import greenfoot.*;  
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.List;
import java.util.ArrayList;




| This class can be used to read animated gif image files and extract the individual
| images of the animation sequence.
|
| @author Michael Berry
| @author Neil Brown
|
| Copyright (c) 2011,2013,2014,2018
|
public class GifImage
{    


| The images used in the animation.
|
private GreenfootImage[] images;
    

| The delay between each frame.
|
private int[] delay;
    

| The index of the current frame in the GIF file.
|
private int currentIndex;
    

| The time passed since the last frame in ms.
|
private long time;
    

| The GIF file that contains the animation.
|
private String file;
    

| Whether the animation is paused or not.
|
private boolean pause;

    


| Set the image of the actor. If the image is a normal picture, it will be displayed as normal.
| If it's an animated GIF file then it will be displayed as an animated actor.
|
public GifImage(String file)
    {
        this.file = file;
        pause = false;
        if(file.toLowerCase().endsWith(".gif")) {
            loadImages();
        }
        else {
            images = new GreenfootImage[] {new GreenfootImage(file)};
            delay = new int[] {1000}; 
            currentIndex = 0;
            time = System.currentTimeMillis();
        }
    }

    


| Get all the images used in the animation
| @return a list of GreenfootImages, corresponding to each frame.
|
public List getImages()
    {
        ArrayList<GreenfootImage> images = new ArrayList<GreenfootImage>(this.images.length);
        for(GreenfootImage image : this.images) {
            images.add(image);
        }
        return images;
    }

    


| Pause the animation.
|
public void pause()
    {
        pause = true;
    }

    


| Resume the animation.
|
public void resume()
    {
        pause = false;
        time = System.currentTimeMillis();
    }

    


| Determines whether the animation is running
| @return true if the animation is running, false otherwise
|
public boolean isRunning()
    {
        return !pause;
    }

    public GreenfootImage getCurrentImage()
    {
        long delta = System.currentTimeMillis() - time;

        while (delta >= delay[currentIndex] && !pause) {
            delta -= delay[currentIndex];
            time += delay[currentIndex];
            currentIndex = (currentIndex+1) % images.length;
        }
        return images[currentIndex];
    }

    


| Load the images
|
private void loadImages()
    {
        GifDecoder decode = new GifDecoder();
        decode.read(file);
        int numFrames = decode.getFrameCount();
        if(numFrames>0) {
            images = new GreenfootImage[numFrames];
            delay = new int[numFrames];
        }
        else {
            images = new GreenfootImage[1];
            images[0] = new GreenfootImage(1, 1);
        }

        for (int i=0 ; i<numFrames ; i++) {
            GreenfootImage image = new GreenfootImage(decode.getFrame(i).getWidth(), decode.getFrame(i).getHeight());
            image.drawImage(decode.getFrame(i), 0, 0);
            delay[i] = decode.getDelay(i);
            images[i] = image;
        }
        time = System.currentTimeMillis();
    }

    


| The Rectangle class represents rectangles. This is essentially a re-implementation
| of the java.awt.Rectangle class, created in order to avoid any dependency on AWT.
|
private static class Rectangle
{        
public int x;
        public int y;
        public int width;
        public int height;
        
        public Rectangle(int x, int y, int width, int height)
        {
            this.x = x;
            this.y = y;
            this.width = width;
            this.height = height;
        }
    }
    
    


| Class GifDecoder - Decodes a GIF file into one or more frames. <br>
|
| <i>I (Michael) edited this slightly on 10/09/08 to bring class up to date with generics and therefore remove warnings.
| Also edited so that resources are grabbed from the jar file and not externally, so no security exceptions.</i>
| <br>
| <pre>
|  Example:
|     GifDecoder d = new GifDecoder();
|     d.read("sample.gif");
|     int n = d.getFrameCount();
|     for (int i = 0; i < n; i++) {
|        BufferedImage frame = d.getFrame(i);  // frame i
|        int t = d.getDelay(i);  // display duration of frame in milliseconds
|        // do something with frame
|     }
| </pre>
|
| No copyright asserted on the source code of this class. May be used for any
| purpose, however, refer to the Unisys LZW patent for any additional
| restrictions. Please forward any corrections to kweiner@fmsware.com.
|
| @author Kevin Weiner, FM Software; LZW decoder adapted from John Cristy's
|         ImageMagick.
| @version 1.03 November 2003
|
private class GifDecoder
{        



| File read status: No errors.
|
public static final int STATUS_OK = 0;

        


| File read status: Error decoding file (may be partially decoded)
|
public static final int STATUS_FORMAT_ERROR = 1;

        


| File read status: Unable to open source.
|
public static final int STATUS_OPEN_ERROR = 2;

        private BufferedInputStream in;

        private int status;

        private int width; 

        private int height; 

        private boolean gctFlag; 

        private int gctSize; 

        private int loopCount = 1; 

        private int[] gct; 

        private int[] lct; 

        private int[] act; 

        private int bgIndex; 

        private Color bgColor; 

        private Color lastBgColor; 

        private int pixelAspect; 

        private boolean lctFlag; 

        private boolean interlace; 

        private int lctSize; 

        private int ix, iy, iw, ih; 

        private Rectangle lastRect; 

        private GreenfootImage image; 

        private GreenfootImage lastImage; 

        private byte[] block = new byte[256]; 

        private int blockSize = 0; 

        
        private int dispose = 0;

        
        private int lastDispose = 0;

        private boolean transparency = false; 

        private int delay = 0; 

        private int transIndex; 

        private static final int MaxStackSize = 4096;

        

        
        private short[] prefix;

        private byte[] suffix;

        private byte[] pixelStack;

        private byte[] pixels;

        private ArrayList<GifFrame> frames; 

        private int frameCount;

        


| A single frame
|
private class GifFrame
{            
public GifFrame(GreenfootImage im, int del)
{                
image = im;
                delay = del;
            }

            private GreenfootImage image;

            private int delay;
        }

        


| Convert an RGB integer value to a Color.
|
private Color colorFromInt(int rgb)
        {
            int r = (rgb & 0xFF0000) >> 16;
            int g = (rgb & 0xFF00) >> 8;
            int b = (rgb & 0xFF);
            return new Color(r,g,b);
        }
        
        


| Gets display duration for specified frame.
|
| @param n
|          int index of frame
| @return delay in milliseconds
|
public int getDelay(int n)
{            

            delay = -1;
            if ((n >= 0) && (n < frameCount)) {
                delay = (frames.get(n)).delay;
            }
            return delay;
        }

        


| Gets the number of frames read from file.
|
| @return frame count
|
public int getFrameCount()
{            
return frameCount;
        }

        


| Gets the first (or only) image read.
|
| @return BufferedImage containing first frame, or null if none.
|
public GreenfootImage getImage()
{            
return getFrame(0);
        }

        


| Gets the "Netscape" iteration count, if any. A count of 0 means repeat
|* indefinitiely.
         * 
         * @return iteration count if one was specified, else 1.
         */
        public int getLoopCount() {
|
|return loopCount;
|
|}
|
|/**
| Creates new frame image from current data (and previous frames as specified
| by their disposition codes).
|
protected void setPixels()
{            

            if (lastDispose > 0) {
                if (lastDispose == 3) {
                    
                    int n = frameCount - 2;
                    if (n > 0) {
                        lastImage = getFrame(n - 1);
                    } else {
                        lastImage = null;
                    }
                }

                if (lastImage != null) {
                    image.clear();
                    image.drawImage(lastImage, 0, 0);
                    
                    

                    if (lastDispose == 2) {
                        
                        Color c = null;
                        if (transparency) {
                            c = new Color(0, 0, 0, 0); 
                        } else {
                            c = lastBgColor; 
                        }
                        for (int x = 0; x < lastRect.width; x++)
                        {
                            for (int y = 0; y < lastRect.height; y++)
                            {
                                image.setColorAt(lastRect.x + x, lastRect.y + y, c);
                            }
                        }
                    }
                }
            }

            
            int pass = 1;
            int inc = 8;
            int iline = 0;
            for (int i = 0; i < ih; i++) {
                int line = i;
                if (interlace) {
                    if (iline >= ih) {
                        pass++;
                        switch (pass) {
                        case 2:
                            iline = 4;
                            break;
                        case 3:
                            iline = 2;
                            inc = 4;
                            break;
                        case 4:
                            iline = 1;
                            inc = 2;
                        }
                    }
                    line = iline;
                    iline += inc;
                }
                line += iy;
                if (line < height) {
                    int k = line * width;
                    int dlim = Math.min(ix + iw, width);
                    int sx = i * iw;
                    
                    for (int dx = ix; dx < dlim; dx++) {
                        int index = ((int) pixels[sx++]) & 0xff;
                        int c = act[index];
                        if (c != 0) {
                            image.setColorAt(dx, line, colorFromInt(c));
                        }
                    }
                }
            }
        }

        


| Gets the image contents of frame n.
|
| @return BufferedImage representation of frame, or null if n is invalid.
|
public GreenfootImage getFrame(int n)
{            
GreenfootImage im = null;
            if ((n >= 0) && (n < frameCount)) {
                im = ((GifFrame) frames.get(n)).image;
            }
            return im;
        }

        


| Gets image size.
|
| @return GIF image dimensions as an array - [0] = width, [1] = height
|
public int[] getFrameSize()
{            
return new int[]{width, height};
        }

        


| Reads GIF image from stream
|
| @param BufferedInputStream
|          containing GIF file.
| @return read status code (0 = no errors)
|
public int read(BufferedInputStream is)
{            
init();
            if (is != null) {
                in = is;
                readHeader();
                if (!err()) {
                    readContents();
                    if (frameCount < 0) {
                        status = STATUS_FORMAT_ERROR;
                    }
                }
            } else {
                status = STATUS_OPEN_ERROR;
            }
            try {
                is.close();
            } catch (IOException e) {
            }
            return status;
        }

        


| Reads GIF image from stream
|
| @param InputStream
|          containing GIF file.
| @return read status code (0 = no errors)
|
public int read(InputStream is)
{            
init();
            if (is != null) {
                if (!(is instanceof BufferedInputStream))
                    is = new BufferedInputStream(is);
                in = (BufferedInputStream) is;
                readHeader();
                if (!err()) {
                    readContents();
                    if (frameCount < 0) {
                        status = STATUS_FORMAT_ERROR;
                    }
                }
            } else {
                status = STATUS_OPEN_ERROR;
            }
            try {
                is.close();
            } catch (IOException e) {
            }
            return status;
        }

        


| Reads GIF file from specified file/URL source (URL assumed if name contains
| ":/" or "file:")
|* 
         * @param name
         *          String containing source
         * @return read status code (0 = no errors)
         */
        public int read(String name) {
            status = STATUS_OK;
|
|InputStream resource = this.getClass().getResourceAsStream(name);
|
|if (resource == null) {
|
|name = "images/" + name;
                resource = this.getClass().getResourceAsStream(name);
                if (resource == null) {
                    throw new RuntimeException("The gif file \"" + name + "\" doesn't exist.");
                }
            }
            in = new BufferedInputStream(resource);
            status = read(in);

            return status;
        }

        /**
         * Decodes LZW image data into pixel array. Adapted from John Cristy's
| ImageMagick.
|
protected void decodeImageData()
{            
int NullCode = -1;
            int npix = iw * ih;
            int available, clear, code_mask, code_size, end_of_information, in_code, old_code, bits, code, count, i, datum, data_size, first, top, bi, pi;

            if ((pixels == null) || (pixels.length < npix)) {
                pixels = new byte[npix]; 
            }
            if (prefix == null)
                prefix = new short[MaxStackSize];
            if (suffix == null)
                suffix = new byte[MaxStackSize];
            if (pixelStack == null)
                pixelStack = new byte[MaxStackSize + 1];

            

            data_size = read();
            clear = 1 << data_size;
            end_of_information = clear + 1;
            available = clear + 2;
            old_code = NullCode;
            code_size = data_size + 1;
            code_mask = (1 << code_size) - 1;
            for (code = 0; code < clear; code++) {
                prefix[code] = 0;
                suffix[code] = (byte) code;
            }

            

            datum = bits = count = first = top = pi = bi = 0;

            for (i = 0; i < npix;) {
                if (top == 0) {
                    if (bits < code_size) {
                        
                        if (count == 0) {
                            
                            count = readBlock();
                            if (count <= 0)
                                break;
                            bi = 0;
                        }
                        datum += (((int) block[bi]) & 0xff) << bits;
                        bits += 8;
                        bi++;
                        count--;
                        continue;
                    }

                    

                    code = datum & code_mask;
                    datum >>= code_size;
                        bits -= code_size;

                        

                        if ((code > available) || (code == end_of_information))
                            break;
                        if (code == clear) {
                            
                            code_size = data_size + 1;
                            code_mask = (1 << code_size) - 1;
                            available = clear + 2;
                            old_code = NullCode;
                            continue;
                        }
                        if (old_code == NullCode) {
                            pixelStack[top++] = suffix[code];
                            old_code = code;
                            first = code;
                            continue;
                        }
                        in_code = code;
                        if (code == available) {
                            pixelStack[top++] = (byte) first;
                            code = old_code;
                        }
                        while (code > clear) {
                            pixelStack[top++] = suffix[code];
                            code = prefix[code];
                        }
                        first = ((int) suffix[code]) & 0xff;

                        

                        if (available >= MaxStackSize)
                            break;
                        pixelStack[top++] = (byte) first;
                        prefix[available] = (short) old_code;
                        suffix[available] = (byte) first;
                        available++;
                        if (((available & code_mask) == 0) && (available < MaxStackSize)) {
                            code_size++;
                            code_mask += available;
                        }
                        old_code = in_code;
                }

                

                top--;
                pixels[pi++] = pixelStack[top];
                i++;
            }

            for (i = pi; i < npix; i++) {
                pixels[i] = 0; 
            } 
        }

        


| Returns true if an error was encountered during reading/decoding
|
protected boolean err()
{            
return status != STATUS_OK;
        }

        


| Initializes or re-initializes reader
|
protected void init()
{            
status = STATUS_OK;
            frameCount = 0;
            frames = new ArrayList<GifFrame>();
            gct = null;
            lct = null;
        }

        


| Reads a single byte from the input stream.
|
protected int read()
{            
int curByte = 0;
            try {
                curByte = in.read();
            } catch (IOException e) {
                status = STATUS_FORMAT_ERROR;
            }
            return curByte;
        }

        


| Reads next variable length block from input.
|
| @return number of bytes stored in "buffer"
|*/
        protected int readBlock() {
            blockSize = read();
            int n = 0;
            if (blockSize > 0) {
                try {
                    int count = 0;
                    while (n < blockSize) {
|
|count = in.read(block, n, blockSize - n);
|
|if (count == -1)
|
|break;
|
|n += count;
|
|}
|
|} catch (IOException e) {
|
|}
|
|if (n < blockSize) {
|
|status = STATUS_FORMAT_ERROR;
|
|}
|
|}
|
|return n;
|
|}
|
|/**
| Reads color table as 256 RGB integer values
|
| @param ncolors
|          int number of colors to read
| @return int array containing 256 colors (packed ARGB with full alpha)
|
protected int[] readColorTable(int ncolors)
{            
int nbytes = 3 * ncolors;
            int[] tab = null;
            byte[] c = new byte[nbytes];
            int n = 0;
            try {
                n = in.read(c);
            } catch (IOException e) {
            }
            if (n < nbytes) {
                status = STATUS_FORMAT_ERROR;
            } else {
                tab = new int[256]; 
                int i = 0;
                int j = 0;
                while (i < ncolors) {
                    int r = ((int) c[j++]) & 0xff;
                    int g = ((int) c[j++]) & 0xff;
                    int b = ((int) c[j++]) & 0xff;
                    tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b;
                }
            }
            return tab;
        }

        


| Main file parser. Reads GIF content blocks.
|
protected void readContents()
{            

            boolean done = false;
            while (!(done || err())) {
                int code = read();
                switch (code) {

                case 0x2C: 
                    readImage();
                    break;

                case 0x21: 
                    code = read();
                    switch (code) {
                    case 0xf9: 
                        readGraphicControlExt();
                        break;

                    case 0xff: 
                        readBlock();
                        String app = "";
                        for (int i = 0; i < 11; i++) {
                            app += (char) block[i];
                        }
                        if (app.equals("NETSCAPE2.0")) {
                            readNetscapeExt();
                        } else
                            skip(); 
                        break;

                    default: 
                        skip();
                    }
                    break;

                case 0x3b: 
                    done = true;
                    break;

                case 0x00: 
                    break;

                default:
                    status = STATUS_FORMAT_ERROR;
                }
            }
        }

        


| Reads Graphics Control Extension values
|
protected void readGraphicControlExt()
{            
read(); 
            int packed = read(); 
            dispose = (packed & 0x1c) >> 2; 
            if (dispose == 0) {
                dispose = 1; 
            }
            transparency = (packed & 1) != 0;
            delay = readShort() * 10; 
            transIndex = read(); 
            read(); 
        }

        


| Reads GIF file header information.
|
protected void readHeader()
{            
String id = "";
            for (int i = 0; i < 6; i++) {
                id += (char) read();
            }
            if (!id.startsWith("GIF")) {
                status = STATUS_FORMAT_ERROR;
                return;
            }

            readLSD();
            if (gctFlag && !err()) {
                gct = readColorTable(gctSize);
                bgColor = colorFromInt(gct[bgIndex]);
            }
        }

        


| Reads next frame image
|
protected void readImage()
{            
ix = readShort(); 
            iy = readShort();
            iw = readShort();
            ih = readShort();

            int packed = read();
            lctFlag = (packed & 0x80) != 0; 
            interlace = (packed & 0x40) != 0; 
            
            
            lctSize = 2 << (packed & 7); 

            if (lctFlag) {
                lct = readColorTable(lctSize); 
                act = lct; 
            } else {
                act = gct; 
                if (bgIndex == transIndex)
                    bgColor = colorFromInt(0);
            }
            int save = 0;
            if (transparency) {
                save = act[transIndex];
                act[transIndex] = 0; 
            }

            if (act == null) {
                status = STATUS_FORMAT_ERROR; 
            }

            if (err())
                return;

            decodeImageData(); 
            skip();

            if (err())
                return;

            frameCount++;

            
            image = new GreenfootImage(width, height);

            setPixels(); 

            frames.add(new GifFrame(image, delay)); 

            if (transparency) {
                act[transIndex] = save;
            }
            resetFrame(); 
        }

        


| Reads Logical Screen Descriptor
|
protected void readLSD()
{             

            width = readShort();
            height = readShort();

            
            int packed = read();
            gctFlag = (packed & 0x80) != 0; 
            
            
            gctSize = 2 << (packed & 7); 

            bgIndex = read(); 
            pixelAspect = read(); 
        }

        


| Reads Netscape extenstion to obtain iteration count
|
protected void readNetscapeExt()
{            
do {
                readBlock();
                if (block[0] == 1) {
                    
                    int b1 = ((int) block[1]) & 0xff;
                    int b2 = ((int) block[2]) & 0xff;
                    loopCount = (b2 << 8) | b1;
                }
            } while ((blockSize > 0) && !err());
        }

        


| Reads next 16-bit value, LSB first
|
protected int readShort()
{            

            return read() | (read() << 8);
        }

        


| Resets frame state for reading next image.
|
protected void resetFrame()
{            
lastDispose = dispose;
            lastRect = new Rectangle(ix, iy, iw, ih);
            lastImage = image;
            lastBgColor = bgColor;
            int dispose = 0;
            boolean transparency = false;
            int delay = 0;
            lct = null;
        }

        


| Skips variable length blocks up to and including next zero length block.
|
protected void skip()
{            
do {
                readBlock();
            } while ((blockSize > 0) && !err());
        }
    } 
}