/*
* $Id: PDFShader.java,v 1.4 2010-05-23 22:07:06 lujke Exp $
*
* Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
* Santa Clara, California 95054, U.S.A. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.sun.pdfview.pattern;
import java.awt.geom.Rectangle2D;
import java.io.IOException;
import java.util.Map;
import com.sun.pdfview.PDFFile;
import com.sun.pdfview.PDFObject;
import com.sun.pdfview.PDFPaint;
import com.sun.pdfview.PDFParseException;
import com.sun.pdfview.colorspace.PDFColorSpace;
/**
* <p>A PDFShader fills a given region with a shading, such as a gradient.</p>
*
* <p>
* Shading Dictionaries (section 4.6)<br>
* A shading dictionary specifies details of a particular gradient fill,
* including the type of shading to be used, the geometry of the area to
* be shaded, and the geometry of the gradient fill. Various shading types
* are available, depending on the value of the dictionary’s ShadingType entry:
*
* <li>Function-based shadings (type 1) define the color of every point in the
* domain using a mathematical function (not necessarily smooth or continuous).</li>
*
* <li>Axial shadings (type 2) define a color blend along a line between two
* points, optionally extended beyond the boundary points by continuing
* the boundary colors.</li>
*
* <li>Radial shadings (type 3) define a blend between two circles,
* optionally extended beyond the boundary circles by continuing the
* boundary colors. This type of shading is commonly used to represent
* three-dimensional spheres and cones.</li>
*
* <li>Free-form Gouraud-shaded triangle meshes (type 4) define a
* common construct used by many three-dimensional applications to
* represent complex colored and shaded shapes. Vertices are specified
* in free-form geometry.</li>
*
* <li>Lattice-form Gouraud-shaded triangle meshes (type 5) are based on
* the same geometrical construct as type 4 but with vertices specified
* as a pseudorectangular lattice.</li>
*
* <li>Coons patch meshes (type 6) construct a shading from one or more
* color patches, each bounded by four cubic Bézier curves.</li>
*
* <li>Tensor-product patch meshes (type 7) are similar to type 6 but
* with additional control points in each patch, affording greater
* control over color mapping.</li>
*
* Table 4.28 shows the entries that all shading dictionaries share
* in common; entries specific to particular shading types are
* described in the relevant sections below.</p>
*/
public abstract class PDFShader {
public final static int FUNCTION_SHADING = 1;
public final static int AXIAL_SHADING = 2;
public final static int RADIAL_SHADING = 3;
public final static int FREE_FORM_SHADING = 4;
public final static int LATTICE_SHADING = 5;
public final static int COONS_PATCH_MESH_SHADING = 6;
public final static int TENSOR_PRODUCTS_MESH_SHADING = 7;
/** the type of the shading (1 through 7)*/
private int type;
/** the colorspace */
private PDFColorSpace colorSpace;
/** the background color */
private PDFPaint background;
/** the bounding box of the pattern */
private Rectangle2D bbox;
/** Creates a new instance of PDFShader */
protected PDFShader(int type) {
this.type = type;
}
/**
* Parse a pdf shader into a shader object
*/
public static PDFShader getShader(PDFObject shaderObj, Map resources)
throws IOException
{
// first see if the shader is already cached
PDFShader shader = (PDFShader) shaderObj.getCache();
if (shader != null) {
return shader;
}
// read the type (required)
PDFObject typeObj = shaderObj.getDictRef("ShadingType");
if (typeObj == null) {
throw new PDFParseException("No shader type defined!");
}
int type = typeObj.getIntValue();
// create the shader
switch (type) {
case AXIAL_SHADING:
shader = new ShaderType2();
break;
case FUNCTION_SHADING:
case RADIAL_SHADING:
case FREE_FORM_SHADING:
case LATTICE_SHADING:
case COONS_PATCH_MESH_SHADING:
case TENSOR_PRODUCTS_MESH_SHADING:
default:
throw new PDFParseException("Unsupported shader type: " + type);
}
// read the color space (required)
PDFObject csObj = shaderObj.getDictRef("ColorSpace");
if (csObj == null) {
throw new PDFParseException("No colorspace defined!");
}
PDFColorSpace cs = PDFColorSpace.getColorSpace(csObj, resources);
shader.setColorSpace(cs);
// read the background color (optional)
PDFObject bgObj = shaderObj.getDictRef("Background");
if (bgObj != null) {
PDFObject[] bgObjs = bgObj.getArray();
float[] bgArray = new float[bgObjs.length];
for (int i = 0; i < bgArray.length; i++) {
bgArray[i] = bgObjs[i].getFloatValue();
}
PDFPaint paint = cs.getPaint(bgArray);
shader.setBackground(paint);
}
// read the bounding box (optional)
PDFObject bboxObj = shaderObj.getDictRef("BBox");
if (bboxObj != null) {
shader.setBBox(PDFFile.parseNormalisedRectangle(bboxObj));
}
// parse the shader-specific attributes
shader.parse(shaderObj);
// set the cache
shaderObj.setCache(shader);
return shader;
}
/**
* Get the type
*/
public int getType() {
return type;
}
/**
* Get the color space
*/
public PDFColorSpace getColorSpace() {
return colorSpace;
}
/**
* Set the color space
*/
protected void setColorSpace(PDFColorSpace colorSpace) {
this.colorSpace = colorSpace;
}
/**
* Get the background color
*/
public PDFPaint getBackground() {
return background;
}
/**
* Set the background color
*/
protected void setBackground(PDFPaint background) {
this.background = background;
}
/**
* Get the bounding box
*/
public Rectangle2D getBBox() {
return bbox;
}
/**
* Set the bounding box
*/
protected void setBBox(Rectangle2D bbox) {
this.bbox = bbox;
}
/**
* Parse the shader-specific data
*/
public abstract void parse(PDFObject shareObj) throws IOException;
/**
* Returns paint that represents the selected shader
*/
public abstract PDFPaint getPaint();
}