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/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id$ */
package org.apache.fop.render;
// Java
import java.io.OutputStream;
import java.io.IOException;
// FOP
import org.apache.fop.apps.FOPException;
import org.apache.fop.area.PageViewport;
import org.apache.fop.area.LineArea;
import org.apache.fop.area.OffDocumentItem;
import org.apache.fop.fonts.FontInfo;
import org.apache.fop.apps.FOUserAgent;
/**
* Interface implemented by all renderers. This interface is used to control
* the rendering of pages and to let block and inline level areas call the
* appropriate method to render themselves. <p>
*
* A Renderer implementation takes areas/spaces and produces output in some
* format.</p> <p>
*
* Typically, most renderers are subclassed from FOP's abstract implementations
* ({@link AbstractRenderer}, {@link PrintRenderer}) which already handle a lot
* of things letting you concentrate on the details of the output format.
*/
public interface Renderer {
/**
* Role constant for Avalon.
*/
String ROLE = Renderer.class.getName();
/**
* Get the MIME type of the renderer.
*
* @return The MIME type of the renderer, may return null if not applicable.
*/
String getMimeType();
/**
* Initiates the rendering phase.
* This must only be called once for a rendering. If
* stopRenderer is called then this may be called again
* for a new document rendering.
*
* @param outputStream The OutputStream to use for output
* @exception IOException If an I/O error occurs
*/
void startRenderer(OutputStream outputStream)
throws IOException;
/**
* Signals the end of the rendering phase.
* The renderer should reset to an initial state and dispose of
* any resources for the completed rendering.
*
* @exception IOException If an I/O error occurs
*/
void stopRenderer()
throws IOException;
/**
* Set the User Agent.
*
* @param agent The User Agent
*/
void setUserAgent(FOUserAgent agent);
/**
* Set up the given FontInfo.
*
* @param fontInfo The font information
*/
void setupFontInfo(FontInfo fontInfo);
/**
* Reports if out of order rendering is supported. <p>
*
* Normally, all pages of a document are rendered in their natural order
* (page 1, page 2, page 3 etc.). Some output formats (such as PDF) allow
* pages to be output in random order. This is helpful to reduce resource
* strain on the system because a page that cannot be fully resolved
* doesn't block subsequent pages that are already fully resolved. </p>
*
* @return True if this renderer supports out of order rendering.
*/
boolean supportsOutOfOrder();
/**
* Tells the renderer to process an item not explicitly placed on the
* document (e.g., PDF bookmarks). Note - not all renderers will process
* all off-document items.
*
* @param ext The extension element to be rendered
*/
public void processOffDocumentItem(OffDocumentItem ext);
/**
* This is called if the renderer supports out of order rendering. The
* renderer should prepare the page so that a page further on in the set of
* pages can be rendered. The body of the page should not be rendered. The
* page will be rendered at a later time by the call to {@link
* #renderPage(PageViewport)}.
*
* @param page The page viewport to use
*/
void preparePage(PageViewport page);
/**
* Tells the renderer that a new page sequence starts.
*
* @param seqTitle The title of the page sequence
*/
void startPageSequence(LineArea seqTitle);
/**
* Tells the renderer to render a particular page. A renderer typically
* reponds by packing up the current page and writing it immediately to the
* output device.
*
* @param page The page to be rendered
* @exception IOException if an I/O error occurs
* @exception FOPException if a FOP interal error occurs.
*/
void renderPage(PageViewport page)
throws IOException, FOPException;
}
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