87 lines
2.3 KiB
Go
87 lines
2.3 KiB
Go
// For more tutorials: https://blog.learngoprogramming.com
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//
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// Copyright © 2018 Inanc Gumus
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// Learn Go Programming Course
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//
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package main
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import (
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"fmt"
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"time"
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"github.com/inancgumus/screen"
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)
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func main() {
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for shift := 0; ; shift++ {
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// we need to clear the screen here.
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// or the previous character will be left on the screen
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//
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// alternative: you can fill the rest of the missing placeholders
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// with empty lines
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screen.Clear()
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screen.MoveTopLeft()
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now := time.Now()
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hour, min, sec := now.Hour(), now.Minute(), now.Second()
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clock := [...]placeholder{
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digits[hour/10], digits[hour%10],
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colon,
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digits[min/10], digits[min%10],
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colon,
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digits[sec/10], digits[sec%10],
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}
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for line := range clock[0] {
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l := len(clock)
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// this sets the beginning and the ending placeholder positions (indexes).
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// shift%l prevents the indexing error.
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s, e := shift%l, l
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// to slide the placeholders from the right part of the screen.
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//
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// here, we assume that as if the clock's length is double of its length.
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// this makes things easy to manage: that's why: l*2 is there.
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//
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// shift is always increasing, for it's to go beyond the clock's length,
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// it should be equal or greater than l*2, right (after the remainder of course)?
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//
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// so, if the clock goes beyond its length; this code detects that,
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// and resets the starting position to the first placeholder's index,
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// and it keeps doing so until the clock is fully displayed again.
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if shift%(l*2) >= l {
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s, e = 0, s
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}
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// print empty lines for the missing place holders.
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// this creates the effect of moving placeholders from right to left.
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//
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// l-e can only be non-zero when the above if statement runs.
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// otherwise, l-e is always zero, because l == e.
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//
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// this is one of the other benefits of assuming the length of the
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// clock as the double of its length. otherwise, l-e would always be 0.
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for j := 0; j < l-e; j++ {
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fmt.Print(" ")
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}
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// draw the digits starting from 's' to 'e'
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for i := s; i < e; i++ {
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next := clock[i][line]
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if clock[i] == colon && sec%2 == 0 {
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next = " "
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}
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fmt.Print(next, " ")
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}
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fmt.Println()
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}
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time.Sleep(time.Second)
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}
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}
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