ncurses does not blink

youngstorm · 04-11-2010, 08:37 PM

Hi,
I am trying to learn ncurses programming with "Programmer's guide to ncurses". Everything seems to work right till I try to make text blink. I get no errors or warnings. Here is my compile command "cc -Wall -lncurses -o twinkle twinkle.c" I am using fedora 12. 'env' shows that TERM=linux. What am I doing wrong?

thank you

#### Code ####
#include <ncurses.h>

int main(void)
{
initscr();

attron(A_BOLD);
addstr("Twinkle, twinkle little star\n");
attron(A_BLINK);
addstr("How I wonder what you are.\n");
attroff(A_BOLD);
addstr("Up above the world so high,\n");
addstr("Like a diamond in the sky.\n");
attrset(A_NORMAL);
addstr("Twinkle, twinkle little star\n");
addstr("How I wonder what you are.\n");
refresh();

endwin();

return 0;
}

BenCollver · 04-12-2010, 09:30 PM

If I change TERM to linux and run this program in konsole on Slackware 13.0, then three lines of text blink.

If I run this program at the Linux console, then those same three lines of text have a gray background color, and they do not blink.

If I pipe to "hexdump -C" then I get the following output.

Code:

00000000  1b 5b 31 3b 32 38 72 1b  5b 30 3b 31 30 6d 1b 5b  |.[1;28r.[0;10m.[|
00000010  34 6c 1b 5b 3f 37 68 1b  5b 48 1b 5b 4a 1b 5b 30  |4l.[?7h.[H.[J.[0|
00000020  3b 31 30 3b 31 6d 54 77  69 6e 6b 6c 65 2c 20 74  |;10;1mTwinkle, t|
00000030  77 69 6e 6b 6c 65 20 6c  69 74 74 6c 65 20 73 74  |winkle little st|
00000040  61 72 0d 0a 1b 5b 30 3b  31 30 3b 35 3b 31 6d 48  |ar...[0;10;5;1mH|
00000050  6f 77 20 49 20 77 6f 6e  64 65 72 20 77 68 61 74  |ow I wonder what|
00000060  20 79 6f 75 20 61 72 65  2e 0d 0a 1b 5b 30 3b 31  | you are....[0;1|
00000070  30 3b 35 6d 55 70 20 61  62 6f 76 65 20 74 68 65  |0;5mUp above the|
00000080  20 77 6f 72 6c 64 20 73  6f 20 68 69 67 68 2c 0d  | world so high,.|
00000090  0a 4c 69 6b 65 20 61 20  64 69 61 6d 6f 6e 64 20  |.Like a diamond |
000000a0  69 6e 20 74 68 65 20 73  6b 79 2e 0d 0a 1b 5b 30  |in the sky....[0|
000000b0  3b 31 30 6d 54 77 69 6e  6b 6c 65 2c 20 74 77 69  |;10mTwinkle, twi|
000000c0  6e 6b 6c 65 20 6c 69 74  74 6c 65 20 73 74 61 72  |nkle little star|
000000d0  0d 0a 48 6f 77 20 49 20  77 6f 6e 64 65 72 20 77  |..How I wonder w|
000000e0  68 61 74 20 79 6f 75 20  61 72 65 2e 0d 0a 1b 5b  |hat you are....[|
000000f0  32 38 3b 31 48 0d                                 |28;1H.|
000000f6

The first blinking line is "How I wonder what you are." It begins with the following escape code.

ESC[0;10;5;1m

Code:

param   result
0       reset all attributes to their defaults
1       set bold
5       set blink
10      reset  selected mapping, display control flag, and toggle meta flag (ECMA-48 says "primary font").

According to console_codes(4), the line ought to boldly blink. I found the above table in the section titled "ECMA-48 Set Graphics Rendition." It says "Several attributes can be set in the same sequence, separated by semicolons."

libncurses, foiled again..

youngstorm · 04-19-2010, 09:39 PM

hello BenCollver2,
Thank you for your reply. I was no fimiliar with hexdump. I tryed "hexdump -C" in fedora 12 but I do not see the ESC[0;10;5;1m anywhere or anything resembling it. I would have assumed it would be in there. Also, how do you know that "ECMA-48" is the correct section? I had no idea.

thanks again,
Mike

BenCollver · 04-19-2010, 10:18 PM

What output do you get from this command? ./twinkle | hexdump -C

Here are the relevant excerpts from my output. The hexadecimal values "1b 5b 30 3b 31 30 3b 35 3b 31 6d" and the ASCII representation ".[0;10;5;1m".

I know that hexadecimal 1b is the same as ESC or the escape character. I did not know about ECMA-48 until I skimmed through the manual and found something that my output resembled.

bigearsbilly · 04-20-2010, 05:15 AM

it's probably more to do with your terminal setup than your program,