vonzepp
Posts: 14
Joined: Fri Mar 08, 2013 5:39 pm

Remote Scrolling

Fri Jun 28, 2013 6:45 am

Hi

I am using my Raspberry Pi as a display (with a 7 inch screen) for various sources of information. Weather, recipes, news etc. Now I have alot of this working(occasionally) with voice control. However what I can not get working is the ability to scroll down the screen without the need to use a keyboard. So what I want is to be able to do is basically emulate say the pressing the "page down" key on the keyboard from a program. So I can have no keyboard attached to the Pi

PiGraham
Posts: 2667
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: Remote Scrolling

Fri Jun 28, 2013 6:52 am

I believe you can run the processes that would require a PgDn keypress (or any keyboard input) to take input from a named pipe and send a PgDn to them when required. Input to a console process comes via the process's stdin and connecting that to a pipe you can send to delivers information to the process as if you typed it.

See here:
http://stackoverflow.com/questions/5374 ... al-process

User avatar
joan
Posts: 12746
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Remote Scrolling

Fri Jun 28, 2013 7:10 am

You don't specify.

Assuming you are using the console text screen you can use VT220 escape codes, to stdout.

E.g.

Code: Select all

void putTTY(char * buf)
{
   write(1, buf, strlen(buf));
}

void putTTY("\033c"); /* clear console */

/* position cursor */
void putTTYstr(int row, int col, char * buf)
{
   char str[256];

   sprintf(str, "\033[%d;%dH%s", row, col, buf);

   putTTY(str);
}

vonzepp
Posts: 14
Joined: Fri Mar 08, 2013 5:39 pm

Re: Remote Scrolling

Fri Jun 28, 2013 7:44 am

Hi

I want to be able to scroll on the Desktop. Mainly the Internet Browser.

PiGraham
Posts: 2667
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: Remote Scrolling

Fri Jun 28, 2013 7:53 am

vonzepp wrote:Hi

I want to be able to scroll on the Desktop. Mainly the Internet Browser.
Is this a page you wrote that you can put some javascript on?
There are ways to scroll web pages:
http://www.mediacollege.com/internet/ja ... croll.html

User avatar
joan
Posts: 12746
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Remote Scrolling

Fri Jun 28, 2013 8:04 am

vonzepp wrote:Hi

I want to be able to scroll on the Desktop. Mainly the Internet Browser.
Under X? Try http://sourceforge.net/projects/xmacro/

vonzepp
Posts: 14
Joined: Fri Mar 08, 2013 5:39 pm

Re: Remote Scrolling

Fri Jun 28, 2013 8:05 am

Hi

I would rather use pages I haven't written. For instance something like http://www.bbc.co.uk/food/recipes/salmo ... h_36704.mp
So basically being able to scroll down the page as I am cooking by voice control.

But maybe if there is no way I might have to look into automatically rewriting the page.

vonzepp
Posts: 14
Joined: Fri Mar 08, 2013 5:39 pm

Re: Remote Scrolling

Fri Jun 28, 2013 8:15 am

Hi

I will give xmacro a go. Thanks for the tip. Also apologies that last link should really have been. http://www.bbc.co.uk/food/recipes/raspb ... e_49934.mp

User avatar
joan
Posts: 12746
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Remote Scrolling

Fri Jun 28, 2013 8:19 am

vonzepp wrote:Hi

I will give xmacro a go. Thanks for the tip. Also apologies that last link should really have been. http://www.bbc.co.uk/food/recipes/raspb ... e_49934.mp
The last time I wanted to do something similar I downloaded a package from the Debian repository. I don't remember which one.

It's worth bearing in mind that there are lots of Linux machines. Try googling for "linux simulate keypress" if xmacro doesn't work for you.

User avatar
joan
Posts: 12746
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Remote Scrolling

Fri Jun 28, 2013 8:22 am

I probably used xdotool.

sudo apt-get install xdotool

PiGraham
Posts: 2667
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: Remote Scrolling

Fri Jun 28, 2013 8:39 am

joan wrote:I probably used xdotool.

sudo apt-get install xdotool
Solid gold Joan!

vonzepp
Posts: 14
Joined: Fri Mar 08, 2013 5:39 pm

Re: Remote Scrolling

Fri Jun 28, 2013 8:52 pm

Hi

Thanks a million this is prefect.

Return to “General discussion”

Who is online

Users browsing this forum: mfa298, stubright, uhclem and 31 guests