是否可以让新的ImageDecoder类手动返回位图，一个帧接着一个帧？
是否可以让新的ImageDecoder类手动返回位图，一个帧接着一个帧？
提问于 2018-10-27 17:02:49
背景
我正在尝试手动查看GIF和WEBP动画文件的位图(一帧一帧)，这样它不仅适用于视图，而且也适用于其他情况(比如活壁纸)。
问题所在
使用ImageDecoder API (例如这里)，只有Android支持动画GIF/WEBP文件。
对于GIF，我想尝试Glide来完成这个任务，但是失败了，所以我尝试通过使用一个允许加载它们的库(这里，解决方案这里)来克服这个问题。我觉得挺好的。
对于WebP，我想我已经找到了另一个库，它可以在较早的安卓版本(这里，made 这里)上工作，但在某些情况下，它似乎不能很好地处理WebP文件(reported 这里)。我试图弄清楚问题是什么以及如何解决，但我没有成功。
因此，假设有一天Google将通过支持库(他们编写它为这里)支持旧版本的GIF&WEBP动画，我决定尝试使用ImageDecoder来完成这项任务。
问题是，在ImageDecoder的整个API中，我们应该如何使用它是非常有限的。我不知道怎样才能克服它的局限性。
我所发现的
这就是如何使用ImageDecoder在ImageView上显示动画WebP (当然，只是一个示例，可用的这里)：
class MainActivity : AppCompatActivity() {
@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(result: Drawable?) {
super.onPostExecute(result)
imageView.setImageDrawable(result)
if (result is AnimatedImageDrawable) {
result.start()
}
}
}.execute()
}
}我试着阅读了ImageDecoder和AnimatedImageDrawable的所有文档，并查看了它们的代码，但我不知道如何能够手动遍历每个帧，并在它们之间等待所需的时间。
问题
- 是否有一种方法可以使用ImageDecoder API手动遍历每个帧，获取要绘制的位图，并知道在帧之间等待需要多长时间？有什么解决办法吗？甚至可能使用AnimatedImageDrawable？
- 我也想在旧的Android版本上做同样的事情。有可能吗？如果是的话，怎么做？也许在不同的API/库上？谷歌写道，它可以在较早的安卓版本上使用ImageDecoder，但我认为它在任何地方都没有提及(除了我提供的链接)。可能还没准备好..。Android P甚至还没有达到0.1%的用户。也许壁画能做到？我也试过在那里检查它，但我也看不出它有这样的能力，而且它是一个巨大的库，只用于这个任务，所以我宁愿使用另一个库来代替.我也知道libwebp是可用的，但它是在C/C++中，不确定它是否适合Android，也不确定它在Java/Kotlin上是否有用于Android的端口。
编辑：
因为我想我已经得到了我想要的，对于第三方库和ImageDecoder，能够从动画WebP中获取位图，所以我仍然想知道如何使用ImageDecoder获取帧计数和当前帧，如果可能的话。我尝试使用ImageDecoder.decodeDrawable(source, object : ImageDecoder.OnHeaderDecodedListener...，但它没有提供帧计数信息，而且在API中我看不到从那里开始到特定的框架索引，或者知道到下一个帧需要多长时间。所以我对那些这里做了个调查。
令人遗憾的是，我也没有发现谷歌的ImageDecoder可以用于更老的安卓版本。
这也是有趣的，如果有某种方式做同样的方式，我做了相对较新的动画文件的HEIC。目前，它只支持在Android。
回答 4
Stack Overflow用户
回答已采纳
发布于 2018-11-09 22:42:10
好的，我找到了一个可能的解决方案，使用滑翔库和GlideWebpDecoder库。
我不确定这是否是最好的方法，但我认为它应该工作得很好。下一段代码显示了如何为动画需要显示的每一帧将可绘图绘制到我创建的Bitmap实例中。这并不是我所要求的，但它可能会帮助到其他人。
下面是代码(项目可用的这里)：
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()
}
}但不确定为什么SimpleTarget被标记为不推荐使用，也不知道我应该使用什么。
使用类似的技术，我还了解了如何使用ImageDecoder，但由于某种原因没有使用相同的功能。一个可用的示例项目这里。
下面是代码：
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()
}
}Stack Overflow用户
发布于 2018-11-10 13:01:34
见ImageDecoder.Source ..。
首先需要创建一个源，其中之一是：
// 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)然后解码，要么是：
// create bitmap
val bitmap = ImageDecoder.decodeBitmap(source)
// create drawable
val drawable = ImageDecoder.decodeDrawable(source)update：问题是，生成的AnimatedImageDrawable没有这两种方法：getNumberOfFrames()和getFrame(int)作为AnimationDrawable。正如@androiddeveloper所指出的.我搞砸了两个不同的类。我已经看过文件了，看来没办法了。使用GIFImageReader，仍然可以提取它(来源)：
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;
}只是试着把它转换成Kotlin，但是javax.imageio.ImageIO在Android上是不可用的。
Stack Overflow用户
发布于 2018-11-12 11:12:28
几年前我玩过GIF图像。我的想法是解码GIF图像为帧，将帧转换为位图添加创建动画从位图和帧之间的延迟。这是解码类：
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's 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());
}}
我上传了完整的演示源这里。希望它能帮到你。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/53024304
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