德codeByteArray和copyPixelsToBuffer不工作。 SkImageDe codeR ::厂返回null [英] decodeByteArray and copyPixelsToBuffer not working. SkImageDecoder::Factory returned null

问题描述

我有一类接触点，它实现Serializable接口，并因为它包含了位图我写的writeObject和readObject该类：

I have a class TouchPoint which implements Serializable and because it contains Bitmap I wrote writeObject and readObject for that class:

private void writeObject(ObjectOutputStream oos) throws IOException {
    long t1 = System.currentTimeMillis();
    oos.defaultWriteObject();
    if(_bmp!=null){
        int bytes = _bmp.getWidth()*_bmp.getHeight()*4;

        ByteBuffer buffer = ByteBuffer.allocate(bytes); 
        _bmp.copyPixelsToBuffer(buffer);

        byte[] array = buffer.array();      

        oos.writeObject(array);

    }
    Log.v("PaintFX","Elapsed Time: "+(System.currentTimeMillis()-t1));
}

private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException{
    ois.defaultReadObject();
    byte[] data = (byte[]) ois.readObject();
    if(data != null && data.length > 0){
        _bmp = BitmapFactory.decodeByteArray(data, 0, data.length);
    }
}

现在的问题是，我得到

The problem is that I get

SkImageDe codeR ::厂返回null

SkImageDecoder::Factory returned null

那么，如何解决这个问题。我知道，可能的解决办法是改变writeObject（）将

So how can I fix it. I know that possible solution is to change writeObject() to

ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
_bmp.compress(Bitmap.CompressFormat.PNG, 100, byteStream);
oos.writeObject(byteStream.toByteArray);

但这种方法比较慢，几乎10+倍。

BUT this method is slower almost 10+ times.

• copyPixelsToBuffer〜14ms的写入图像
• _bmp.com preSS〜160毫秒

更新 找出实际的问题是，后

UPDATE Find out that the actual problem is that after

buffer.array();

所有的byte []数组元素：0

All byte[] array elements are: 0

推荐答案

最后，我找到一种方法，使工作和更快的同时。我遇到过使用这种方法的两个问题：

Finally I find a way to make it work and be faster at the same time. I was encountered two issues using this method:

1. 我要通过Bitmap.Config参数也没有，我不能去code中的字节数组
2. _bmp.com preSS和_bmp.copyPixelsToBuffer给出不同的阵列，所以我不能C $ cByteArray使用去$。

我解决了他们这样

private void writeObject(ObjectOutputStream oos) throws IOException {
    oos.defaultWriteObject();

    if(_bmp!=null){
        int bytes = _bmp.getWidth()*_bmp.getHeight()*4;

        ByteBuffer buffer = ByteBuffer.allocate(bytes);
        _bmp.copyPixelsToBuffer(buffer);

        byte[] array = new byte[bytes]; // looks like this is extraneous memory allocation

        if (buffer.hasArray()) {
            try{
                array = buffer.array();
            } catch (BufferUnderflowException e) {
                e.printStackTrace();
            }
        }

        String configName = _bmp.getConfig().name();

        oos.writeObject(array);
        oos.writeInt(_bmp.getWidth());
        oos.writeInt(_bmp.getHeight());
        oos.writeObject(configName);
    } else {
        oos.writeObject(null);
    }
}

private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException{
    ois.defaultReadObject();

    byte[] data = (byte[]) ois.readObject();
    if (data != null) {
        int w = ois.readInt();
        int h = ois.readInt();
        String configName = (String) ois.readObject();

        Bitmap.Config configBmp = Bitmap.Config.valueOf(configName);
        Bitmap bitmap_tmp = Bitmap.createBitmap(w, h, configBmp);
        ByteBuffer buffer = ByteBuffer.wrap(data);

        bitmap_tmp.copyPixelsFromBuffer(buffer);

        _bmp = bitmap_tmp.copy(configBmp,true);

        bitmap_tmp.recycle();
    } else {
        _bmp = null;
    }
}

这是速度不够快，我 - 约15倍的速度，然后在bmp.com preSS方式​​。希望这有助于：）

This is enough fast for me - about 15x faster then the bmp.compress way. hope this helps :)

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