com.itextpdf.layout.renderer

Interface IRenderer

All Superinterfaces:

IPropertyContainer

All Known Subinterfaces:

ILeafElementRenderer

All Known Implementing Classes:

AbstractRenderer, AreaBreakRenderer, BlockRenderer, CanvasRenderer, CellRenderer, ColumnDocumentRenderer, DivRenderer, DocumentRenderer, ImageRenderer, LineRenderer, LineSeparatorRenderer, LinkRenderer, ListItemRenderer, ListRenderer, ParagraphRenderer, RootRenderer, TableRenderer, TabRenderer, TextRenderer

public interface IRenderer
extends IPropertyContainer

A renderer object is responsible for drawing a corresponding layout object on a document or canvas. Every layout object has a renderer, by default one of the corresponding type, e.g. you can ask an Image for its ImageRenderer. Renderers are designed to be extensible, and custom implementations can be seeded to layout objects (or their custom subclasses) at runtime.

Method Summary

Modifier and Type	Method and Description
void	addChild(IRenderer renderer) Adds a child to the current renderer
void	draw(DrawContext drawContext) Flushes the renderer subtree contents, i.e.
List<IRenderer>	getChildRenderers() Gets the child IRenderers.
IPropertyContainer	getModelElement() Gets the model element associated with this renderer.
IRenderer	getNextRenderer() Gets a new instance of this class to be used as a next renderer, after this renderer is used, if layout(LayoutContext) is called more than once.
LayoutArea	getOccupiedArea() Gets the resultant occupied area after the last call to the layout(LayoutContext) method.
<T1> T1	getProperty(int property, T1 defaultValue) Gets a property from this entity or one of its hierarchical parents.
boolean	isFlushed() Indicates whether this renderer is flushed or not, i.e.
LayoutResult	layout(LayoutContext layoutContext) This method simulates positioning of the renderer, including all of its children, and returns the LayoutResult, representing the layout result, including occupied area, status, i.e.
void	move(float dx, float dy) Moves the renderer subtree by the specified offset.
IRenderer	setParent(IRenderer parent) Explicitly sets this object as the child of another IRenderer in the renderer hierarchy.

Methods inherited from interface com.itextpdf.layout.IPropertyContainer

deleteOwnProperty, getDefaultProperty, getOwnProperty, getProperty, hasOwnProperty, hasProperty, setProperty

Method Detail

addChild

void addChild(IRenderer renderer)

Adds a child to the current renderer

Parameters:

renderer - a child to be added

layout

LayoutResult layout(LayoutContext layoutContext)

This method simulates positioning of the renderer, including all of its children, and returns the LayoutResult, representing the layout result, including occupied area, status, i.e. if there was enough place to fit the renderer subtree, etc. LayoutResult can be extended to return custom layout results for custom elements, e.g. TextRenderer uses TextLayoutResult as its result. This method can be called standalone to learn how much area the renderer subtree needs, or can be called before draw(DrawContext), to prepare the renderer to be flushed to the output stream.

Parameters:

layoutContext - the description of layout area and any other additional information

Returns:

result of the layout process

draw

void draw(DrawContext drawContext)

Flushes the renderer subtree contents, i.e. draws itself on canvas, adds necessary objects to the PdfDocument etc.

Parameters:

drawContext - contains the PdfDocument to which the renderer subtree if flushed, the PdfCanvas on which the renderer subtree is drawn and other additional parameters needed to perform drawing

getOccupiedArea

LayoutArea getOccupiedArea()

Gets the resultant occupied area after the last call to the layout(LayoutContext) method.

Returns:

LayoutArea instance

getProperty

<T1> T1 getProperty(int property,
                    T1 defaultValue)

Gets a property from this entity or one of its hierarchical parents. If the property is not found, defaultValue will be returned.

Type Parameters:

T1 - the return type associated with the property

Parameters:

property - the property to be retrieved

defaultValue - a fallback value

Returns:

the value of the given property

setParent

IRenderer setParent(IRenderer parent)

Explicitly sets this object as the child of another IRenderer in the renderer hierarchy. Some implementations also use this method internally to create a consistent hierarchy tree.

Parameters:

parent - the object to place higher in the renderer hierarchy

Returns:

by default, this object

getModelElement

IPropertyContainer getModelElement()

Gets the model element associated with this renderer.

Returns:

the model element, as a container of properties

getChildRenderers

List<IRenderer> getChildRenderers()

Gets the child IRenderers.

Returns:

a list of direct child renderers of this instance

isFlushed

boolean isFlushed()

Indicates whether this renderer is flushed or not, i.e. if draw(DrawContext) has already been called.

Returns:

whether the renderer has been flushed

move

void move(float dx,
          float dy)

Moves the renderer subtree by the specified offset. This method affects occupied area of the renderer.

Parameters:

dx - the x-axis offset in points. Positive value will move the renderer subtree to the right.

dy - the y-axis offset in points. Positive value will move the renderer subtree to the top.

getNextRenderer

IRenderer getNextRenderer()

Gets a new instance of this class to be used as a next renderer, after this renderer is used, if layout(LayoutContext) is called more than once.

Returns:

new renderer instance