wxPython: images from URLs

[Jonathan Daugherty]

Does anyone here know if the wxImage class in wxPython supports dislaying
images from URLs?

--

Jonathan Daugherty
http://www.cprogrammer.org

"It's a book about a Spanish guy called Manual, you should read it."
-- Dilbert

[Kevin Altis]

"Jonathan Daugherty" <cy****@cprogra mmer.org> wrote in message
news:ma******** *************** *************** @python.org...

Does anyone here know if the wxImage class in wxPython supports dislaying
images from URLs?

Yes, the trick is to use StringIO to convert the data rather than saving to
a file and loading it from disk. Here's a concrete example...

ka
---

import urllib
from wxPython import wx
from cStringIO import StringIO

# I'll assume you already have an app, frame...
# to draw into if that's what you want to do

wx.wxInitAllIma geHandlers()

# here's a real URL for testing purposes
url = 'http://pythoncard.sour ceforge.net/images/addresses_01.pn g'

try:
fp = urllib.urlopen( url)
data = fp.read()
fp.close()
img = wx.wxImageFromS tream(StringIO( data))
except:
# decide what you want to do in case of errors
# there could be a problem getting the data
# or the data might not be a valid jpeg, png...
pass

# now you can do whatever you want with the image

[Tim Roberts]

Jonathan Daugherty <cy****@cprogra mmer.org> wrote:

Does anyone here know if the wxImage class in wxPython supports dislaying
images from URLs?

wxImage will read from a file or from a wxWindows stream. It won't
download from a web site, but that's trivially easy using something like
urllib.
--
- Tim Roberts, ti**@probo.com
Providenza & Boekelheide, Inc.

[Anand Pillai]

I have written some code for this in my PyWiew application
which allows one to open image urls directly.

Copying some relevant code from the application...

self._imgstream = urllib2.urlopen (url).read()
stream=cStringI O.StringIO(self ._imgstream)

try:
img=wxImageFrom Stream(stream)
except:
pass

In short you do the following.

1. Use urllib or urllib2 to open the image data stream
2. Make a cStringIO string buffer from the data stream
3. Pass it to "wxImageFromStr eam()" method to get the
wxImage object.
4. Display the image directly or by converting to
a suitable format using PIL.

In my experience I found that wxWindows tend to
display an error message window when the image is displayed
directly as a wxImage though the image data is quite ok.
(Something like a corrupt stream dialog). So what I have
done in the application is, use PIL to convert the wxImage
to Windows BMP format and then display it. This seems
to work for all images.

HTH.

-Anand

Tim Roberts <ti**@probo.com > wrote in message news:<fg******* *************** **********@4ax. com>...

Jonathan Daugherty <cy****@cprogra mmer.org> wrote:

Does anyone here know if the wxImage class in wxPython supports dislaying
images from URLs?

wxImage will read from a file or from a wxWindows stream. It won't
download from a web site, but that's trivially easy using something like
urllib.

[Jonathan Daugherty]

# self._imgstream = urllib2.urlopen (url).read()
# stream=cStringI O.StringIO(self ._imgstream)
#
# try:
# img=wxImageFrom Stream(stream)
# except:
# pass

I have tried this and it appears to work, but once I have
the image (from wxImageFromStre am), I use it as follows:

try:
bm = wxBitmap(img)
self.bitmap.set Bitmap(bm)
except Exception, e:
print e

And the exception (raised by wxBitmap(img)) is:

String or Unicode type required

(The exception is a TypeError exception.)

Any ideas? No exceptions are raised by the block that
creates the image from the data stream. The image is
a JPG image, and I pass wxBITMAP_TYPE_J PEG to
wxImageFromStre am. I have also tried omitting it as
well.

--

Jonathan Daugherty
http://www.cprogrammer.org

"It's a book about a Spanish guy called Manual, you should read it."
-- Dilbert

[Anand Pillai]

This is the straight forward way to do this in wxPython
but somehow it always pops up that ugly error window.
I remember trying many options to do this purely using
wxPython (wxWindows), but I failed.

If you use PIL in your program you can conver the
wx Image instance to a PIL image of type BMP and then
display it by reconverting it back to the wxImage
instance. PyWiew has methods to do this. The source code
is available somewhere in my Python page at
http://members.lycos.co.uk/anandpillai . I no longer
maintain that program, but the latest source code should
be available there.

Regards

-Anand

Jonathan Daugherty <cy****@cprogra mmer.org> wrote in message news:<ma******* *************** *************** *@python.org>.. .

# self._imgstream = urllib2.urlopen (url).read()
# stream=cStringI O.StringIO(self ._imgstream)
#
# try:
# img=wxImageFrom Stream(stream)
# except:
# pass

I have tried this and it appears to work, but once I have
the image (from wxImageFromStre am), I use it as follows:

try:
bm = wxBitmap(img)
self.bitmap.set Bitmap(bm)
except Exception, e:
print e

And the exception (raised by wxBitmap(img)) is:

String or Unicode type required

(The exception is a TypeError exception.)

Any ideas? No exceptions are raised by the block that
creates the image from the data stream. The image is
a JPG image, and I pass wxBITMAP_TYPE_J PEG to
wxImageFromStre am. I have also tried omitting it as
well.

[Kevin Altis]

"Anand Pillai" <py*******@Hotp op.com> wrote in message
news:84******** *************** **@posting.goog le.com...

I have written some code for this in my PyWiew application
which allows one to open image urls directly.

Copying some relevant code from the application...

self._imgstream = urllib2.urlopen (url).read()
stream=cStringI O.StringIO(self ._imgstream)

try:
img=wxImageFrom Stream(stream)
except:
pass

In short you do the following.

1. Use urllib or urllib2 to open the image data stream
2. Make a cStringIO string buffer from the data stream
3. Pass it to "wxImageFromStr eam()" method to get the
wxImage object.
4. Display the image directly or by converting to
a suitable format using PIL.

In my experience I found that wxWindows tend to
display an error message window when the image is displayed
directly as a wxImage though the image data is quite ok.
(Something like a corrupt stream dialog). So what I have
done in the application is, use PIL to convert the wxImage
to Windows BMP format and then display it. This seems
to work for all images.

HTH.

-Anand

Tim Roberts <ti**@probo.com > wrote in message

news:<fg******* *************** **********@4ax. com>...

Jonathan Daugherty <cy****@cprogra mmer.org> wrote:

Does anyone here know if the wxImage class in wxPython supports dislayingimages from URLs?

wxImage will read from a file or from a wxWindows stream. It won't
download from a web site, but that's trivially easy using something like
urllib.

In general you don't display a wxImage object directly. In wxWindows,
wxImage is the platform-independent image class and wxBitmap is the
platform-specific image class. So, when you set an image to be used with a
wxStaticBitmap or wxBitmapButton or draw to a wxDC you use a wxBitmap.
Certain image operations not yet supported by wxWindows are easier to handle
with PIL in which case your solution of keeping a working image in PIL
format and then converting a wxBitmap prior to display is also a good
solution. Conversion is covered in the wxPython wiki.

http://wiki.wxpython.org/

Here are some of the conversion routines PythonCard uses to deal with PIL,
wxImage, wxBitmap, and NumPy numeric arrays.

def PILToImage(pilI mage):
if (pilImage.mode != 'RGB'):
pilImage = pilImage.conver t('RGB')
imageData = pilImage.tostri ng('raw', 'RGB')
img = wx.wxEmptyImage (pilImage.size[0], pilImage.size[1])
img.SetData(ima geData)
return img

def PILToBitmap(ima ge):
return wx.wxBitmapFrom Image(PILToImag e(image))

def BitmapToPIL(bmp ):
imageData = wx.wxImageFromB itmap(bmp).GetD ata()
imagePIL = fromstring('RGB ', (bmp.GetWidth() , bmp.GetHeight() ),
imageData)
imagePIL = imagePIL.conver t('RGB')
return imagePIL

def numericArrayToI mage(array):
height, width = array.shape[:2]
img = wx.wxEmptyImage (width, height)
img.SetData(arr ay.tostring())
return img

ka

[Tim Roberts]

Jonathan Daugherty <cy****@cprogra mmer.org> wrote:

# self._imgstream = urllib2.urlopen (url).read()
# stream=cStringI O.StringIO(self ._imgstream)
#
# try:
# img=wxImageFrom Stream(stream)
# except:
# pass

I have tried this and it appears to work, but once I have
the image (from wxImageFromStre am), I use it as follows:

try:
bm = wxBitmap(img)
self.bitmap.set Bitmap(bm)
except Exception, e:
print e

Why wouldn't you use wxBitmapFromIma ge?
--
- Tim Roberts, ti**@probo.com
Providenza & Boekelheide, Inc.

[Jonathan Daugherty]

# Why wouldn't you use wxBitmapFromIma ge?

The api docs suggest that using the wxBitmap(image) constructor
is better. Besides: this is beside the point -- this code fails:

stream = cStringIO.Strin gIO(imgdata)
imgobj = wx.wxImage(stre am)

The second line raises a TypeError: "String or Unicode type
required."

--

Jonathan Daugherty
http://www.cprogrammer.org

"It's a book about a Spanish guy called Manual, you should read it."
-- Dilbert