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/** * Copyright (c) 2013 Xcellent Creations, Inc. *//from ww w. j a v a2 s .c om * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ package com.felipecsl.gifimageview.library; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.nio.BufferUnderflowException; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.util.ArrayList; import android.graphics.Bitmap; import android.util.Log; /** * Reads frame data from a GIF image source and decodes it into individual frames * for animation purposes. Image data can be read from either and InputStream source * or a byte[]. * * This class is optimized for running animations with the frames, there * are no methods to get individual frame images, only to decode the next frame in the * animation sequence. Instead, it lowers its memory footprint by only housing the minimum * data necessary to decode the next frame in the animation sequence. * * The animation must be manually moved forward using {@link #advance()} before requesting the next * frame. This method must also be called before you request the first frame or an error will * occur. * * Implementation adapted from sample code published in Lyons. (2004). <em>Java for Programmers</em>, * republished under the MIT Open Source License */ public class GifDecoder { private static final String TAG = GifDecoder.class.getSimpleName(); /** * 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; /** * max decoder pixel stack size */ protected static final int MAX_STACK_SIZE = 4096; /** * GIF Disposal Method meaning take no action */ private static final int DISPOSAL_UNSPECIFIED = 0; /** * GIF Disposal Method meaning leave canvas from previous frame */ private static final int DISPOSAL_NONE = 1; /** * GIF Disposal Method meaning clear canvas to background color */ private static final int DISPOSAL_BACKGROUND = 2; /** * GIF Disposal Method meaning clear canvas to frame before last */ private static final int DISPOSAL_PREVIOUS = 3; /** * Global status code of GIF data parsing */ protected int status; // Global File Header values and parsing flags protected int width; // full image width protected int height; // full image height protected boolean 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[] act; // active color table protected int bgIndex; // background color index protected int bgColor; // background color protected int pixelAspect; // pixel aspect ratio protected boolean lctFlag; // local color table flag protected int lctSize; // local color table size // Raw GIF data from input source protected ByteBuffer rawData; // Raw data read working array protected byte[] block = new byte[256]; // current data block protected int blockSize = 0; // block size last graphic control extension info // LZW decoder working arrays protected short[] prefix; protected byte[] suffix; protected byte[] pixelStack; protected byte[] mainPixels; protected int[] mainScratch, copyScratch; protected ArrayList<GifFrame> frames; // frames read from current file protected GifFrame currentFrame; protected Bitmap previousImage, currentImage, renderImage; protected int framePointer; protected int frameCount; /** * Inner model class housing metadata for each frame */ private static class GifFrame { public int ix, iy, iw, ih; /* Control Flags */ public boolean interlace; public boolean transparency; /* Disposal Method */ public int dispose; /* Transparency Index */ public int transIndex; /* Delay, in ms, to next frame */ public int delay; /* Index in the raw buffer where we need to start reading to decode */ public int bufferFrameStart; /* Local Color Table */ public int[] lct; } /** * Move the animation frame counter forward */ public void advance() { if (frameCount > 0) framePointer = (framePointer + 1) % frameCount; } /** * Gets display duration for specified frame. * * @param n int index of frame * @return delay in milliseconds */ public int getDelay(final int n) { int delay = 0; if ((n >= 0) && (n < frameCount)) { delay = frames.get(n).delay; } return delay; } /** * Gets display duration for the upcoming frame */ public int getNextDelay() { if (frameCount <= 0 || framePointer < 0) { return 0; } return getDelay(framePointer); } /** * Gets the number of frames read from file. * * @return frame count */ public int getFrameCount() { return frameCount; } /** * Gets the current index of the animation frame, or -1 if animation hasn't not yet started * * @return frame index */ public int getCurrentFrameIndex() { return framePointer; } /** * 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; } /** * Get the next frame in the animation sequence. * * @return Bitmap representation of frame */ public Bitmap getNextFrame() { if (frameCount <= 0 || framePointer < 0 || currentImage == null) { return null; } final GifFrame frame = frames.get(framePointer); // Set the appropriate color table if (frame.lct == null) { act = gct; } else { act = frame.lct; if (bgIndex == frame.transIndex) { bgColor = 0; } } int save = 0; if (frame.transparency) { save = act[frame.transIndex]; act[frame.transIndex] = 0; // set transparent color if specified } if (act == null) { Log.w(TAG, "No Valid Color Table"); status = STATUS_FORMAT_ERROR; // no color table defined return null; } setPixels(framePointer); // transfer pixel data to image // Reset the transparent pixel in the color table if (frame.transparency) { act[frame.transIndex] = save; } return currentImage; } /** * Reads GIF image from stream * * @param is containing GIF file. * @return read status code (0 = no errors) */ public int read(final InputStream is, final int contentLength) { if (is != null) { try { final int capacity = (contentLength > 0) ? (contentLength + 4096) : 4096; final ByteArrayOutputStream buffer = new ByteArrayOutputStream(capacity); int nRead; final byte[] data = new byte[16384]; while ((nRead = is.read(data, 0, data.length)) != -1) { buffer.write(data, 0, nRead); } buffer.flush(); read(buffer.toByteArray()); } catch (final IOException e) { Log.w(TAG, "Error reading data from stream", e); } } else { status = STATUS_OPEN_ERROR; } try { is.close(); } catch (final Exception e) { Log.w(TAG, "Error closing stream", e); } return status; } /** * Reads GIF image from byte array * * @param data containing GIF file. * @return read status code (0 = no errors) */ public int read(final byte[] data) { init(); if (data != null) { // Initialiaze the raw data buffer rawData = ByteBuffer.wrap(data); rawData.rewind(); rawData.order(ByteOrder.LITTLE_ENDIAN); readHeader(); if (!err()) { readContents(); if (frameCount < 0) { status = STATUS_FORMAT_ERROR; } } } else { status = STATUS_OPEN_ERROR; } return status; } /** * Creates new frame image from current data (and previous frames as specified by their disposition codes). */ protected void setPixels(final int frameIndex) { final GifFrame currentFrame = frames.get(frameIndex); GifFrame previousFrame = null; final int previousIndex = frameIndex - 1; if (previousIndex >= 0) { previousFrame = frames.get(previousIndex); } // final location of blended pixels final int[] dest = mainScratch; // fill in starting image contents based on last image's dispose code if (previousFrame != null && previousFrame.dispose > DISPOSAL_UNSPECIFIED) { if (previousFrame.dispose == DISPOSAL_NONE && currentImage != null) { // Start with the current image currentImage.getPixels(dest, 0, width, 0, 0, width, height); } if (previousFrame.dispose == DISPOSAL_BACKGROUND) { // Start with a canvas filled with the background color int c = 0; if (!currentFrame.transparency) { c = bgColor; } for (int i = 0; i < previousFrame.ih; i++) { final int n1 = (previousFrame.iy + i) * width + previousFrame.ix; final int n2 = n1 + previousFrame.iw; for (int k = n1; k < n2; k++) { dest[k] = c; } } } if (previousFrame.dispose == DISPOSAL_PREVIOUS && previousImage != null) { // Start with the previous frame previousImage.getPixels(dest, 0, width, 0, 0, width, height); } } // Decode pixels for this frame into the global pixels[] scratch decodeBitmapData(currentFrame, mainPixels); // decode pixel data // 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 < currentFrame.ih; i++) { int line = i; if (currentFrame.interlace) { if (iline >= currentFrame.ih) { pass++; switch (pass) { case 2: iline = 4; break; case 3: iline = 2; inc = 4; break; case 4: iline = 1; inc = 2; break; default: break; } } line = iline; iline += inc; } line += currentFrame.iy; if (line < height) { final int k = line * width; int dx = k + currentFrame.ix; // start of line in dest int dlim = dx + currentFrame.iw; // end of dest line if ((k + width) < dlim) { dlim = k + width; // past dest edge } int sx = i * currentFrame.iw; // start of line in source while (dx < dlim) { // map color and insert in destination final int index = (mainPixels[sx++]) & 0xff; final int c = act[index]; if (c != 0) { dest[dx] = c; } dx++; } } } // Copy pixels into previous image currentImage.getPixels(copyScratch, 0, width, 0, 0, width, height); previousImage.setPixels(copyScratch, 0, width, 0, 0, width, height); // Set pixels for current image currentImage.setPixels(dest, 0, width, 0, 0, width, height); } /** * Decodes LZW image data into pixel array. Adapted from John Cristy's BitmapMagick. */ protected void decodeBitmapData(final GifFrame frame, byte[] dstPixels) { if (frame != null) { // Jump to the frame start position rawData.position(frame.bufferFrameStart); } final int nullCode = -1; final int npix = (frame == null) ? width * height : frame.iw * frame.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 (dstPixels == null || dstPixels.length < npix) { dstPixels = new byte[npix]; // allocate new pixel array } if (prefix == null) { prefix = new short[MAX_STACK_SIZE]; } if (suffix == null) { suffix = new byte[MAX_STACK_SIZE]; } if (pixelStack == null) { pixelStack = new byte[MAX_STACK_SIZE + 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; // XXX ArrayIndexOutOfBoundsException 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 += ((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 = (suffix[code]) & 0xff; // Add a new string to the string table, if (available >= MAX_STACK_SIZE) { break; } pixelStack[top++] = (byte)first; prefix[available] = (short)old_code; suffix[available] = (byte)first; available++; if (((available & code_mask) == 0) && (available < MAX_STACK_SIZE)) { code_size++; code_mask += available; } old_code = in_code; } // Pop a pixel off the pixel stack. top--; dstPixels[pi++] = pixelStack[top]; i++; } for (i = pi; i < npix; i++) { dstPixels[i] = 0; // clear missing pixels } } /** * 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; framePointer = -1; frames = new ArrayList<GifFrame>(); gct = null; } /** * Reads a single byte from the input stream. */ protected int read() { int curByte = 0; try { curByte = (rawData.get() & 0xFF); } catch (final Exception 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; while (n < blockSize) { count = blockSize - n; rawData.get(block, n, count); n += count; } } catch (final Exception e) { Log.w(TAG, "Error Reading Block", e); 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(final int ncolors) { final int nbytes = 3 * ncolors; int[] tab = null; final byte[] c = new byte[nbytes]; try { rawData.get(c); tab = new int[256]; // max size to avoid bounds checks int i = 0; int j = 0; while (i < ncolors) { final int r = (c[j++]) & 0xff; final int g = (c[j++]) & 0xff; final int b = (c[j++]) & 0xff; tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b; } } catch (final BufferUnderflowException e) { Log.w(TAG, "Format Error Reading Color Table", e); status = STATUS_FORMAT_ERROR; } return tab; } /** * Main file parser. Reads GIF content blocks. */ protected void readContents() { // read GIF file content blocks boolean done = false; while (!(done || err())) { int code = read(); switch (code) { case 0x2C: // image separator readBitmap(); break; case 0x21: // extension code = read(); switch (code) { case 0xf9: // graphics control extension // Start a new frame currentFrame = new GifFrame(); 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; case 0xfe:// comment extension skip(); break; case 0x01:// plain text extension skip(); break; default: // uninteresting extension skip(); } break; case 0x3b: // terminator done = true; break; case 0x00: // bad byte, but keep going and see what happens break; default: status = STATUS_FORMAT_ERROR; } } } /** * 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 = gct[bgIndex]; } } /** * Reads Graphics Control Extension values */ protected void readGraphicControlExt() { read(); // block size final int packed = read(); // packed fields currentFrame.dispose = (packed & 0x1c) >> 2; // disposal method if (currentFrame.dispose == 0) { currentFrame.dispose = 1; // elect to keep old image if discretionary } currentFrame.transparency = (packed & 1) != 0; currentFrame.delay = readShort() * 10; // delay in milliseconds currentFrame.transIndex = read(); // transparent color index read(); // block terminator } /** * Reads next frame image */ protected void readBitmap() { currentFrame.ix = readShort(); // (sub)image position & size currentFrame.iy = readShort(); currentFrame.iw = readShort(); currentFrame.ih = readShort(); final int packed = read(); lctFlag = (packed & 0x80) != 0; // 1 - local color table flag interlace lctSize = (int)Math.pow(2, (packed & 0x07) + 1); // 3 - sort flag // 4-5 - reserved lctSize = 2 << (packed & 7); // 6-8 - local color // table size currentFrame.interlace = (packed & 0x40) != 0; if (lctFlag) { currentFrame.lct = readColorTable(lctSize); // read table } else { currentFrame.lct = null; // No local color table } currentFrame.bufferFrameStart = rawData.position(); // Save this as the decoding position pointer skipBitmapData(); if (err()) { return; } frameCount++; frames.add(currentFrame); // add image to frame } private void skipBitmapData() { read(); // code size skip(); } /** * Reads Logical Screen Descriptor */ protected void readLSD() { // logical screen size width = readShort(); height = readShort(); // packed fields final 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 // Now that we know the size, init scratch arrays try { mainPixels = new byte[width * height]; mainScratch = new int[width * height]; copyScratch = new int[width * height]; previousImage = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565); currentImage = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565); } catch (final OutOfMemoryError e) { // Try with halving down the bitmap size final int dimension = (width * height) / 2; mainPixels = new byte[dimension]; mainScratch = new int[dimension]; copyScratch = new int[dimension]; previousImage = Bitmap.createBitmap(width / 2, height / 2, Bitmap.Config.RGB_565); currentImage = Bitmap.createBitmap(width / 2, height / 2, Bitmap.Config.RGB_565); } } /** * Reads Netscape extenstion to obtain iteration count */ protected void readNetscapeExt() { do { readBlock(); if (block[0] == 1) { // loop count sub-block final int b1 = (block[1]) & 0xff; final int b2 = (block[2]) & 0xff; loopCount = (b2 << 8) | b1; } } while ((blockSize > 0) && !err()); } /** * Reads next 16-bit value, LSB first */ protected int readShort() { // read 16-bit value return rawData.getShort(); } /** * Skips variable length blocks up to and including next zero length block. */ protected void skip() { do { readBlock(); } while ((blockSize > 0) && !err()); } public int getWidth() { return width; } public int getHeight() { return height; } }