termui/canvas.go

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// Copyright 2017 Zack Guo <zack.y.guo@gmail.com>. All rights reserved.
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// Use of this source code is governed by a MIT license that can
// be found in the LICENSE file.
package termui
/*
dots:
,___,
|1 4|
|2 5|
|3 6|
|7 8|
`````
*/
var brailleBase = '\u2800'
var brailleOftMap = [4][2]rune{
{'\u0001', '\u0008'},
{'\u0002', '\u0010'},
{'\u0004', '\u0020'},
{'\u0040', '\u0080'}}
// Canvas contains drawing map: i,j -> rune
type Canvas map[[2]int]rune
// NewCanvas returns an empty Canvas
func NewCanvas() Canvas {
return make(map[[2]int]rune)
}
func chOft(x, y int) rune {
return brailleOftMap[y%4][x%2]
}
func (c Canvas) rawCh(x, y int) rune {
if ch, ok := c[[2]int{x, y}]; ok {
return ch
}
return '\u0000' //brailleOffset
}
// return coordinate in terminal
func chPos(x, y int) (int, int) {
return y / 4, x / 2
}
// Set sets a point (x,y) in the virtual coordinate
func (c Canvas) Set(x, y int) {
i, j := chPos(x, y)
ch := c.rawCh(i, j)
ch |= chOft(x, y)
c[[2]int{i, j}] = ch
}
// Unset removes point (x,y)
func (c Canvas) Unset(x, y int) {
i, j := chPos(x, y)
ch := c.rawCh(i, j)
ch &= ^chOft(x, y)
c[[2]int{i, j}] = ch
}
// Buffer returns un-styled points
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func (c Canvas) Buffer() Buffer {
buf := NewBuffer()
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for k, v := range c {
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buf.Set(k[0], k[1], Cell{Ch: v + brailleBase})
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}
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return buf
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}