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The Apache PDFBox library is an open source Java tool for working with PDF documents.
/*
* 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.pdmodel.graphics.shading;
import java.awt.PaintContext;
import java.awt.geom.AffineTransform;
import java.awt.geom.NoninvertibleTransformException;
import java.awt.image.ColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pdfbox.pdmodel.graphics.color.PDColorSpace;
import org.apache.pdfbox.util.Matrix;
/**
* AWT PaintContext for function-based (Type 1) shading.
*
* @author Tilman Hausherr
*/
class Type1ShadingContext extends ShadingContext implements PaintContext
{
private static final Log LOG = LogFactory.getLog(Type1ShadingContext.class);
private PDShadingType1 type1ShadingType;
private AffineTransform rat;
private final float[] domain;
/**
* 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
*/
Type1ShadingContext(PDShadingType1 shading, ColorModel colorModel, AffineTransform xform,
Matrix matrix) throws IOException
{
super(shading, colorModel, xform, matrix);
this.type1ShadingType = shading;
// (Optional) An array of four numbers [ xmin xmax ymin ymax ]
// specifying the rectangular domain of coordinates over which the
// color function(s) are defined. Default value: [ 0.0 1.0 0.0 1.0 ].
if (shading.getDomain() != null)
{
domain = shading.getDomain().toFloatArray();
}
else
{
domain = new float[] { 0, 1, 0, 1 };
}
try
{
// get inverse transform to be independent of
// shading matrix and current user / device space
// when handling actual pixels in getRaster()
rat = shading.getMatrix().createAffineTransform().createInverse();
rat.concatenate(matrix.createAffineTransform().createInverse());
rat.concatenate(xform.createInverse());
}
catch (NoninvertibleTransformException ex)
{
LOG.error(ex, ex);
}
}
@Override
public void dispose()
{
super.dispose();
type1ShadingType = null;
}
@Override
public ColorModel getColorModel()
{
return super.getColorModel();
}
@Override
public Raster getRaster(int x, int y, int w, int h)
{
WritableRaster raster = getColorModel().createCompatibleWritableRaster(w, h);
int[] data = new int[w * h * 4];
for (int j = 0; j < h; j++)
{
int currentY = y + j;
if (bboxRect != null && (currentY < minBBoxY || currentY > maxBBoxY))
{
continue;
}
for (int i = 0; i < w; i++)
{
int currentX = x + i;
if (bboxRect != null && (currentX < minBBoxX || currentX > maxBBoxX))
{
continue;
}
int index = (j * w + i) * 4;
boolean useBackground = false;
float[] values = new float[] { x + i, y + j };
rat.transform(values, 0, values, 0, 1);
if (values[0] < domain[0] || values[0] > domain[1] ||
values[1] < domain[2] || values[1] > domain[3])
{
if (getBackground() == null)
{
continue;
}
useBackground = true;
}
// evaluate function
if (useBackground)
{
values = getBackground();
}
else
{
try
{
values = type1ShadingType.evalFunction(values);
}
catch (IOException e)
{
LOG.error("error while processing a function", e);
}
}
// convert color values from shading color space to RGB
PDColorSpace shadingColorSpace = getShadingColorSpace();
if (shadingColorSpace != null)
{
try
{
values = shadingColorSpace.toRGB(values);
}
catch (IOException e)
{
LOG.error("error processing color space", e);
}
}
data[index] = (int) (values[0] * 255);
data[index + 1] = (int) (values[1] * 255);
data[index + 2] = (int) (values[2] * 255);
data[index + 3] = 255;
}
}
raster.setPixels(0, 0, w, h, data);
return raster;
}
public float[] getDomain()
{
return domain;
}
}