“adb screencap /sdcard/screenshot.raw”生成什么格式？ （没有“-p”标志）

我正在寻找使用adb screencap实用程序没有-p旗帜。我想象输出将以原始格式转储，但看起来并非如此。我尝试打开原始图像文件Pillow(python) 库导致：

$ adb pull /sdcard/screenshot.raw screenshot.raw
$ python
>>> from PIL import Image
>>> Image.open('screenshot.raw')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/....../lib/python2.7/site-packages/PIL/Image.py", line 2025, in open
    raise IOError("cannot identify image file")
IOError: cannot identify image file

发现这样的读取原始图像的正确方法不正确，我什至尝试了以下方法：如何使用PIL读取原始图像？

>>> with open('screenshot.raw', 'rb') as f:
...     d = f.read()
... 
>>> from PIL import Image
>>> Image.frombuffer('RGB', len(d), d)
__main__:1: RuntimeWarning: the frombuffer defaults may change in a future release; for portability, change the call to read:
  frombuffer(mode, size, data, 'raw', mode, 0, 1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/..../lib/python2.7/site-packages/PIL/Image.py", line 1896, in frombuffer
    return frombytes(mode, size, data, decoder_name, args)
  File "/Users/..../lib/python2.7/site-packages/PIL/Image.py", line 1821, in frombytes
    im = new(mode, size)
  File "/Users/..../lib/python2.7/site-packages/PIL/Image.py", line 1787, in new
    return Image()._new(core.fill(mode, size, color))
TypeError: must be 2-item sequence, not int

所有可能的模式选项都会导致相同的结果TypeError例外。

这是什么hexdump实用程序揭示：

$ hexdump -C img.raw | head
00000000  d0 02 00 00 00 05 00 00  01 00 00 00 1e 1e 1e ff  |................|
00000010  1e 1e 1e ff 1e 1e 1e ff  1e 1e 1e ff 1e 1e 1e ff  |................|
*
000038c0  1e 1e 1e ff 1e 1e 1e ff  21 21 21 ff 2b 2b 2b ff  |........!!!.+++.|
000038d0  1e 1e 1e ff 1e 1e 1e ff  1e 1e 1e ff 1e 1e 1e ff  |................|
*
00004400  1e 1e 1e ff 1e 1e 1e ff  47 47 47 ff 65 65 65 ff  |........GGG.eee.|
00004410  20 20 20 ff 1e 1e 1e ff  1e 1e 1e ff 1e 1e 1e ff  |   .............|
00004420  1e 1e 1e ff 1e 1e 1e ff  1e 1e 1e ff 1e 1e 1e ff  |................|
*

On osx:

$ file screenshot.raw 
screenshot.raw: data

screencap帮助页面没有透露太多关于输出数据格式的信息-p flag:

$ adb shell screencap -h
usage: screencap [-hp] [FILENAME]
   -h: this message
   -p: save the file as a png.
If FILENAME ends with .png it will be saved as a png.
If FILENAME is not given, the results will be printed to stdout.

Format:

• 4 个字节作为 uint32 -width
• 4 个字节作为 uint32 -height
• 4 个字节作为 uint32 -pixel format
• (width * heigth * bytespp) 字节作为字节数组 -image data, where bytespp是每像素的字节数，取决于pixel format。通常bytespp is 4.

信息来自截屏源代码.

对于你的例子：

00000000  d0 02 00 00 00 05 00 00  01 00 00 00 1e 1e 1e ff

• d0 02 00 00- 宽度 - uint32 0x000002d0 = 720
• 00 05 00 00- 高度 - uint32 0x00000500 = 1280
• 01 00 00 00- 像素格式 - uint32 0x00000001 = 1 =PixelFormat.RGBA_8888 => bytespp = 4=> RGBA
• 1e 1e 1e ff- 第一个像素数据 -R = 0x1e; G = 0x1e; B = 0x1e; A = 0xff;

数据存储在大小为 720*1280*4 的字节数组中的像素。