Java tutorial
package me.aerovulpe.crawler.ui; import android.content.Context; import android.graphics.Bitmap; import android.os.Handler; import android.support.annotation.NonNull; import android.util.AttributeSet; import android.util.Log; import android.widget.ImageView; import org.apache.commons.io.IOUtils; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InterruptedIOException; import java.io.OutputStream; import java.lang.ref.WeakReference; import java.net.URL; import java.nio.BufferUnderflowException; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.util.ArrayList; import me.aerovulpe.crawler.Utils; import me.aerovulpe.crawler.data.SimpleDiskCache; import me.aerovulpe.crawler.fragments.SettingsFragment; /** * Created by Aaron on 04/07/2015. */ public class GifImageView extends ImageView { private static volatile SimpleDiskCache sGifCache; private GifThread mGifThread; public GifImageView(Context context) { super(context); } public GifImageView(Context context, AttributeSet attrs) { super(context, attrs); } public GifImageView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); stopGif(); } public void playGif(String url) { stopGif(); mGifThread = new GifThread(this, url); playGif(); } public void playGif(InputStream inputStream) { stopGif(); mGifThread = new GifThread(this, inputStream); playGif(); } private void playGif() { try { mGifThread.start(); } catch (OutOfMemoryError e) { e.printStackTrace(); System.gc(); } } public void stopGif() { if (mGifThread == null) return; mGifThread.interrupt(); mGifThread.forgetGifImageView(); } private static void initGifCache(Context context) { synchronized (GifThread.class) { if (sGifCache != null) return; try { final int appVersion = 1; final int maxSize = SettingsFragment.getCurrentCacheValueInBytes(context) / 4; sGifCache = SimpleDiskCache.open(new File(context.getCacheDir().getAbsolutePath() + "/gifCache"), appVersion, maxSize); } catch (IOException e) { e.printStackTrace(); } } } public static void clearGifCache(Context context) { try { initGifCache(context); sGifCache.clear(); } catch (IOException e) { e.printStackTrace(); } } public static void setMaxGifCacheSize(Context context, long maxSize) { initGifCache(context); sGifCache.setMaxSize(maxSize); } public static boolean saveGif(Context context, String url, File file) throws IOException { initGifCache(context); if (!sGifCache.contains(url)) { return false; } else { SimpleDiskCache.InputStreamEntry streamEntry = null; InputStream inputStream = null; OutputStream outputStream = null; try { streamEntry = sGifCache.getInputStream(url); inputStream = streamEntry.getInputStream(); outputStream = new FileOutputStream(file); return IOUtils.copy(inputStream, outputStream) > 0; } finally { IOUtils.closeQuietly(inputStream); if (outputStream != null) outputStream.close(); if (streamEntry != null) streamEntry.close(); } } } private static class GifThread extends Thread { private static final String TAG = "GifThread"; private WeakReference<GifImageView> mGifImageViewRef; private Handler mHandler; private String mUrl; private InputStream mInputStream; private GifThread(GifImageView gifImageView) { mGifImageViewRef = new WeakReference<>(gifImageView); mHandler = new Handler(); initGifCache(gifImageView.getContext()); } private GifThread(GifImageView gifImageView, @NonNull String url) { this(gifImageView); mUrl = url; } private GifThread(GifImageView gifImageView, @NonNull InputStream inputStream) { this(gifImageView); mInputStream = inputStream; } @Override public void run() { try { GifDecoder gifDecoder = new GifDecoder(); if (mUrl != null) { if (!sGifCache.contains(mUrl)) { GifImageView gifImageView = mGifImageViewRef.get(); Context context = gifImageView != null ? gifImageView.getContext() : null; if (context != null && !Utils.Android.isConnectedToWifi(context) && !Utils.Android.isConnectedToWired(context) && !SettingsFragment.downloadOffWifi(context)) return; InputStream inputStream = gifDecoder.read(new URL(mUrl).openStream()); if (inputStream != null) { sGifCache.put(mUrl, inputStream); inputStream.close(); } else return; } else { SimpleDiskCache.InputStreamEntry streamEntry = sGifCache.getInputStream(mUrl); gifDecoder.read(streamEntry.getInputStream(), 0); streamEntry.close(); } } else { gifDecoder.read(mInputStream, 0); } final int frameCount = gifDecoder.getFrameCount(); while (!Thread.currentThread().isInterrupted() && mGifImageViewRef.get() != null) { for (int i = 0; i < frameCount; i++) { final Bitmap nextBitmap = gifDecoder.getNextFrame(); int delay = gifDecoder.getDelay(i); if (delay <= 0) delay = 50; mHandler.post(new Runnable() { public void run() { if (nextBitmap != null && !nextBitmap.isRecycled()) { GifImageView gifImageView; if ((gifImageView = mGifImageViewRef.get()) != null) gifImageView.setImageBitmap(nextBitmap); } } }); try { Thread.sleep(delay); } catch (InterruptedException e) { return; } } } } catch (InterruptedIOException ignored) { } catch (IOException e) { e.printStackTrace(); } catch (IllegalStateException e) { Log.w(TAG, "Bitmap was not ready."); } } private void forgetGifImageView() { mGifImageViewRef.clear(); } } /** * 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[]. * <p/> * 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. * Implementation adapted from sample code published in Lyons. (2004). <em>Java for Programmers</em>, * republished under the MIT Open Source License */ private static 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; 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 */ private void advance() { framePointer = (framePointer + 1) % frameCount; } /** * Gets display duration for specified frame. * * @param n int index of frame * @return delay in milliseconds */ public int getDelay(int n) { int delay = -1; 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 -1; } 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() throws IllegalStateException { advance(); if (frameCount <= 0 || framePointer < 0 || currentImage == null || currentImage.isRecycled()) { return null; } 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(InputStream is, int contentLength) throws IOException { if (is != null) { int capacity = (contentLength > 0) ? (contentLength + 4096) : 4096; ByteArrayOutputStream buffer = new ByteArrayOutputStream(capacity); int nRead; byte[] data = new byte[16384]; while ((nRead = is.read(data, 0, data.length)) != -1) { buffer.write(data, 0, nRead); } buffer.flush(); read(buffer.toByteArray()); } else { status = STATUS_OPEN_ERROR; } try { if (is != null) { is.close(); } } catch (Exception e) { Log.w(TAG, "Error closing stream", e); } return status; } public InputStream read(InputStream is) throws IOException { ByteArrayOutputStream buffer = null; if (is != null) { try { int capacity = 4096; buffer = new ByteArrayOutputStream(capacity); int nRead; byte[] data = new byte[16384]; while ((nRead = is.read(data, 0, data.length)) != -1) buffer.write(data, 0, nRead); buffer.flush(); read(buffer.toByteArray()); } finally { is.close(); } } else status = STATUS_OPEN_ERROR; byte[] bytes = buffer != null ? buffer.toByteArray() : null; return bytes != null && isGif(bytes) ? new ByteArrayInputStream(bytes) : null; } /** * Reads GIF image from byte array * * @param data containing GIF file. * @return read status code (0 = no errors) */ public int read(byte[] data) { init(); if (data != null) { //Initiliaze 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(int frameIndex) { if (currentImage.isRecycled()) return; GifFrame currentFrame = frames.get(frameIndex); GifFrame previousFrame = null; 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++) { int n1 = (previousFrame.iy + i) * width + previousFrame.ix; 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) { 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 int index = ((int) mainPixels[sx++]) & 0xff; 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(GifFrame frame, byte[] dstPixels) { if (frame != null) { //Jump to the frame start position rawData.position(frame.bufferFrameStart); } int nullCode = -1; 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 += (((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 >= 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<>(); gct = null; } /** * Reads a single byte from the input stream. */ protected int read() { int curByte = 0; try { curByte = (rawData.get() & 0xFF); } catch (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 (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(int ncolors) { int nbytes = 3 * ncolors; int[] tab = null; 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) { 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; } } catch (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 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() { if (currentFrame == null) return; currentFrame.ix = readShort(); // (sub)image position & size currentFrame.iy = readShort(); currentFrame.iw = readShort(); currentFrame.ih = readShort(); 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 decodeBitmapData(null, mainPixels); // false decode pixel data to advance buffer skip(); if (err()) { return; } frameCount++; frames.add(currentFrame); // add image to frame } /** * 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 //Now that we know the size, init scratch arrays 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); } /** * 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) && !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()); } private static boolean isGif(byte[] bytes) { final char[] hexArray = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; final int headerSize = 6; char[] hexChars = new char[6 * 2]; int i; for (int j = 0; j < headerSize; j++) { i = bytes[j] & 0xFF; hexChars[j * 2] = hexArray[i >>> 4]; hexChars[j * 2 + 1] = hexArray[i & 0x0F]; } String hex = new String(hexChars); return hex.startsWith("474946") || hex.startsWith("474946383761") || hex.startsWith("474946383961"); } } }