This reminds me of a general muse 'it would be nice if...' thought: it
would be nice if there was a way of defining more featureful dialogs, so
that in this case for instance, you could browse for a file (or put a
pathname in), and also add a file offset, or something like that.
I am aware that such a thing would tend to suffer from featuritis, however.
J^n
On Tuesday, June 11, 2024 at 12:53:51 AM UTC+1 [email protected] wrote:
> Sometimes it is useful to view the first N bytes of a file without reading
> the whole file. The file might be much too large to load into a text
> editor or a Leo node, for example. The Linux command *head* will show you
> just the start of a file, but Windows doesn't have that command out of the
> box. Often it's better to look at the hex bytes rather than the text,
> especially if the file is binary. Say, for example, that you want to see
> if a file is a zip file or not, or if the EXIF data is embedded in a .jpg
> picture file.
>
> Here is a Leo command that loads a file using the file dialog. It creates
> a new node at the end of your outline and fills it with a classic hex view
> of the first 4096 bytes.
>
> I have this script as an *@command* node in my myLeoSettings.leo file,
> and I also have a custom menu item for it. I don't use it all the time but
> it's invaluable when it is needed.
>
> Here is the script:
>
> """Display as hex the first 4096 bytes of a file in body of a new node."""
>
> data = ''
>
> def format_bytes(bytes):
> """Format byte data into classic hex bytes display."""
> text = ''
> asc = ' ' * 3 # For translation of bytes to ascii characters
> n = 0
> for i, b in enumerate(bytes):
> text += f'{b:02x}'
> asc += chr(b) if b > 0x1F else '.'
> if i > 0 and i % 10 == 9:
> # Complete the current line
> text += asc
> text += '\n'
> asc = ' ' * 3
> n += 1
> if n % 8 == 0:
> # Insert a blank line for readability
> text += '\n'
> else:
> text += ' '
> return text
>
> filetypes = [('Any', '*.*'),]
> path = g.app.gui.runOpenFileDialog(c, 'Choose File To Sample',
> filetypes=filetypes)
> g.es(path)
>
> if path:
> try:
> with open(path, 'rb') as f:
> data = f.read(4096)
> except IOError as e:
> g.es(e)
>
> if data:
> # Create and select target node
> p_last = c.lastVisible()
> target = p_last.insertAfter()
> target.h = f'first bytes of {path}'
> target.b = f'{format_bytes(data)}'
> target.setDirty()
> c.selectPosition(target)
> while c.canMoveOutlineLeft():
> c.moveOutlineLeft()
> c.redraw()
>
> Here is (just the first part) of the bytes of an image file of mine. We
> can see the signature of a .jpg file. and that it uses the *sRGB* color
> map.
>
> ff d8 ff e0 00 10 4a 46 49 46 ÿØÿà..JFIF
> 00 01 01 00 00 01 00 01 00 00 ..........
> ff e2 0c 58 49 43 43 5f 50 52 ÿâ.XICC_PR
> 4f 46 49 4c 45 00 01 01 00 00 OFILE.....
> 0c 48 6c 63 6d 73 02 10 00 00 .Hlcms....
> 6d 6e 74 72 52 47 42 20 58 59 mntrRGB XY
> 5a 20 07 ce 00 02 00 09 00 06 Z .Î......
> 00 31 00 00 61 63 73 70 4d 53 .1..acspMS
>
> 46 54 00 00 00 00 49 45 43 20 FT....IEC
> 73 52 47 42 00 00 00 00 00 00 sRGB......
> 00 00 00 00 00 00 00 00 f6 d6 ........öÖ
> 00 01 00 00 00 00 d3 2d 6c 63 ......Ó-lc
> 6d 73 00 00 00 00 00 00 00 00 ms........
> 00 00 00 00 00 00 00 00 00 00 ..........
> 00 00 00 00 00 00 00 00 00 00 ..........
> 00 00 00 00 00 00 00 00 00 00 ..........
>
>
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