Class GraphicContext

java.lang.Object
org.apache.xmlgraphics.java2d.GraphicContext
All Implemented Interfaces:
Cloneable
public class GraphicContext extends Object implements Cloneable
Handles the attributes in a graphic context:
+ Composite
+ Font
+ Paint
+ Stroke
+ Clip
+ RenderingHints
+ AffineTransform
Version:
$Id$ Originally authored by Vincent Hardy and Christophe Jolif.

  • Field Details

    • defaultTransform

      protected AffineTransform defaultTransform
      Default Transform to be used for creating FontRenderContext.

    • transform

      protected AffineTransform transform
      Current AffineTransform. This is the concatenation of the original AffineTransform (i.e., last setTransform invocation) and the following transform invocations, as captured by originalTransform and the transformStack.

    • transformStack

      protected List transformStack
      Transform stack

    • transformStackValid

      protected boolean transformStackValid
      Defines whether the transform stack is valid or not. This is for use by the class clients. The client should validate the stack every time it starts using it. The stack becomes invalid when a new transform is set.
      See Also:

    • paint

      protected Paint paint
      Current Paint

    • stroke

      protected Stroke stroke
      Current Stroke

    • composite

      protected Composite composite
      Current Composite

    • clip

      protected Shape clip
      Current clip

    • hints

      protected RenderingHints hints
      Current set of RenderingHints

    • font

      protected Font font
      Current Font

    • background

      protected Color background
      Current background color.

    • foreground

      protected Color foreground
      Current foreground color

  • Constructor Details

    • GraphicContext

      public GraphicContext()
      Default constructor

    • GraphicContext

      public GraphicContext(AffineTransform defaultDeviceTransform)
      Parameters:
      defaultDeviceTransform - Default affine transform applied to map the user space to the user space.

    • GraphicContext

      protected GraphicContext(GraphicContext template)
      Copy constructor.
      Parameters:
      template - the instance to make a copy of

  • Method Details

    • clone

      public Object clone()
      Overrides:
      clone in class Object
      Returns:
      a deep copy of this context

    • getColor

      public Color getColor()
      Gets this graphics context's current color.
      Returns:
      this graphics context's current color.
      See Also:

    • setColor

      public void setColor(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.
      Parameters:
      c - the new rendering color.
      See Also:

    • getFont

      public Font getFont()
      Gets the current font.
      Returns:
      this graphics context's current font.
      See Also:

    • setFont

      public void setFont(Font font)
      Sets this graphics context's font to the specified font. All subsequent text operations using this graphics context use this font.
      Parameters:
      font - the font.
      See Also:

    • getClipBounds

      public 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.
      Returns:
      the bounding rectangle of the current clipping area, or null if no clip is set.
      Since:
      JDK1.1
      See Also:

    • clipRect

      public 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.
      Parameters:
      x - the x coordinate of the rectangle to intersect the clip with
      y - the y coordinate of the rectangle to intersect the clip with
      width - the width of the rectangle to intersect the clip with
      height - the height of the rectangle to intersect the clip with
      See Also:

    • setClip

      public 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.
      Parameters:
      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.
      Since:
      JDK1.1
      See Also:

    • getClip

      public 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.
      Returns:
      a Shape object representing the current clipping area, or null if no clip is set.
      Since:
      JDK1.1
      See Also:

    • setClip

      public void setClip(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.
      Parameters:
      clip - the Shape to use to set the clip
      Since:
      JDK1.1
      See Also:

    • setComposite

      public void setComposite(Composite comp)
      Sets the Composite for the Graphics2D context. The Composite is used in all drawing methods such as drawImage, drawString, draw, and fill. It specifies how new pixels are to be combined with the existing pixels on the graphics device during the rendering process.

      If this Graphics2D context is drawing to a Component on the display screen and the Composite is a custom object rather than an instance of the AlphaComposite class, and if there is a security manager, its checkPermission method is called with an AWTPermission("readDisplayPixels") permission.

      Parameters:
      comp - the Composite object to be used for rendering
      Throws:
      SecurityException - if a custom Composite object is being used to render to the screen and a security manager is set and its checkPermission method does not allow the operation.
      See Also:

    • setPaint

      public void setPaint(Paint paint)
      Sets the Paint attribute for the Graphics2D context. Calling this method with a null Paint object does not have any effect on the current Paint attribute of this Graphics2D.
      Parameters:
      paint - the Paint object to be used to generate color during the rendering process, or null
      See Also:

    • setStroke

      public void setStroke(Stroke s)
      Sets the Stroke for the Graphics2D context.
      Parameters:
      s - the Stroke object to be used to stroke a Shape during the rendering process
      See Also:

    • setRenderingHint

      public void setRenderingHint(RenderingHints.Key hintKey, Object hintValue)
      Sets the value of a single preference for the rendering algorithms. Hint categories include controls for rendering quality and overall time/quality trade-off in the rendering process. Refer to the RenderingHints class for definitions of some common keys and values.
      Parameters:
      hintKey - the key of the hint to be set.
      hintValue - the value indicating preferences for the specified hint category.
      See Also:

    • getRenderingHint

      public Object getRenderingHint(RenderingHints.Key hintKey)
      Returns the value of a single preference for the rendering algorithms. Hint categories include controls for rendering quality and overall time/quality trade-off in the rendering process. Refer to the RenderingHints class for definitions of some common keys and values.
      Parameters:
      hintKey - the key corresponding to the hint to get.
      Returns:
      an object representing the value for the specified hint key. Some of the keys and their associated values are defined in the RenderingHints class.
      See Also:

    • setRenderingHints

      public void setRenderingHints(Map<RenderingHints.Key, Object> hints)
      Replaces the values of all preferences for the rendering algorithms with the specified hints. The existing values for all rendering hints are discarded and the new set of known hints and values are initialized from the specified Map object. Hint categories include controls for rendering quality and overall time/quality trade-off in the rendering process. Refer to the RenderingHints class for definitions of some common keys and values.
      Parameters:
      hints - the rendering hints to be set
      See Also:

    • addRenderingHints

      public void addRenderingHints(Map<String,Object> hints)
      Sets the values of an arbitrary number of preferences for the rendering algorithms. Only values for the rendering hints that are present in the specified Map object are modified. All other preferences not present in the specified object are left unmodified. Hint categories include controls for rendering quality and overall time/quality trade-off in the rendering process. Refer to the RenderingHints class for definitions of some common keys and values.
      Parameters:
      hints - the rendering hints to be set
      See Also:

    • getRenderingHints

      public RenderingHints getRenderingHints()
      Gets the preferences for the rendering algorithms. Hint categories include controls for rendering quality and overall time/quality trade-off in the rendering process. Returns all of the hint key/value pairs that were ever specified in one operation. Refer to the RenderingHints class for definitions of some common keys and values.
      Returns:
      a reference to an instance of RenderingHints that contains the current preferences.
      See Also:

    • translate

      public 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.
      Parameters:
      x - the x coordinate.
      y - the y coordinate.

    • translate

      public void translate(double tx, double ty)
      Concatenates the current Graphics2D Transform with a translation transform. Subsequent rendering is translated by the specified distance relative to the previous position. This is equivalent to calling transform(T), where T is an AffineTransform represented by the following matrix: 
               [   1    0    tx  ]
         [   0    1    ty  ]
         [   0    0    1   ]
      Parameters:
      tx - the distance to translate along the x-axis
      ty - the distance to translate along the y-axis

    • rotate

      public void rotate(double theta)
      Concatenates the current Graphics2D Transform with a rotation transform. Subsequent rendering is rotated by the specified radians relative to the previous origin. This is equivalent to calling transform(R), where R is an AffineTransform represented by the following matrix: 
               [   cos(theta)    -sin(theta)    0   ]
         [   sin(theta)     cos(theta)    0   ]
         [       0              0         1   ]
      Rotating with a positive angle theta rotates points on the positive x axis toward the positive y axis.
      Parameters:
      theta - the angle of rotation in radians

    • rotate

      public void rotate(double theta, double x, double y)
      Concatenates the current Graphics2D Transform with a translated rotation transform. Subsequent rendering is transformed by a transform which is constructed by translating to the specified location, rotating by the specified radians, and translating back by the same amount as the original translation. This is equivalent to the following sequence of calls: 
               translate(x, y);
         rotate(theta);
         translate(-x, -y);
      Rotating with a positive angle theta rotates points on the positive x axis toward the positive y axis.
      Parameters:
      theta - the angle of rotation in radians
      x - x coordinate of the origin of the rotation
      y - y coordinate of the origin of the rotation

    • scale

      public void scale(double sx, double sy)
      Concatenates the current Graphics2D Transform with a scaling transformation Subsequent rendering is resized according to the specified scaling factors relative to the previous scaling. This is equivalent to calling transform(S), where S is an AffineTransform represented by the following matrix: 
               [   sx   0    0   ]
         [   0    sy   0   ]
         [   0    0    1   ]
      Parameters:
      sx - the amount by which X coordinates in subsequent rendering operations are multiplied relative to previous rendering operations.
      sy - the amount by which Y coordinates in subsequent rendering operations are multiplied relative to previous rendering operations.

    • shear

      public void shear(double shx, double shy)
      Concatenates the current Graphics2D Transform with a shearing transform. Subsequent renderings are sheared by the specified multiplier relative to the previous position. This is equivalent to calling transform(SH), where SH is an AffineTransform represented by the following matrix: 
               [   1   shx   0   ]
         [  shy   1    0   ]
         [   0    0    1   ]
      Parameters:
      shx - the multiplier by which coordinates are shifted in the positive X axis direction as a function of their Y coordinate
      shy - the multiplier by which coordinates are shifted in the positive Y axis direction as a function of their X coordinate

    • transform

      public void transform(AffineTransform tx)
      Composes an AffineTransform object with the Transform in this Graphics2D according to the rule last-specified-first-applied. If the current Transform is Cx, the result of composition with Tx is a new Transform Cx'. Cx' becomes the current Transform for this Graphics2D. Transforming a point p by the updated Transform Cx' is equivalent to first transforming p by Tx and then transforming the result by the original Transform Cx. In other words, Cx'(p) = Cx(Tx(p)). A copy of the Tx is made, if necessary, so further modifications to Tx do not affect rendering.
      Parameters:
      tx - the AffineTransform object to be composed with the current Transform
      See Also:

    • setTransform

      public void setTransform(AffineTransform tx)
      Sets the Transform in the Graphics2D context.
      Parameters:
      tx - the AffineTransform object to be used in the rendering process
      See Also:

    • validateTransformStack

      public void validateTransformStack()
      Marks the GraphicContext's isNewTransformStack to false as a memento that the current transform stack was read and has not been reset. Only the setTransform method can override this memento.

    • isTransformStackValid

      public boolean isTransformStackValid()
      Checks the status of the transform stack.
      Returns:
      true if the transform stack is valid

    • getTransformStack

      public TransformStackElement[] getTransformStack()
      Returns:
      array containing the successive transforms that were concatenated with the original one.

    • invalidateTransformStack

      protected void invalidateTransformStack()
      Marks the GraphicContext's isNewTransformStack to true as a memento that the current transform stack was reset since it was last read. Only validateTransformStack can override this memento

    • getTransform

      public AffineTransform getTransform()
      Returns a copy of the current Transform in the Graphics2D context.
      Returns:
      the current AffineTransform in the Graphics2D context.
      See Also:

    • getPaint

      public Paint getPaint()
      Returns the current Paint of the Graphics2D context.
      Returns:
      the current Graphics2D Paint, which defines a color or pattern.
      See Also:

    • getComposite

      public Composite getComposite()
      Returns the current Composite in the Graphics2D context.
      Returns:
      the current Graphics2D Composite, which defines a compositing style.
      See Also:

    • setBackground

      public void setBackground(Color color)
      Sets the background color for the Graphics2D context. The background color is used for clearing a region. When a Graphics2D is constructed for a Component, the background color is inherited from the Component. Setting the background color in the Graphics2D context only affects the subsequent clearRect calls and not the background color of the Component. To change the background of the Component, use appropriate methods of the Component.
      Parameters:
      color - the background color that isused in subsequent calls to clearRect
      See Also:

    • getBackground

      public Color getBackground()
      Returns the background color used for clearing a region.
      Returns:
      the current Graphics2D Color, which defines the background color.
      See Also:

    • getStroke

      public Stroke getStroke()
      Returns the current Stroke in the Graphics2D context.
      Returns:
      the current Graphics2D Stroke, which defines the line style.
      See Also:

    • clip

      public void clip(Shape s)
      Intersects the current Clip with the interior of the specified Shape and sets the Clip to the resulting intersection. The specified Shape is transformed with the current Graphics2D Transform before being intersected with the current Clip. This method is used to make the current Clip smaller. To make the Clip larger, use setClip. The user clip modified by this method is independent of the clipping associated with device bounds and visibility. If no clip has previously been set, or if the clip has been cleared using setClip with a null argument, the specified Shape becomes the new user clip.
      Parameters:
      s - the Shape to be intersected with the current Clip. If s is null, this method clears the current Clip.

    • getFontRenderContext

      public FontRenderContext getFontRenderContext()
      Get the rendering context of the Font within this Graphics2D context. The FontRenderContext encapsulates application hints such as anti-aliasing and fractional metrics, as well as target device specific information such as dots-per-inch. This information should be provided by the application when using objects that perform typographical formatting, such as Font and TextLayout. This information should also be provided by applications that perform their own layout and need accurate measurements of various characteristics of glyphs such as advance and line height when various rendering hints have been applied to the text rendering.
      Returns:
      a reference to an instance of FontRenderContext.
      Since:
      JDK1.2
      See Also: