I am doing a monitoring system using Django. In my views file, I have defined one class called showImage which collects the information necessary to plot a graph using matplotlib.
At the beginning, I just stored the image in a string buffer to represent it with HttpResponse:
buffer = StringIO.StringIO()
canvas = pylab.get_current_fig_manager().canvas
canvas.draw()
pilImage = PIL.Image.fromstring("RGB", canvas.get_width_height(), canvas.tostring_rgb())
pilImage.save(buffer, "PNG")
# Send buffer in a http response the the browser with the mime type image/png set
return HttpResponse(buffer.getvalue(), mimetype="image/png")
However, I need to implement some javaScript in the html file to add more applications. For that reason, I have decided to save the image in a variable and plot it in the html file:
# serialize to HTTP response
response = HttpResponse(buffer.getvalue(), mimetype="image/png")
return render_to_response('eQL/dev/showImage.html', {'response':response})
My question is that I don't really know how to represent it in the html file because I didn't find any example doing it. Any one knows the answer?
Thanks in advance!
Do you mean that in your first implementation, your response was a PNG file, but now you wish to make the response an HTML file instead, containing the image?
Well firstly, you need to change the response MIME type from image/png to text/html or similar.
Secondly, I'm not sure why you are passing a HttpResponse object (containing the PNG data) into the template. Can the template even read that? Surely you just want to be passing the raw PNG data, not a HttpResponse object.
Finally, how to do it. Well as you may know, HTML isn't so great at embedding images. As with normal websites, you can include text in the page, but if you want an image, you need a separate file and link to it using the <img src="..." /> element. This is tricky to do dynamically: it means you need to setup two separate URLs (one for the PNG and one for the HTML), which run independently of one another (you can't just have one piece of code; you need one handler for generating the PNG and the other for generating the HTML), and have the HTML link to the PNG URL.
If that is too hard, there is another way out, but it is a bit hacky: data URLs. They let you include image data in the HTML page itself, so you only need to produce one response. Unfortunately it is not well supported in Internet Explorer pre-9. IE8 supports images less than 32K, IE7 and below don't work. See the example on Wikipedia -- you are aiming to generate something like this:
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA
AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
9TXL0Y4OHwAAAABJRU5ErkJggg==" alt="Red dot" />
Basically, take the PNG data, and Base64-encode it (use Python's base64 library). Then just put "data:image/png;base64," in front of it, and set that as the URL for the img src. In other words, pass the Base64-encoded string to Django's template engine, and construct the URL as part of the img tag in the template.
Related
I want to extract and process text from a text document uploaded by the user without actually saving the document. I use Django's REST framework and I want this to happen in the serializer.
I get the document from a FileField. Because the text document is likely to be small, it will be wrapped into InMemoryUploadedFile automatically. However, text-extraction modules (e.g. docx2python) need to open files from paths, not from memory.
How can I turn an InMemoryUploadedFile into a TemporaryUploadedFile, so I can get a path to use? Or how do I force a particular field (without changing the app settings) to always wrap a file in TemporaryUploadedFile?
I am trying to test a webservice's performance, and having a few issues with using and passing variables. There are multiple sequential requests, which depend on some data coming from a previous response. All requests need to be encoded to base64 and placed in a SOAP envelope namespace before sending it to the endpoint. It returns and encoded response which needs to be decoded to see the xml values which need to be used for the next request. What I have done so far is:
1) Beanshell preprocessor added to first sample to encode the payload which is called from a file.
2) Regex to pull the encoded response bit from whole response.
3) Beanshell post processor to decode the response and write to a file (just in case). I have stored the decoded response in a variable 'Output' and I know this works since it writes the response to file correctly.
4) After this, I have added 4 regex extractors and tried various things such as apply to different parts, check different fields, check JMeter variable etc. However, it doesn't seem to work.
This is what my tree is looking like.
JMeter Tree
I am storing the decoded response to 'Output' variable like this and it works since it's writing to file properly:
import org.apache.commons.io.FileUtils;
import org.apache.commons.codec.binary.Base64;
String Createresponse= vars.get("Createregex");
vars.put("response",new String(Base64.decodeBase64(Createresponse.getBytes("UTF-8"))));
Output = vars.get("response");
f = new FileOutputStream("filepath/Createresponse.txt");
p = new PrintStream(f);
this.interpreter.setOut(p);
print(Output);
f.close();
And this is how I using Regex after that, I have tried different options:
Regex settings
Unfortunately though, the regex is not picking up these values from 'Output' variable. I basically need them saved so i can use ${docID} in the payload file for next request.
Any help on this is appreciated! Also happy to provide more detail if needed.
EDIT:
I had a follow up question. I am trying to run this with multiple users. I have a field ${searchuser} in my payload xml file called in the pre-processor here.
The CSV Data set above it looks like this:
However, it is not picking up the values from CSV and substituting in the payload file. Any help is appreciated!
You have 2 problems with your Regular Expression Extractor configuration:
Apply to: needs to be response
Field to check: needs to be Body, Body as a Document is being used for binary file formants like PDF or Word.
By the way, you can do Base64 decoding and encoding using __base64Decode() and __base64Encode() functions available via JMeter Plugins. The plugins in their turn can be installed in one click using Plugin Manager
I have a Qt program that downloads webpages (HTML), parses them and then generates its own HTML which is then displayed with QWebPage. Some times the HTML that I download contains IMG tags, which work fine when the src attribute contains a full URL. However, some times the IMG tag might use a relative path like:
<IMG SRC="images/foo.png" />
Since I know the URL that should be prepended to the SRC my first thought was to just tack it onto my resulting HTML when I'm parsing. However, this is proving more difficult than I anticipated and now I'm wondering if there's a better way.
If there any mechanism/property with QWebPage that I can say "use this URL for relative paths"? Or maybe someone can suggest a better way to accomplish what I want?
Thanks!
In the comments, you mentioned that you're using QWebView::setHtml(). The second, optional parameter of this method sets the URL to use for resolving relative paths. According to the documentation:
External objects such as stylesheets or images referenced in the HTML
document are located relative to baseUrl.
Setting that parameter should be all that's needed here.
I am not able to understand what actually parsing the html means ?
As i understand -
- it means that suppose we have any html file by parsing we can have the contents of the html file and we can edit them using parsing. Am i right ?? (parsing simply gives the idea about the contents and structure inside the file.)
I have one more question-
- I also want to know that suppose i have html file contents stored in a stream suppose (inside IStream *HTMLContents - No matter for now that how i got these contents). Is there any process exist that using these file contents may i create the preview on any window/Dialog Box/Preview pane with the same way exactly as i get the view of that html file in the browser.(for now you can imagine that i have downloded the HTML File contents from any web page(or from any where-No matter- But i have contents of html file in my stream i am sure about it) and i want to render that html file view in my own created window/Dialog Box/Preview pane(i mean it should view exactly as it appears in browser-Yes i know it won't be avle to display some pictures in html file but thats not a problem for me). How to do that ?? (I am using Visual c++ for my accomplishing my task)
Parsing basically means analyzing any data. When you parse HTML, it could be that you are figuring out where all the various elements are located and what do they do.
As for displaying HTML, it depends on what do you want to do:
If you want to open the file in your browser, use something like this.
As for displaying HTML directly in your form, I don't really know of any other way than parsing the HTML and creating your own web rendering engine. Good luck and have fun with that I guess.
Parse HTML means build object model such as DOM: https://en.wikipedia.org/wiki/Document_Object_Model in your program
Background: I'm starting off with Django, and have limited experience with Python, so please bear with me. I've written a Python script that runs periodically (in a cron job) to store data into a SQLite3 database, from which I'd like to read from and generate images with Matplotlib (more specifically, with Basemap). This started off as an interest in learning Python and building an "interesting" enough project. I'm picking the Django framework because it seems reasonably-well documented, although I was pleasantly surprised by web.py because of its "lightweightness" in its requirements (but web.py's sparse documentation makes it a bit harder to start off with); but at the moment, I'm not entirely dead-set on a framework.
The example in question 1874642 is almost what I'm looking for, with an image being generated on-the-fly without requiring having to write it to disk (and thusly having to deal with periodically cleaning up the generated files).
However, what is not clear to me is how the generated image can be incorporated in a template, instead of having the browser simply showing the image. From the tutorial material, I'm guessing that it should be possible to represent the variables incorporated in some django.template.Context into the django.http.HttpResponse, but the referenced example shortcuts it by responding directly with a Mime object instead of building it with a Context.
So what I'm asking is:
Is it necessary to invoke a print_png on the generated Matplotlib FigureCanvas object? Or is the FigureCanvas copyied "unprinted" to the Context, so that in the Django template I explicity write the HTML img tag and put by hand the tag's attributes?
I'm under the impression that I have to write the Canvas to disk (i.e. do a canvas.print_figure("image.png")), so that the HTML img tag sees it in the Django template. But I want to be sure that there isn't a "more manageable way" -- i.e. passing the image in the Context and having the template "magically" generate it. If it's really necessary to write to disk, I suppose I could use Django's filesystem caching facility to write the generated images in some way (checking whether an image was already written for a given input parameter set, of course). I welcome your suggestions on this regard, since it's not yet clear at this time the size and number of the images that will be generated, and thusly I'm looking to avoid spending disk space and instead prefer waiting for an image to be generated (even if it takes a few seconds).
Thank you in advance.
you can pass a StringIO object to pyplot.savefig(), and get the PNG file content by StringIO.getvalue().
This view would serve a PNG image. Just bind it to some URL like "img.png" and use that in an img tag.
def create_fig(request):
# MPL stuff
response = HttpResponse(content_type='image/png')
fig.savefig(response)
return response
Of course, that assumes that you can generate the image independent of the main view. You can pass arguments to the image, like (in urls.py):
url(r'^img(?P<nr>\d+).png$', create_fig),
which passes a (string repr. of) a number nr to create_fig.