I wanted to create a program where I can stop, start and monitor processes and their outputs, notifications, errors, etc. Probably has been done but I haven't found it.
This my first ncurses program and I'm having a styling issue. I'm reading in an XML file which contains all the initial layout information. This breaks up the terminal into a few sections. Each section I wanted to have a title bar. This would simply be A_REVERSE, or a specified fg/bg color pair.
I hadn't discovered the wattr_on() wattr_off() functions til a minute ago. That's a step in the right direction. But I make a call to wborder() and I'm getting characters where I want none. Specifically:
wborder(pwin, '\0', '\0', ' ', '\0', ' ', ' ', '\0', '\0');
I wanted the NULLs to be no character, not the default. I was trying to do this without loops. Is it possible?
Answer
mvwhline(pwin,0,0,' ',xmax);
wprintw(pwin,"%s",sztitle);
mvwchgat(pwin,0,0,-1,A_REVERSE,0,0);
window borders are window borders, not a headline. If you only want that, it's probably best to just use mvwchgat() to make the headline stand out.
Related
I'm currently designing a CLI interface for linux, and for various reasons I am not able to use ncurses. I am using exclusively C++ and the Qt framework.
Therefore, in order to have a user-friendly interface, I have to run this getch loop in a separate thread:
https://stackoverflow.com/a/912796/3605689
Which basically means I have to implement all basic functionalities (such as backspace) by myself. I have already implemented command completion and command history(like when you press tab or uparrow/downarrow in linux), but I can't figure out how to implement leftarrow/rightarrow (aka seeking through the typeahead).
Normally, I implement it like this: upon every gech which is not equal to -1, I check whether the user has pressed a special key (one that modifies the typeahead somehow). I then clear the stdout using the following function:
void inputobject::clear_line(int nletters)
{
QTextStream(stdout) << "\033[2K";
for(int i = 0; i < nletters;i++){
QTextStream(stdout) << "\b";
}
rewind(stdout);
}
And replace it with something else, effectively simulating the typeahead. For example, in the case of backspace, I would save the command call clear_line, and print the command out again, just with one less letter, behaving exactly as a normal console application would.
My real problem is with the cursor, in the case of left/rightarrow, I need to move the cursor visual in order to be able to indicate where in the text is the user seeking:
Because of the nature of how I rewrite the given stdout line to simulate the typeahead, it does not really matter where the cursor REALLY is, as long as it stays on the same line - it is just the visual that matters. How can I achieve moving the cursor visual on linux?
The answer was provided in the comment by Evilruff:
Cursor Movement
ANSI escape sequences allow you to move the cursor around the screen at will. This is more useful for full screen user interfaces generated by shell scripts, but can also be used in prompts. The movement escape sequences are as follows:
Position the Cursor:
\033[;H
Or
\033[L;Cf
puts the cursor at line L and column C.
Move the cursor up N lines:
\033[NA
Move the cursor down N lines:
\033[NB
Move the cursor forward N columns:
\033[NC
Move the cursor backward N columns:
\033[ND
Clear the screen, move to (0,0):
\033[2J
Erase to end of line:
\033[K
Save cursor position:
\033[s
Restore cursor position:
\033[u
Not using ncurses and co is a serious limitation.
It is hell to make correct input/output on shell for displaying anything.
The only others real solutions (I can't think as a solution to reimplement a ncurse-like library) I think of are:
making call to dialog (for some example www.linuxjournal.com/article/2807 and for the doc: http://linux.die.net/man/1/dialog)
using the framebuffer mecanism with Qt4 (here)
I'm currently designing a CLI interface for linux, and for various reasons I am not able to use ncurses. I am using exclusively C++ and the Qt framework.
Therefore, in order to have a user-friendly interface, I have to run this getch loop in a separate thread:
https://stackoverflow.com/a/912796/3605689
Which basically means I have to implement all basic functionalities (such as backspace) by myself. I have already implemented command completion and command history(like when you press tab or uparrow/downarrow in linux), but I can't figure out how to implement leftarrow/rightarrow (aka seeking through the typeahead).
Normally, I implement it like this: upon every gech which is not equal to -1, I check whether the user has pressed a special key (one that modifies the typeahead somehow). I then clear the stdout using the following function:
void inputobject::clear_line(int nletters)
{
QTextStream(stdout) << "\033[2K";
for(int i = 0; i < nletters;i++){
QTextStream(stdout) << "\b";
}
rewind(stdout);
}
And replace it with something else, effectively simulating the typeahead. For example, in the case of backspace, I would save the command call clear_line, and print the command out again, just with one less letter, behaving exactly as a normal console application would.
My real problem is with the cursor, in the case of left/rightarrow, I need to move the cursor visual in order to be able to indicate where in the text is the user seeking:
Because of the nature of how I rewrite the given stdout line to simulate the typeahead, it does not really matter where the cursor REALLY is, as long as it stays on the same line - it is just the visual that matters. How can I achieve moving the cursor visual on linux?
The answer was provided in the comment by Evilruff:
Cursor Movement
ANSI escape sequences allow you to move the cursor around the screen at will. This is more useful for full screen user interfaces generated by shell scripts, but can also be used in prompts. The movement escape sequences are as follows:
Position the Cursor:
\033[;H
Or
\033[L;Cf
puts the cursor at line L and column C.
Move the cursor up N lines:
\033[NA
Move the cursor down N lines:
\033[NB
Move the cursor forward N columns:
\033[NC
Move the cursor backward N columns:
\033[ND
Clear the screen, move to (0,0):
\033[2J
Erase to end of line:
\033[K
Save cursor position:
\033[s
Restore cursor position:
\033[u
Not using ncurses and co is a serious limitation.
It is hell to make correct input/output on shell for displaying anything.
The only others real solutions (I can't think as a solution to reimplement a ncurse-like library) I think of are:
making call to dialog (for some example www.linuxjournal.com/article/2807 and for the doc: http://linux.die.net/man/1/dialog)
using the framebuffer mecanism with Qt4 (here)
I use the following lines to output my simulation's progress info in my c++ program,
double N=0;
double percent=0;
double total = 1000000;
for (int i; i<total; ++i)
{
percent = 100*i/total;
printf("\r[%6.4f%%]",percent);
}
It works fine!
But the problem is I see the terminal cursor keeps blinking cyclically through the numbers, this is very annoying, anyone knows how to get rid of this?
I've seen some programs like wget or ubuntu apt, they use progress bar or percentages too, but they seems no blinking cursor issue, I am wondering how did they do that?
Thanks!
You can hide and show the cursor using the DECTCEM (DEC text cursor enable mode) mode in DECSM and DECRM:
fputs("\e[?25l", stdout); /* hide the cursor */
fputs("\e[?25h", stdout); /* show the cursor */
Just a guess: try to use a proper number of '\b' (backspace) characters instead of '\r'.
== EDIT ==
I'm not a Linux shell wizard, but this may work:
system("setterm -cursor off");
// ...display percentages...
system("setterm -cursor on");
Don't forget to #include <cstdlib> or <iostream>.
One way to avoid a blinking cursor is (as suggested) to hide the cursor temporarily.
However, that is only part of the solution. Your program should also take this into account:
after hiding the cursor and modifying the screen, before showing the cursor again move it back to the original location.
hiding/showing the cursor only keeps the cursor from noticeably blinking when your updates take only a small amount of time. If you happened to mix this with some time-consuming process, your cursor will blink.
The suggested solution using setterm is not portable; it is specific to the Linux console. And running an executable using system is not really necessary. But even running
system("tput civis");
...
system("tput cnorm");
is an improvement over using setterm.
Checking the source-code for wget doesn't find any cursor-hiding escape sequences. What you're seeing with its progress bar is that it leaves the cursor in roughly the same place whenever it does something time-consuming. The output to the terminal takes so little time that you do not notice the momentary rewrite of the line (by printing a carriage return, then writing most of the line over again). If it were slower, then hiding the cursor would help — up to a point.
By the way — this cursor-hiding technique is used in the terminal drivers for some editors (vim and vile).
Those apps are probably using ncurses. See mvaddstr
The reason the cursor jumps around is because stdout is buffered, so you don't know actually how many characters are being printed at some point in time. The reason wget does not have a jumping cursor is that they are actually printing to stderr instead, which is unbuffered. Try the following:
fprintf(stderr, "\r[%6.4f%%]", percent);
This also has the advantage of not cluttering the file if you are saving the rest of the output somewhere using a pipe like:
$ ./executable > log.data
Press insert key...if that doesn't work then press the fn key in your keyboard.
This will definitely work
Hope this helps
Is it possible to set how many lines the console will print before it starts to erase the top ones? For example, is it possible to set it to 3 and only make the last 3 lines be visible? So:
std::cout<<"line 1!"<<std::endl;
std::cout<<"line 2!"<<std::endl;
std::cout<<"line 3!"<<std::endl;
std::cout<<"line 4!"<<std::endl;
system("pause");
Would output:
line 3!
line 4!
Press any key to continue...
^without creating a scroll bar on the side.
I've been trying to use Console::BufferHeight but I can't seem to get it to work. This is the only thing I've been able to find that seems to be close to what I want to do: http://msdn.microsoft.com/en-us/library/system.console.bufferheight.aspx But It just shows how to read it, not how to set the size. And for some reason typing just std::cout<<System::Console::BufferHeight; gives me scope errors. Any help would be greatly appreciated. Thanks!
I think you want this:
SetConsoleWindowInfo
Example,
HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
SMALL_RECT rect = {0,0, 100, 100};
SetConsoleWindowInfo(hConsole, TRUE, &rect)
Have a look at these as well (experiment with them):
SetConsoleScreenBufferSize()
SetConsoleScreenBufferInfoEx
There is an example on MSDN here.
Im new to programming also, but I tried:
while(!cin.get())
{
}
and it worked,try to place it in the bottom of the code. It will work wonders on your console!
Try changing its position (put it in the middle of the code)
I'd suggest keeping the lines yourself, in a quick class, say that cycles where to put the next line by using an iterator that is always set to point at the next line to be input into.
Next, use FillConsoleOutputCharacter() to print blanks over the lines you previously had printed there.
Then, use SetConsoleCursorPosition() to four(or however many lines you wanted) lines above where you want your input to start, and output each line in you cycle, starting at the one after your iterator. This prints all the lines in order from eldest to youngest.It's been a while, so my knowledge of C++ is kinda hazy, but this should be pretty simple with the standard library and win32 library.
I have been making a program that outputs each character before a given one to the screen, but... I've been doing it with Brainfuck! :)
I would like to be able to input a character, and see all the characters that come before it. The code I have so far only outputs a space and then waits for the next key press before exiting.
++++++++
[>+++++++++<-]>.>++++++++++[>++++++++++<-]>+.+++++++..+++.>
++++++++[>++++<-]>.>++++++++[>++++++++++++<-]>+.+++ ++++++++++.
----------.>++++++++[>++++<-]>.>++++++++++
[>++++++++<-]>+++++++.
++++++++++++++.>+++++++++[>++++++++++++<-]>.---------.>
++++++++++[>+++++++++++<-]>+.--.--------.>+++
[>++++++++++<-]>+++.>++++++++++
..>+[,[>+>+<<-][>>-<<+>>]>[[-.]<]],
I've tried for ages to figure out what's wrong with this code, but everything I've done has messed it up.
Works for me, try this BF interpreter
------[>++++++++++<+]>--.+<------[>---<+]>.