gifdecoder.java

Android游戏开发入门

package com.bgstudy.app.game.gifPlay;

import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;

public class GifDecoder
{
	private int					E0;
	private int					E1[];
	private int					E2;
	private int					E6;
	private boolean				E7;
	private int					E8[];
	private int					width;
	private int					height;
	private int					ED;
	private boolean				EE;
	private boolean				EF;
	private int					F0[];
	private int					F1;
	private boolean				F2;
	private int					F3;
	private long				F4;
	private int					F5;
	private static final int	F6[]	= { 8, 8, 4, 2 };
	private static final int	F8[]	= { 0, 4, 2, 1 };

	int							curFrame;
	int							poolsize;
	int							FA;
	byte						C2[];
	int							FB;
	int							FC;
	int							FD;


	public GifDecoder(byte abyte0[])
	{
		E0 = -1;
		E1 = new int[280];
		E2 = -1;
		E6 = 0;
		E7 = false;
		E8 = null;
		width = 0;
		height = 0;
		ED = 0;
		EE = false;
		EF = false;
		F0 = null;
		F1 = 0;
		F5 = 0;
		curFrame = 0;
		C2 = abyte0;
		poolsize = C2.length;
		FA = 0;
	}


	public boolean moreFrames()
	{
		return poolsize - FA >= 16;
	}


	public void nextFrame()
	{
		curFrame++;
	}


	public Bitmap decodeImage()
	{
		return decodeImage(curFrame);
	}


	public Bitmap decodeImage(int i)
	{
		if (i <= E0)
		{
			return null;
		}
		if (E0 < 0)
		{
			if (!E3())
			{
				return null;
			}
			if (!E4())
			{
				return null;
			}
		}
		do
		{
			if (!E9(1))
			{
				return null;
			}
			int j = E1[0];
			if (j == 59)
			{
				return null;
			}
			if (j == 33)
			{
				if (!E7())
				{
					return null;
				}
			}
			else if (j == 44)
			{
				if (!E5())
				{
					return null;
				}
				Bitmap image = createImage();
				E0++;
				if (E0 < i)
				{
					image = null;
				}
				else
				{
					return image;
				}
			}
		}
		while (true);
	}


	public void clear()
	{
		C2 = null;
		E1 = null;
		E8 = null;
		F0 = null;
	}


	private Bitmap createImage()
	{
		int i = width;
		int j = height;
		int j1 = 0;
		int k1 = 0;
		int ai[] = new int[4096];
		int ai1[] = new int[4096];
		int ai2[] = new int[8192];
		if (!E9(1))
		{
			return null;
		}
		int k = E1[0];
		int[] image = new int[width * height];
		int ai3[] = E8;
		if (EE)
		{
			ai3 = F0;
		}
		if (E2 >= 0)
		{
			ai3[E2] = 0xffffff;
		}
		int l2 = 1 << k;
		int j3 = l2 + 1;
		int k2 = k + 1;
		int l3 = l2 + 2;
		int k3 = -1;
		int j4 = -1;
		for (int l1 = 0; l1 < l2; l1++)
		{
			ai1[l1] = l1;
		}

		int j2 = 0;
		E2();
		j1 = 0;
		label0: for (int i2 = 0; i2 < j; i2++)
		{
			int i1 = 0;
			do
			{
				if (i1 >= i)
				{
					break;
				}
				if (j2 == 0)
				{
					int i4 = E1(k2);
					if (i4 < 0)
					{
						return Bitmap.createBitmap(image, width, height, Config.RGB_565);
					}
					if (i4 > l3 || i4 == j3)
					{
						return Bitmap.createBitmap(image, width, height, Config.RGB_565);
					}
					if (i4 == l2)
					{
						k2 = k + 1;
						l3 = l2 + 2;
						k3 = -1;
						continue;
					}
					if (k3 == -1)
					{
						ai2[j2++] = ai1[i4];
						k3 = i4;
						j4 = i4;
						continue;
					}
					int i3 = i4;
					if (i4 == l3)
					{
						ai2[j2++] = j4;
						i4 = k3;
					}
					for (; i4 > l2; i4 = ai[i4])
					{
						ai2[j2++] = ai1[i4];
					}

					j4 = ai1[i4];
					if (l3 >= 4096)
					{
						return Bitmap.createBitmap(image, width, height, Config.RGB_565);
					}
					ai2[j2++] = j4;
					ai[l3] = k3;
					ai1[l3] = j4;
					if (++l3 >= 1 << k2 && l3 < 4096)
					{
						k2++;
					}
					k3 = i3;
				}
				int l = ai2[--j2];
				if (l < 0)
				{
					return Bitmap.createBitmap(image, width, height, Config.RGB_565);
				}
				if (i1 == 0)
				{
					FC = 0;
					FB = ai3[l];
					FD = 0;
				}
				else if (FB != ai3[l])
				{

					for (int mm = FD; mm <= FD + FC; mm++)
					{
						image[j1 * width + mm] = FB;
					}
					FC = 0;
					FB = ai3[l];
					FD = i1;
					if (i1 == i - 1)
					{
						image[j1 * width + i1] = ai3[l];
					}
				}
				else
				{
					FC++;
					if (i1 == i - 1)
					{
						for (int mm = FD; mm <= FD + FC; mm++)
						{
							image[j1 * width + mm] = FB;
						}
					}
				}
				i1++;
			}
			while (true);
			if (EF)
			{
				j1 += F6[k1];
				do
				{
					if (j1 < j)
					{
						continue label0;
					}
					if (++k1 > 3)
					{
						return Bitmap.createBitmap(image, width, height, Config.RGB_565);
					}
					j1 = F8[k1];
				}
				while (true);
			}
			j1++;
		}

		return Bitmap.createBitmap(image, width, height, Config.RGB_565);
	}


	private int E1(int i)
	{
		while (F5 < i)
		{
			if (F2)
			{
				return -1;
			}
			if (F1 == 0)
			{
				F1 = E8();
				F3 = 0;
				if (F1 <= 0)
				{
					F2 = true;
					break;
				}
			}
			F4 += E1[F3] << F5;
			F3++;
			F5 += 8;
			F1--;
		}
		int j = (int) F4 & (1 << i) - 1;
		F4 >>= i;
		F5 -= i;
		return j;
	}


	private void E2()
	{
		F5 = 0;
		F1 = 0;
		F4 = 0L;
		F2 = false;
		F3 = -1;
	}


	private boolean E3()
	{
		if (!E9(6))
		{
			return false;
		}
		return E1[0] == 71 && E1[1] == 73 && E1[2] == 70 && E1[3] == 56 && (E1[4] == 55 || E1[4] == 57) && E1[5] == 97;
	}


	private boolean E4()
	{
		if (!E9(7))
		{
			return false;
		}
		int i = E1[4];
		E6 = 2 << (i & 7);
		E7 = EB(i, 128);
		E8 = null;
		return !E7 || E6(E6, true);
	}


	private boolean E5()
	{
		if (!E9(9))
		{
			return false;
		}
		width = EA(E1[4], E1[5]);
		height = EA(E1[6], E1[7]);
		int i = E1[8];
		EE = EB(i, 128);
		ED = 2 << (i & 7);
		EF = EB(i, 64);
		F0 = null;
		return !EE || E6(ED, false);
	}


	private boolean E6(int i, boolean flag)
	{
		int ai[] = new int[i];
		for (int j = 0; j < i; j++)
		{
			if (!E9(3))
			{
				return false;
			}
			ai[j] = E1[0] << 16 | E1[1] << 8 | E1[2] | 0xff000000;
		}

		if (flag)
		{
			E8 = ai;
		}
		else
		{
			F0 = ai;
		}
		return true;
	}


	private boolean E7()
	{
		if (!E9(1))
		{
			return false;
		}
		int i = E1[0];
		int j = -1;
		switch (i)
		{
			case 249:
				j = E8();
				if (j < 0)
				{
					return true;
				}
				if ((E1[0] & 1) != 0)
				{
					E2 = E1[3];
				}
				else
				{
					E2 = -1;
				}
				break;
		}
		do
		{
			j = E8();
		}
		while (j > 0);
		return true;
	}


	private int E8()
	{
		if (!E9(1))
		{
			return -1;
		}
		int i = E1[0];
		if (i != 0 && !E9(i))
		{
			return -1;
		}
		else
		{
			return i;
		}
	}


	private boolean E9(int i)
	{
		if (FA + i >= poolsize)
		{
			return false;
		}
		for (int j = 0; j < i; j++)
		{
			int k = C2[FA + j];
			if (k < 0)
			{
				k += 256;
			}
			E1[j] = k;
		}

		FA += i;
		return true;
	}


	private static final int EA(int i, int j)
	{
		return j << 8 | i;
	}


	private static final boolean EB(int i, int j)
	{
		return (i & j) == j;
	}
}