src/java/org/apache/fop/image/PNGImage.java

/*
 * 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.
 */

/* $Id$ */

package org.apache.fop.image;

import java.io.IOException;

import org.apache.xmlgraphics.image.codec.png.PNGRed;
import org.apache.xmlgraphics.image.codec.png.PNGDecodeParam;
import org.apache.xmlgraphics.image.codec.util.SeekableStream;
import org.apache.xmlgraphics.image.rendered.CachableRed;
import org.apache.commons.io.IOUtils;

/**
 * FopImage object using PNG
 * @author Eric SCHAEFFER
 * @see AbstractFopImage
 * @see FopImage
 */
public class PNGImage extends XmlGraphicsCommonsImage {

    /**
     * Constructs a new PNGImage instance.
     * @param imgReader basic metadata for the image
     */
    public PNGImage(FopImage.ImageInfo imgReader) {
        super(imgReader);
        this.loaded = 0; //TODO The PNGReader cannot read the resolution, yet. 
    }

    /**
     * @see org.apache.fop.image.XmlGraphicsCommonsImage#decodeImage(
     *          org.apache.xmlgraphics.image.codec.util.SeekableStream)
     */
    protected CachableRed decodeImage(SeekableStream stream) throws IOException {
        PNGDecodeParam param = new PNGDecodeParam();
        param.setPerformGammaCorrection(true);
        param.setDisplayExponent(2.2f); // sRGB gamma
        PNGRed red = new PNGRed(stream, param); 
        String unit = (String)red.getProperty("pixel_units");
        if ("Meters".equals(unit)) {
            this.dpiHorizontal = ((Integer)red.getProperty("x_pixels_per_unit")).intValue() 
                * 25.4f / 1000f;
            this.dpiVertical = ((Integer)red.getProperty("y_pixels_per_unit")).intValue()
                * 25.4f / 1000f;
        }
        return red;
    }
    
    /**
     * Load the original PNG data.
     * This loads the original PNG data as is into memory.
     *
     * @return true if loaded false for any error
     */
    protected boolean loadOriginalData() {
        try {
            seekableInput.seek(0);
            this.raw = IOUtils.toByteArray(seekableInput);
        
        } catch (java.io.IOException ex) {
            log.error("Error while loading raw image: " + ex.getMessage(), ex);
            return false;
        } finally {
            IOUtils.closeQuietly(inputStream);
            inputStream = null;
        }

        return true;
    }
    
}