Add theme support

Fix some minor bugs
Add default and helloworld themes
Update README

example/dashboard.go

@@ -13,7 +13,7 @@ func main() {
 	}
 	defer ui.Close()
 
-	p := ui.NewP(":PRESS q TO QUIT DEMO")
+	p := ui.NewPar(":PRESS q TO QUIT DEMO")
 	p.Height = 3
 	p.Width = 50
 	p.TextFgColor = ui.ColorWhite
@@ -96,7 +96,7 @@ func main() {
 	lc1 := ui.NewLineChart()
 	lc1.Border.Label = "Line Chart"
 	rndwalk := (func() []float64 {
-		n := 100
+		n := 150
 		d := make([]float64, n)
 		for i := 1; i < n; i++ {
 			if i < 20 {
@@ -116,7 +116,7 @@ func main() {
 	lc1.AxesColor = ui.ColorWhite
 	lc1.LineColor = ui.ColorYellow | ui.AttrBold
 
-	p1 := ui.NewP("Hey!\nI am a borderless block!")
+	p1 := ui.NewPar("Hey!\nI am a borderless block!")
 	p1.HasBorder = false
 	p1.Width = 26
 	p1.Height = 2

example/theme.go

@@ -0,0 +1,144 @@
+package main
+
+import ui "github.com/gizak/termui"
+import tm "github.com/nsf/termbox-go"
+import "math"
+
+import "time"
+
+func main() {
+	err := ui.Init()
+	if err != nil {
+		panic(err)
+	}
+	defer ui.Close()
+
+	ui.UseTheme("helloworld")
+
+	p := ui.NewPar(":PRESS q TO QUIT DEMO")
+	p.Height = 3
+	p.Width = 50
+	p.Border.Label = "Text Box"
+
+	strs := []string{"[0] gizak/termui", "[1] editbox.go", "[2] iterrupt.go", "[3] keyboard.go", "[4] output.go", "[5] random_out.go", "[6] dashboard.go", "[7] nsf/termbox-go"}
+	list := ui.NewList()
+	list.Items = strs
+	list.Border.Label = "List"
+	list.Height = 7
+	list.Width = 25
+	list.Y = 4
+
+	g := ui.NewGauge()
+	g.Percent = 50
+	g.Width = 50
+	g.Height = 3
+	g.Y = 11
+	g.Border.Label = "Gauge"
+
+	spark := ui.NewSparkline()
+	spark.Title = "srv 0:"
+	spdata := []int{4, 2, 1, 6, 3, 9, 1, 4, 2, 15, 14, 9, 8, 6, 10, 13, 15, 12, 10, 5, 3, 6, 1, 7, 10, 10, 14, 13, 6}
+	spark.Data = spdata
+
+	spark1 := ui.NewSparkline()
+	spark1.Title = "srv 1:"
+	spark1.Data = spdata
+
+	sp := ui.NewSparklines(spark, spark1)
+	sp.Width = 25
+	sp.Height = 7
+	sp.Border.Label = "Sparkline"
+	sp.Y = 4
+	sp.X = 25
+
+	lc := ui.NewLineChart()
+	sinps := (func() []float64 {
+		n := 100
+		ps := make([]float64, n)
+		for i := range ps {
+			ps[i] = 1 + math.Sin(float64(i)/4)
+		}
+		return ps
+	})()
+
+	lc.Border.Label = "Line Chart"
+	lc.Data = sinps
+	lc.Width = 50
+	lc.Height = 11
+	lc.X = 0
+	lc.Y = 14
+	lc.Mode = "dot"
+
+	bc := ui.NewBarChart()
+	bcdata := []int{3, 2, 5, 3, 9, 5, 3, 2, 5, 8, 3, 2, 4, 5, 3, 2, 5, 7, 5, 3, 2, 6, 7, 4, 6, 3, 6, 7, 8, 3, 6, 4, 5, 3, 2, 4, 6, 4, 8, 5, 9, 4, 3, 6, 5, 3, 6}
+	bclabels := []string{"S0", "S1", "S2", "S3", "S4", "S5"}
+	bc.Border.Label = "Bar Chart"
+	bc.Width = 26
+	bc.Height = 10
+	bc.X = 51
+	bc.Y = 0
+	bc.DataLabels = bclabels
+
+	lc1 := ui.NewLineChart()
+	lc1.Border.Label = "Line Chart"
+	rndwalk := (func() []float64 {
+		n := 150
+		d := make([]float64, n)
+		for i := 1; i < n; i++ {
+			if i < 20 {
+				d[i] = d[i-1] + 0.01
+			}
+			if i > 20 {
+				d[i] = d[i-1] - 0.05
+			}
+		}
+		return d
+	})()
+	lc1.Data = rndwalk
+	lc1.Width = 26
+	lc1.Height = 11
+	lc1.X = 51
+	lc1.Y = 14
+
+	p1 := ui.NewPar("Hey!\nI am a borderless block!")
+	p1.HasBorder = false
+	p1.Width = 26
+	p1.Height = 2
+	p1.X = 52
+	p1.Y = 11
+
+	draw := func(t int) {
+		g.Percent = t % 101
+		list.Items = strs[t%9:]
+		sp.Lines[0].Data = spdata[t%10:]
+		sp.Lines[1].Data = spdata[t/2%10:]
+		lc.Data = sinps[t/2:]
+		lc1.Data = rndwalk[t:]
+		bc.Data = bcdata[t/2%10:]
+		ui.Render(p, list, g, sp, lc, bc, lc1, p1)
+	}
+
+	evt := make(chan tm.Event)
+	go func() {
+		for {
+			evt <- tm.PollEvent()
+		}
+	}()
+
+	i := 0
+	for {
+		select {
+		case e := <-evt:
+			if e.Type == tm.EventKey && e.Ch == 'q' {
+				return
+			}
+		default:
+			draw(i)
+			i++
+			if i == 102 {
+				return
+			}
+			time.Sleep(time.Second / 2)
+		}
+	}
+}