Graphicspublic abstract class Graphics extends Object The 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:
- The
Component object on which to draw.
- A translation origin for rendering and clipping coordinates.
- The current clip.
- The current color.
- The current font.
- The current logical pixel operation function (XOR or Paint).
- The current XOR alternation color
(see {@link Graphics#setXORMode}).
Coordinates are infinitely thin and lie between the pixels of the
output device.
Operations that 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 that fill a figure operate by filling the interior
of that infinitely thin path.
Operations that 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:
- If you draw a figure that covers a given rectangle, that
figure occupies one extra row of pixels on the right and bottom edges
as compared to filling a figure that is bounded by that same rectangle.
- If you draw a horizontal line along the same y coordinate as
the baseline of a line of text, that line is drawn entirely below
the text, except for any descenders.
All coordinates that 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 the current clip, which is specified by a {@link Shape}
in user space and is controlled by the program using the
Graphics object. This user clip
is transformed into device space and combined with the
device clip, which is defined by the visibility of windows and
device extents. The combination of the user clip and device clip
defines the composite clip, which determines the final clipping
region. The user clip cannot be modified by the rendering
system to reflect the resulting composite clip. The user clip can only
be changed through the setClip or clipRect
methods.
All drawing or writing is done in the current color,
using the current paint mode, and in the current font. |
| Constructors Summary |
|---|
protected Graphics()Constructs a new 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.
|
| Methods Summary |
|---|
| public abstract void | clearRect(int x, int y, int width, int height)Clears the specified rectangle by filling it with the background
color of the current drawing surface. This operation does not
use the current paint mode.
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.
| | public abstract void | clipRect(int x, int y, int width, int height)Intersects the current clip with the specified rectangle.
The resulting clipping area is the intersection of the current
clipping area and the specified rectangle. If there is no
current clipping area, either because the clip has never been
set, or the clip has been cleared using setClip(null),
the specified rectangle becomes the new clip.
This method sets the user clip, which is independent of the
clipping associated with device bounds and window visibility.
This method can only be used to make the current clip smaller.
To set the current clip larger, use any of the setClip methods.
Rendering operations have no effect outside of the clipping area.
| | public abstract void | copyArea(int x, int y, int width, int height, int dx, int dy)Copies an area of the component by a distance specified by
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.
| | public abstract java.awt.Graphics | create()Creates a new Graphics object that is
a copy of this Graphics object.
| | public java.awt.Graphics | create(int x, int y, int width, int height)Creates a new 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:
-
The new graphics context is translated by (x, y).
That is to say, the point (
0, 0) in the
new graphics context is the same as (x, y) in
the original graphics context.
-
The new graphics context has an additional clipping rectangle, in
addition to whatever (translated) clipping rectangle it inherited
from the original graphics context. The origin of the new clipping
rectangle is at (
0, 0), and its size
is specified by the width and height
arguments.
Graphics g = create();
if (g == null) return null;
g.translate(x, y);
g.clipRect(0, 0, width, height);
return g;
| | public abstract void | dispose()Disposes of this graphics context and releases
any system resources that it is using.
A 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.
| | public void | draw3DRect(int x, int y, int width, int height, boolean raised)Draws a 3-D highlighted outline of the specified rectangle.
The edges of the rectangle are highlighted so that they
appear to be beveled and lit from the upper left corner.
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.
Color c = getColor();
Color brighter = c.brighter();
Color darker = c.darker();
setColor(raised ? brighter : darker);
drawLine(x, y, x, y + height);
drawLine(x + 1, y, x + width - 1, y);
setColor(raised ? darker : brighter);
drawLine(x + 1, y + height, x + width, y + height);
drawLine(x + width, y, x + width, y + height - 1);
setColor(c);
| | public abstract void | drawArc(int x, int y, int width, int height, int startAngle, int arcAngle)Draws the outline of a circular or elliptical arc
covering the specified rectangle.
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.
The angles are specified relative to the non-square extents of
the bounding rectangle such that 45 degrees always falls on the
line from the center of the ellipse to the upper right corner of
the bounding rectangle. As a result, if the bounding rectangle is
noticeably longer in one axis than the other, the angles to the
start and end of the arc segment will be skewed farther along the
longer axis of the bounds.
| | public void | drawBytes(byte[] data, int offset, int length, int x, int y)Draws the text given by the specified byte array, using this
graphics context's current font and color. The baseline of the
first character is at position (x, y) in this
graphics context's coordinate system.
drawString(new String(data, 0, offset, length), x, y);
| | public void | drawChars(char[] data, int offset, int length, int x, int y)Draws the text given by the specified character array, using this
graphics context's current font and color. The baseline of the
first character is at position (x, y) in this
graphics context's coordinate system.
drawString(new String(data, offset, length), x, y);
| | public abstract boolean | drawImage(java.awt.Image img, int x, int y, java.awt.image.ImageObserver observer)Draws as much of the specified image as is currently available.
The image is drawn with its top-left corner at
(x, y) in this graphics context's coordinate
space. Transparent pixels in the image do not affect whatever
pixels are already there.
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 completely loaded and its pixels are
no longer being changed, then
drawImage returns true.
Otherwise, drawImage returns false
and as more of
the image becomes available
or it is time to draw another frame of animation,
the process that loads the image notifies
the specified image observer.
| | public abstract boolean | drawImage(java.awt.Image img, int x, int y, int width, int height, java.awt.image.ImageObserver observer)Draws as much of the specified image as has already been scaled
to fit inside the specified rectangle.
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 loads 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.
| | public abstract boolean | drawImage(java.awt.Image img, int x, int y, java.awt.Color bgcolor, java.awt.image.ImageObserver observer)Draws as much of the specified image as is currently available.
The image is drawn with its top-left corner at
(x, y) in this graphics context's coordinate
space. 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
complete image has not yet been loaded, and it has not been dithered
and converted for the current output device.
If the image has completely loaded and its pixels are
no longer being changed, then
drawImage returns true.
Otherwise, drawImage returns false
and as more of
the image becomes available
or it is time to draw another frame of animation,
the process that loads the image notifies
the specified image observer.
| | public abstract boolean | drawImage(java.awt.Image img, int x, int y, int width, int height, java.awt.Color bgcolor, java.awt.image.ImageObserver observer)Draws as much of the specified image as has already been scaled
to fit inside the specified rectangle.
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 loads 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.
| | public abstract boolean | drawImage(java.awt.Image img, int dx1, int dy1, int dx2, int dy2, int sx1, int sy1, int sx2, int sy2, java.awt.image.ImageObserver observer)Draws as much of the specified area of the specified image as is
currently available, scaling it on the fly to fit inside the
specified area of the destination drawable surface. Transparent pixels
do not affect whatever pixels are already there.
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 loads 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.
| | public abstract boolean | drawImage(java.awt.Image img, int dx1, int dy1, int dx2, int dy2, int sx1, int sy1, int sx2, int sy2, java.awt.Color bgcolor, java.awt.image.ImageObserver observer)Draws as much of the specified area of the specified image as is
currently available, scaling it on the fly to fit inside the
specified area of the destination drawable surface.
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 loads 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.
| | public abstract void | drawLine(int x1, int y1, int x2, int y2)Draws a line, using the current color, between the points
(x1, y1) and (x2, y2)
in this graphics context's coordinate system.
| | public abstract void | drawOval(int x, int y, int width, int height)Draws the outline of an oval.
The result is a circle or ellipse that fits within the
rectangle specified by the x, y,
width, and height arguments.
The oval covers an area that is
width + 1 pixels wide
and height + 1 pixels tall.
| | public abstract void | drawPolygon(int[] xPoints, int[] yPoints, int nPoints)Draws a closed polygon defined by
arrays of x and y coordinates.
Each pair of (x, y) coordinates defines a point.
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.
| | public void | drawPolygon(java.awt.Polygon p)Draws the outline of a polygon defined by the specified
Polygon object.
drawPolygon(p.xpoints, p.ypoints, p.npoints);
| | public abstract void | drawPolyline(int[] xPoints, int[] yPoints, int nPoints)Draws a sequence of connected lines defined by
arrays of x and y coordinates.
Each pair of (x, y) coordinates defines a point.
The figure is not closed if the first point
differs from the last point.
| | public void | drawRect(int x, int y, int width, int height)Draws the outline of the specified rectangle.
The left and right edges of the rectangle are at
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.
if ((width < 0) || (height < 0)) {
return;
}
if (height == 0 || width == 0) {
drawLine(x, y, x + width, y + height);
} else {
drawLine(x, y, x + width - 1, y);
drawLine(x + width, y, x + width, y + height - 1);
drawLine(x + width, y + height, x + 1, y + height);
drawLine(x, y + height, x, y + 1);
}
| | public abstract void | drawRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight)Draws an outlined round-cornered rectangle using this graphics
context's current color. The left and right edges of the rectangle
are at x and x + width,
respectively. The top and bottom edges of the rectangle are at
y and y + height.
| | public abstract void | drawString(java.lang.String str, int x, int y)Draws the text given by the specified string, using this
graphics context's current font and color. The baseline of the
leftmost character is at position (x, y) in this
graphics context's coordinate system.
| | public abstract void | drawString(java.text.AttributedCharacterIterator iterator, int x, int y)Draws the text given by the specified iterator, using this
graphics context's current color. The iterator has to specify a font
for each character. The baseline of the
leftmost character is at position (x, y) in this
graphics context's coordinate system.
| | public void | fill3DRect(int x, int y, int width, int height, boolean raised)Paints a 3-D highlighted rectangle filled with the current color.
The edges of the rectangle will be highlighted so that it appears
as if the edges were beveled and lit from the upper left corner.
The colors used for the highlighting effect will be determined from
the current color.
Color c = getColor();
Color brighter = c.brighter();
Color darker = c.darker();
if (!raised) {
setColor(darker);
}
fillRect(x+1, y+1, width-2, height-2);
setColor(raised ? brighter : darker);
drawLine(x, y, x, y + height - 1);
drawLine(x + 1, y, x + width - 2, y);
setColor(raised ? darker : brighter);
drawLine(x + 1, y + height - 1, x + width - 1, y + height - 1);
drawLine(x + width - 1, y, x + width - 1, y + height - 2);
setColor(c);
| | public abstract void | fillArc(int x, int y, int width, int height, int startAngle, int arcAngle)Fills a circular or elliptical arc covering the specified rectangle.
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.
The angles are specified relative to the non-square extents of
the bounding rectangle such that 45 degrees always falls on the
line from the center of the ellipse to the upper right corner of
the bounding rectangle. As a result, if the bounding rectangle is
noticeably longer in one axis than the other, the angles to the
start and end of the arc segment will be skewed farther along the
longer axis of the bounds.
| | public abstract void | fillOval(int x, int y, int width, int height)Fills an oval bounded by the specified rectangle with the
current color.
| | public abstract void | fillPolygon(int[] xPoints, int[] yPoints, int nPoints)Fills a closed polygon defined by
arrays of x and y coordinates.
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.
| | public void | fillPolygon(java.awt.Polygon p)Fills the polygon defined by the specified Polygon object with
the graphics context's current color.
The area inside the polygon is defined using an
even-odd fill rule, also known as the alternating rule.
fillPolygon(p.xpoints, p.ypoints, p.npoints);
| | public abstract void | fillRect(int x, int y, int width, int height)Fills the specified rectangle.
The left and right edges of the rectangle are at
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.
| | public abstract void | fillRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight)Fills the specified rounded corner rectangle with the current color.
The left and right edges of the rectangle
are at x and x + width - 1,
respectively. The top and bottom edges of the rectangle are at
y and y + height - 1.
| | public void | finalize()Disposes of this graphics context once it is no longer referenced.
dispose();
| | public abstract java.awt.Shape | getClip()Gets the current clipping area.
This method returns the user clip, which is independent of the
clipping associated with device bounds and window visibility.
If no clip has previously been set, or if the clip has been
cleared using setClip(null), this method returns
null.
| | public abstract java.awt.Rectangle | getClipBounds()Returns the bounding rectangle of the current clipping area.
This method refers to the user clip, which is independent of the
clipping associated with device bounds and window visibility.
If no clip has previously been set, or if the clip has been
cleared using setClip(null), this method returns
null.
The coordinates in the rectangle are relative to the coordinate
system origin of this graphics context.
| | public java.awt.Rectangle | getClipBounds(java.awt.Rectangle r)Returns the bounding rectangle of the current clipping area.
The coordinates in the rectangle are relative to the coordinate
system origin of this graphics context. This method differs
from {@link #getClipBounds() getClipBounds} in that an existing
rectangle is used instead of allocating a new one.
This method refers to the user clip, which is independent of the
clipping associated with device bounds and window visibility.
If no clip has previously been set, or if the clip has been
cleared using setClip(null), this method returns the
specified Rectangle.
// Note, this implementation is not very efficient.
// Subclasses should override this method and avoid
// the allocation overhead of getClipBounds().
Rectangle clipRect = getClipBounds();
if (clipRect != null) {
r.x = clipRect.x;
r.y = clipRect.y;
r.width = clipRect.width;
r.height = clipRect.height;
} else if (r == null) {
throw new NullPointerException("null rectangle parameter");
}
return r;
| | public java.awt.Rectangle | getClipRect()Returns the bounding rectangle of the current clipping area.
return getClipBounds();
| | public abstract java.awt.Color | getColor()Gets this graphics context's current color.
| | public abstract java.awt.Font | getFont()Gets the current font.
| | public java.awt.FontMetrics | getFontMetrics()Gets the font metrics of the current font.
return getFontMetrics(getFont());
| | public abstract java.awt.FontMetrics | getFontMetrics(java.awt.Font f)Gets the font metrics for the specified font.
| | public boolean | hitClip(int x, int y, int width, int height)Returns true if the specified rectangular area might intersect
the current clipping area.
The coordinates of the specified rectangular area are in the
user coordinate space and are relative to the coordinate
system origin of this graphics context.
This method may use an algorithm that calculates a result quickly
but which sometimes might return true even if the specified
rectangular area does not intersect the clipping area.
The specific algorithm employed may thus trade off accuracy for
speed, but it will never return false unless it can guarantee
that the specified rectangular area does not intersect the
current clipping area.
The clipping area used by this method can represent the
intersection of the user clip as specified through the clip
methods of this graphics context as well as the clipping
associated with the device or image bounds and window visibility.
// Note, this implementation is not very efficient.
// Subclasses should override this method and calculate
// the results more directly.
Rectangle clipRect = getClipBounds();
if (clipRect == null) {
return true;
}
return clipRect.intersects(x, y, width, height);
| | public abstract void | setClip(int x, int y, int width, int height)Sets the current clip to the rectangle specified by the given
coordinates. This method sets the user clip, which is
independent of the clipping associated with device bounds
and window visibility.
Rendering operations have no effect outside of the clipping area.
| | public abstract void | setClip(java.awt.Shape clip)Sets the current clipping area to an arbitrary clip shape.
Not all objects that implement the Shape
interface can be used to set the clip. The only
Shape objects that are guaranteed to be
supported are Shape objects that are
obtained via the getClip method and via
Rectangle objects. This method sets the
user clip, which is independent of the clipping associated
with device bounds and window visibility.
| | public abstract void | setColor(java.awt.Color c)Sets this graphics context's current color to the specified
color. All subsequent graphics operations using this graphics
context use this specified color.
| | public abstract void | setFont(java.awt.Font font)Sets this graphics context's font to the specified font.
All subsequent text operations using this graphics context
use this font.
| | public abstract void | setPaintMode()Sets the paint mode of this graphics context to overwrite the
destination with this graphics context's current color.
This sets the logical pixel operation function to the paint or
overwrite mode. All subsequent rendering operations will
overwrite the destination with the current color.
| | public abstract void | setXORMode(java.awt.Color c1)Sets the paint mode of this graphics context to alternate between
this graphics context's current color and the new specified color.
This specifies that logical pixel operations are performed in the
XOR mode, which alternates pixels between the current color and
a specified XOR color.
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.
| | public java.lang.String | toString()Returns a String object representing this
Graphics object's value.
return getClass().getName() + "[font=" + getFont() + ",color=" + getColor() + "]";
| | public abstract void | translate(int x, int y)Translates the origin of the graphics context to the point
(x, y) in the current coordinate system.
Modifies this graphics context so that its new origin corresponds
to the point (x, y) in this graphics context's
original coordinate system. All coordinates used in subsequent
rendering operations on this graphics context will be relative
to this new origin.
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