Можно ли заставить новый класс ImageDecoder возвращать растровые изображения, один кадр за другим, вручную?

Ответ 1

Хорошо, я получил возможное решение, используя библиотеку Glide вместе с библиотекой GlideWebpDecoder.

Я не уверен, что это лучший способ сделать это, но я думаю, что это должно работать нормально. Следующий код показывает, как можно нарисовать нарисованное изображение в экземпляре Bitmap, который я создаю, для каждого кадра, который должна показать анимация. Это не совсем то, что я просил, но это может помочь другим.

Вот код (проект доступен здесь):

CallbackEx.kt

abstract class CallbackEx : Drawable.Callback {
    override fun unscheduleDrawable(who: Drawable, what: Runnable) {}
    override fun invalidateDrawable(who: Drawable) {}
    override fun scheduleDrawable(who: Drawable, what: Runnable, 'when': Long) {}
}

MyAppGlideModule.kt

@GlideModule
class MyAppGlideModule : AppGlideModule()

MainActivity.kt

class MainActivity : AppCompatActivity() {
    var webpDrawable: WebpDrawable? = null
    var gifDrawable: GifDrawable? = null
    var callback: Drawable.Callback? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        useFrameByFrameDecoding()
//        useNormalDecoding()
    }

    fun useNormalDecoding() {
        //webp url : https://res.cloudinary.com/demo/image/upload/fl_awebp/bored_animation.webp
        Glide.with(this)
                //                .load(R.raw.test)
                //                .load(R.raw.fast)
                .load(R.raw.example2)

                //                .load("https://res.cloudinary.com/demo/image/upload/fl_awebp/bored_animation.webp")
                .into(object : SimpleTarget<Drawable>() {
                    override fun onResourceReady(drawable: Drawable, transition: Transition<in Drawable>?) {
                        imageView.setImageDrawable(drawable)
                        when (drawable) {
                            is GifDrawable -> {
                                drawable.start()
                            }
                            is WebpDrawable -> {
                                drawable.start()
                            }
                        }
                    }
                })
    }

    fun useFrameByFrameDecoding() {
        //webp url : https://res.cloudinary.com/demo/image/upload/fl_awebp/bored_animation.webp
        Glide.with(this)
                .load(R.raw.test)
                //                .load(R.raw.fast)
                //                .load(R.raw.example2)
                //                .load("https://res.cloudinary.com/demo/image/upload/fl_awebp/bored_animation.webp")
                .into(object : SimpleTarget<Drawable>() {
                    override fun onResourceReady(drawable: Drawable, transition: Transition<in Drawable>?) {
                        //                        val callback
                        when (drawable) {
                            is GifDrawable -> {
                                gifDrawable = drawable
                                val bitmap = Bitmap.createBitmap(drawable.intrinsicWidth, drawable.intrinsicHeight, Bitmap.Config.ARGB_8888)
                                val canvas = Canvas(bitmap)
                                drawable.setBounds(0, 0, bitmap.width, bitmap.height)
                                drawable.setLoopCount(GifDrawable.LOOP_FOREVER)
                                callback = object : CallbackEx() {
                                    override fun invalidateDrawable(who: Drawable) {
                                        who.draw(canvas)
                                        imageView.setImageBitmap(bitmap)
                                        Log.d("AppLog", "invalidateDrawable ${drawable.toString().substringAfter('@')} ${drawable.frameIndex}/${drawable.frameCount}")
                                    }
                                }
                                drawable.callback = callback
                                drawable.start()
                            }
                            is WebpDrawable -> {
                                webpDrawable = drawable
                                val bitmap = Bitmap.createBitmap(drawable.intrinsicWidth, drawable.intrinsicHeight, Bitmap.Config.ARGB_8888)
                                val canvas = Canvas(bitmap)
                                drawable.setBounds(0, 0, bitmap.width, bitmap.height)
                                drawable.setLoopCount(WebpDrawable.LOOP_FOREVER)
                                callback = object : CallbackEx() {
                                    override fun invalidateDrawable(who: Drawable) {
                                        who.draw(canvas)
                                        imageView.setImageBitmap(bitmap)
                                        Log.d("AppLog", "invalidateDrawable ${drawable.toString().substringAfter('@')} ${drawable.frameIndex}/${drawable.frameCount}")
                                    }
                                }
                                drawable.callback = callback
                                drawable.start()
                            }
                        }
                    }
                })
    }

    override fun onStart() {
        super.onStart()
        gifDrawable?.start()
        gifDrawable?.start()
    }

    override fun onStop() {
        super.onStop()
        Log.d("AppLog", "onStop")
        webpDrawable?.stop()
        gifDrawable?.stop()
    }

}

Не уверен, почему SimpleTarget помечен как устаревший, и что я должен использовать вместо этого, хотя.

Используя аналогичную технику, я также узнал, как это сделать, используя ImageDecoder, но по какой-то причине не с той же функциональностью. Пример проекта доступен здесь.

Вот код:

MainActivity.kt

class MainActivity : AppCompatActivity() {
    var webpDrawable: AnimatedImageDrawable? = null

    @SuppressLint("StaticFieldLeak")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val source = ImageDecoder.createSource(resources, R.raw.test)
        object : AsyncTask<Void, Void, Drawable?>() {
            override fun doInBackground(vararg params: Void?): Drawable? {
                return try {
                    ImageDecoder.decodeDrawable(source)
                } catch (e: Exception) {
                    null
                }
            }

            override fun onPostExecute(drawable: Drawable?) {
                super.onPostExecute(drawable)
//                imageView.setImageDrawable(result)
                if (drawable is AnimatedImageDrawable) {
                    webpDrawable = drawable
                    val bitmap =
                        Bitmap.createBitmap(drawable.intrinsicWidth, drawable.intrinsicHeight, Bitmap.Config.ARGB_8888)
                    val canvas = Canvas(bitmap)
                    drawable.setBounds(0, 0, bitmap.width, bitmap.height)
                    drawable.repeatCount = AnimatedImageDrawable.REPEAT_INFINITE
                    drawable.callback = object : Drawable.Callback {
                        val handler = Handler()
                        override fun unscheduleDrawable(who: Drawable, what: Runnable) {
                            Log.d("AppLog", "unscheduleDrawable")
                        }

                        override fun invalidateDrawable(who: Drawable) {
                            who.draw(canvas)
                            imageView.setImageBitmap(bitmap)
                            Log.d("AppLog", "invalidateDrawable")
                        }

                        override fun scheduleDrawable(who: Drawable, what: Runnable, 'when': Long) {
                            Log.d("AppLog", "scheduleDrawable next frame in ${'when' - SystemClock.uptimeMillis()} ms")
                            handler.postAtTime(what, 'when')
                        }
                    }
                    drawable.start()
                }
            }
        }.execute()
    }

    override fun onStart() {
        super.onStart()
        webpDrawable?.start()
    }

    override fun onStop() {
        super.onStop()
        webpDrawable?.stop()
    }

}

Ответ 2

см. ImageDecoder.Source...

сначала нужно создать источник:

// source from file
val source = ImageDecoder.createSource(file)

// source from byte buffer
val source = ImageDecoder.createSource(byteBuffer)

// source from resource
val source = ImageDecoder.createSource(resources, resId)

// source from URI
val source = ImageDecoder.createSource(contentResolver, uri)

// source from asset file
val source = ImageDecoder.createSource(assetManager, assetFileName)

а затем декодировать, либо:

// create bitmap
val bitmap = ImageDecoder.decodeBitmap(source)

// create drawable
val drawable = ImageDecoder.decodeDrawable(source)

обновление: проблема в том, что результирующий AnimatedImageDrawable не имеет двух методов: getNumberOfFrames() и getFrame (int), как у AnimationDrawable. как указал @androiddeveloper... Я перепутал два разных класса. Я дважды проверил документацию, и, кажется, нет никакого способа. с помощью GIFImageReader его все еще можно извлечь (источник):

ArrayList<BufferedImage> getFrames(File gif) throws IOException {
    ArrayList<BufferedImage> frames = new ArrayList<BufferedImage>();
    ImageReader ir = new GIFImageReader(new GIFImageReaderSpi());
    ir.setInput(ImageIO.createImageInputStream(gif));
    for(int i = 0; i < ir.getNumImages(true); i++) {
        frames.add(ir.read(i));
    }
    return frames;
}

только что попытался преобразовать его в Kotlin, но javax.imageio.ImageIO недоступно на Android.

Ответ 3

Я играл с изображениями GIF несколько лет назад. Моя идея состоит в том, чтобы декодировать изображения GIF в кадры, преобразовывать кадры в растровые изображения, добавлять создавать анимированные рисунки из растровых изображений и задержку между кадрами. Это класс декодирования:

public class GifDecoder extends Thread {

public static final int STATUS_PARSING = 0;
public static final int STATUS_FORMAT_ERROR = 1;
public static final int STATUS_OPEN_ERROR = 2;
public static final int STATUS_FINISH = -1;
private static final int MaxStackSize = 4096;
public int width; // full image width
public int height; // full image height
int[] lastPixels;
int[] dest;
private InputStream in;
private int status;
private boolean gctFlag; // global color table used
private int gctSize; // size of global color table
private int loopCount = 1; // iterations; 0 = repeat forever
private int[] gct; // global color table
private int[] lct; // local color table
private int[] act; // active color table
private int bgIndex; // background color index
private int bgColor; // background color
private int lastBgColor; // previous bg color
private int pixelAspect; // pixel aspect ratio
private boolean lctFlag; // local color table flag
private boolean interlace; // interlace flag
private int lctSize; // local color table size
private int ix, iy, iw, ih; // current image rectangle
private int lrx, lry, lrw, lrh;
private GifFrame currentFrame = null;
private boolean isShow = false;
private byte[] block = new byte[256]; // current data block
private int blockSize = 0; // block size
private int dispose = 0;
private int lastDispose = 0;
private boolean transparency = false; // use transparent color
// max decoder pixel stack size
private int delay = 0; // delay in milliseconds
private int transIndex; // transparent color index
// LZW decoder working arrays
private short[] prefix;
private byte[] suffix;
private byte[] pixelStack;
private byte[] pixels;
private GifFrame gifFrame; // frames read from current file
private int frameCount;
private GifAction action = null;
private byte[] gifData = null;
private int gifDataOffset;
private int gifDataLength;

private GifDecoder() {

}

public GifDecoder(byte[] data, GifAction act) {
    this(data, 0, data.length, act);
}

public GifDecoder(byte[] data, int offset, int length, GifAction act) {
    gifData = data;
    action = act;
    gifDataOffset = offset;
    gifDataLength = length;
}

public GifDecoder(InputStream is, GifAction act) {
    in = is;
    action = act;
}

public void run() {
    if (in != null) {
        readStream();
    } else if (gifData != null) {
        readByte();
    }
}

public void free() {
    GifFrame fg = gifFrame;
    while (fg != null) {
        if (fg.image != null) {
            fg.image.recycle();
        }
        fg.image = null;
        fg = null;
        gifFrame = gifFrame.nextFrame;
        fg = gifFrame;
    }
    if (in != null) {
        try {
            in.close();
        } catch (Exception ex) {
        }
        in = null;
    }
    gifData = null;
}

public int getStatus() {
    return status;
}

public boolean parseOk() {
    return status == STATUS_FINISH;
}

public int getDelay(int n) {
    delay = -1;
    if ((n >= 0) && (n < frameCount)) {
        GifFrame f = getFrame(n);
        if (f != null) delay = f.delay;
    }
    return delay;
}

public GifFrame getFrame(int n) {
    GifFrame frame = gifFrame;
    int i = 0;
    while (frame != null) {
        if (i == n) {
            return frame;
        } else {
            frame = frame.nextFrame;
        }
        i++;
    }
    return null;
}

public int[] getDelays() {
    GifFrame f = gifFrame;
    int[] d = new int[frameCount];
    int i = 0;
    while (f != null && i < frameCount) {
        d[i] = f.delay;
        f = f.nextFrame;
        i++;
    }
    return d;
}

public int getFrameCount() {
    return frameCount;
}

public Bitmap getImage() {
    return getFrameImage(0);
}

public Bitmap getFrameImage(int n) {
    GifFrame frame = getFrame(n);
    if (frame == null) {
        return null;
    } else {
        return frame.image;
    }
}

public int getLoopCount() {
    return loopCount;
}

public GifFrame getCurrentFrame() {
    return currentFrame;
}

public void reset() {
    currentFrame = gifFrame;
}

public GifFrame next() {
    if (isShow == false) {
        isShow = true;
        return gifFrame;
    } else {
        if (status == STATUS_PARSING) {
            if (currentFrame.nextFrame != null) currentFrame = currentFrame.nextFrame;
            //currentFrame = gifFrame;
        } else {
            currentFrame = currentFrame.nextFrame;
            if (currentFrame == null) {
                currentFrame = gifFrame;
            }
        }
        return currentFrame;
    }
}

private Bitmap setPixels() {
    if (dest == null) dest = new int[width * height];
    // fill in starting image contents based on last image dispose code
    if (lastDispose > 0) {
        if (lastDispose == 3) {
            // use image before last
            int n = frameCount - 2;
            if (n > 0) {
                Bitmap lastImage = getFrameImage(n - 1);
                if (lastPixels == null) lastPixels = new int[width * height];
                lastImage.getPixels(lastPixels, 0, width, 0, 0, width, height);
            } else {
                lastPixels = null;
            }
        }
        if (lastPixels != null) {
            dest = Arrays.copyOf(lastPixels, lastPixels.length);
            // copy pixels
            if (lastDispose == 2) {
                // fill last image rect area with background color
                int c = 0;
                if (!transparency) {
                    c = lastBgColor;
                }
                for (int i = 0; i < lrh; i++) {
                    int n1 = (lry + i) * width + lrx;
                    int n2 = n1 + lrw;
                    for (int k = n1; k < n2; k++) {
                        dest[k] = c;
                    }
                }
            }
        }
    }

    // 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;
                }
            }
            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++;
            }
        }
    }
    return Bitmap.createBitmap(dest, width, height, Config.ARGB_4444);
}

private int readByte() {
    in = new ByteArrayInputStream(gifData, gifDataOffset, gifDataLength);
    gifData = null;
    return readStream();
}

private int readStream() {
    init();
    if (in != null) {
        readHeader();
        if (!err()) {
            readContents();
            if (frameCount < 0) {
                status = STATUS_FORMAT_ERROR;
                action.parseOk(false, -1);
            } else {
                status = STATUS_FINISH;
                action.parseOk(true, -1);
            }
        }
        try {
            in.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    } else {
        status = STATUS_OPEN_ERROR;
        action.parseOk(false, -1);
    }
    return status;
}

private 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
    }
}

private boolean err() {
    return status != STATUS_PARSING;
}

private void init() {
    status = STATUS_PARSING;
    frameCount = 0;
    gifFrame = null;
    gct = null;
    lct = null;
}

private int read() {
    int curByte = 0;
    try {

        curByte = in.read();
    } catch (Exception e) {
        status = STATUS_FORMAT_ERROR;
    }
    return curByte;
}

private int readBlock() {
    blockSize = read();
    int n = 0;
    if (blockSize > 0) {
        try {
            int count = 0;
            while (n < blockSize) {
                count = in.read(block, n, blockSize - n);
                if (count == -1) {
                    break;
                }
                n += count;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        if (n < blockSize) {
            status = STATUS_FORMAT_ERROR;
        }
    }
    return n;
}

private int[] readColorTable(int ncolors) {
    int nbytes = 3 * ncolors;
    int[] tab = null;
    byte[] c = new byte[nbytes];
    int n = 0;
    try {
        n = in.read(c);
    } catch (Exception e) {
        e.printStackTrace();
    }
    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++] = 0xff000000 | (r << 16) | (g << 8) | b;
        }
    }
    return tab;
}

private void readContents() {
    // read GIF file content blocks
    boolean done = false;
    while (!(done || err())) {
        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;
            case 0x3b: // terminator
                done = true;
                break;
            case 0x00: // bad byte, but keep going and see what happens
                break;
            default:
                status = STATUS_FORMAT_ERROR;
        }
    }
}

private 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
}

private 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];
    }
}

private 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 (err()) {
        return;
    }
    try {
        decodeImageData(); // decode pixel data
        skip();
        if (err()) {
            return;
        }
        frameCount++;
        // create new image to receive frame data
        // createImage(width, height);
        Bitmap image = setPixels(); // transfer pixel data to image
        if (gifFrame == null) {
            gifFrame = new GifFrame(image, delay);
            currentFrame = gifFrame;
        } else {
            GifFrame f = gifFrame;
            while (f.nextFrame != null) {
                f = f.nextFrame;
            }
            f.nextFrame = new GifFrame(image, delay);
        }
        // frames.addElement(new GifFrame(image, delay)); // add image to frame
        // list
        if (transparency) {
            act[transIndex] = save;
        }
        resetFrame();
        if (!action.parseOk(true, frameCount)) {
            status = STATUS_FINISH;
            return;
        }
    } catch (OutOfMemoryError e) {
        Log.e("GifDecoder", ">>> log  : " + e.toString());
        e.printStackTrace();
    }
}

private 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
}

private 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());
}

private int readShort() {
    // read 16-bit value, LSB first
    return read() | (read() << 8);
}

private void resetFrame() {
    lastDispose = dispose;
    lrx = ix;
    lry = iy;
    lrw = iw;
    lrh = ih;
    lastPixels = dest;
    lastBgColor = bgColor;
    dispose = 0;
    transparency = false;
    delay = 0;
    lct = null;
}

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

}

Я загружаю полный демонстрационный источник здесь. Надеюсь, это поможет вам.

Ответ 4

Я не пробовал, но я предполагаю, что вы можете сделать что-то подобное, чтобы получить доступ к каждому кадру в то время, когда он должен отображаться.

Handler h = new Handler();
Drawable.Callback frameListener = new Drawable.Callback() {
    @Override public void scheduleDrawable(Drawable who, Runnable what, long when) {
        h.postAtTime(what, who, when);
    }
    @Override public void unscheduleDrawable(Drawable who, Runnable what) {
        h.removeCallbacks(what, who);
    }
    @Override public void invalidateDrawable(Drawable who) {
        // time for next frame; draw it to any canvas you want
        who.draw(myCanvas);
    }
}
// set our frame listener
myAnimatedImageDrawable.setCallback(frameListener);
// draw the first frame
myAnimatedImageDrawable.draw(myCanvas);
// start collecting subsequent frames
myAnimatedImageDrawable.start();