More & More Fun w/ Pics & MySQL

Victor Subervi victorsubervi at gmail.com
Sun Oct 18 18:23:17 CEST 2009


Thank you all. I have __no__idea__ why the link I sent you, that you tested,
__didn't__ work for me. Was it a problem with the browser? Why did it render
other images fine? Strange! Well, glad it works *today*. Hopefully it'll
work tomorrow, when I try and pick up a check from my client!

Regarding Carsten's misunderstanding of my mentioning of commenting out
statements,  are the following two statements identical or not?

print 'Content-type: image/jpeg'


print 'Content-type: image/jpeg'
#print 'Content-type: text/plain'

This is what I mean. Sorry it was so difficult to communicate that to you.
Thanks again,
V


On Sat, Oct 17, 2009 at 2:57 PM, Neo <neo at picture-art.eu> wrote:

> Hi,
>
> Victor Subervi schrieb:
> > Let me clarify. This prints out "all sorts of crap", which means an
> > image string, the image as a string, to the screen:
> >
> > print 'Content-type: image/jpeg'
> > print 'Content-Encoding: base64'
> > print
> > print pic().encode('base64')
> > print '</body></html>'
> >
> > The following once upon a time printed images, but now it doesn't. Why
> > would that be? I would refresh the screen, and it would print. I'd
> > change a line and it wouldn't. I'd change it back to what it was and it
> > would no longer the image to the screen. Why is that? The same happens
> > with or without the base64 stuff. Commenting out a line seemed to make a
> > difference!
> >
> > print 'Content-type: text/plain'
> > #print 'Content-type: image/jpeg'
> > print
> > print pic()
> > print '</body></html>'
> >
> > The above prints out a broken image of correct dimensions.
>
> Only with a broken client (I assume Internetexplorer here?)
> Any you don't know what it does in guessing and caching (Try
> shift-reload when you test things)
>
> You should work from a static page and a static image and look what
> is transferred by the server (wireshark or tcpflow are of great help,
> but nc | hexdump -C | more is probably more easy if you work out the
> HTTP protocol (see rfc2616)
>
> You script needs to do the same as a server would do serving a static
> resource. Just look how it works and rebuild it.
>
> You will quickly find out, that there is obviously no reason to have
> </body> </html> at the end of a binary resource an Image is.
> Also correct mime type is important unless you deal with broken clients.
>
> There are a lot more HTTP-Headers you want to understand and use but the
> simple usage above, provided pic() indeed returns the binary data of the
> image unaltered, should work (w/o the html crap at the end).
> You would not use print since it adds a linefeed at the end which is not
> part of the data. sys.stdout.write() should work better (and can be used
> incremental to avoid returning the whole image data from memory)
>
> > Of course I try and figure out how things work once they get working.
> > Sometimes, however, there is __no__ logic to it __at__all__. Sorry.
> > After years of struggling with python I've come to realize that even
> > though I may not be a good programmer, it isn't me. It may not be python
> > itself. It may be the crappy hardware the server farms use. It may be
> > the way they tweak their python interpreter. But it isn't just me.
>
> Sorry to tell you that but its just you. There is no magic in that.
> Ok, there is one thing: what makes you sure the data in the database
> is really unaltered image data? I mean, you are using mysql...
> for a first thing I'd write the output into a file and try to open it
> in a graphic viewer.
>
> > It would be nice if I could get this code printing images to the screen
> > as it was before I had to put out another unnecessary fire when code
>
> Images are not "printed to screen" the whole idea is just wrong.
>
> > that previously uploaded the images in the first place inexplicably no
> > longer worked. Then, lo and behold, when I came back to this code that I
> > hadn't touched and was working fine earlier this week, it no longer
> > works. Lovely. My "plug-and-play" program has devoured two weeks of my
> > time and I'm still up the creek without a paddle. Sure would appreciate
> > any help you can give.
>
> I see "plug and play" and read cargo-cult. You need to read a bit about
> the basics on the matter or you will constantly run uphill - and even if
> it seems to work it has no value if you don't know _why_.
>
> Regards
> Tino
>
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