skroll

text scroller
git clone git://git.2f30.org/skroll.git
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commit 1a40c6b37cd6aec6c0e0694d95b2bf43a7d51a96
parent e5cfcfc2a35661baa401312bc9506fd3e3069b7d
Author: z3bra <willy@mailoo.org>
Date:   Wed,  3 Sep 2014 17:10:28 +0200

Introducing 'smooth scrolling'. text now starts from the right and scrolls from here

Diffstat:
skroll.c | 60+++++++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 53 insertions(+), 7 deletions(-)

diff --git a/skroll.c b/skroll.c @@ -26,7 +26,7 @@ static bool newline = false;/* print a new line after each step */ static bool loop = false; /* wether to loop text or not */ -static float delay = 1; /* scroll speed, in usec */ +static float delay = 0.5; /* scroll speed, in seconds */ static int number = 10; /* number of chars to be shown at the same time */ /* fills a string with spaces if it has less than <num> chars */ @@ -52,22 +52,68 @@ void zero_fill (char **str, size_t num) return; /* void */ } +/* + * pad a string with <num> spaces, and append chars from <str> to it, until its + * lenght is <len> + */ +void zero_pad (char **pad, const char *str, size_t len, size_t num) +{ + /* fill the memory with zeros */ + memset ( (*pad), 0, len ); + + /* pad the string with 0x20 (space char) */ + memset ( (*pad), 0x20, num ); + + /* append char of the *original* string at the end of the pad */ + strncat ( (*pad), str, len ); + + /* fill the stirng with spaces, in case it's too short */ + zero_fill ( pad, len ); + + return; /* void */ +} + /* scroll <input> to stdout */ void skroll (const char *input) { - int offset = 0; + int offset, padder; char *buf = NULL; if ( !(buf = calloc (number, sizeof(char))) ) return; buf[number] = 0; + /* main loop. will loop forever if run with -l */ do { - for (offset=0; input[offset]; ++offset) { - /* copy the number of char we want to the buffer */ - strncpy(buf, input + offset, number-1); - /* fill missing chars with spaces */ - zero_fill(&buf, number); + offset = 0; + padder = number; + + /* loop executed on each step, after <delay> seconds */ + while ( input[offset] != 0 ) { + /* + * There are two different parts: padding, and filling. + * padding is adding spaces at the beginning to simulate text + * arrival from the right. filling is adding spaces at the end of + * the text so that the currently displayed text has always the + * same size, even if there is only a single char + */ + if ( padder > 0 ) { + /* + * While the first letter has not reach the left edge, pad the + * text, decrementing padding after each step. + */ + zero_pad(&buf, input, number, padder); + padder--; + } else + /* Once padding is finished, we start "hiding" text to the left */ + if ( offset < number ) { + /* copy the number of char we want to the buffer */ + strncpy(buf, input + offset, number-1); + + /* fill missing chars with spaces */ + zero_fill(&buf, number); + offset++; + } /* print out the buffer ! */ printf("\r%s", buf);