capture screen from /dev/fb0

fb_scrshot.py

#!/usr/bin/python2

FBIOGET_VSCREENINFO = 0x4600
FBIOPUT_VSCREENINFO = 0x4601
FBIOGET_FSCREENINFO = 0x4602
FBIOGETCMAP = 0x4604
FBIOPUTCMAP = 0x4605
FBIOPAN_DISPLAY = 0x4606
BI_BITFIELDS = 3
BI_RAW = 0
__comment__ = '''
struct fb_bitfield {
	__u32 offset;			/* beginning of bitfield	*/
	__u32 length;			/* length of bitfield		*/
	__u32 msb_right;		/* != 0 : Most significant bit is */ 
					/* right */ 
'''


import os
import sys
import struct
from fcntl import ioctl


def usage():
    print('nothing yet..')
    pass


def convert(fname):
    from PIL import Image
    from PIL import ImageFile
    ImageFile.LOAD_TRUNCATED_IMAGES = True
    with Image.open(fname) as f:
        print('converting ' + fname + ' to png...')
        f.save(fname[:-3] + 'png')
        f.close()
        print('done.')
        os.unlink(fname)


def cap_fb(fname):
    with open('/dev/fb0') as f:
        l = list(struct.unpack(
            'I' * 40, ioctl(f, FBIOGET_VSCREENINFO, '\x00' * 160)))
        w = l[0]
        h = l[1]
        vw = l[2]
        vh = l[3]
        xo = l[4]
        yo = l[5]
        bitdepth = l[6]
        bytesofpixel = bitdepth / 8
        is_color = l[7]
        # [8:11],[11:14],[14:17],[17:20]
        rgba_bitfields = zip(*[iter(l[8:20])] * 3)
        print 'fb layout:', l[:7]

        ones = int('1' * bitdepth, 2)
        masks = struct.pack(
            '4I',  *[(ones & (~(ones << bitfield[1])) << bitfield[0]) for bitfield in rgba_bitfields])

        fb_memsize = vw * vh * bytesofpixel
        raw = f.read()
        d = raw[:fb_memsize]
        #d = f.read(fb_memsize)
        #open('fb_raw.save', 'wb').write(raw)

        dd = [d[i * vw * bytesofpixel:(i + 1) * vw * bytesofpixel]
              for i in range(vh)]  # split to vh rows
        dd = dd[yo:h + yo]  # chop y

        d = [row[xo * bytesofpixel:(w + xo) * bytesofpixel]
             for row in dd]  # chop x
        d = ''.join(d)

        bmp_sign = 'BM'
        bmp_size = struct.pack('I', 0)
        bmp_reserved = '\x00' * 4
        bmp_dataoff = struct.pack('I', 0)
    #-----------14--------------------
        bmp_szinfohdr = struct.pack('I', 40)
        bmp_w = struct.pack('I', w)
        bmp_h = struct.pack('i', -h)  # so i dont have to reverse all data
        bmp_planes = struct.pack('h', 1)
        bmp_bitcount = struct.pack('h', bitdepth)

        # define BI_BITFIELDS 3 /* RGB bitmap with RGB masks */

        bmp_bicompress = struct.pack(
            'I', {24: BI_RAW, 32: BI_RAW}.get(bitdepth, BI_BITFIELDS))
        bmp_imsize = struct.pack('I', fb_memsize)
        bmp_xresolution = struct.pack('I', 0)
        bmp_yresolution = struct.pack('I', 0)
        bmp_colorused = struct.pack('I', 0)
        bmp_colorsimportant = struct.pack('I', 0)
    #--------------40----------------------
    #--------------mask=4*4--------------

        bmp_raw_h1 = bmp_sign + bmp_size + bmp_reserved + bmp_dataoff
        bmp_raw_h2 = bmp_szinfohdr + bmp_w + bmp_h + bmp_planes + bmp_bitcount + bmp_bicompress + \
            bmp_imsize + bmp_xresolution + bmp_yresolution + \
            bmp_colorused + bmp_colorsimportant
        if bitdepth not in (24, 32):
            bmp_raw_h2 += masks
    # header filled

    # process alignment
        align = w % 4
        if bitdepth != 32 and align:  # dont need when bitdepth==32
            align = 4 - align
            splits = [d[0 + i:w + i] for i in range(0, len(d), w)]
            d = ''.join([p + '\x00' * align for p in splits])
    # re-calc size & offsets
        bmp_dataoff = struct.pack('I', len(bmp_raw_h1) + len(bmp_raw_h2))
        bmp_size = struct.pack('I', len(bmp_raw_h1) + len(bmp_raw_h2) + len(d))
        bmp_raw_h1 = bmp_sign + bmp_size + bmp_reserved + bmp_dataoff
        bmp_raw = bmp_raw_h1 + bmp_raw_h2 + d

        print('saving: ' + fname)
        with open(fname, 'wb') as ff:
            ff.write(bmp_raw)
            print('..OK')
    try:
        from PIL import Image
        convert(fname)
    except:
        pass


if __name__ == '__main__':
    if len(sys.argv) <= 1:  # scrshot.py
        cap_fb('scrshot_last.bmp')
    elif sys.argv[1] == 'convert':
        if len(sys.argv) < 3:  # scrshot.py convert
            usage()
        else:  # scrshot.py convert xx xxx xxx
            args = sys.argv[2:]
            for fname in args:
                convert(fname)
    else:  # scrshot.py xxx
        fname = sys.argv[1]
        if sys.argv[1][-3:].lower() != 'bmp':
            fname += '.bmp'
        if os.path.exists(fname):
            fname = fname[:-4] + '_2.bmp'
            while os.path.exists(fname) :
                fname = fname[:-4] + '_2.bmp'
        cap_fb(fname)