I need to automatically extract some random screenshots from Flash content (swf) in linux.
I will appreciate any advice on this.
Thanks in advance.
I don't think this is going to be easy, a guess at a possible implementation may be
Run a virtual X server such as Xvfb (this is easy)
Write a program which encapsulates the flash plugin, either by using a browser (for example Mozilla / xulrunner) or implementing the plugin interface directly and invoking the necessary logic. The Netscape plugin interface is documented.
Have some way of waiting for the SWF to fully load, including all sub-components; I don't know how easy it is to tell, as there may not be callbacks for this.
Wait until the flash has got to an interesting section (You may use some arbitrary criteria for this, either just time-based or content based)
Stop the flash (possibly just by suspending the thread etc), and snapshot the window / screen you're using.
If you've got a Xvfb server you can use whatever resolution you want and use the whole screen.
Related
A few years back, we had a programmer create a type of calculator for use in the audio industry. It was created/compiled in C - and is an .exe we offer for free download. once a user downloads it, they can run it locally.
Our goal is to move that application/calculator to the "cloud" where any user can hypothetically visit a URL, and the calculator is there, running, and ready for user interaction by multiple users.
Is what I describe possible?
Will I need Azure?
What exactly in Azure will I need (i.e. which products/resources)?
Do I need to use the compiled/decompiled version?
Will we need to change any code in the .exe to make this work?
What do I not know that I should know?
I sincerely appreciate any and all input from those that are probably reading this and fully understanding the simplicity of it while I struggle to wrap my head around it.
Thank you!
#Alex, Thank you so much for the response. I apologize I was late getting back to you - have 4 kiddos home - I am actually not sure how to answer that fully. Here is a link to the freely downloadable file we offer to anyone and everyone - it does require an email, but that is just for notifications when the version is updated. https://caf.prosoundtraining.com/verify/ and here is the home page of the site: https://caf.prosoundtraining.com - It works by the user downloading the program (which is what we would like to move to the cloud), and then inputing various values for determining what watt amplifier to use based on speaker selection, length of cables, distance of audience from speakers, etc. basically several calculation tools like that, and then the main program that allows users to visualize amplifier performance via running signal tests through the amplifier. Once a user downloads the program, the calculators (which are separate in the decompiled version I have), they can choose to just use the calculators, or the complete program.
Is what I describe possible?
Well, If you are talking about a pure command-line application: yes.
But, If you are talking about a GUI application: If your application not fully usable from the command line, Go back to the source code and strip down all windows, buttons, UI stuff, etc.. AND make it usable from the command line.
Will I need Azure?
Any cloud provider will do just fine. Depending on the traffic, an old laptop with an internet connection might be enough for your case.
What exactly in Azure will I need (i.e. which products/resources)?
Azure virtual machine with a publicly accessible IP.
Do I need to use the compiled/decompiled version?
Will we need to change any code in the .exe to make this work?
What do I not know that I should know?
Using decompiled version (Source code):
WebAssembly
WebAssembly is a new type of code that can be run in modern web browsers — it is a low-level assembly-like language with a compact binary format that runs with near-native performance and provides languages such as C/C++, C# and Rust with a compilation target so that they can run on the web. It is also designed to run alongside JavaScript, allowing both to work together.
Emscripten
Compile C and C++ code, or any other language that uses LLVM, into WebAssembly, and run it on the Web, Node.js, or other wasm runtimes.
Using compiled verison (executable):
Common Gateway Interface-ish approach
Common Gateway Interface (CGI) is an interface specification for web servers to execute programs like console applications (also called command-line interface programs) running on a server that generates web pages dynamically. Such programs are known as CGI scripts or simply as CGIs. The specifics of how the script is executed by the server are determined by the server. In the common case, a CGI script executes at the time a request is made and generates HTML.
My suggestion would be to use python, PHP or any scripting language you are familiar with to spin up a webserver and execute command based on incoming requests.
Python example:
import subprocess
from flask import Flask
app = Flask(__name__)
#app.route('/calculator') # Accessible from http://[ipaddress]:[port]/calculator
def hello_RedPanda():
command = "..." # as if you are running your program from cmd.
result = subprocess.check_output(command) # execute given command
return result # to your web browser
Once you are done with all the back-end pluming, you can add your buttons and tabs back by rebuilding your UI on the client-side using HTML, CSS and Javascript.
Building the UI in client-side is actually the easy part. The really tricky part in your case is (as I mentioned above) making your application usable from the command line.
See more:
WebAssembly
Emscripten
CGI
A case similar to yours
I am writing an application that will occasionally save data. The Problem is now, when a user logs out of X11 and my application did not yet save the changes, is there a way to detect the logout and write the changes to disk? I tried inmplementing a signal handler for SIGHUP and SIGQUIT without success. Is there a signal that gets emitted or is there a way to lsiten for a logout?
Read ICCCM and EWMH (both are quite large specifications that you should read carefully).
In practice, your X11 application is likely to use some existing GUI toolkit like e.g. Qt or GTK (be sure to use at least GTK3). Then that toolkit should have support related to sessions.
For Qt: look into QSessionManager.
For GTK: see GtkApplication
(if you are stuck with GTK2 - e.g. with lablgtk -, you'll spend months or one or two years of efforts to implement EWMH sessions in your code; porting it to GTK3 -or even to Qt5- should be wiser and might be less work) Since GTK (both GTK2 and GTK3) is free software, you could study the source code (and perhaps be inspired by it, or adapt it to your needs, and/or make an educated guess of the amount of efforts to rewrite it).
Remember that X11 is a network protocol, and the server and the client (and the window manager) could run on different machines (e.g. thru ssh -X). Sending SIGTERM through the network has no sense (and that could explain why EWMH don't mention it).
A workaround might perhaps be to save the state periodically (e.g. every two minutes; then only two minutes of work is lost).
Basile's recommendation of looking at your toolkit's relevant classes (QSessionManager and GtkApplication) is good. I'm thankful he posted that because it helped me find the specific stuff I was looking for.
But if it's as you say, and your toolkit doesn't have built-in session management support, the relevant specification is not EWMH, but rather XSMP. There's a small amount of additional information included in ICCCM that you should also watch out for.
This is far from being a couple years of work. The relevant client-side portions of the session manager protocol should only take a few hours, maybe a couple days if you're unfamiliar with integrating low-level X11 protocols into an existing application stack.
I'll be the first to admit that my programming experience and skill in web services is practically non-existent. I usually program things that run completely isolated or locally, with either C or assembly. I'm proficient enough to get a website going, with some basic authentication and directory read access on the system. That's about it.
I'm trying to do a project that's well outside of my comfort zone and get some experience in controlling stuff remotely/via web. Using a Raspberry Pi running Debian, I'm running a program on it in C that takes in information such as video and UART data, does some crunching and triggers some outputs and writes events to a file/folder. This component is fairly straightforward to get running automatically. Getting a webserver up so a remote user can look at the files and pictures the driver program creates is also extremely easy.
The problem for me comes in trying to make a GUI on a webpage that can be used to manually control these outputs. I'm going to need some scripting to handle the button presses on the web page, clearly, but is there a scripting language in particular that stands out for using kernel objects/system calls so I can actually talk to that process? I figure the best way is to use message queues, but I don't know if Python or PHP (or another scripting language) are capable of doing this, and if there are any that are better at this than others. What is the preferred way of doing this?
I know it's possible since we've all seen those kitten-cams with the flash container where you can move the camera or trigger things. I just have no idea where to start.
Thanks for any help
Java can call native commands via JNI (http://en.wikipedia.org/wiki/Java_Native_Interface) from within a JVM. So if you already have C code that can handle the controls, it's just a matter of getting Java code to call them.
As for the scripts to handle button presses, there are several options. One way is to do it asynchronously via AJAX (which requires some JavaScript knowledge) or the other is by doing the traditional page refresh on each press. Sorry to be a bit vague on the answer, but this requires a lengthy explanation of how the whole JSP (Java Server Pages)/Servlets eco system works.
Here's a good place to start:
http://www.apl.jhu.edu/~hall/java/Servlet-Tutorial/
Okay, here's a complicated one I've been breaking my head over all week.
I'm creating a self service system, which allows people to identify themselves by barcode or by smartcard, and then perform an arbitrary action. I run a Tomcat application container locally on each machine to serve up the pages and connect to external resources that are required. It also allows me to serve webpages which I then can use to display content on the screen.
I chose HTML as a display technology because it gives a lot of freedom as to how things could look. The program also involves a lot of Javascript to interact with the customer and hardware (through a RESTful API). I picked Javascript because it's a natural complement to HTML and is supported by all modern browsers.
Currently this system is being tested at a number of sites, and everything seems to work okay. I'm running it in Chrome's kiosk mode. Which serves me well, but there are a number of downsides. Here is where the problems start. ;-)
First of all I am petrified that Chrome's auto-update will eventually break my Javascript code. Secondly, I run a small Chrome plugin to read smartcard numbers, and every time the workstation is shutdown incorrectly Chrome's user profile becomes corrupted and the extension needs to be set up again. I could easily fix the first issue by turning off auto-update but it complicates my installation procedure.
Actually, having to install any browser complicates my installation procedure.
I did consider using internet explorer because it's basically everywhere, but with the three dominant versions out there I'm not sure if it's a good approach. My Javascript is quite complex and making it work on older versions will be a pain. Not even mentioning having to write an ActiveX component for my smartcards.
This is why I set out to make a small browser wrapper that runs in full screen, and can read smartcard numbers. This also has downsides. I use Qt: Qt's QtWebkit weighs a hefty 10MB, and it adds another number of dependencies to my application.
It really feels like I have to pick from three options that all have downsides. It really is something I should have investigated before I wrote the entire program. I guess it is a lesson learnt well.
On to the questions:
Is there a pain free way out of this situation? (probably not)
Is there a browser I can depend on without adding tens of megabytes to my project?
Is there another alternative you could suggest?
If you do not see another way out, which option would you pick?
gud day!.
i am to develop a system that would simply list all URL accessed in a browser with its response time.
my probtion is alem is this applica standalone program(not a plug-in to a certain browser) written in c++. every time a user browse, the program then performs certain method.
so it is like, my program would listen to the browsers events. i dont know how to create an EVEN SINK implemetation for the above mention event in web browsers like Internet explorer, mozilla firefox and google chrome.
any suggestion, advise or idea i cant get from you for me to be able to start the development. any areas i need to focus in studying.
thanks alot for your time! hope for your response!:)
best regards!
The easiest way to achieve what you need is intercepting network traffic and extracting URLs from HTTP packets.
You can do this in many ways, e.g.:
using WinPCAP/libPCAP libarary
modifying LSP stack
intercepting winsock functions calls
If you're on the Windows platform, I think your best shot is using the MSAA interface, which is supported by all three browsers.
Documentation:
MSDN Overview and C++ API
Firefox statement of support for MSAA
Chrome
You could take a lower-level approach (such as an LSP), but they're much harder to debug.