Question

I m trying to access the raw pixel data of an image in Android.
The code looks something like this:

   Bitmap bitmap =  BitmapFactory.decodeFile("image.png"); 
   // assert valid input
   if ((bitmap.getConfig() == null) || bitmap.getConfig() == Config.ARGB_8888)
      throw new Exception("bad config");

  ByteBuffer buffer = ByteBuffer.allocate(4 * bitmap.getWidth() * bitmap.getHeight());
  bitmap.copyPixelsToBuffer(buffer);        
  return buffer.array();

如何储存1D条线的颜料?

First element is top-left pixel or bottom-left pixel (or something else)?
Row-major (row after row) or column-major (column after column)?
Channel order ARGB or BGRA?
Row-major or column-major for each channel separately?
Something else

Answer 1

具体pixel x,y<> 采用这一公式:



offsetForPixel = (y * width + x) * bytesPerPixel


换言之,阵列中的第一个要素是头盔,以下要素是row。  p的所有数据都储存在邻近的tes中,没有根据渠道传播。 这是对上述1、2和4的答复。 现在让我讨论第3条,这就是事情变得复杂的地方。

What you get with Bitmap.copyPixelsToBuffer() is the raw bitmap data representation used by Android s low-level drawing library skia. This has three significant consequences:


The channel order depends on endianness
The channels are premultiplied with alpha
How channels are packed into containing data types is configurable

最后一点是,使用<条码>得 a。比图.copyPixels ToBuffer()完全是如果你想要检查个别的餐厅,因为你可以知道如何将天空配置到包装渠道。作为试验,尝试这一法典:

int inputPixel = 0x336699cc;
int[] pixels = new int[] { inputPixel };
Bitmap bm = Bitmap.createBitmap(pixels, 1, 1, Config.ARGB_8888);
ByteBuffer bb = ByteBuffer.allocate(4);
bm.copyPixelsToBuffer(bb);
Log.i("TAG", "inputPixel = 0x" + Integer.toHexString(inputPixel));
for (int i = 0; i < 4; i++) {
    String byteString = "0x" + Integer.toHexString(bb.array()[i] & 0xff);
    Log.i("TAG", "outputPixel byte " + i + " = " + byteString);
}

在我执政时,我取得了这一成果:

I/TAG ( 1995): inputPixel = 0x336699cc
I/TAG ( 1995): outputPixel byte 0 = 0x14
I/TAG ( 1995): outputPixel byte 1 = 0x1f
I/TAG ( 1995): outputPixel byte 2 = 0x29
I/TAG ( 1995): outputPixel byte 3 = 0x33

我们可以看到,我们正与大端人打交道,中间派代表先是多面派代表,而且各种渠道已经从大不列颠及北爱尔兰联合党重新安排到欧洲复兴开发银行(根据斯基纳源法,这一代言与开放式代表相同)。

如果你读到六分的数据,我建议你使用

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