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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.PaintContext;
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.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import javax.imageio.stream.ImageInputStream;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.pdmodel.common.PDRange;
import org.apache.pdfbox.util.Matrix;
/**
* Shades Gouraud triangles for Type4ShadingContext and Type5ShadingContext.
*
* @author Andreas Lehmk?hler
* @author Tilman Hausherr
* @author Shaola Ren
*/
abstract class GouraudShadingContext extends TriangleBasedShadingContext implements PaintContext
{
private static final Log LOG = LogFactory.getLog(GouraudShadingContext.class);
/**
* triangle list.
*/
protected ArrayList triangleList;
/**
* background values.
*/
protected float[] background;
protected int rgbBackground;
protected HashMap pixelTable;
/**
* 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 ctm current transformation matrix
* @param pageHeight height of the current page
* @throws IOException if something went wrong
*/
protected GouraudShadingContext(PDShadingResources shading, ColorModel colorModel, AffineTransform xform,
Matrix ctm, int pageHeight, Rectangle dBounds) throws IOException
{
super(shading, colorModel, xform, ctm, pageHeight, dBounds);
triangleList = new ArrayList();
LOG.debug("Background: " + shading.getBackground());
COSArray bg = shading.getBackground();
if (bg != null)
{
background = bg.toFloatArray();
rgbBackground = convertToRGB(background);
}
}
/**
* Read a vertex from the bit input stream performs interpolations.
*
* @param input bit input stream
* @param flag the flag or any value if not relevant
* @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
* @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 ctm,
AffineTransform xform) throws IOException
{
float[] colorComponentTab = new float[numberOfColorComponents];
long x = input.readBits(bitsPerCoordinate);
long y = input.readBits(bitsPerCoordinate);
double dstX = interpolate(x, maxSrcCoord, rangeX.getMin(), rangeX.getMax());
double dstY = interpolate(y, maxSrcCoord, rangeY.getMin(), rangeY.getMax());
LOG.debug("coord: " + String.format("[%06X,%06X] -> [%f,%f]", x, y, dstX, dstY));
Point2D tmp = new Point2D.Double(dstX, dstY);
transformPoint(tmp, ctm, xform);
for (int n = 0; n < numberOfColorComponents; ++n)
{
int color = (int) input.readBits(bitsPerColorComponent);
colorComponentTab[n] = (float) 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(tmp, colorComponentTab);
}
protected HashMap calcPixelTable()
{
HashMap map = new HashMap();
super.calcPixelTable(triangleList, map);
return map;
}
/**
* {@inheritDoc}
*/
public void dispose()
{
triangleList = null;
outputColorModel = null;
shadingColorSpace = null;
shadingTinttransform = null;
}
/**
* {@inheritDoc}
*/
public final ColorModel getColorModel()
{
return outputColorModel;
}
/**
* 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);
}
/**
* {@inheritDoc}
*/
public final Raster getRaster(int x, int y, int w, int h)
{
WritableRaster raster = getColorModel().createCompatibleWritableRaster(w, h);
int[] data = new int[w * h * 4];
if (!triangleList.isEmpty() || background != null)
{
for (int row = 0; row < h; row++)
{
int currentY = y + row;
if (bboxRect != null)
{
if (currentY < minBBoxY || currentY > maxBBoxY)
{
continue;
}
}
for (int col = 0; col < w; col++)
{
int currentX = x + col;
if (bboxRect != null)
{
if (currentX < minBBoxX || currentX > maxBBoxX)
{
continue;
}
}
Point p = new Point(currentX, currentY);
int value;
if (pixelTable.containsKey(p))
{
value = pixelTable.get(p);
}
else
{
if (background != null)
{
value = rgbBackground;
}
else
{
continue;
}
}
int index = (row * w + col) * 4;
data[index] = value & 255;
value >>= 8;
data[index + 1] = value & 255;
value >>= 8;
data[index + 2] = value & 255;
data[index + 3] = 255;
}
}
}
raster.setPixels(0, 0, w, h, data);
return raster;
}
}