So I'm writing an accesibility app that needs to know the location of the text entry caret. I tried GUIThreadInfo, but while that works in basic apps like Notepad, it fails in more complex ones like Chrome, iTunes, etc. that handle their own UI.
Is there even a way to get the caret position from apps like this?
Yes, doesn't work. The caret is an implementation detail of user32, associated with a window. Applications like browsers don't use window controls, far too expensive. And they don't have to, there's a separate API to allow such programs to provide an interface to accessibility apps like screen readers. Start reading here. Not easy to use from a C# app, this project can lessen the pain. No endorsement, never actually used it myself.
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i need to block any screen capture software on the computer from taking screen shots. Since all of them are work on standard API-functions, i think i could monitor and block them.
I need to use C#.
All i have found is how to monitor and block them in a certain program (screen capture program). They are looking for a function in the program, then they change it address on mine function address.
But how can i do it, if i haven't any certain programs? I need to block anyone which tries to take a screenshot.
If your final goal is possible or not I don't know, but for the hooking the API portion I can help you out.
I have used the library EasyHook many times in the past, this will let you hook and intercept system function calls from C# code fairly easily. Just read through the PDF tutorial for setup instructions.
For actually finding the API's I recommend Rohitab's API Monitor, it's still in Alpha stages but it works really well and is free. You just hook it on to a processes and it tells you every external DLL call it makes (with the parameters it passed if you have the xml definition file for the DLL, the program comes with almost all of the windows API dll's pre-defined).
The combination of EasyHook and API Monitor is a great 1-2 punch for mucking with other program's calls.
It is not possible to prevent screenshots from being taken. The battle is already lost because of the DWM (Desktop Window Manager). It's lower level than Win32 and device contexts.
If you want to protect the text in your program, there are a lot easier ways to extract it than doing screenshots and OCR. TextOut and/or Direct2D hooking and accessibility APIs.
If there's a lot of IP in your program. Then don't make it all available onscreen. Make sure it's tedious to crawl the GUI for text, and hard to automate it. And don't load whole texts in memory of the program.
Possible solutions:
1. To prevent copying of text. Draw the text as an image.
2. To prevent accessibility technologies, like screen readers - override WndProc in your control, handle and ignore the window message WM_GETOBJECT.
3. To make it harder if they try to use OCR. Draw graphics behind the text. Human readable, but much harder for a machine to interpret it.
Neither of these methods are invasive for the user.
** A very invasive suggestion **:
If you are really serious about preventing anyone from "stealing" your content.
Implement mouse and keyboard hooks. Filter out typical copy shortcuts. Prevent the mouse from leaving the boundaries of your application.
Allow your application to only run when the OS runs well-known processes and services.
If any process starts which you don't recognize, black out the application and notify the user about it, and request the user to close it. And ofc make sure someone is not just spoofing a well-known process.
Monitor the clipboard as you suggested yourself.
You can ofc soften some of these suggestions based on the context of your application.
As Scott just posted it likely can be prevented with API hooks to see that paint events only go to desktop bound handles and not others, and refuse to paint otherwise. However, you need to consider the following scenarios and see if they're relevant threat to your approach or not:
Your software may be running in a virtual machine like VMWare. Such software has capapbilities to capture screen that does so at "virtual hardware" level, and your API hooks will not be able to discern it - and this would be the easiest way approach if I wanted to bypass your protections.
As a post suggests here, nothing also prevents someone to take monitor cable and plug it into another computer's capture card, and take screenshot that way. Again, your hooks will be helpless here.
Bottom line, you can make it somewhat harder to do, but bypassing such protection may be pretty trivial thing to do.
My 2c.
Is it possible, without modifying the Windows OS, to have a piece of software intercept the rendering of the desktop, and modify it before it is displayed? For example, if I wanted to intercept it, and apply a fish-eye effect to my entire screen, would this be possible?
If so, how would I go about doing so? (Don't worry about the effects, was only an example, i merely need the interception side of things)
Also, I need to be able to intercept mouse clicks, and modify their position before Windows responds to the input.
If anyone has links to this, or similar projects in C# or C++, that would also be extremely helpful.
Yes it's possible. E.g. the WinAmp player does that. However that code is very unstable so be prepared to reboot if you try it.
I have a ASP.NET Web Application. I want to access this application in Smart phones and tablet computer. So please help me on this. What are the changes required?
The answer to your question could range from nothing to everything. At the end of the day, it all depends on what you existing app looks like in a target mobile device (iPad, Android, etc). If your existing app looks and functions properly, then you don't have to do anything. If not, well, you figure out what's wrong and make it work.
Your question really isn't suited for StackOverflow because it is way to broad and impossible to answer.
Asp.net applications can run in web browsers, including the ones that come with smart phones and tablets. The main concern would be the various screen sizes of the various devices. Because they vary so much, a good design concept for your asp.net application would be to layout content in a way it can adapt to the screen size.
The best technology for this within an asp.net application, especially for an application that was already built, would be to implement style sheets (.css)
Look at these styles as an example:
float, clear, max-width and max-height
Check these and other styles at: http://www.w3schools.com/css/
Now, there is also the concept of having your asp.net application detect which device is being used and then generate UI code (or load .ascx controls) accordingly to provide device specific displays.
Check:
Request.Browser.IsMobileDevice
Request.UserAgent (http://msdn.microsoft.com/en-us/library/system.web.httprequest.useragent.aspx)
However, I would only suggest using this to a minimum, because if you make a change to your UI, you won’t want to keep updating multiple instances of the UI for different devices.
A good compromise would be to build a style sheet for each group of screen sizes (smart phone, tablet, PC, etc.) and then detect which device is in use and include the respective style sheet.
NB: there are many open source projects, which could get you running more quickly with mobile development in mind. Check sourceforge.net and codeplex.com for examples.
I was wondering how I could set a specific application (as in any running application, not just my own)'s volume level in c#.
I know I'd probably have to use P/invoke, this is fine. I'm just not sure on how the sound api's work and how I would go about getting/setting the volume of specific applications (like the volume mixer in vista/7 can).
I know it's possible to do programattically because nircmd has a feature that can do it.
Any help would be appriciated, thanks.
I think you should look here. Following the links you'll find interfaces and API functions to use to manipulate endpoints' volume. Together with the documentation, Microsoft provided some code samples in C++. As you said, it is possible to get the same functionalities to work in .NET using platform invoke.
I think (and hope) your request is, for all intents and purposes, impossible. Allowing an application to set its own volume is like allowing an application to override the user's notification icon settings. These settings are user settings, so you can't circumvent them.
Imagine for an instance that a user has the volume of his speakers set way up, but has dimmed the volumes of all individual applications. Your application comes along and goes 'whatevs, I'll just set myself to full volume'. You've just made a user go deaf, or at least cower in a corner of the room, scared to death.
my main language is vb/c#.net and I'd like to make a console program but with a menu system.
If any of you have worked with "dos" like programs or iSeries from IBM then thats the style I am going for.
so, was wondering if anyone knows of a "winforms" library that will make my form look like this. I dont mind a "fake winforms look" or a console application but thats how I'd like.
I've used iSeries extensively and I remember exactly what you're talking about. To simulate this look and feel in a C# app, you'll want to create a console project and write text to different areas of the screen with the help of the Console.CursorTop and Console.CursorLeft properties, then calling Console.Write or Console.WriteLine to write out the text in the previously set position. To change colors, before calling WriteLine you'll want to use the Console.ForegroundColor and Console.BackgroundColor properties.
You'll need to listen for input and upon finding a tab character, your program can use its own internal logic to determine where the cursor should appear next (on the next line in the same column, for instance, to simulate those left columns of input fields in your screenshot).
Doing this with a Windows Forms app will be a little trickier and you'd definitely want to write your own control for it (possibly sub-classed from one of the many types of standard multi-line text controls already available).
It's a good question. For many Use Cases the standard Windows (or other windowing) paradigm can be overkill, intimidating, and confusing.
Back in DOS days there were a number of "Windowing" libraries that created various abstractions for doing this.
[After Googling]
Here's a site that lists various libraries including a several that appear to be of interest.
A resource like this would also be handy for Mobile apps, where mouse-driven window apps tend to be not the best fit, especially for workflow-type processes. The Console is a pretty universal lowest-common-denominator abstraction available in most every environment.
You are looking for a curses like library but for windows. And usable from VB & C#.
Curses provides for a even richer text based UI than even iSeries. All sorts of widgetry!
Windows is not really supportive of text interfaces whether on purpose or not so are out of luck.
But ...
Well, how about MonoCurses? I don't know if it will work though. Also look at PDCurses.
And if you don't mind using Python for just the front-end see this.
There are a couple of webifiers or screen scraping programs for iSeries that will create a web or windows user interface on top of your iSeries application. I have never used any of those so there is not a particular one that I can recommend, but you might want to look their for inspiration or reuse.