enabledList list in the correct order.
    
    Usage:
    
    gc.updateEnabledList();

Class GCanvas

Nested Class Summary

Nested classes/interfaces inherited from class javax.swing.JComponent

Nested classes/interfaces inherited from class java.awt.Container

Nested classes/interfaces inherited from class java.awt.Component

Field Summary

Fields inherited from class javax.swing.JComponent

Fields inherited from class java.awt.Component

Fields inherited from interface acm.graphics.GContainer

Fields inherited from interface java.awt.image.ImageObserver

Constructor Summary

Method Summary

Methods inherited from class javax.swing.JComponent

Methods inherited from class java.awt.Container

Methods inherited from class java.awt.Component

Methods inherited from class java.lang.Object

Methods inherited from interface acm.graphics.GCanvasInterface

Methods inherited from interface java.lang.Iterable

Constructor Detail

GCanvas

Method Detail

add

add

add

add

add

add

clear

conditionalRepaint

diff

diff

diff

diff

dispatchMouseEvent

draw

drawArc

drawLine

drawOval

drawPolarLine

drawPolarLine

drawRect

fill

fillArc

fillOval

fillRect

getAutoRepaintFlag

getElement

getElementAt

getElementAt

getElementAt

getElementCount

getNativeArcFlag

getOSG

getPixelsAsString

getRGB

hasElementAt

hasElementAt

inBounds

isAntiAliasing

iterator

iterator

paintComponent

remove

remove

remove

remove

removeAll

removeAll

removeAll

removeAll

save

save

sendBackward

sendForward

sendToBack

sendToFront

setAntiAliasing

setAutoRepaintFlag

setBackground

setBorder