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java.lang.Object
|
+----java.awt.Graphics
Graphics class is the abstract base class for
all graphics contexts that allow an application to draw onto
components that are realized on various devices, as well as
onto off-screen images.
A Graphics object encapsulates state information needed
for the basic rendering operations that Java supports. This
state information includes the following properties:
Component object on which to draw.
setXORMode).
Coordinates are infinitely thin and lie between the pixels of the output device. Operations which draw the outline of a figure operate by traversing an infinitely thin path between pixels with a pixel-sized pen that hangs down and to the right of the anchor point on the path. Operations which fill a figure operate by filling the interior of that infinitely thin path. Operations which render horizontal text render the ascending portion of character glyphs entirely above the baseline coordinate.
The graphics pen hangs down and to the right from the path it traverses. This has the following implications:
All coordinates which appear as arguments to the methods of this
Graphics object are considered relative to the
translation origin of this Graphics object prior to
the invocation of the method.
All rendering operations modify only pixels which lie within the
area bounded by both the current clip of the graphics context
and the extents of the component used to create the
Graphics object.
All drawing or writing is done in the current color,
using the current paint mode, and in the current font.
Graphics()
Graphics object.
clearRect(int, int, int, int)
clipRect(int, int, int, int)
copyArea(int, int, int, int, int, int)
dx and dy.
create()
Graphics object that is
a copy of this Graphics object.
create(int, int, int, int)
Graphics object based on this
Graphics object, but with a new translation and clip area.
dispose()
draw3DRect(int, int, int, int, boolean)
drawArc(int, int, int, int, int, int)
drawBytes(byte[], int, int, int, int)
drawChars(char[], int, int, int, int)
drawImage(Image, int, int, Color, ImageObserver)
drawImage(Image, int, int, ImageObserver)
drawImage(Image, int, int, int, int, Color, ImageObserver)
drawImage(Image, int, int, int, int, ImageObserver)
drawImage(Image, int, int, int, int, int, int, int, int, Color, ImageObserver)
drawImage(Image, int, int, int, int, int, int, int, int, ImageObserver)
drawLine(int, int, int, int)
(x1, y1) and (x2, y2)
in this graphics context's coordinate system.
drawOval(int, int, int, int)
drawPolygon(int[], int[], int)
drawPolygon(Polygon)
Polygon object.
drawPolyline(int[], int[], int)
drawRect(int, int, int, int)
drawRoundRect(int, int, int, int, int, int)
drawString(String, int, int)
fill3DRect(int, int, int, int, boolean)
fillArc(int, int, int, int, int, int)
fillOval(int, int, int, int)
fillPolygon(int[], int[], int)
fillPolygon(Polygon)
fillRect(int, int, int, int)
fillRoundRect(int, int, int, int, int, int)
finalize()
getClip()
getClipBounds()
getClipRect()
getColor()
getFont()
getFontMetrics()
getFontMetrics(Font)
setClip(int, int, int, int)
setClip(Shape)
setColor(Color)
setFont(Font)
setPaintMode()
setXORMode(Color)
toString()
String object representing this
Graphics object's value.
translate(int, int)
Graphics
protected Graphics()
Graphics object.
This constructor is the default contructor for a graphics
context.
Since Graphics is an abstract class, applications
cannot call this constructor directly. Graphics contexts are
obtained from other graphics contexts or are created by calling
getGraphics on a component.
create
public abstract Graphics create()
Graphics object that is
a copy of this Graphics object.
create
public Graphics create(int x,
int y,
int width,
int height)
Graphics object based on this
Graphics object, but with a new translation and clip area.
The new Graphics object has its origin
translated to the specified point (x, y).
Its clip area is determined by the intersection of the original
clip area with the specified rectangle. The arguments are all
interpreted in the coordinate system of the original
Graphics object. The new graphics context is
identical to the original, except in two respects:
0, 0) in the
new graphics context is the same as (x, y) in
the original graphics context.
0, 0), and its size
is specified by the width and height arguments.
translate
public abstract void translate(int x,
int y)
getColor
public abstract Color getColor()
setColor
public abstract void setColor(Color c)
setPaintMode
public abstract void setPaintMode()
setXORMode
public abstract void setXORMode(Color c1)
When drawing operations are performed, pixels which are the current color are changed to the specified color, and vice versa.
Pixels that are of colors other than those two colors are changed in an unpredictable but reversible manner; if the same figure is drawn twice, then all pixels are restored to their original values.
getFont
public abstract Font getFont()
setFont
public abstract void setFont(Font font)
getFontMetrics
public FontMetrics getFontMetrics()
getFontMetrics
public abstract FontMetrics getFontMetrics(Font f)
getClipBounds
public abstract Rectangle getClipBounds()
clipRect
public abstract void clipRect(int x,
int y,
int width,
int height)
setClip
public abstract void setClip(int x,
int y,
int width,
int height)
getClip
public abstract Shape getClip()
Shape object representing the
current clipping area.
setClip
public abstract void setClip(Shape clip)
Shape
interface can be used to set the clip. The only
Shape objects which are guaranteed to be
supported are Shape objects which are
obtained via the getClip method and via
Rectangle objects.
copyArea
public abstract void copyArea(int x,
int y,
int width,
int height,
int dx,
int dy)
dx and dy. From the point specified
by x and y, this method
copies downwards and to the right. To copy an area of the
component to the left or upwards, specify a negative value for
dx or dy.
If a portion of the source rectangle lies outside the bounds
of the component, or is obscured by another window or component,
copyArea will be unable to copy the associated
pixels. The area that is omitted can be refreshed by calling
the component's paint method.
drawLine
public abstract void drawLine(int x1,
int y1,
int x2,
int y2)
(x1, y1) and (x2, y2)
in this graphics context's coordinate system.
fillRect
public abstract void fillRect(int x,
int y,
int width,
int height)
x and x + width - 1.
The top and bottom edges are at
y and y + height - 1.
The resulting rectangle covers an area
width pixels wide by
height pixels tall.
The rectangle is filled using the graphics context's current color.
drawRect
public void drawRect(int x,
int y,
int width,
int height)
x and x + width.
The top and bottom edges are at
y and y + height.
The rectangle is drawn using the graphics context's current color.
clearRect
public abstract void clearRect(int x,
int y,
int width,
int height)
Beginning with Java 1.1, the background color
of offscreen images may be system dependent. Applications should
use setColor followed by fillRect to
ensure that an offscreen image is cleared to a specific color.
drawRoundRect
public abstract void drawRoundRect(int x,
int y,
int width,
int height,
int arcWidth,
int arcHeight)
x and x + width,
respectively. The top and bottom edges of the rectangle are at
y and y + height.
fillRoundRect
public abstract void fillRoundRect(int x,
int y,
int width,
int height,
int arcWidth,
int arcHeight)
x and x + width - 1,
respectively. The top and bottom edges of the rectangle are at
y and y + height - 1.
draw3DRect
public void draw3DRect(int x,
int y,
int width,
int height,
boolean raised)
The colors used for the highlighting effect are determined
based on the current color.
The resulting rectangle covers an area that is
width + 1 pixels wide
by height + 1 pixels tall.
fill3DRect
public void fill3DRect(int x,
int y,
int width,
int height,
boolean raised)
drawOval
public abstract void drawOval(int x,
int y,
int width,
int height)
x, y,
width, and height arguments.
The oval covers an area that is
width + 1 pixels wide
and height + 1 pixels tall.
fillOval
public abstract void fillOval(int x,
int y,
int width,
int height)
drawArc
public abstract void drawArc(int x,
int y,
int width,
int height,
int startAngle,
int arcAngle)
The resulting arc begins at startAngle and extends
for arcAngle degrees, using the current color.
Angles are interpreted such that 0 degrees
is at the 3 o'clock position.
A positive value indicates a counter-clockwise rotation
while a negative value indicates a clockwise rotation.
The center of the arc is the center of the rectangle whose origin
is (x, y) and whose size is specified by the
width and height arguments.
The resulting arc covers an area
width + 1 pixels wide
by height + 1 pixels tall.
fillArc
public abstract void fillArc(int x,
int y,
int width,
int height,
int startAngle,
int arcAngle)
The resulting arc begins at startAngle and extends
for arcAngle degrees.
Angles are interpreted such that 0 degrees
is at the 3 o'clock position.
A positive value indicates a counter-clockwise rotation
while a negative value indicates a clockwise rotation.
The center of the arc is the center of the rectangle whose origin
is (x, y) and whose size is specified by the
width and height arguments.
The resulting arc covers an area
width + 1 pixels wide
by height + 1 pixels tall.
drawPolyline
public abstract void drawPolyline(int xPoints[],
int yPoints[],
int nPoints)
drawPolygon
public abstract void drawPolygon(int xPoints[],
int yPoints[],
int nPoints)
This method draws the polygon defined by nPoint line
segments, where the first nPoint - 1
line segments are line segments from
(xPoints[i - 1], yPoints[i - 1])
to (xPoints[i], yPoints[i]), for
1 ≤ i ≤ nPoints.
The figure is automatically closed by drawing a line connecting
the final point to the first point, if those points are different.
x coordinates.
y coordinates.
drawPolygon
public void drawPolygon(Polygon p)
Polygon object.
fillPolygon
public abstract void fillPolygon(int xPoints[],
int yPoints[],
int nPoints)
This method draws the polygon defined by nPoint line
segments, where the first nPoint - 1
line segments are line segments from
(xPoints[i - 1], yPoints[i - 1])
to (xPoints[i], yPoints[i]), for
1 ≤ i ≤ nPoints.
The figure is automatically closed by drawing a line connecting
the final point to the first point, if those points are different.
The area inside the polygon is defined using an even-odd fill rule, also known as the alternating rule.
x coordinates.
y coordinates.
fillPolygon
public void fillPolygon(Polygon p)
The area inside the polygon is defined using an even-odd fill rule, also known as the alternating rule.
drawString
public abstract void drawString(String str,
int x,
int y)
drawChars
public void drawChars(char data[],
int offset,
int length,
int x,
int y)
drawBytes
public void drawBytes(byte data[],
int offset,
int length,
int x,
int y)
drawImage
public abstract boolean drawImage(Image img,
int x,
int y,
ImageObserver observer)
This method returns immediately in all cases, even if the complete image has not yet been loaded, and it has not been dithered and converted for the current output device.
If the image has not yet been completely loaded, then
drawImage returns false. As more of
the image becomes available, the process that draws the image notifies
the specified image observer.
drawImage
public abstract boolean drawImage(Image img,
int x,
int y,
int width,
int height,
ImageObserver observer)
The image is drawn inside the specified rectangle of this graphics context's coordinate space, and is scaled if necessary. Transparent pixels do not affect whatever pixels are already there.
This method returns immediately in all cases, even if the
entire image has not yet been scaled, dithered, and converted
for the current output device.
If the current output representation is not yet complete, then
drawImage returns false. As more of
the image becomes available, the process that draws the image notifies
the image observer by calling its imageUpdate method.
A scaled version of an image will not necessarily be available immediately just because an unscaled version of the image has been constructed for this output device. Each size of the image may be cached separately and generated from the original data in a separate image production sequence.
drawImage
public abstract boolean drawImage(Image img,
int x,
int y,
Color bgcolor,
ImageObserver observer)
This operation is equivalent to filling a rectangle of the width and height of the specified image with the given color and then drawing the image on top of it, but possibly more efficient.
This method returns immediately in all cases, even if the complete image has not yet been loaded, and it has not been dithered and converted for the current output device.
If the image has not yet been completely loaded, then
drawImage returns false. As more of
the image becomes available, the process that draws the image notifies
the specified image observer.
drawImage
public abstract boolean drawImage(Image img,
int x,
int y,
int width,
int height,
Color bgcolor,
ImageObserver observer)
The image is drawn inside the specified rectangle of this graphics context's coordinate space, and is scaled if necessary. Transparent pixels are drawn in the specified background color. This operation is equivalent to filling a rectangle of the width and height of the specified image with the given color and then drawing the image on top of it, but possibly more efficient.
This method returns immediately in all cases, even if the
entire image has not yet been scaled, dithered, and converted
for the current output device.
If the current output representation is not yet complete then
drawImage returns false. As more of
the image becomes available, the process that draws the image notifies
the specified image observer.
A scaled version of an image will not necessarily be available immediately just because an unscaled version of the image has been constructed for this output device. Each size of the image may be cached separately and generated from the original data in a separate image production sequence.
drawImage
public abstract boolean drawImage(Image img,
int dx1,
int dy1,
int dx2,
int dy2,
int sx1,
int sy1,
int sx2,
int sy2,
ImageObserver observer)
This method returns immediately in all cases, even if the
image area to be drawn has not yet been scaled, dithered, and converted
for the current output device.
If the current output representation is not yet complete then
drawImage returns false. As more of
the image becomes available, the process that draws the image notifies
the specified image observer.
This method always uses the unscaled version of the image to render the scaled rectangle and performs the required scaling on the fly. It does not use a cached, scaled version of the image for this operation. Scaling of the image from source to destination is performed such that the first coordinate of the source rectangle is mapped to the first coordinate of the destination rectangle, and the second source coordinate is mapped to the second destination coordinate. The subimage is scaled and flipped as needed to preserve those mappings.
drawImage
public abstract boolean drawImage(Image img,
int dx1,
int dy1,
int dx2,
int dy2,
int sx1,
int sy1,
int sx2,
int sy2,
Color bgcolor,
ImageObserver observer)
Transparent pixels are drawn in the specified background color. This operation is equivalent to filling a rectangle of the width and height of the specified image with the given color and then drawing the image on top of it, but possibly more efficient.
This method returns immediately in all cases, even if the
image area to be drawn has not yet been scaled, dithered, and converted
for the current output device.
If the current output representation is not yet complete then
drawImage returns false. As more of
the image becomes available, the process that draws the image notifies
the specified image observer.
This method always uses the unscaled version of the image to render the scaled rectangle and performs the required scaling on the fly. It does not use a cached, scaled version of the image for this operation. Scaling of the image from source to destination is performed such that the first coordinate of the source rectangle is mapped to the first coordinate of the destination rectangle, and the second source coordinate is mapped to the second destination coordinate. The subimage is scaled and flipped as needed to preserve those mappings.
dispose
public abstract void dispose()
Graphics object cannot be used after
disposehas been called.
When a Java program runs, a large number of Graphics
objects can be created within a short time frame.
Although the finalization process of the garbage collector
also disposes of the same system resources, it is preferable
to manually free the associated resources by calling this
method rather than to rely on a finalization process which
may not run to completion for a long period of time.
Graphics objects which are provided as arguments to the
paint and update methods
of components are automatically released by the system when
those methods return. For efficiency, programmers should
call dispose when finished using
a Graphics object only if it was created
directly from a component or another Graphics object.
finalize
public void finalize()
toString
public String toString()
String object representing this
Graphics object's value.
getClipRect
public Rectangle getClipRect()
getClipBounds().
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