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old_flsystem/应用/TBAppraisalTools/AnimatedGifEncoder.cs

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C#
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2022-09-20 03:10:29 +00:00
using System;
using System.Collections;
using System.Drawing;
using System.IO;
namespace TBAppraisalTools
{
public class AnimatedGifEncoder
{
protected int width; // image size
protected int height;
protected Color transparent = Color.Empty; // transparent color if given
protected int transIndex; // transparent index in color table
protected int repeat = -1; // no repeat
protected int delay = 0; // frame delay (hundredths)
protected bool started = false; // ready to output frames
// protected BinaryWriter bw;
protected FileStream fs;
protected Image image; // current frame
protected byte[] pixels; // BGR byte array from frame
protected byte[] indexedPixels; // converted frame indexed to palette
protected int colorDepth; // number of bit planes
protected byte[] colorTab; // RGB palette
protected bool[] usedEntry = new bool[256]; // active palette entries
protected int palSize = 7; // color table size (bits-1)
protected int dispose = -1; // disposal code (-1 = use default)
protected bool closeStream = false; // close stream when finished
protected bool firstFrame = true;
protected bool sizeSet = false; // if false, get size from first frame
protected int sample = 10; // default sample interval for quantizer
/**
* Sets the delay time between each frame, or changes it
* for subsequent frames (applies to last frame added).
*
* @param ms int delay time in milliseconds
*/
public void SetDelay(int ms)
{
delay = (int)Math.Round(ms / 10.0f);
}
/**
* Sets the GIF frame disposal code for the last added frame
* and any subsequent frames. Default is 0 if no transparent
* color has been set, otherwise 2.
* @param code int disposal code.
*/
public void SetDispose(int code)
{
if (code >= 0)
{
dispose = code;
}
}
/**
* Sets the number of times the set of GIF frames
* should be played. Default is 1; 0 means play
* indefinitely. Must be invoked before the first
* image is added.
*
* @param iter int number of iterations.
* @return
*/
public void SetRepeat(int iter)
{
if (iter >= 0)
{
repeat = iter;
}
}
/**
* Sets the transparent color for the last added frame
* and any subsequent frames.
* Since all colors are subject to modification
* in the quantization process, the color in the final
* palette for each frame closest to the given color
* becomes the transparent color for that frame.
* May be set to null to indicate no transparent color.
*
* @param c Color to be treated as transparent on display.
*/
public void SetTransparent(Color c)
{
transparent = c;
}
/**
* Adds next GIF frame. The frame is not written immediately, but is
* actually deferred until the next frame is received so that timing
* data can be inserted. Invoking <code>finish()</code> flushes all
* frames. If <code>setSize</code> was not invoked, the size of the
* first image is used for all subsequent frames.
*
* @param im BufferedImage containing frame to write.
* @return true if successful.
*/
public bool AddFrame(Image im)
{
if ((im == null) || !started)
{
return false;
}
bool ok = true;
try
{
if (!sizeSet)
{
// use first frame's size
SetSize(im.Width, im.Height);
}
image = im;
GetImagePixels(); // convert to correct format if necessary
AnalyzePixels(); // build color table & map pixels
if (firstFrame)
{
WriteLSD(); // logical screen descriptior
WritePalette(); // global color table
if (repeat >= 0)
{
// use NS app extension to indicate reps
WriteNetscapeExt();
}
}
WriteGraphicCtrlExt(); // write graphic control extension
WriteImageDesc(); // image descriptor
if (!firstFrame)
{
WritePalette(); // local color table
}
WritePixels(); // encode and write pixel data
firstFrame = false;
}
catch (IOException e)
{
ok = false;
}
return ok;
}
/**
* Flushes any pending data and closes output file.
* If writing to an OutputStream, the stream is not
* closed.
*/
public bool Finish()
{
if (!started) return false;
bool ok = true;
started = false;
try
{
fs.WriteByte(0x3b); // gif trailer
fs.Flush();
if (closeStream)
{
fs.Close();
}
}
catch (IOException e)
{
ok = false;
}
// reset for subsequent use
transIndex = 0;
fs = null;
image = null;
pixels = null;
indexedPixels = null;
colorTab = null;
closeStream = false;
firstFrame = true;
return ok;
}
/**
* Sets frame rate in frames per second. Equivalent to
* <code>setDelay(1000/fps)</code>.
*
* @param fps float frame rate (frames per second)
*/
public void SetFrameRate(float fps)
{
if (fps != 0f)
{
delay = (int)Math.Round(100f / fps);
}
}
/**
* Sets quality of color quantization (conversion of images
* to the maximum 256 colors allowed by the GIF specification).
* Lower values (minimum = 1) produce better colors, but slow
* processing significantly. 10 is the default, and produces
* good color mapping at reasonable speeds. Values greater
* than 20 do not yield significant improvements in speed.
*
* @param quality int greater than 0.
* @return
*/
public void SetQuality(int quality)
{
if (quality < 1) quality = 1;
sample = quality;
}
/**
* Sets the GIF frame size. The default size is the
* size of the first frame added if this method is
* not invoked.
*
* @param w int frame width.
* @param h int frame width.
*/
public void SetSize(int w, int h)
{
if (started && !firstFrame) return;
width = w;
height = h;
if (width < 1) width = 320;
if (height < 1) height = 240;
sizeSet = true;
}
/**
* Initiates GIF file creation on the given stream. The stream
* is not closed automatically.
*
* @param os OutputStream on which GIF images are written.
* @return false if initial write failed.
*/
public bool Start(FileStream os)
{
if (os == null) return false;
bool ok = true;
closeStream = false;
fs = os;
try
{
WriteString("GIF89a"); // header
}
catch (IOException e)
{
ok = false;
}
return started = ok;
}
/**
* Initiates writing of a GIF file with the specified name.
*
* @param file String containing output file name.
* @return false if open or initial write failed.
*/
public bool Start(String file)
{
bool ok = true;
try
{
// bw = new BinaryWriter( new FileStream( file, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None ) );
fs = new FileStream(file, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None);
ok = Start(fs);
closeStream = true;
}
catch (IOException e)
{
ok = false;
}
return started = ok;
}
/**
* Analyzes image colors and creates color map.
*/
protected void AnalyzePixels()
{
int len = pixels.Length;
int nPix = len / 3;
indexedPixels = new byte[nPix];
NeuQuant nq = new NeuQuant(pixels, len, sample);
// initialize quantizer
colorTab = nq.Process(); // create reduced palette
// convert map from BGR to RGB
// for (int i = 0; i < colorTab.Length; i += 3)
// {
// byte temp = colorTab[i];
// colorTab[i] = colorTab[i + 2];
// colorTab[i + 2] = temp;
// usedEntry[i / 3] = false;
// }
// map image pixels to new palette
int k = 0;
for (int i = 0; i < nPix; i++)
{
int index =
nq.Map(pixels[k++] & 0xff,
pixels[k++] & 0xff,
pixels[k++] & 0xff);
usedEntry[index] = true;
indexedPixels[i] = (byte)index;
}
pixels = null;
colorDepth = 8;
palSize = 7;
// get closest match to transparent color if specified
if (transparent != Color.Empty)
{
transIndex = FindClosest(transparent);
}
}
/**
* Returns index of palette color closest to c
*
*/
protected int FindClosest(Color c)
{
if (colorTab == null) return -1;
int r = c.R;
int g = c.G;
int b = c.B;
int minpos = 0;
int dmin = 256 * 256 * 256;
int len = colorTab.Length;
for (int i = 0; i < len;)
{
int dr = r - (colorTab[i++] & 0xff);
int dg = g - (colorTab[i++] & 0xff);
int db = b - (colorTab[i] & 0xff);
int d = dr * dr + dg * dg + db * db;
int index = i / 3;
if (usedEntry[index] && (d < dmin))
{
dmin = d;
minpos = index;
}
i++;
}
return minpos;
}
/**
* Extracts image pixels into byte array "pixels"
*/
protected void GetImagePixels()
{
int w = image.Width;
int h = image.Height;
// int type = image.GetType().;
if ((w != width)
|| (h != height)
)
{
// create new image with right size/format
Image temp =
new Bitmap(width, height);
Graphics g = Graphics.FromImage(temp);
g.DrawImage(image, 0, 0);
image = temp;
g.Dispose();
}
/*
ToDo:
improve performance: use unsafe code
*/
pixels = new Byte[3 * image.Width * image.Height];
int count = 0;
Bitmap tempBitmap = new Bitmap(image);
for (int th = 0; th < image.Height; th++)
{
for (int tw = 0; tw < image.Width; tw++)
{
Color color = tempBitmap.GetPixel(tw, th);
pixels[count] = color.R;
count++;
pixels[count] = color.G;
count++;
pixels[count] = color.B;
count++;
}
}
// pixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
}
/**
* Writes Graphic Control Extension
*/
protected void WriteGraphicCtrlExt()
{
fs.WriteByte(0x21); // extension introducer
fs.WriteByte(0xf9); // GCE label
fs.WriteByte(4); // data block size
int transp, disp;
if (transparent == Color.Empty)
{
transp = 0;
disp = 0; // dispose = no action
}
else
{
transp = 1;
disp = 2; // force clear if using transparent color
}
if (dispose >= 0)
{
disp = dispose & 7; // user override
}
disp <<= 2;
// packed fields
fs.WriteByte(Convert.ToByte(0 | // 1:3 reserved
disp | // 4:6 disposal
0 | // 7 user input - 0 = none
transp)); // 8 transparency flag
WriteShort(delay); // delay x 1/100 sec
fs.WriteByte(Convert.ToByte(transIndex)); // transparent color index
fs.WriteByte(0); // block terminator
}
/**
* Writes Image Descriptor
*/
protected void WriteImageDesc()
{
fs.WriteByte(0x2c); // image separator
WriteShort(0); // image position x,y = 0,0
WriteShort(0);
WriteShort(width); // image size
WriteShort(height);
// packed fields
if (firstFrame)
{
// no LCT - GCT is used for first (or only) frame
fs.WriteByte(0);
}
else
{
// specify normal LCT
fs.WriteByte(Convert.ToByte(0x80 | // 1 local color table 1=yes
0 | // 2 interlace - 0=no
0 | // 3 sorted - 0=no
0 | // 4-5 reserved
palSize)); // 6-8 size of color table
}
}
/**
* Writes Logical Screen Descriptor
*/
protected void WriteLSD()
{
// logical screen size
WriteShort(width);
WriteShort(height);
// packed fields
fs.WriteByte(Convert.ToByte(0x80 | // 1 : global color table flag = 1 (gct used)
0x70 | // 2-4 : color resolution = 7
0x00 | // 5 : gct sort flag = 0
palSize)); // 6-8 : gct size
fs.WriteByte(0); // background color index
fs.WriteByte(0); // pixel aspect ratio - assume 1:1
}
/**
* Writes Netscape application extension to define
* repeat count.
*/
protected void WriteNetscapeExt()
{
fs.WriteByte(0x21); // extension introducer
fs.WriteByte(0xff); // app extension label
fs.WriteByte(11); // block size
WriteString("NETSCAPE" + "2.0"); // app id + auth code
fs.WriteByte(3); // sub-block size
fs.WriteByte(1); // loop sub-block id
WriteShort(repeat); // loop count (extra iterations, 0=repeat forever)
fs.WriteByte(0); // block terminator
}
/**
* Writes color table
*/
protected void WritePalette()
{
fs.Write(colorTab, 0, colorTab.Length);
int n = (3 * 256) - colorTab.Length;
for (int i = 0; i < n; i++)
{
fs.WriteByte(0);
}
}
/**
* Encodes and writes pixel data
*/
protected void WritePixels()
{
LZWEncoder encoder =
new LZWEncoder(width, height, indexedPixels, colorDepth);
encoder.Encode(fs);
}
/**
* Write 16-bit value to output stream, LSB first
*/
protected void WriteShort(int value)
{
fs.WriteByte(Convert.ToByte(value & 0xff));
fs.WriteByte(Convert.ToByte((value >> 8) & 0xff));
}
/**
* Writes string to output stream
*/
protected void WriteString(String s)
{
char[] chars = s.ToCharArray();
for (int i = 0; i < chars.Length; i++)
{
fs.WriteByte((byte)chars[i]);
}
}
}
public class NeuQuant
{
protected static readonly int netsize = 256; /* number of colours used */
/* four primes near 500 - assume no image has a length so large */
/* that it is divisible by all four primes */
protected static readonly int prime1 = 499;
protected static readonly int prime2 = 491;
protected static readonly int prime3 = 487;
protected static readonly int prime4 = 503;
protected static readonly int minpicturebytes = (3 * prime4);
/* minimum size for input image */
/* Program Skeleton
----------------
[select samplefac in range 1..30]
[read image from input file]
pic = (unsigned char*) malloc(3*width*height);
initnet(pic,3*width*height,samplefac);
learn();
unbiasnet();
[write output image header, using writecolourmap(f)]
inxbuild();
write output image using inxsearch(b,g,r) */
/* Network Definitions
------------------- */
protected static readonly int maxnetpos = (netsize - 1);
protected static readonly int netbiasshift = 4; /* bias for colour values */
protected static readonly int ncycles = 100; /* no. of learning cycles */
/* defs for freq and bias */
protected static readonly int intbiasshift = 16; /* bias for fractions */
protected static readonly int intbias = (((int)1) << intbiasshift);
protected static readonly int gammashift = 10; /* gamma = 1024 */
protected static readonly int gamma = (((int)1) << gammashift);
protected static readonly int betashift = 10;
protected static readonly int beta = (intbias >> betashift); /* beta = 1/1024 */
protected static readonly int betagamma =
(intbias << (gammashift - betashift));
/* defs for decreasing radius factor */
protected static readonly int initrad = (netsize >> 3); /* for 256 cols, radius starts */
protected static readonly int radiusbiasshift = 6; /* at 32.0 biased by 6 bits */
protected static readonly int radiusbias = (((int)1) << radiusbiasshift);
protected static readonly int initradius = (initrad * radiusbias); /* and decreases by a */
protected static readonly int radiusdec = 30; /* factor of 1/30 each cycle */
/* defs for decreasing alpha factor */
protected static readonly int alphabiasshift = 10; /* alpha starts at 1.0 */
protected static readonly int initalpha = (((int)1) << alphabiasshift);
protected int alphadec; /* biased by 10 bits */
/* radbias and alpharadbias used for radpower calculation */
protected static readonly int radbiasshift = 8;
protected static readonly int radbias = (((int)1) << radbiasshift);
protected static readonly int alpharadbshift = (alphabiasshift + radbiasshift);
protected static readonly int alpharadbias = (((int)1) << alpharadbshift);
/* Types and Global Variables
-------------------------- */
protected byte[] thepicture; /* the input image itself */
protected int lengthcount; /* lengthcount = H*W*3 */
protected int samplefac; /* sampling factor 1..30 */
// typedef int pixel[4]; /* BGRc */
protected int[][] network; /* the network itself - [netsize][4] */
protected int[] netindex = new int[256];
/* for network lookup - really 256 */
protected int[] bias = new int[netsize];
/* bias and freq arrays for learning */
protected int[] freq = new int[netsize];
protected int[] radpower = new int[initrad];
/* radpower for precomputation */
/* Initialise network in range (0,0,0) to (255,255,255) and set parameters
----------------------------------------------------------------------- */
public NeuQuant(byte[] thepic, int len, int sample)
{
int i;
int[] p;
thepicture = thepic;
lengthcount = len;
samplefac = sample;
network = new int[netsize][];
for (i = 0; i < netsize; i++)
{
network[i] = new int[4];
p = network[i];
p[0] = p[1] = p[2] = (i << (netbiasshift + 8)) / netsize;
freq[i] = intbias / netsize; /* 1/netsize */
bias[i] = 0;
}
}
public byte[] ColorMap()
{
byte[] map = new byte[3 * netsize];
int[] index = new int[netsize];
for (int i = 0; i < netsize; i++)
index[network[i][3]] = i;
int k = 0;
for (int i = 0; i < netsize; i++)
{
int j = index[i];
map[k++] = (byte)(network[j][0]);
map[k++] = (byte)(network[j][1]);
map[k++] = (byte)(network[j][2]);
}
return map;
}
/* Insertion sort of network and building of netindex[0..255] (to do after unbias)
------------------------------------------------------------------------------- */
public void Inxbuild()
{
int i, j, smallpos, smallval;
int[] p;
int[] q;
int previouscol, startpos;
previouscol = 0;
startpos = 0;
for (i = 0; i < netsize; i++)
{
p = network[i];
smallpos = i;
smallval = p[1]; /* index on g */
/* find smallest in i..netsize-1 */
for (j = i + 1; j < netsize; j++)
{
q = network[j];
if (q[1] < smallval)
{ /* index on g */
smallpos = j;
smallval = q[1]; /* index on g */
}
}
q = network[smallpos];
/* swap p (i) and q (smallpos) entries */
if (i != smallpos)
{
j = q[0];
q[0] = p[0];
p[0] = j;
j = q[1];
q[1] = p[1];
p[1] = j;
j = q[2];
q[2] = p[2];
p[2] = j;
j = q[3];
q[3] = p[3];
p[3] = j;
}
/* smallval entry is now in position i */
if (smallval != previouscol)
{
netindex[previouscol] = (startpos + i) >> 1;
for (j = previouscol + 1; j < smallval; j++)
netindex[j] = i;
previouscol = smallval;
startpos = i;
}
}
netindex[previouscol] = (startpos + maxnetpos) >> 1;
for (j = previouscol + 1; j < 256; j++)
netindex[j] = maxnetpos; /* really 256 */
}
/* Main Learning Loop
------------------ */
public void Learn()
{
int i, j, b, g, r;
int radius, rad, alpha, step, delta, samplepixels;
byte[] p;
int pix, lim;
if (lengthcount < minpicturebytes)
samplefac = 1;
alphadec = 30 + ((samplefac - 1) / 3);
p = thepicture;
pix = 0;
lim = lengthcount;
samplepixels = lengthcount / (3 * samplefac);
delta = samplepixels / ncycles;
alpha = initalpha;
radius = initradius;
rad = radius >> radiusbiasshift;
if (rad <= 1)
rad = 0;
for (i = 0; i < rad; i++)
radpower[i] =
alpha * (((rad * rad - i * i) * radbias) / (rad * rad));
//fprintf(stderr,"beginning 1D learning: initial radius=%d\n", rad);
if (lengthcount < minpicturebytes)
step = 3;
else if ((lengthcount % prime1) != 0)
step = 3 * prime1;
else
{
if ((lengthcount % prime2) != 0)
step = 3 * prime2;
else
{
if ((lengthcount % prime3) != 0)
step = 3 * prime3;
else
step = 3 * prime4;
}
}
i = 0;
while (i < samplepixels)
{
b = (p[pix + 0] & 0xff) << netbiasshift;
g = (p[pix + 1] & 0xff) << netbiasshift;
r = (p[pix + 2] & 0xff) << netbiasshift;
j = Contest(b, g, r);
Altersingle(alpha, j, b, g, r);
if (rad != 0)
Alterneigh(rad, j, b, g, r); /* alter neighbours */
pix += step;
if (pix >= lim)
pix -= lengthcount;
i++;
if (delta == 0)
delta = 1;
if (i % delta == 0)
{
alpha -= alpha / alphadec;
radius -= radius / radiusdec;
rad = radius >> radiusbiasshift;
if (rad <= 1)
rad = 0;
for (j = 0; j < rad; j++)
radpower[j] =
alpha * (((rad * rad - j * j) * radbias) / (rad * rad));
}
}
//fprintf(stderr,"finished 1D learning: readonly alpha=%f !\n",((float)alpha)/initalpha);
}
/* Search for BGR values 0..255 (after net is unbiased) and return colour index
---------------------------------------------------------------------------- */
public int Map(int b, int g, int r)
{
int i, j, dist, a, bestd;
int[] p;
int best;
bestd = 1000; /* biggest possible dist is 256*3 */
best = -1;
i = netindex[g]; /* index on g */
j = i - 1; /* start at netindex[g] and work outwards */
while ((i < netsize) || (j >= 0))
{
if (i < netsize)
{
p = network[i];
dist = p[1] - g; /* inx key */
if (dist >= bestd)
i = netsize; /* stop iter */
else
{
i++;
if (dist < 0)
dist = -dist;
a = p[0] - b;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd)
{
a = p[2] - r;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd)
{
bestd = dist;
best = p[3];
}
}
}
}
if (j >= 0)
{
p = network[j];
dist = g - p[1]; /* inx key - reverse dif */
if (dist >= bestd)
j = -1; /* stop iter */
else
{
j--;
if (dist < 0)
dist = -dist;
a = p[0] - b;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd)
{
a = p[2] - r;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd)
{
bestd = dist;
best = p[3];
}
}
}
}
}
return (best);
}
public byte[] Process()
{
Learn();
Unbiasnet();
Inxbuild();
return ColorMap();
}
/* Unbias network to give byte values 0..255 and record position i to prepare for sort
----------------------------------------------------------------------------------- */
public void Unbiasnet()
{
int i, j;
for (i = 0; i < netsize; i++)
{
network[i][0] >>= netbiasshift;
network[i][1] >>= netbiasshift;
network[i][2] >>= netbiasshift;
network[i][3] = i; /* record colour no */
}
}
/* Move adjacent neurons by precomputed alpha*(1-((i-j)^2/[r]^2)) in radpower[|i-j|]
--------------------------------------------------------------------------------- */
protected void Alterneigh(int rad, int i, int b, int g, int r)
{
int j, k, lo, hi, a, m;
int[] p;
lo = i - rad;
if (lo < -1)
lo = -1;
hi = i + rad;
if (hi > netsize)
hi = netsize;
j = i + 1;
k = i - 1;
m = 1;
while ((j < hi) || (k > lo))
{
a = radpower[m++];
if (j < hi)
{
p = network[j++];
try
{
p[0] -= (a * (p[0] - b)) / alpharadbias;
p[1] -= (a * (p[1] - g)) / alpharadbias;
p[2] -= (a * (p[2] - r)) / alpharadbias;
}
catch (Exception e)
{
} // prevents 1.3 miscompilation
}
if (k > lo)
{
p = network[k--];
try
{
p[0] -= (a * (p[0] - b)) / alpharadbias;
p[1] -= (a * (p[1] - g)) / alpharadbias;
p[2] -= (a * (p[2] - r)) / alpharadbias;
}
catch (Exception e)
{
}
}
}
}
/* Move neuron i towards biased (b,g,r) by factor alpha
---------------------------------------------------- */
protected void Altersingle(int alpha, int i, int b, int g, int r)
{
/* alter hit neuron */
int[] n = network[i];
n[0] -= (alpha * (n[0] - b)) / initalpha;
n[1] -= (alpha * (n[1] - g)) / initalpha;
n[2] -= (alpha * (n[2] - r)) / initalpha;
}
/* Search for biased BGR values
---------------------------- */
protected int Contest(int b, int g, int r)
{
/* finds closest neuron (min dist) and updates freq */
/* finds best neuron (min dist-bias) and returns position */
/* for frequently chosen neurons, freq[i] is high and bias[i] is negative */
/* bias[i] = gamma*((1/netsize)-freq[i]) */
int i, dist, a, biasdist, betafreq;
int bestpos, bestbiaspos, bestd, bestbiasd;
int[] n;
bestd = ~(((int)1) << 31);
bestbiasd = bestd;
bestpos = -1;
bestbiaspos = bestpos;
for (i = 0; i < netsize; i++)
{
n = network[i];
dist = n[0] - b;
if (dist < 0)
dist = -dist;
a = n[1] - g;
if (a < 0)
a = -a;
dist += a;
a = n[2] - r;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd)
{
bestd = dist;
bestpos = i;
}
biasdist = dist - ((bias[i]) >> (intbiasshift - netbiasshift));
if (biasdist < bestbiasd)
{
bestbiasd = biasdist;
bestbiaspos = i;
}
betafreq = (freq[i] >> betashift);
freq[i] -= betafreq;
bias[i] += (betafreq << gammashift);
}
freq[bestpos] += beta;
bias[bestpos] -= betagamma;
return (bestbiaspos);
}
}
public class LZWEncoder
{
private static readonly int EOF = -1;
private int imgW, imgH;
private byte[] pixAry;
private int initCodeSize;
private int remaining;
private int curPixel;
// GIFCOMPR.C - GIF Image compression routines
//
// Lempel-Ziv compression based on 'compress'. GIF modifications by
// David Rowley (mgardi@watdcsu.waterloo.edu)
// General DEFINEs
static readonly int BITS = 12;
static readonly int HSIZE = 5003; // 80% occupancy
// GIF Image compression - modified 'compress'
//
// Based on: compress.c - File compression ala IEEE Computer, June 1984.
//
// By Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
// Jim McKie (decvax!mcvax!jim)
// Steve Davies (decvax!vax135!petsd!peora!srd)
// Ken Turkowski (decvax!decwrl!turtlevax!ken)
// James A. Woods (decvax!ihnp4!ames!jaw)
// Joe Orost (decvax!vax135!petsd!joe)
int n_bits; // number of bits/code
int maxbits = BITS; // user settable max # bits/code
int maxcode; // maximum code, given n_bits
int maxmaxcode = 1 << BITS; // should NEVER generate this code
int[] htab = new int[HSIZE];
int[] codetab = new int[HSIZE];
int hsize = HSIZE; // for dynamic table sizing
int free_ent = 0; // first unused entry
// block compression parameters -- after all codes are used up,
// and compression rate changes, start over.
bool clear_flg = false;
// Algorithm: use open addressing double hashing (no chaining) on the
// prefix code / next character combination. We do a variant of Knuth's
// algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
// secondary probe. Here, the modular division first probe is gives way
// to a faster exclusive-or manipulation. Also do block compression with
// an adaptive reset, whereby the code table is cleared when the compression
// ratio decreases, but after the table fills. The variable-length output
// codes are re-sized at this point, and a special CLEAR code is generated
// for the decompressor. Late addition: construct the table according to
// file size for noticeable speed improvement on small files. Please direct
// questions about this implementation to ames!jaw.
int g_init_bits;
int ClearCode;
int EOFCode;
// output
//
// Output the given code.
// Inputs:
// code: A n_bits-bit integer. If == -1, then EOF. This assumes
// that n_bits =< wordsize - 1.
// Outputs:
// Outputs code to the file.
// Assumptions:
// Chars are 8 bits long.
// Algorithm:
// Maintain a BITS character long buffer (so that 8 codes will
// fit in it exactly). Use the VAX insv instruction to insert each
// code in turn. When the buffer fills up empty it and start over.
int cur_accum = 0;
int cur_bits = 0;
int[] masks =
{
0x0000,
0x0001,
0x0003,
0x0007,
0x000F,
0x001F,
0x003F,
0x007F,
0x00FF,
0x01FF,
0x03FF,
0x07FF,
0x0FFF,
0x1FFF,
0x3FFF,
0x7FFF,
0xFFFF };
// Number of characters so far in this 'packet'
int a_count;
// Define the storage for the packet accumulator
byte[] accum = new byte[256];
//----------------------------------------------------------------------------
public LZWEncoder(int width, int height, byte[] pixels, int color_depth)
{
imgW = width;
imgH = height;
pixAry = pixels;
initCodeSize = Math.Max(2, color_depth);
}
// Add a character to the end of the current packet, and if it is 254
// characters, flush the packet to disk.
void Add(byte c, Stream outs)
{
accum[a_count++] = c;
if (a_count >= 254)
Flush(outs);
}
// Clear out the hash table
// table clear for block compress
void ClearTable(Stream outs)
{
ResetCodeTable(hsize);
free_ent = ClearCode + 2;
clear_flg = true;
Output(ClearCode, outs);
}
// reset code table
void ResetCodeTable(int hsize)
{
for (int i = 0; i < hsize; ++i)
htab[i] = -1;
}
void Compress(int init_bits, Stream outs)
{
int fcode;
int i /* = 0 */;
int c;
int ent;
int disp;
int hsize_reg;
int hshift;
// Set up the globals: g_init_bits - initial number of bits
g_init_bits = init_bits;
// Set up the necessary values
clear_flg = false;
n_bits = g_init_bits;
maxcode = MaxCode(n_bits);
ClearCode = 1 << (init_bits - 1);
EOFCode = ClearCode + 1;
free_ent = ClearCode + 2;
a_count = 0; // clear packet
ent = NextPixel();
hshift = 0;
for (fcode = hsize; fcode < 65536; fcode *= 2)
++hshift;
hshift = 8 - hshift; // set hash code range bound
hsize_reg = hsize;
ResetCodeTable(hsize_reg); // clear hash table
Output(ClearCode, outs);
outer_loop: while ((c = NextPixel()) != EOF)
{
fcode = (c << maxbits) + ent;
i = (c << hshift) ^ ent; // xor hashing
if (htab[i] == fcode)
{
ent = codetab[i];
continue;
}
else if (htab[i] >= 0) // non-empty slot
{
disp = hsize_reg - i; // secondary hash (after G. Knott)
if (i == 0)
disp = 1;
do
{
if ((i -= disp) < 0)
i += hsize_reg;
if (htab[i] == fcode)
{
ent = codetab[i];
goto outer_loop;
}
} while (htab[i] >= 0);
}
Output(ent, outs);
ent = c;
if (free_ent < maxmaxcode)
{
codetab[i] = free_ent++; // code -> hashtable
htab[i] = fcode;
}
else
ClearTable(outs);
}
// Put out the final code.
Output(ent, outs);
Output(EOFCode, outs);
}
//----------------------------------------------------------------------------
public void Encode(Stream os)
{
os.WriteByte(Convert.ToByte(initCodeSize)); // write "initial code size" byte
remaining = imgW * imgH; // reset navigation variables
curPixel = 0;
Compress(initCodeSize + 1, os); // compress and write the pixel data
os.WriteByte(0); // write block terminator
}
// Flush the packet to disk, and reset the accumulator
void Flush(Stream outs)
{
if (a_count > 0)
{
outs.WriteByte(Convert.ToByte(a_count));
outs.Write(accum, 0, a_count);
a_count = 0;
}
}
int MaxCode(int n_bits)
{
return (1 << n_bits) - 1;
}
//----------------------------------------------------------------------------
// Return the next pixel from the image
//----------------------------------------------------------------------------
private int NextPixel()
{
if (remaining == 0)
return EOF;
--remaining;
int temp = curPixel + 1;
if (temp < pixAry.GetUpperBound(0))
{
byte pix = pixAry[curPixel++];
return pix & 0xff;
}
return 0xff;
}
void Output(int code, Stream outs)
{
cur_accum &= masks[cur_bits];
if (cur_bits > 0)
cur_accum |= (code << cur_bits);
else
cur_accum = code;
cur_bits += n_bits;
while (cur_bits >= 8)
{
Add((byte)(cur_accum & 0xff), outs);
cur_accum >>= 8;
cur_bits -= 8;
}
// If the next entry is going to be too big for the code size,
// then increase it, if possible.
if (free_ent > maxcode || clear_flg)
{
if (clear_flg)
{
maxcode = MaxCode(n_bits = g_init_bits);
clear_flg = false;
}
else
{
++n_bits;
if (n_bits == maxbits)
maxcode = maxmaxcode;
else
maxcode = MaxCode(n_bits);
}
}
if (code == EOFCode)
{
// At EOF, write the rest of the buffer.
while (cur_bits > 0)
{
Add((byte)(cur_accum & 0xff), outs);
cur_accum >>= 8;
cur_bits -= 8;
}
Flush(outs);
}
}
}
public class GifDecoder
{
/**
* File read status: No errors.
*/
public static readonly int STATUS_OK = 0;
/**
* File read status: Error decoding file (may be partially decoded)
*/
public static readonly int STATUS_FORMAT_ERROR = 1;
/**
* File read status: Unable to open source.
*/
public static readonly int STATUS_OPEN_ERROR = 2;
protected Stream inStream;
protected int status;
protected int width; // full image width
protected int height; // full image height
protected bool gctFlag; // global color table used
protected int gctSize; // size of global color table
protected int loopCount = 1; // iterations; 0 = repeat forever
protected int[] gct; // global color table
protected int[] lct; // local color table
protected int[] act; // active color table
protected int bgIndex; // background color index
protected int bgColor; // background color
protected int lastBgColor; // previous bg color
protected int pixelAspect; // pixel aspect ratio
protected bool lctFlag; // local color table flag
protected bool interlace; // interlace flag
protected int lctSize; // local color table size
protected int ix, iy, iw, ih; // current image rectangle
protected Rectangle lastRect; // last image rect
protected Image image; // current frame
protected Bitmap bitmap;
protected Image lastImage; // previous frame
protected byte[] block = new byte[256]; // current data block
protected int blockSize = 0; // block size
// last graphic control extension info
protected int dispose = 0;
// 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev
protected int lastDispose = 0;
protected bool transparency = false; // use transparent color
protected int delay = 0; // delay in milliseconds
protected int transIndex; // transparent color index
protected static readonly int MaxStackSize = 4096;
// max decoder pixel stack size
// LZW decoder working arrays
protected short[] prefix;
protected byte[] suffix;
protected byte[] pixelStack;
protected byte[] pixels;
protected ArrayList frames; // frames read from current file
protected int frameCount;
public class GifFrame
{
public GifFrame(Image im, int del)
{
image = im;
delay = del;
}
public Image image;
public int delay;
}
/**
* 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 = ((GifFrame)frames[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 Image 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).
*/
int[] GetPixels(Bitmap bitmap)
{
int[] pixels = new int[3 * image.Width * image.Height];
int count = 0;
for (int th = 0; th < image.Height; th++)
{
for (int tw = 0; tw < image.Width; tw++)
{
Color color = bitmap.GetPixel(tw, th);
pixels[count] = color.R;
count++;
pixels[count] = color.G;
count++;
pixels[count] = color.B;
count++;
}
}
return pixels;
}
void SetPixels(int[] pixels)
{
int count = 0;
for (int th = 0; th < image.Height; th++)
{
for (int tw = 0; tw < image.Width; tw++)
{
Color color = Color.FromArgb(pixels[count++]);
bitmap.SetPixel(tw, th, color);
}
}
}
protected void SetPixels()
{
// expose destination image's pixels as int array
// int[] dest =
// (( int ) image.getRaster().getDataBuffer()).getData();
int[] dest = GetPixels(bitmap);
// fill in starting image contents based on last image's dispose code
if (lastDispose > 0)
{
if (lastDispose == 3)
{
// use image before last
int n = frameCount - 2;
if (n > 0)
{
lastImage = GetFrame(n - 1);
}
else
{
lastImage = null;
}
}
if (lastImage != null)
{
// int[] prev =
// ((DataBufferInt) lastImage.getRaster().getDataBuffer()).getData();
int[] prev = GetPixels(new Bitmap(lastImage));
Array.Copy(prev, 0, dest, 0, width * height);
// copy pixels
if (lastDispose == 2)
{
// fill last image rect area with background color
Graphics g = Graphics.FromImage(image);
Color c = Color.Empty;
if (transparency)
{
c = Color.FromArgb(0, 0, 0, 0); // assume background is transparent
}
else
{
c = Color.FromArgb(lastBgColor);
// c = new Color(lastBgColor); // use given background color
}
Brush brush = new SolidBrush(c);
g.FillRectangle(brush, lastRect);
brush.Dispose();
g.Dispose();
}
}
}
// copy each source line to the appropriate place in the destination
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;
break;
}
}
line = iline;
iline += inc;
}
line += iy;
if (line < height)
{
int k = line * width;
int dx = k + ix; // start of line in dest
int dlim = dx + iw; // end of dest line
if ((k + width) < dlim)
{
dlim = k + width; // past dest edge
}
int sx = i * iw; // start of line in source
while (dx < dlim)
{
// map color and insert in destination
int index = ((int)pixels[sx++]) & 0xff;
int c = act[index];
if (c != 0)
{
dest[dx] = c;
}
dx++;
}
}
}
SetPixels(dest);
}
/**
* Gets the image contents of frame n.
*
* @return BufferedImage representation of frame, or null if n is invalid.
*/
public Image GetFrame(int n)
{
Image im = null;
if ((n >= 0) && (n < frameCount))
{
im = ((GifFrame)frames[n]).image;
}
return im;
}
/**
* Gets image size.
*
* @return GIF image dimensions
*/
public Size GetFrameSize()
{
return new Size(width, height);
}
/**
* Reads GIF image from stream
*
* @param BufferedInputStream containing GIF file.
* @return read status code (0 = no errors)
*/
public int Read(Stream inStream)
{
Init();
if (inStream != null)
{
this.inStream = inStream;
ReadHeader();
if (!Error())
{
ReadContents();
if (frameCount < 0)
{
status = STATUS_FORMAT_ERROR;
}
}
inStream.Close();
}
else
{
status = STATUS_OPEN_ERROR;
}
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;
try
{
name = name.Trim().ToLower();
status = Read(new FileInfo(name).OpenRead());
}
catch (IOException e)
{
status = STATUS_OPEN_ERROR;
}
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]; // allocate new pixel array
}
if (prefix == null) prefix = new short[MaxStackSize];
if (suffix == null) suffix = new byte[MaxStackSize];
if (pixelStack == null) pixelStack = new byte[MaxStackSize + 1];
// Initialize GIF data stream decoder.
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;
}
// Decode GIF pixel stream.
datum = bits = count = first = top = pi = bi = 0;
for (i = 0; i < npix;)
{
if (top == 0)
{
if (bits < code_size)
{
// Load bytes until there are enough bits for a code.
if (count == 0)
{
// Read a new data block.
count = ReadBlock();
if (count <= 0)
break;
bi = 0;
}
datum += (((int)block[bi]) & 0xff) << bits;
bits += 8;
bi++;
count--;
continue;
}
// Get the next code.
code = datum & code_mask;
datum >>= code_size;
bits -= code_size;
// Interpret the code
if ((code > available) || (code == end_of_information))
break;
if (code == clear)
{
// Reset decoder.
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;
// Add a new string to the string table,
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;
}
// Pop a pixel off the pixel stack.
top--;
pixels[pi++] = pixelStack[top];
i++;
}
for (i = pi; i < npix; i++)
{
pixels[i] = 0; // clear missing pixels
}
}
/**
* Returns true if an error was encountered during reading/decoding
*/
protected bool Error()
{
return status != STATUS_OK;
}
/**
* Initializes or re-initializes reader
*/
protected void Init()
{
status = STATUS_OK;
frameCount = 0;
frames = new ArrayList();
gct = null;
lct = null;
}
/**
* Reads a single byte from the input stream.
*/
protected int Read()
{
int curByte = 0;
try
{
curByte = inStream.ReadByte();
}
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 = inStream.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 = inStream.Read(c, 0, c.Length);
}
catch (IOException e)
{
}
if (n < nbytes)
{
status = STATUS_FORMAT_ERROR;
}
else
{
tab = new int[256]; // max size to avoid bounds checks
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++] = (int)(0xff000000 | (r << 16) | (g << 8) | b);
}
}
return tab;
}
/**
* Main file parser. Reads GIF content blocks.
*/
protected void ReadContents()
{
// read GIF file content blocks
bool done = false;
while (!(done || Error()))
{
int code = Read();
switch (code)
{
case 0x2C: // image separator
ReadImage();
break;
case 0x21: // extension
code = Read();
switch (code)
{
case 0xf9: // graphics control extension
ReadGraphicControlExt();
break;
case 0xff: // application extension
ReadBlock();
String app = "";
for (int i = 0; i < 11; i++)
{
app += (char)block[i];
}
if (app.Equals("NETSCAPE2.0"))
{
ReadNetscapeExt();
}
else
Skip(); // don't care
break;
default: // uninteresting extension
Skip();
break;
}
break;
case 0x3b: // terminator
done = true;
break;
case 0x00: // bad byte, but keep going and see what happens
break;
default:
status = STATUS_FORMAT_ERROR;
break;
}
}
}
/**
* Reads Graphics Control Extension values
*/
protected void ReadGraphicControlExt()
{
Read(); // block size
int packed = Read(); // packed fields
dispose = (packed & 0x1c) >> 2; // disposal method
if (dispose == 0)
{
dispose = 1; // elect to keep old image if discretionary
}
transparency = (packed & 1) != 0;
delay = ReadShort() * 10; // delay in milliseconds
transIndex = Read(); // transparent color index
Read(); // block terminator
}
/**
* 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 && !Error())
{
gct = ReadColorTable(gctSize);
bgColor = gct[bgIndex];
}
}
/**
* Reads next frame image
*/
protected void ReadImage()
{
ix = ReadShort(); // (sub)image position & size
iy = ReadShort();
iw = ReadShort();
ih = ReadShort();
int packed = Read();
lctFlag = (packed & 0x80) != 0; // 1 - local color table flag
interlace = (packed & 0x40) != 0; // 2 - interlace flag
// 3 - sort flag
// 4-5 - reserved
lctSize = 2 << (packed & 7); // 6-8 - local color table size
if (lctFlag)
{
lct = ReadColorTable(lctSize); // read table
act = lct; // make local table active
}
else
{
act = gct; // make global table active
if (bgIndex == transIndex)
bgColor = 0;
}
int save = 0;
if (transparency)
{
save = act[transIndex];
act[transIndex] = 0; // set transparent color if specified
}
if (act == null)
{
status = STATUS_FORMAT_ERROR; // no color table defined
}
if (Error()) return;
DecodeImageData(); // decode pixel data
Skip();
if (Error()) return;
frameCount++;
// create new image to receive frame data
// image =
// new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB_PRE);
bitmap = new Bitmap(width, height);
image = bitmap;
SetPixels(); // transfer pixel data to image
frames.Add(new GifFrame(bitmap, delay)); // add image to frame list
if (transparency)
{
act[transIndex] = save;
}
ResetFrame();
}
/**
* Reads Logical Screen Descriptor
*/
protected void ReadLSD()
{
// logical screen size
width = ReadShort();
height = ReadShort();
// packed fields
int packed = Read();
gctFlag = (packed & 0x80) != 0; // 1 : global color table flag
// 2-4 : color resolution
// 5 : gct sort flag
gctSize = 2 << (packed & 7); // 6-8 : gct size
bgIndex = Read(); // background color index
pixelAspect = Read(); // pixel aspect ratio
}
/**
* Reads Netscape extenstion to obtain iteration count
*/
protected void ReadNetscapeExt()
{
do
{
ReadBlock();
if (block[0] == 1)
{
// loop count sub-block
int b1 = ((int)block[1]) & 0xff;
int b2 = ((int)block[2]) & 0xff;
loopCount = (b2 << 8) | b1;
}
} while ((blockSize > 0) && !Error());
}
/**
* Reads next 16-bit value, LSB first
*/
protected int ReadShort()
{
// read 16-bit value, LSB first
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;
bool 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) && !Error());
}
}
}