org.apache.fop.svg

## Class PDFGraphics2D

- java.lang.Object
- - java.awt.Graphics
  - - java.awt.Graphics2D
    - - org.apache.xmlgraphics.java2d.AbstractGraphics2D
      - - org.apache.fop.svg.PDFGraphics2D

- All Implemented Interfaces:
    Cloneable, NativeImageHandler
  Direct Known Subclasses:
    PDFDocumentGraphics2D

      public class PDFGraphics2D
      extends org.apache.xmlgraphics.java2d.AbstractGraphics2D
      implements NativeImageHandler

  PDF Graphics 2D. Used for drawing into a pdf document as if it is a graphics object. This takes a pdf document and draws into it.

  This work was authored by Keiron Liddle (keiron@aftexsw.com).

  See Also:
    `AbstractGraphics2D`

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static interface` | `PDFGraphics2D.TransparencyIgnoredEventListener` May be used to give proper feedback to the user when a particular PDF profile is being used that disallows transparency.

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected int` | `baseLevel` The PDF graphics state level that this svg is being drawn into.
    `protected PDFColorHandler` | `colorHandler` the PDF color handler
    `protected String` | `currentFontName` the current (internal) font name
    `protected float` | `currentFontSize` the current font size in millipoints
    `protected StringWriter` | `currentStream` the current stream to add PDF commands to
    `protected FontInfo` | `fontInfo` The current font information.
    `protected int` | `nativeCount` The count of natively handled images added to document so they receive unique keys.
    `protected OutputStream` | `outputStream` The output stream for the pdf document.
    `protected Font` | `ovFontState` The override font state used when drawing text and the font cannot be set using java fonts.
    `protected PDFReference` | `pageRef` The PDF reference of the current page.
    `protected PDFPaintingState` | `paintingState` The PDF painting state
    `protected PDFDocument` | `pdfDoc` the PDF Document being created
    `protected PDFResourceContext` | `resourceContext` The current resource context for adding fonts, patterns etc.

    - ### Fields inherited from class org.apache.xmlgraphics.java2d.AbstractGraphics2D

      `gc, inPossibleRecursion, textAsShapes`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `PDFGraphics2D(boolean textAsShapes)` Create a new PDFGraphics2D.
    `` | `PDFGraphics2D(boolean textAsShapes, FontInfo fi, PDFDocument doc, PDFResourceContext page, PDFReference pref, String font, float size, PDFGraphics2D.TransparencyIgnoredEventListener listener)` Create a new PDFGraphics2D with the given pdf document info.
    `` | `PDFGraphics2D(PDFGraphics2D g)` This constructor supports the create method.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods Deprecated Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addLink(Rectangle2D bounds, AffineTransform trans, String dest, int linkType)` This is a pdf specific method used to add a link to the pdf document.
    `void` | `addNativeImage(org.apache.xmlgraphics.image.loader.Image image, float x, float y, float width, float height)` Add a natively handled image directly to the PDF document.
    `protected void` | `applyAlpha(int fillAlpha, int strokeAlpha)` Applies the given alpha values for filling and stroking.
    `protected void` | `applyColor(Color col, boolean fill)` Apply the java Color to PDF.
    `protected boolean` | `applyPaint(Paint paint, boolean fill)` Apply the java paint to the PDF.
    `protected void` | `applyStroke(Stroke stroke)` Apply the stroke to the PDF.
    `protected boolean` | `applyUnknownPaint(Paint paint, Shape shape)`
    `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`.
    `Graphics` | `create()` Creates a new `Graphics` object that is a copy of this `Graphics` object.
    `void` | `dispose()` Disposes of this graphics context and releases any system resources that it is using.
    `protected void` | `doDrawing(boolean fill, boolean stroke, boolean nonzero)` Do the PDF drawing command.
    `void` | `draw(Shape s)` Strokes the outline of a `Shape` using the settings of the current `Graphics2D` context.
    `boolean` | `drawImage(Image img, int x, int y, ImageObserver observer)` Draws as much of the specified image as is currently available.
    `boolean` | `drawImage(Image img, int x, int y, int width, int height, ImageObserver observer)`
    `void` | `drawInnerRenderedImage(String key, RenderedImage img, AffineTransform xform)`
    `void` | `drawRenderableImage(RenderableImage img, AffineTransform xform)`
    `void` | `drawRenderedImage(RenderedImage img, AffineTransform xform)`
    `void` | `drawString(String s, float x, float y)` Renders the text specified by the specified `String`, using the current `Font` and `Paint` attributes in the `Graphics2D` context.
    `void` | `fill(Shape s)` Fills the interior of a `Shape` using the settings of the `Graphics2D` context.
    `protected AffineTransform` | `getBaseTransform()` This is mainly used for shading patterns which use the document-global coordinate system instead of the local one.
    `StringBuffer` | `getBuffer()` Get the string buffer from the currentStream, containing all the commands written into this Graphics so far.
    `GraphicsConfiguration` | `getDeviceConfiguration()` Returns the device configuration associated with this `Graphics2D`.
    `FontMetrics` | `getFontMetrics(Font f)` Gets the font metrics for the specified font.
    `protected Font` | `getInternalFontForAWTFont(Font awtFont)` Deprecated. use FontInfo.getFontInstanceForAWTFont(java.awt.Font awtFont) instead
    `PDFReference` | `getPageReference()` Gets the PDF reference of the current page.
    `String` | `getString()` Get the string containing all the commands written into this Graphics.
    `protected void` | `handleIOException(IOException ioe)` Central handler for IOExceptions for this class.
    `protected boolean` | `isMultiByteFont(String name)` Determines whether the font with the given name is a multi-byte font.
    `protected Object` | `isTransparencyAllowed()` Checks whether the use of transparency is allowed.
    `protected void` | `preparePainting()` This method is used by PDFDocumentGraphics2D to prepare a new page if necessary.
    `void` | `processPathIterator(PathIterator iter)` Processes a path iterator generating the necessary painting operations.
    `PDFFunction` | `registerFunction(PDFFunction function)` Registers a function object against the output format document
    `PDFPattern` | `registerPattern(PDFPattern pattern)` Registers a pattern object against the output format document
    `PDFShading` | `registerShading(PDFShading shading)` Registers a shading object against the otuput format document
    `void` | `setGraphicContext(org.apache.xmlgraphics.java2d.GraphicContext c)` Set the Graphics context.
    `void` | `setOutputStream(OutputStream os)` Set the output stream that this PDF document is being drawn to.
    `void` | `setOverrideFontState(Font infont)` Set the override font state for drawing text.
    `void` | `setPaintingState(PDFPaintingState state)` Set the PDF state to use when starting to draw into the PDF graphics.
    `void` | `setXORMode(Color c1)` Sets the paint mode of this graphics context to alternate between this graphics context's current color and the new specified color.
    `protected void` | `updateCurrentFont(Font font)` Updates the currently selected font.
    `protected void` | `writeClip(Shape s)` Set the clipping shape for future PDF drawing in the current graphics state.

    - ### Methods inherited from class org.apache.xmlgraphics.java2d.AbstractGraphics2D

      `addRenderingHints, clearRect, clip, clipRect, drawArc, drawGlyphVector, drawImage, drawImage, drawImage, drawImage, drawImage, drawImage, drawLine, drawOval, drawPolygon, drawPolyline, drawRect, drawRoundRect, drawString, drawString, drawString, fillArc, fillOval, fillPolygon, fillRect, fillRoundRect, getBackground, getClip, getClipBounds, getColor, getComposite, getFont, getFontRenderContext, getGraphicContext, getPaint, getRenderingHint, getRenderingHints, getStroke, getTransform, hit, rotate, rotate, scale, setBackground, setClip, setClip, setColor, setComposite, setFont, setPaint, setPaintMode, setRenderingHint, setRenderingHints, setStroke, setTransform, shear, transform, translate, translate`

    - ### Methods inherited from class java.awt.Graphics2D

      `draw3DRect, fill3DRect`

    - ### Methods inherited from class java.awt.Graphics

      `create, drawBytes, drawChars, drawPolygon, fillPolygon, finalize, getClipBounds, getClipRect, getFontMetrics, hitClip, toString`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### pdfDoc

          protected PDFDocument pdfDoc

      the PDF Document being created

    - #### resourceContext

          protected PDFResourceContext resourceContext

      The current resource context for adding fonts, patterns etc.

    - #### pageRef

          protected PDFReference pageRef

      The PDF reference of the current page.

    - #### paintingState

          protected PDFPaintingState paintingState

      The PDF painting state

    - #### colorHandler

          protected PDFColorHandler colorHandler

      the PDF color handler

    - #### baseLevel

          protected int baseLevel

      The PDF graphics state level that this svg is being drawn into.

    - #### nativeCount

          protected int nativeCount

      The count of natively handled images added to document so they receive unique keys.

    - #### fontInfo

          protected FontInfo fontInfo

      The current font information.

    - #### ovFontState

          protected Font ovFontState

      The override font state used when drawing text and the font cannot be set using java fonts.

    - #### currentStream

          protected StringWriter currentStream

      the current stream to add PDF commands to

    - #### currentFontName

          protected String currentFontName

      the current (internal) font name

    - #### currentFontSize

          protected float currentFontSize

      the current font size in millipoints

    - #### outputStream

          protected OutputStream outputStream

      The output stream for the pdf document. If this is set then it can progressively output the pdf document objects to reduce memory. Especially with images.

  - ### Constructor Detail

    - #### PDFGraphics2D

          public PDFGraphics2D(boolean textAsShapes,
                               FontInfo fi,
                               PDFDocument doc,
                               PDFResourceContext page,
                               PDFReference pref,
                               String font,
                               float size,
                               PDFGraphics2D.TransparencyIgnoredEventListener listener)

      Create a new PDFGraphics2D with the given pdf document info. This is used to create a Graphics object for use inside an already existing document.
      Parameters:
        `textAsShapes` - if true then draw text as shapes
        `fi` - the current font information
        `doc` - the pdf document for creating pdf objects
        `page` - the current resource context or page
        `pref` - the PDF reference of the current page
        `font` - the current font name
        `size` - the current font size

    - #### PDFGraphics2D

          protected PDFGraphics2D(boolean textAsShapes)

      Create a new PDFGraphics2D.
      Parameters:
        `textAsShapes` - true if drawing text as shapes

    - #### PDFGraphics2D

          public PDFGraphics2D(PDFGraphics2D g)

      This constructor supports the create method. This is not implemented properly.
      Parameters:
        `g` - the PDF graphics to make a copy of

  - ### Method Detail

    - #### create

          public Graphics create()

      Creates a new `Graphics` object that is a copy of this `Graphics` object.
      Specified by:
        `create` in class `Graphics`
      Returns:
        a new graphics context that is a copy of this graphics context.

    - #### handleIOException

          protected void handleIOException(IOException ioe)

      Central handler for IOExceptions for this class.
      Parameters:
        `ioe` - IOException to handle

    - #### preparePainting

          protected void preparePainting()

      This method is used by PDFDocumentGraphics2D to prepare a new page if necessary.

    - #### setPaintingState

          public void setPaintingState(PDFPaintingState state)

      Set the PDF state to use when starting to draw into the PDF graphics.
      Parameters:
        `state` - the PDF state

    - #### setOutputStream

          public void setOutputStream(OutputStream os)

      Set the output stream that this PDF document is being drawn to. This is so that it can progressively use the PDF document to output data such as images. This results in a significant saving on memory.
      Parameters:
        `os` - the output stream that is being used for the PDF document

    - #### getString

          public String getString()

      Get the string containing all the commands written into this Graphics.
      Returns:
        the string containing the PDF markup

    - #### getBuffer

          public StringBuffer getBuffer()

      Get the string buffer from the currentStream, containing all the commands written into this Graphics so far.
      Returns:
        the StringBuffer containing the PDF markup

    - #### getPageReference

          public PDFReference getPageReference()

      Gets the PDF reference of the current page.
      Returns:
        the PDF reference of the current page

    - #### setGraphicContext

          public void setGraphicContext(org.apache.xmlgraphics.java2d.GraphicContext c)

      Set the Graphics context.
      Parameters:
        `c` - the graphics context to use

    - #### setOverrideFontState

          public void setOverrideFontState(Font infont)

      Set the override font state for drawing text. This is used by the PDF text painter so that it can temporarily set the font state when a java font cannot be used. The next drawString will use this font state.
      Parameters:
        `infont` - the font state to use

    - #### getBaseTransform

          protected AffineTransform getBaseTransform()

      This is mainly used for shading patterns which use the document-global coordinate system instead of the local one.
      Returns:
        the transformation matrix that established the basic user space for this document

    - #### addLink

          public void addLink(Rectangle2D bounds,
                              AffineTransform trans,
                              String dest,
                              int linkType)

      This is a pdf specific method used to add a link to the pdf document.
      Parameters:
        `bounds` - the bounds of the link in user coordinates
        `trans` - the transform of the current drawing position
        `dest` - the PDF destination
        `linkType` - the type of link, internal or external

    - #### addNativeImage

          public void addNativeImage(org.apache.xmlgraphics.image.loader.Image image,
                                     float x,
                                     float y,
                                     float width,
                                     float height)

      Add a natively handled image directly to the PDF document. This is used by the PDFImageElementBridge to draw a natively handled image (like JPEG or CCITT images) directly into the PDF document rather than converting the image into a bitmap and increasing the size.
      Specified by:
        `addNativeImage` in interface `NativeImageHandler`
      Parameters:
        `image` - the image to draw
        `x` - the x position
        `y` - the y position
        `width` - the width to draw the image
        `height` - the height to draw the image

    - #### drawImage

          public boolean drawImage(Image img,
                                   int x,
                                   int y,
                                   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 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.

      Specified by:
        `drawImage` in class `Graphics`
      Parameters:
        `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.
      Returns:
        true if the image was drawn
      See Also:
        `Image`, `ImageObserver`, `ImageObserver.imageUpdate(java.awt.Image, int, int, int, int, int)`

    - #### drawImage

          public boolean drawImage(Image img,
                                   int x,
                                   int y,
                                   int width,
                                   int height,
                                   ImageObserver observer)

      Specified by:
        `drawImage` in class `Graphics`

    - #### dispose

          public void dispose()

      Disposes of this graphics context and releases any system resources that it is using. A `Graphics` object cannot be used after `dispose`has 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.

      Specified by:
        `dispose` in class `Graphics`
      See Also:
        `Graphics.finalize()`, `Component.paint(java.awt.Graphics)`, `Component.update(java.awt.Graphics)`, `Component.getGraphics()`, `Graphics.create()`

    - #### draw

          public void draw(Shape s)

      Strokes the outline of a `Shape` using the settings of the current `Graphics2D` context. The rendering attributes applied include the `Clip`, `Transform`, `Paint`, `Composite` and `Stroke` attributes.
      Specified by:
        `draw` in class `Graphics2D`
      Parameters:
        `s` - the `Shape` to be rendered
      See Also:
        `AbstractGraphics2D.setStroke(java.awt.Stroke)`, `AbstractGraphics2D.setPaint(java.awt.Paint)`, `Graphics.setColor(java.awt.Color)`, `AbstractGraphics2D.transform(java.awt.geom.AffineTransform)`, `AbstractGraphics2D.setTransform(java.awt.geom.AffineTransform)`, `AbstractGraphics2D.clip(java.awt.Shape)`, `AbstractGraphics2D.setClip(int, int, int, int)`, `AbstractGraphics2D.setComposite(java.awt.Composite)`

    - #### writeClip

          protected void writeClip(Shape s)

      Set the clipping shape for future PDF drawing in the current graphics state. This sets creates and writes a clipping shape that will apply to future drawings in the current graphics state.
      Parameters:
        `s` - the clipping shape

    - #### applyColor

          protected void applyColor(Color col,
                                    boolean fill)

      Apply the java Color to PDF. This converts the java colour to a PDF colour and sets it for the next drawing.
      Parameters:
        `col` - the java colour
        `fill` - true if the colour will be used for filling

    - #### applyPaint

          protected boolean applyPaint(Paint paint,
                                       boolean fill)

      Apply the java paint to the PDF. This takes the java paint sets up the appropraite PDF commands for the drawing with that paint. Currently this supports the gradients and patterns from batik.
      Parameters:
        `paint` - the paint to convert to PDF
        `fill` - true if the paint should be set for filling
      Returns:
        true if the paint is handled natively, false if the paint should be rasterized

    - #### applyUnknownPaint

          protected boolean applyUnknownPaint(Paint paint,
                                              Shape shape)

      Parameters:
        `paint` - some paint
        `shape` - a shape
      Returns:
        true (always)

    - #### applyStroke

          protected void applyStroke(Stroke stroke)

      Apply the stroke to the PDF. This takes the java stroke and outputs the appropriate settings to the PDF so that the stroke attributes are handled.
      Parameters:
        `stroke` - the java stroke

    - #### drawRenderedImage

          public void drawRenderedImage(RenderedImage img,
                                        AffineTransform xform)

      Specified by:
        `drawRenderedImage` in class `Graphics2D`

    - #### drawInnerRenderedImage

          public void drawInnerRenderedImage(String key,
                                             RenderedImage img,
                                             AffineTransform xform)

      Parameters:
        `key` - a key
        `img` - an image
        `xform` - a transform

    - #### drawRenderableImage

          public void drawRenderableImage(RenderableImage img,
                                          AffineTransform xform)

      Specified by:
        `drawRenderableImage` in class `Graphics2D`

    - #### drawString

          public void drawString(String s,
                                 float x,
                                 float y)

      Renders the text specified by the specified `String`, using the current `Font` and `Paint` attributes in the `Graphics2D` context. The baseline of the first character is at position (x, y) in the User Space. The rendering attributes applied include the `Clip`, `Transform`, `Paint`, `Font` and `Composite` attributes. For characters in script systems such as Hebrew and Arabic, the glyphs can be rendered from right to left, in which case the coordinate supplied is the location of the leftmost character on the baseline.
      Specified by:
        `drawString` in class `Graphics2D`
      Parameters:
        `s` - the `String` to be rendered
        `x` - the coordinate where the `String` should be rendered
        `y` - the coordinate where the `String` should be rendered
      See Also:
        `AbstractGraphics2D.setPaint(java.awt.Paint)`, `Graphics.setColor(java.awt.Color)`, `Graphics.setFont(java.awt.Font)`, `AbstractGraphics2D.setTransform(java.awt.geom.AffineTransform)`, `AbstractGraphics2D.setComposite(java.awt.Composite)`, `AbstractGraphics2D.setClip(int, int, int, int)`

    - #### applyAlpha

          protected void applyAlpha(int fillAlpha,
                                    int strokeAlpha)

      Applies the given alpha values for filling and stroking.
      Parameters:
        `fillAlpha` - A value between 0 and 255 (=OPAQUE) for filling
        `strokeAlpha` - A value between 0 and 255 (=OPAQUE) for stroking

    - #### updateCurrentFont

          protected void updateCurrentFont(Font font)

      Updates the currently selected font.
      Parameters:
        `font` - the new font to use

    - #### getInternalFontForAWTFont

          @Deprecated
          protected Font getInternalFontForAWTFont(Font awtFont)

      Deprecated. use FontInfo.getFontInstanceForAWTFont(java.awt.Font awtFont) instead
      Returns a suitable internal font given an AWT Font instance.
      Parameters:
        `awtFont` - the AWT font
      Returns:
        the internal Font

    - #### isMultiByteFont

          protected boolean isMultiByteFont(String name)

      Determines whether the font with the given name is a multi-byte font.
      Parameters:
        `name` - the name of the font
      Returns:
        true if it's a multi-byte font

    - #### fill

          public void fill(Shape s)

      Fills the interior of a `Shape` using the settings of the `Graphics2D` context. The rendering attributes applied include the `Clip`, `Transform`, `Paint`, and `Composite`.
      Specified by:
        `fill` in class `Graphics2D`
      Parameters:
        `s` - the `Shape` to be filled
      See Also:
        `AbstractGraphics2D.setPaint(java.awt.Paint)`, `Graphics.setColor(java.awt.Color)`, `AbstractGraphics2D.transform(java.awt.geom.AffineTransform)`, `AbstractGraphics2D.setTransform(java.awt.geom.AffineTransform)`, `AbstractGraphics2D.setComposite(java.awt.Composite)`, `AbstractGraphics2D.clip(java.awt.Shape)`, `AbstractGraphics2D.setClip(int, int, int, int)`

    - #### isTransparencyAllowed

          protected Object isTransparencyAllowed()

      Checks whether the use of transparency is allowed.

    - #### processPathIterator

          public void processPathIterator(PathIterator iter)

      Processes a path iterator generating the necessary painting operations.
      Parameters:
        `iter` - PathIterator to process

    - #### doDrawing

          protected void doDrawing(boolean fill,
                                   boolean stroke,
                                   boolean nonzero)

      Do the PDF drawing command. This does the PDF drawing command according to fill stroke and winding rule.
      Parameters:
        `fill` - true if filling the path
        `stroke` - true if stroking the path
        `nonzero` - true if using the non-zero winding rule

    - #### getDeviceConfiguration

          public GraphicsConfiguration getDeviceConfiguration()

      Returns the device configuration associated with this `Graphics2D`.
      Specified by:
        `getDeviceConfiguration` in class `Graphics2D`
      Returns:
        the PDF graphics configuration

    - #### getFontMetrics

          public FontMetrics getFontMetrics(Font f)

      Gets the font metrics for the specified font.
      Specified by:
        `getFontMetrics` in class `Graphics`
      Parameters:
        `f` - the specified font
      Returns:
        the font metrics for the specified font.
      See Also:
        `Graphics.getFont()`, `FontMetrics`, `Graphics.getFontMetrics()`

    - #### setXORMode

          public void setXORMode(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.

      Specified by:
        `setXORMode` in class `Graphics`
      Parameters:
        `c1` - the XOR alternation color

    - #### copyArea

          public 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.
      Specified by:
        `copyArea` in class `Graphics`
      Parameters:
        `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.

    - #### registerFunction

          public PDFFunction registerFunction(PDFFunction function)

      Registers a function object against the output format document
      Parameters:
        `function` - The function object to register
      Returns:
        Returns either the function which has already been registered or the current new registered object.

    - #### registerShading

          public PDFShading registerShading(PDFShading shading)

      Registers a shading object against the otuput format document
      Parameters:
        `shading` - The shading object to register
      Returns:
        Returs either the shading which has already been registered or the current new registered object

    - #### registerPattern

          public PDFPattern registerPattern(PDFPattern pattern)

      Registers a pattern object against the output format document
      Parameters:
        `pattern` - The pattern object to register
      Returns:
        Returns either the pattern which has already been registered or the current new registered object

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