CreateGradientShadingPDF.java
/*
* Copyright 2014 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.
*/
package org.apache.pdfbox.examples.pdmodel;
import java.io.IOException;
import java.io.OutputStream;
import javax.imageio.stream.MemoryCacheImageOutputStream;
import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSInteger;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSNumber;
import org.apache.pdfbox.cos.COSStream;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.common.function.PDFunctionType2;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.PDPageContentStream.AppendMode;
import org.apache.pdfbox.pdmodel.graphics.color.PDDeviceRGB;
import org.apache.pdfbox.pdmodel.graphics.shading.PDShading;
import org.apache.pdfbox.pdmodel.graphics.shading.PDShadingType2;
import org.apache.pdfbox.pdmodel.graphics.shading.PDShadingType3;
import org.apache.pdfbox.pdmodel.graphics.shading.PDShadingType4;
/**
* This example creates a PDF with type 2 (axial) and type 3 (radial) shadings with a type 2
* (exponential) function, and a type 4 (gouraud triangle shading) without function.
*
* @author Tilman Hausherr
*/
public class CreateGradientShadingPDF
{
/**
* This will create the PDF and write the contents to a file.
*
* @param file The name of the file to write to.
*
* @throws IOException If there is an error writing the data.
*/
public void create(String file) throws IOException
{
try (PDDocument document = new PDDocument())
{
PDPage page = new PDPage();
document.addPage(page);
// type 2 (exponential) function with attributes
// can be used by both shadings
COSDictionary fdict = new COSDictionary();
fdict.setInt(COSName.FUNCTION_TYPE, 2);
COSArray domain = new COSArray();
domain.add(COSInteger.ZERO);
domain.add(COSInteger.ONE);
COSArray c0 = new COSArray();
c0.add(COSInteger.ONE);
c0.add(COSInteger.ZERO);
c0.add(COSInteger.ZERO);
COSArray c1 = new COSArray();
c1.add(COSNumber.get("0.5"));
c1.add(COSInteger.ONE);
c1.add(COSNumber.get("0.5"));
fdict.setItem(COSName.DOMAIN, domain);
fdict.setItem(COSName.C0, c0);
fdict.setItem(COSName.C1, c1);
fdict.setInt(COSName.N, 1);
PDFunctionType2 func = new PDFunctionType2(fdict);
// axial shading with attributes
PDShadingType2 axialShading = new PDShadingType2(new COSDictionary());
axialShading.setColorSpace(PDDeviceRGB.INSTANCE);
axialShading.setShadingType(PDShading.SHADING_TYPE2);
COSArray coords1 = new COSArray();
coords1.add(COSInteger.get(100));
coords1.add(COSInteger.get(400));
coords1.add(COSInteger.get(400));
coords1.add(COSInteger.get(600));
axialShading.setCoords(coords1);
axialShading.setFunction(func);
// radial shading with attributes
PDShadingType3 radialShading = new PDShadingType3(new COSDictionary());
radialShading.setColorSpace(PDDeviceRGB.INSTANCE);
radialShading.setShadingType(PDShading.SHADING_TYPE3);
COSArray coords2 = new COSArray();
coords2.add(COSInteger.get(100));
coords2.add(COSInteger.get(400));
coords2.add(COSInteger.get(50)); // radius1
coords2.add(COSInteger.get(400));
coords2.add(COSInteger.get(600));
coords2.add(COSInteger.get(150)); // radius2
radialShading.setCoords(coords2);
radialShading.setFunction(func);
// Gouraud shading
// See PDF 32000 specification,
// 8.7.4.5.5 Type 4 Shadings (Free-Form Gouraud-Shaded Triangle Meshes)
PDShadingType4 gouraudShading = new PDShadingType4(document.getDocument().createCOSStream());
gouraudShading.setShadingType(PDShading.SHADING_TYPE4);
// we use multiple of 8, so that no padding is needed
gouraudShading.setBitsPerFlag(8);
gouraudShading.setBitsPerCoordinate(16);
gouraudShading.setBitsPerComponent(8);
COSArray decodeArray = new COSArray();
// coordinates x y map 16 bits 0..FFFF to 0..FFFF to make your life easy
// so no calculation is needed, but you can only use integer coordinates
// for real numbers, you'll need smaller bounds, e.g. 0xFFFF / 0xA = 0x1999
// would allow 1 point decimal result coordinate.
// See in PDF specification: 8.9.5.2 Decode Arrays
decodeArray.add(COSInteger.ZERO);
decodeArray.add(COSInteger.get(0xFFFF));
decodeArray.add(COSInteger.ZERO);
decodeArray.add(COSInteger.get(0xFFFF));
// colors r g b map 8 bits from 0..FF to 0..1
decodeArray.add(COSInteger.ZERO);
decodeArray.add(COSInteger.ONE);
decodeArray.add(COSInteger.ZERO);
decodeArray.add(COSInteger.ONE);
decodeArray.add(COSInteger.ZERO);
decodeArray.add(COSInteger.ONE);
gouraudShading.setDecodeValues(decodeArray);
gouraudShading.setColorSpace(PDDeviceRGB.INSTANCE);
// Function is not required for type 4 shadings and not really useful,
// because if a function would be used, each corner "color" of a triangle would be one value,
// which would then transformed into n color components by the function so it is
// difficult to get 3 "extremes".
// fill the vertex stream
try (OutputStream os = ((COSStream) gouraudShading.getCOSObject()).createOutputStream();
MemoryCacheImageOutputStream mcos = new MemoryCacheImageOutputStream(os))
{
// Vertex 1, starts with flag1
// (flags always 0 for vertices of start triangle)
mcos.writeByte(0);
// x1 y1 (left corner)
mcos.writeShort(0);
mcos.writeShort(0);
// r1 g1 b1 (red)
mcos.writeByte(0xFF);
mcos.writeByte(0);
mcos.writeByte(0);
// Vertex 2, starts with flag2
mcos.writeByte(0);
// x2 y2 (top corner)
mcos.writeShort(100);
mcos.writeShort(100);
// r2 g2 b2 (green)
mcos.writeByte(0);
mcos.writeByte(0xFF);
mcos.writeByte(0);
// Vertex 3, starts with flag3
mcos.writeByte(0);
// x3 y3 (right corner)
mcos.writeShort(200);
mcos.writeShort(0);
// r3 g3 b3 (blue)
mcos.writeByte(0);
mcos.writeByte(0);
mcos.writeByte(0xFF);
}
// invoke shading from content stream
// compress parameter is set to false so that you can see the stream in a text editor
try (PDPageContentStream contentStream = new PDPageContentStream(document, page, AppendMode.APPEND, false))
{
contentStream.shadingFill(axialShading);
contentStream.shadingFill(radialShading);
contentStream.shadingFill(gouraudShading);
}
document.save(file);
}
}
/**
* This will create a blank document.
*
* @param args The command line arguments.
*
* @throws IOException If there is an error writing the document data.
*/
public static void main(String[] args) throws IOException
{
if (args.length != 1)
{
usage();
}
else
{
CreateGradientShadingPDF creator = new CreateGradientShadingPDF();
creator.create(args[0]);
}
}
/**
* This will print the usage of this class.
*/
private static void usage()
{
System.err.println("usage: java " + CreateGradientShadingPDF.class.getName() + " <outputfile.pdf>");
}
}