SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package cc.squirreljme.runtime.lcdui.image;

import cc.squirreljme.jvm.mle.callbacks.NativeImageLoadCallback;
import java.io.IOException;
import javax.microedition.lcdui.Image;
import net.multiphasicapps.io.ExtendedDataInputStream;

/**
 * This class is used to read and parse GIF images.
 *
 * @since 2021/12/04
 */
public class GIFReader
    implements ImageReader
{
    /** The source data stream. */
    protected final ExtendedDataInputStream in;
    
    /** The image loader to use. */
    protected final NativeImageLoadCallback loader;
    
    /**
     * Initializes the GIF reader.
     *
     * @param __in The stream to read from.
     * @param __loader The native loader to use.
     * @throws NullPointerException On null arguments.
     * @since 2021/12/04
     */
    public GIFReader(ExtendedDataInputStream __in,
        NativeImageLoadCallback __loader)
        throws NullPointerException
    {
        if (__in == null || __loader == null)
            throw new NullPointerException("NARG");
        
        this.in = __in;
        this.loader = __loader;
    }
    
    /**
     * Parses the image.
     * 
     * @throws IOException On read errors.
     * @since 2021/12/04
     */
    @Override
    public void parse()
        throws IOException
    {
        NativeImageLoadCallback loader = this.loader;
        
        // Skip header
        ExtendedDataInputStream in = this.in;
        for (int i = 0; i < 6; i++)
            in.readByte();
        
        // Read "screen" size
        int screenWidth = in.readUnsignedShort();
        int screenHeight = in.readUnsignedShort();
        
        // Build image
        loader.initialize(screenWidth, screenHeight,
            false, false);
        loader.addImage(new int[screenWidth * screenHeight], 0,
            screenWidth * screenHeight, 0, false);
    }
}