From 2d8fd3efda1cb3bba0d96c82f4e9eb484026b95d Mon Sep 17 00:00:00 2001
From: gizak <gizak@icloud.com>
Date: Thu, 26 Mar 2015 18:11:41 -0400
Subject: [PATCH] Add braille canvas

---
 canvas.go      | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++
 canvas_test.go | 55 +++++++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 canvas.go
 create mode 100644 canvas_test.go

diff --git a/canvas.go b/canvas.go
new file mode 100644
index 0000000..614635e
--- /dev/null
+++ b/canvas.go
@@ -0,0 +1,74 @@
+// Copyright 2015 Zack Guo <gizak@icloud.com>. All rights reserved.
+// 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
+func (c Canvas) Buffer() []Point {
+	ps := make([]Point, len(c))
+	i := 0
+	for k, v := range c {
+		ps[i] = newPoint(v+brailleBase, k[0], k[1])
+		i++
+	}
+	return ps
+}
diff --git a/canvas_test.go b/canvas_test.go
new file mode 100644
index 0000000..021949c
--- /dev/null
+++ b/canvas_test.go
@@ -0,0 +1,55 @@
+package termui
+
+import (
+	"testing"
+
+	"github.com/davecgh/go-spew/spew"
+)
+
+func TestCanvasSet(t *testing.T) {
+	c := NewCanvas()
+	c.Set(0, 0)
+	c.Set(0, 1)
+	c.Set(0, 2)
+	c.Set(0, 3)
+	c.Set(1, 3)
+	c.Set(2, 3)
+	c.Set(3, 3)
+	c.Set(4, 3)
+	c.Set(5, 3)
+	spew.Dump(c)
+}
+
+func TestCanvasUnset(t *testing.T) {
+	c := NewCanvas()
+	c.Set(0, 0)
+	c.Set(0, 1)
+	c.Set(0, 2)
+	c.Unset(0, 2)
+	spew.Dump(c)
+	c.Unset(0, 3)
+	spew.Dump(c)
+}
+
+func TestCanvasBuffer(t *testing.T) {
+	c := NewCanvas()
+	c.Set(0, 0)
+	c.Set(0, 1)
+	c.Set(0, 2)
+	c.Set(0, 3)
+	c.Set(1, 3)
+	c.Set(2, 3)
+	c.Set(3, 3)
+	c.Set(4, 3)
+	c.Set(5, 3)
+	c.Set(6, 3)
+	c.Set(7, 2)
+	c.Set(8, 1)
+	c.Set(9, 0)
+	bufs := c.Buffer()
+	rs := make([]rune, len(bufs))
+	for i, v := range bufs {
+		rs[i] = v.Ch
+	}
+	spew.Dump(string(rs))
+}