Add help text

src/help.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"github.com/gdamore/tcell"
+	"strings"
+)
+
+const helpTxt = `Press Ctrl-q to quit help
+
+Micro keybindings:
+
+Ctrl-q:   Quit
+Ctrl-s:   Save
+Ctrl-o:   Open file
+
+Ctrl-z:   Undo
+Ctrl-y:   Redo
+
+Ctrl-a:   Select all
+
+Ctrl-c:   Copy
+Ctrl-x:   Cut
+Ctrl-v:   Paste
+
+Ctrl-h:   Open help
+
+Ctrl-u:   Half page up
+Ctrl-d:   Half page down
+PageUp:   Page up
+PageDown: Page down
+
+Ctrl-e:   Set option
+
+Micro options:
+
+colorscheme: loads the colorscheme stored in ~/.micro/colorschemes/'option'.micro
+	default value: 'default'
+
+tabsize: sets the tab size to 'option'
+	default value: '4'
+`
+
+// DisplayHelp displays the help txt
+// It blocks the main loop
+func DisplayHelp() {
+	topline := 0
+	_, height := screen.Size()
+	screen.HideCursor()
+	totalLines := strings.Split(helpTxt, "\n")
+	for {
+		screen.Clear()
+
+		lineEnd := topline + height
+		if lineEnd > len(totalLines) {
+			lineEnd = len(totalLines)
+		}
+		lines := totalLines[topline:lineEnd]
+		for y, line := range lines {
+			for x, ch := range line {
+				st := tcell.StyleDefault
+				screen.SetContent(x, y, ch, nil, st)
+			}
+		}
+
+		screen.Show()
+
+		event := screen.PollEvent()
+		switch e := event.(type) {
+		case *tcell.EventResize:
+			_, height = e.Size()
+		case *tcell.EventKey:
+			switch e.Key() {
+			case tcell.KeyUp:
+				if topline > 0 {
+					topline--
+				}
+			case tcell.KeyDown:
+				if topline < len(totalLines)-height {
+					topline++
+				}
+			case tcell.KeyCtrlQ, tcell.KeyCtrlW, tcell.KeyEscape, tcell.KeyCtrlC:
+				return
+			}
+		}
+	}
+}