bitmover.java

来自「Mapserver的一个java客户端,包含两个applet支持地图显示。」· Java 代码 · 共 49 行

// Copyright (C) 1998, 1999, 2001 Chris Nokleberg
// Please see included LICENSE.TXT

package com.sixlegs.image.png;

import java.io.IOException;
import java.io.InputStream;

abstract class BitMover
{
    int trans = -1;
    int transgray = -1;
    int translow = -1;
    int[] gammaTable;

    abstract int fill(int[] pixels, InputStream str, int off, int len)
    throws IOException;

    static BitMover getBitMover(PngImage img)
    throws PngException
    {
        StringBuffer clsname = new StringBuffer("com.sixlegs.image.png.BitMover");
        clsname.append(img.data.header.depth);
        if (img.data.header.paletteUsed) {
            clsname.append('P');
        } else {
            clsname.append(img.data.header.colorUsed ? "RGB" : "G");
        }
        if (img.data.header.alphaUsed) clsname.append('A');
        try {
            BitMover b = (BitMover)Class.forName(clsname.toString()).newInstance();
            b.gammaTable = img.data.gammaTable;
            if (img.data.header.colorType == PngImage.COLOR_TYPE_GRAY || 
                img.data.header.colorType == PngImage.COLOR_TYPE_RGB) {
                Chunk_tRNS trans = (Chunk_tRNS)img.getChunk(Chunk.tRNS);
                if (trans != null) {
                    b.trans = trans.rgb;
                    b.translow = trans.rgb_low;
                    b.transgray = trans.r;
                }
            }
            return b;
        } catch (Exception e) {
            throw new PngException("Error loading " + clsname);
        }
    }
}