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The Apache PDFBox library is an open source Java tool for working with PDF documents.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.pdmodel.graphics.shading;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.geom.AffineTransform;
import java.awt.geom.Point2D;
import java.awt.image.ColorModel;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.imageio.stream.ImageInputStream;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pdfbox.pdmodel.common.PDRange;
import org.apache.pdfbox.util.Matrix;
/**
* Shades Gouraud triangles for Type4ShadingContext and Type5ShadingContext.
*
* @author Tilman Hausherr
* @author Shaola Ren
*/
abstract class GouraudShadingContext extends TriangleBasedShadingContext
{
private static final Log LOG = LogFactory.getLog(GouraudShadingContext.class);
/**
* triangle list.
*/
private List triangleList = new ArrayList();
/**
* Constructor creates an instance to be used for fill operations.
*
* @param shading the shading type to be used
* @param colorModel the color model to be used
* @param xform transformation for user to device space
* @param matrix the pattern matrix concatenated with that of the parent content stream
* @throws IOException if something went wrong
*/
protected GouraudShadingContext(PDShading shading, ColorModel colorModel, AffineTransform xform,
Matrix matrix) throws IOException
{
super(shading, colorModel, xform, matrix);
}
/**
* Read a vertex from the bit input stream performs interpolations.
*
* @param input bit input stream
* @param maxSrcCoord max value for source coordinate (2^bits-1)
* @param maxSrcColor max value for source color (2^bits-1)
* @param rangeX dest range for X
* @param rangeY dest range for Y
* @param colRangeTab dest range array for colors
* @param matrix the pattern matrix concatenated with that of the parent content stream
* @return a new vertex with the flag and the interpolated values
* @throws IOException if something went wrong
*/
protected Vertex readVertex(ImageInputStream input, long maxSrcCoord, long maxSrcColor,
PDRange rangeX, PDRange rangeY, PDRange[] colRangeTab,
Matrix matrix, AffineTransform xform) throws IOException
{
float[] colorComponentTab = new float[numberOfColorComponents];
long x = input.readBits(bitsPerCoordinate);
long y = input.readBits(bitsPerCoordinate);
float dstX = interpolate(x, maxSrcCoord, rangeX.getMin(), rangeX.getMax());
float dstY = interpolate(y, maxSrcCoord, rangeY.getMin(), rangeY.getMax());
LOG.debug("coord: " + String.format("[%06X,%06X] -> [%f,%f]", x, y, dstX, dstY));
Point2D p = matrix.transformPoint(dstX, dstY);
xform.transform(p, p);
for (int n = 0; n < numberOfColorComponents; ++n)
{
int color = (int) input.readBits(bitsPerColorComponent);
colorComponentTab[n] = interpolate(color, maxSrcColor, colRangeTab[n].getMin(),
colRangeTab[n].getMax());
LOG.debug("color[" + n + "]: " + color + "/" + String.format("%02x", color)
+ "-> color[" + n + "]: " + colorComponentTab[n]);
}
// "Each set of vertex data shall occupy a whole number of bytes.
// If the total number of bits required is not divisible by 8, the last data byte
// for each vertex is padded at the end with extra bits, which shall be ignored."
int bitOffset = input.getBitOffset();
if (bitOffset != 0)
{
input.readBits(8 - bitOffset);
}
return new Vertex(p, colorComponentTab);
}
final void setTriangleList(List triangleList)
{
this.triangleList = triangleList;
}
@Override
protected Map calcPixelTable(Rectangle deviceBounds) throws IOException
{
Map map = new HashMap();
super.calcPixelTable(triangleList, map, deviceBounds);
return map;
}
@Override
public void dispose()
{
triangleList = null;
super.dispose();
}
/**
* Calculate the interpolation, see p.345 pdf spec 1.7.
*
* @param src src value
* @param srcMax max src value (2^bits-1)
* @param dstMin min dst value
* @param dstMax max dst value
* @return interpolated value
*/
private float interpolate(float src, long srcMax, float dstMin, float dstMax)
{
return dstMin + (src * (dstMax - dstMin) / srcMax);
}
@Override
protected boolean isDataEmpty()
{
return triangleList.isEmpty();
}
}