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. 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:
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 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.
| Constructor Detail |
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.
| Method Detail |
public abstract java.awt.Graphics create()
Graphics object that is a copy of this Graphics object.
public java.awt.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. x - the x coordinate.y - the y coordinate.width - the width of the clipping rectangle.height - the height of the clipping rectangle.
public abstract void translate(int x,
int y)
x - the x coordinate.y - the y coordinate.public abstract java.awt.Color getColor()
public abstract void setColor(java.awt.Color c)
c - the new rendering color.public abstract void setPaintMode()
public abstract void setXORMode(java.awt.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.
c1 - the XOR alternation colorpublic abstract java.awt.Font getFont()
public abstract void setFont(java.awt.Font font)
font - the font.public java.awt.FontMetrics getFontMetrics()
public abstract java.awt.FontMetrics getFontMetrics(java.awt.Font f)
f - the specified fontpublic abstract java.awt.Rectangle getClipBounds()
setClip(null), this method returns null. The coordinates in the rectangle are relative to the coordinate system origin of this graphics context.null if no clip is set.
public abstract void clipRect(int x,
int y,
int width,
int height)
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.x - the x coordinate of the rectangle to intersect the clip withy - the y coordinate of the rectangle to intersect the clip withwidth - the width of the rectangle to intersect the clip withheight - the height of the rectangle to intersect the clip with
public abstract void setClip(int x,
int y,
int width,
int height)
x - the x coordinate of the new clip rectangle.y - the y coordinate of the new clip rectangle.width - the width of the new clip rectangle.height - the height of the new clip rectangle.public abstract java.awt.Shape getClip()
setClip(null), this method returns null.Shape object representing the current clipping area, or null if no clip is set.public abstract void setClip(java.awt.Shape clip)
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.clip - the Shape to use to set the clip
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.x - the x coordinate of the source rectangle.y - the y coordinate of the source rectangle.width - the width of the source rectangle.height - the height of the source rectangle.dx - the horizontal distance to copy the pixels.dy - the vertical distance to copy the pixels.
public abstract void drawLine(int x1,
int y1,
int x2,
int y2)
(x1, y1) and (x2, y2) in this graphics context's coordinate system.x1 - the first point's x coordinate.y1 - the first point's y coordinate.x2 - the second point's x coordinate.y2 - the second point's y coordinate.
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.x - the x coordinate of the rectangle to be filled.y - the y coordinate of the rectangle to be filled.width - the width of the rectangle to be filled.height - the height of the rectangle to be filled.
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.x - the x coordinate of the rectangle to be drawn.y - the y coordinate of the rectangle to be drawn.width - the width of the rectangle to be drawn.height - the height of the rectangle to be drawn.
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.
x - the x coordinate of the rectangle to clear.y - the y coordinate of the rectangle to clear.width - the width of the rectangle to clear.height - the height of the rectangle to clear.
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.x - the x coordinate of the rectangle to be drawn.y - the y coordinate of the rectangle to be drawn.width - the width of the rectangle to be drawn.height - the height of the rectangle to be drawn.arcWidth - the horizontal diameter of the arc at the four corners.arcHeight - the vertical diameter of the arc at the four corners.
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.x - the x coordinate of the rectangle to be filled.y - the y coordinate of the rectangle to be filled.width - the width of the rectangle to be filled.height - the height of the rectangle to be filled.arcWidth - the horizontal diameter of the arc at the four corners.arcHeight - the vertical diameter of the arc at the four corners.
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.
x - the x coordinate of the rectangle to be drawn.y - the y coordinate of the rectangle to be drawn.width - the width of the rectangle to be drawn.height - the height of the rectangle to be drawn.raised - a boolean that determines whether the rectangle appears to be raised above the surface or sunk into the surface.
public void fill3DRect(int x,
int y,
int width,
int height,
boolean raised)
x - the x coordinate of the rectangle to be filled.y - the y coordinate of the rectangle to be filled.width - the width of the rectangle to be filled.height - the height of the rectangle to be filled.raised - a boolean value that determines whether the rectangle appears to be raised above the surface or etched into the surface.
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.
x - the x coordinate of the upper left corner of the oval to be drawn.y - the y coordinate of the upper left corner of the oval to be drawn.width - the width of the oval to be drawn.height - the height of the oval to be drawn.
public abstract void fillOval(int x,
int y,
int width,
int height)
x - the x coordinate of the upper left corner of the oval to be filled.y - the y coordinate of the upper left corner of the oval to be filled.width - the width of the oval to be filled.height - the height of the oval to be filled.
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.
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.
x - the x coordinate of the upper-left corner of the arc to be drawn.y - the y coordinate of the upper-left corner of the arc to be drawn.width - the width of the arc to be drawn.height - the height of the arc to be drawn.startAngle - the beginning angle.arcAngle - the angular extent of the arc, relative to the start angle.
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.
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.
x - the x coordinate of the upper-left corner of the arc to be filled.y - the y coordinate of the upper-left corner of the arc to be filled.width - the width of the arc to be filled.height - the height of the arc to be filled.startAngle - the beginning angle.arcAngle - the angular extent of the arc, relative to the start angle.
public abstract void drawPolyline(int[] xPoints,
int[] yPoints,
int nPoints)
xPoints - an array of x pointsyPoints - an array of y pointsnPoints - the total number of points
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.
xPoints - a an array of x coordinates.yPoints - a an array of y coordinates.nPoints - a the total number of points.public void drawPolygon(java.awt.Polygon p)
Polygon object.p - the polygon to draw.
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.
xPoints - a an array of x coordinates.yPoints - a an array of y coordinates.nPoints - a the total number of points.public void fillPolygon(java.awt.Polygon p)
The area inside the polygon is defined using an even-odd fill rule, also known as the alternating rule.
p - the polygon to fill.
public abstract void drawString(java.lang.String str,
int x,
int y)
str - the string to be drawn.x - the x coordinate.y - the y coordinate.
public abstract void drawString(java.text.AttributedCharacterIterator iterator,
int x,
int y)
iterator - the iterator whose text is to be drawnx - the x coordinate.y - the y coordinate.
public void drawChars(char[] data,
int offset,
int length,
int x,
int y)
data - the array of characters to be drawnoffset - the start offset in the datalength - the number of characters to be drawnx - the x coordinate of the baseline of the texty - the y coordinate of the baseline of the text
public void drawBytes(byte[] data,
int offset,
int length,
int x,
int y)
data - the data to be drawnoffset - the start offset in the datalength - the number of bytes that are drawnx - the x coordinate of the baseline of the texty - the y coordinate of the baseline of the text
public abstract boolean drawImage(java.awt.Image img,
int x,
int y,
java.awt.image.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.
img - the specified image to be drawn.x - the x coordinate.y - the y coordinate.observer - object to be notified as more of the image is converted.true if the image is completely loaded; false otherwise.
public abstract boolean drawImage(java.awt.Image img,
int x,
int y,
int width,
int height,
java.awt.image.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.
img - the specified image to be drawn.x - the x coordinate.y - the y coordinate.width - the width of the rectangle.height - the height of the rectangle.observer - object to be notified as more of the image is converted.true if the current output representation is complete; false otherwise.
public abstract boolean drawImage(java.awt.Image img,
int x,
int y,
java.awt.Color bgcolor,
java.awt.image.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.
img - the specified image to be drawn.x - the x coordinate.y - the y coordinate.bgcolor - the background color to paint under the non-opaque portions of the image.observer - object to be notified as more of the image is converted.true if the image is completely loaded; false otherwise.
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)
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.
img - the specified image to be drawn.x - the x coordinate.y - the y coordinate.width - the width of the rectangle.height - the height of the rectangle.bgcolor - the background color to paint under the non-opaque portions of the image.observer - object to be notified as more of the image is converted.true if the current output representation is complete; false otherwise.
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)
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.
img - the specified image to be drawndx1 - the x coordinate of the first corner of the destination rectangle.dy1 - the y coordinate of the first corner of the destination rectangle.dx2 - the x coordinate of the second corner of the destination rectangle.dy2 - the y coordinate of the second corner of the destination rectangle.sx1 - the x coordinate of the first corner of the source rectangle.sy1 - the y coordinate of the first corner of the source rectangle.sx2 - the x coordinate of the second corner of the source rectangle.sy2 - the y coordinate of the second corner of the source rectangle.observer - object to be notified as more of the image is scaled and converted.true if the current output representation is complete; false otherwise.
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)
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.
img - the specified image to be drawndx1 - the x coordinate of the first corner of the destination rectangle.dy1 - the y coordinate of the first corner of the destination rectangle.dx2 - the x coordinate of the second corner of the destination rectangle.dy2 - the y coordinate of the second corner of the destination rectangle.sx1 - the x coordinate of the first corner of the source rectangle.sy1 - the y coordinate of the first corner of the source rectangle.sx2 - the x coordinate of the second corner of the source rectangle.sy2 - the y coordinate of the second corner of the source rectangle.bgcolor - the background color to paint under the non-opaque portions of the image.observer - object to be notified as more of the image is scaled and converted.true if the current output representation is complete; false otherwise.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.
public void finalize()
public java.lang.String toString()
String object representing this Graphics object's value.public java.awt.Rectangle getClipRect()
getClipBounds().null if no clip is set.
public boolean hitClip(int x,
int y,
int width,
int height)
x - the x coordinate of the rectangle to test against the clipy - the y coordinate of the rectangle to test against the clipwidth - the width of the rectangle to test against the clipheight - the height of the rectangle to test against the cliptrue if the specified rectangle intersects the bounds of the current clip; false otherwise.public java.awt.Rectangle getClipBounds(java.awt.Rectangle r)
setClip(null), this method returns the specified Rectangle.r - the rectangle where the current clipping area is copied to. Any current values in this rectangle are overwritten.