https://github.com/hackergrrl/txt-blit
Draw lines of text onto other lines of text. Cooler than it sounds.
https://github.com/hackergrrl/txt-blit
Last synced: 9 months ago
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Draw lines of text onto other lines of text. Cooler than it sounds.
- Host: GitHub
- URL: https://github.com/hackergrrl/txt-blit
- Owner: hackergrrl
- Created: 2018-05-25T00:51:49.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2024-08-28T00:44:56.000Z (almost 2 years ago)
- Last Synced: 2024-12-27T17:39:24.848Z (over 1 year ago)
- Language: JavaScript
- Homepage:
- Size: 14.6 KB
- Stars: 29
- Watchers: 4
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# txt-blit
> Draw lines of text onto other lines of text.
Handy low-level module that can be used for building
[choo](https://github.com/choojs/choo)-like apps for the terminal.
Combines nicely with [neat-log](https://github.com/joehand/neat-log) for
building reactive terminal apps.
Unicode code points of 0-2 fixed-width font cells are supported, to the extent
made possible by [wcswidth](https://github.com/timoxley/wcwidth).
# Usage: simple component
Let's make a reusable render component (a pure function that returns an array of
text lines) and draw it at different offsets:
```js
var blit = require('txt-blit')
function renderHelloBox () {
return [
'|-----------------------|',
'| |',
'| HELLO THERE |',
'| ~~~~~~~~~~~~~~~ |',
'| |',
'|-----------------------|',
]
}
var screen = [] // empty; blank screen
blit(screen, renderHelloBox(), 2, 2)
blit(screen, renderHelloBox(), 25, 10)
blit(screen, renderHelloBox(), 10, 7)
console.log(screen.join('\n'))
```
outputs
```
|-----------------------|
| |
| HELLO THERE |
| ~~~~~~~~~~~~~~~ |
| |
|-------|-----------------------|
| |
| HELLO THERE |
| ~~~~~~~~~~~~~~~ |--------------|
| | |
|-----------------------|LO THERE |
| ~~~~~~~~~~~~~~~ |
| |
|-----------------------|
```
## Usage: reactive terminal app
Let's combine txt-blit with [neat-log](https://github.com/joehand/neat-log) to
combine some dynamic components:
```js
var blit = require('.')
var neatLog = require('neat-log')
var chalk = require('chalk')
var app = neatLog(view)
app.use(countTheSeconds)
// update state
function countTheSeconds (state, bus) {
state.seconds = 0
setInterval(function () {
state.seconds++
bus.emit('render')
}, 200)
}
// draw screen based on state
function view (state) {
var screen = []
// move hello-box in a sine wave
var x = Math.floor(Math.sin(state.seconds / 5.0) * 10 + process.stdout.columns/2)
blit(screen, renderHelloBox(), x, 3)
// draw timer
blit(screen, renderTimer(state), 10, 10)
// dump screen string to standard out
return screen.join('\n')
}
function renderHelloBox (state) {
return [
'|-----------------------|',
'| |',
'| HELLO THERE |',
'| ~~~~~~~~~~~~~~~ |',
'| |',
'|-----------------------|',
]
}
function renderTimer (state) {
var colours = [
chalk.black,
chalk.red,
chalk.green,
chalk.yellow,
chalk.blue,
chalk.magenta,
chalk.cyan,
chalk.white,
chalk.gray,
chalk.redBright,
chalk.greenBright,
chalk.yellowBright,
chalk.blueBright,
chalk.magentaBright,
chalk.cyanBright,
chalk.whiteBright
]
var colourize = colours[Math.floor(Math.random() * colours.length)]
return [
colours[7]('|TIME: ') + colourize(state.seconds) + colours[7](' |')
]
}
function renderHelloBox () {
return [
'|-----------------------|',
'| |',
'| HELLO THERE |',
'| ~~~~~~~~~~~~~~~ |',
'| |',
'|-----------------------|',
]
}
```
outputs something like
## API
```js
var blit = require('txt-blit')
```
### blit(screen, component, x, y)
Mutates the array of strings (lines) `screen` so that the array of strings
`component` is drawn at the offset `x, y`.
`blit` is smart enough to recognize ANSI escape codes (like colours) and compute
the correct offsets.
`blit` operates fastest if you pass in an array of lines for `screen`, but you
can also pass in a newline-delimited string and `blit` will split/re-join it for
you, though it will not be as fast.
## Install
With [npm](https://npmjs.org/) installed, run
```
$ npm install txt-blit
```
## License
ISC