Four Js Development Tools Forum

Hello List,

I am looking for a way to display a PDF-File in a GDC-Window.
I want not open the file with a PDF-Viewer, or convert the pages in a JPEG-Format.
It must be possible to "browse" through the File.
I tried to use the Integrated-Browser Function of the GDC. But this is not working.

Has anybody done something like this before?
Thanks in advance.


Stefan Serwe

Hi Stefan,

From a Support point of view, I would highly recommend to use a launchurl frontcall which is fully compatible with all front-ends and which will open the PDF file with the program associated to the PDF extension on the client workstation.

Concerning using PDF files inside integrated browser or else a webcomponent (integrated browser in deprecated in GDC v3, it's better to use an URL-based webcomponent), this is a solution I would not recommend. As mentioned in the documentation (https://4js.com/online_documentation/fjs-fgl-manual-html/?path=fjs-fgl-manual#c_fgl_webcomponent_intro.html), webcomponents may have limitations as they are implemented with a "webview" widget, which is not a full-featured web browser.

So for the GDC, it highly depends on the default PDF viewer installed on the workstation: some of them might be supported by the webview, some others might not. But this is something whereon we don't have control.

Best regards,
Lionel

This topic did come up during the Genero 3.0 EAP.  I think Snorri mentioned he had some success incorporating PDF.js https://github.com/mozilla/pdf.js/blob/master/README.md into a WebComponent.

Reuben 

Helo,

thanks.
I'm not sure if I understand pdf.js correctly.
I read that it is standard PDF-Viewer in firefox.
So I installed Firefox, and tried to display the PDF File to a webcomponent Field.
But it doesn't work.
I tired to wirte a littel html File with an included PDF-Object, but this is not working too.....

Stefan Serwe

Hi.

I have successfully implemented view of PDF files in Genero v3.0. It was impossible in prior versions unless you converted each page to an image. I use the PDF.js viewer from Mozilla. To view your files you have to install it on your webserver.

Here is code and a form that will allow you to see how this works. Save the 4gl to main.4gl and the form to form.per, compile and then you can try it out:

$  fglrun main http://mozilla.github.io/pdf.js/web/viewer.html

Then you can enter any url to see the capabilities.

main.4gl:

DEFINE browser, url STRING

MAIN

let url = arg_val(1)
OPEN WINDOW w WITH FORM "form"
let browser=url
while true
  INPUT BY NAME url, browser  without defaults attributes(unbuffered)
    on action exit exit program
    after field url
      if url is null then next field url end if
      let browser=url
   END INPUT
end while
close window w
END MAIN

form.per:
LAYOUT
GRID
{
Enter url:[e1                                  ]


[browser                                                                             ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
[                                                                                    ]
}
END --GRID
END --LAYOUT

ATTRIBUTES

WEBCOMPONENT browser=FORMONLY.browser
   , STRETCH=BOTH
                   ;
EDIT e1=formonly.url type varchar, scroll;
END --ATTRIBUTES

I hope this helps,
-Snorri
 

Hello Snorri,

thanks, but can you give me a tip how to install pdf.js ?
What do you mean: "install it on your webserver" ?
Have I to install pdf.js on every client ?


Stefan

Hi Stefan.

You need a webserver, like apache running.

To download pdf.js go here: https://mozilla.github.io/pdf.js/getting_started/#download

And download the stable version. Follow the instructions there.

You don't need to install ANYTHING on the clients, that's the beauty of it.

Regards,
-Snorri

Stefan, are you on 2.50 or 3.00 ?
In principle you don't need necessarily apache installed somewhere.
Webcomponents do work without apache in GDC , but in GDC2.50 the automatic deployment of webcomponents is a bit tricky.
(via GAS there is a special location, without GAS there is a special frontcall CALL("standard","setwebcomponentpath",[location],[] which allows you to fgl_putfile the component somewhere to your client and inform GDC where to find it)
In GDC3.00 (assuming then also a 3.00 runtime) webcomponents can be at the same location as the program location and are automatically deployed to the GDC , no matter if the GDC runs via GAS or in direct/ssh mode.
So tell me your version and I'll try to assemble a sample.
Regards, Leo

I you want to use PDF.js, you definitely need a webserver. You also need to put the file you want to display somewhere in the webservers document directory. For example, when I display a PDF file in GDC through PDF.js the url looks something like:

http://MY_SERVER/pdfview/web/viewer.html?file=../../FILES/filename.pdf

Regards,
-Snorri

thanks Snorri,

that was what I was looking for.
I just copied the pdf-js into the webserver directory and put a pdf in the same Directory.
And with the Sample-URL you send me, the PDF ist displayed in the GDC-Window!

Thanks Stefan

Glad to help!

Regs,
-Snorri

Hello Leo,

The Project I need this for is a completely new Project.
This will be written in Genero 3.0 (even a Windows only enviroment)

But we have a lot of Genero 2.50 Projects and it would be fine to see, if it possible too.

Thanks
Stefan

Snorri, for a URL based web component this is absolutely correct.
I was referring to a gICAPI based web component.
This requires giving a componentType in the .per and a bit tweaking of the PDFJS  viewer.html (adding the gICAPI boilerplate routines) and then everything is handled locally at the client side without Apache.
I take the  challenge and will come back to this topic if I have something running out of the box.
Regards, Leo

Thank you Leo!

Regards,
-Snorri

Hi Leo.

Have you managed to look into this? It would be nice to handle everything locally!

Regards,
-Snorri

Hi Snorri, I got it to work , but...
I would not actually recommend to use it.
Why?
We did prepare webcomponents in 3.00 to use build in transmission for the web components html/javascript/css assets to the client.
Unfortunately this transmission does not work for this particular component (its a bug, but a bug being deeply in QtWebKit, so we are unable to fix this easily),
the visual effect is that the html page is shown as source code instead of being rendered... I hope that we can fix that for vNext .
What does work is uploading all needed pieces via fgl_putfile() to the clients data dir and using the setwebcomponentpath frontcall...this implies however that all webcomponents using this particular program need to be uploaded.
You need to check also the assets needed for uploading: the sample works for US locale but for other locales you might need to upload additional assets.
I attach the solution here, as said, its not really nice and understandable due to the uploading hassles.
Note that the makefile is pretty OSX centric : it uses curl to download the pdfjs stuff, but it should be easily adaptable to Linux.
The core of the trick: a small patch implants a gICAPI.js in the main page and enables you to call the displayPDF JS function via a webco frontcall.
% make main.run
press the "show" button and it should show a little demo with a pdf file.

Small addition: the problem appears only if GDC is connected directly or via SSH with the server.
Going via GAS and loading the webcomponent via http does work flawlessly (btw it does work also for GWC-JS)
I updated the main.4gl and attach here (you see  the different ways are distinguished with the viaGAS variable)
Leo

Thanks Leo.

I will look into this. Probably it's just easier to have it all server side. Too many things could go wrong on > 300 clients.

Regards,
-Snorri

Hi Snorri , I'd like to add that it would work anyway only for GDC3.00 , not 2.50 .
Regards, Leo

Yes, I'm aware of that.

Thanks,
-Snorri