├── README
├── calculator.go
└── gui.go


/README:
--------------------------------------------------------------------------------
1 | Simple Go Gtk Calculator using go-gtk (github.com/mattn/go-gtk)
2 | 
3 | 	go get github.com/abiosoft/gocalc
4 | 
5 | Depends on go-gtk
6 | 
7 | 	go get github.com/mattn/go-gtk/gtk


--------------------------------------------------------------------------------
/calculator.go:
--------------------------------------------------------------------------------
 1 | package main
 2 | 
 3 | import (
 4 | 	"fmt"
 5 | )
 6 | 
 7 | // Stores the result of calculations
 8 | var result struct {
 9 | 	last     float32 // stores last result
10 | 	operator string  // the next operator to use
11 | 	active   bool    // whether calculation has started
12 | }
13 | 
14 | // Perform calculation
15 | func Calculation(val float32, operator string) {
16 | 	if !result.active {
17 | 		result.last = val
18 | 		result.operator = operator
19 | 		result.active = true
20 | 		return
21 | 	}
22 | 	switch result.operator {
23 | 	case "+":
24 | 		result.last += val
25 | 	case "-":
26 | 		result.last -= val
27 | 	case "/":
28 | 		result.last /= val
29 | 	case "x":
30 | 		result.last *= val
31 | 	}
32 | 	result.operator = operator
33 | }
34 | 
35 | // Resets the calculator
36 | func Reset() {
37 | 	result.last = 0
38 | 	result.operator = ""
39 | 	result.active = false
40 | }
41 | 
42 | // Generate formatted output, returns a function
43 | func GetResult() string {
44 | 	val := fmt.Sprintf("%f", result.last)
45 | 	exp := fmt.Sprintf("%E", result.last)
46 | 	trim := val[0 : len(val)-7]
47 | 	if len(trim) <= 10 {
48 | 		if val[len(val)-7:] == ".000000" {
49 | 			return trim
50 | 		}
51 | 		if len(val) <= 10 {
52 | 			return func() string {
53 | 				for i := len(val) - 1; i >= len(val)-7; i-- {
54 | 					if val[i] != '0' {
55 | 						return val[0 : i+1]
56 | 					}
57 | 				}
58 | 				return val
59 | 			}()
60 | 		}
61 | 	}
62 | 	return exp
63 | }
64 | 


--------------------------------------------------------------------------------
/gui.go:
--------------------------------------------------------------------------------
  1 | package main
  2 | 
  3 | import (
  4 | 	gtk "github.com/mattn/go-gtk/gtk"
  5 | 	"os"
  6 | 	"strconv"
  7 | 	"strings"
  8 | )
  9 | 
 10 | var (
 11 | 	display   *gtk.Entry // where values are displayed
 12 | 	inputMode = false
 13 | 	nums      = "789/456x123-0.=+"
 14 | 	operators = "/x-+="
 15 | )
 16 | 
 17 | // End the program
 18 | func Quit() {
 19 | 	gtk.MainQuit()
 20 | }
 21 | 
 22 | // Action to be performed by each button, returns a handler function
 23 | func Input(b *gtk.Button) func() {
 24 | 	return func() {
 25 | 		if strings.Index(operators, b.GetLabel()) != -1 {
 26 | 			val, _ := strconv.ParseFloat(display.GetText(), 32)
 27 | 			Calculation(float32(val), b.GetLabel())
 28 | 			display.SetText(GetResult())
 29 | 			inputMode = false
 30 | 		} else {
 31 | 			if inputMode {
 32 | 				display.SetText(display.GetText() + b.GetLabel())
 33 | 			} else {
 34 | 				display.SetText(b.GetLabel())
 35 | 				inputMode = true
 36 | 				if result.operator == "=" {
 37 | 					Reset()
 38 | 				}
 39 | 			}
 40 | 		}
 41 | 	}
 42 | }
 43 | 
 44 | func main() {
 45 | 	gtk.Init(&os.Args)
 46 | 	display = gtk.NewEntry()
 47 | 	window := gtk.NewWindow(gtk.WINDOW_TOPLEVEL)
 48 | 	window.SetTitle("Simple Go Calculator")
 49 | 	window.Connect("destroy", Quit, nil)
 50 | 
 51 | 	// Vertical box containing all components
 52 | 	vbox := gtk.NewVBox(false, 1)
 53 | 
 54 | 	// Menu bar
 55 | 	menubar := gtk.NewMenuBar()
 56 | 	vbox.PackStart(menubar, false, false, 0)
 57 | 
 58 | 	// Add calculator display to vertical box
 59 | 	display.SetCanFocus(false) // disable focus on calcuator display
 60 | 	display.SetText("0")
 61 | 	display.SetAlignment(1.0) //align text to right
 62 | 	vbox.Add(display)
 63 | 
 64 | 	// Menu items
 65 | 	filemenu := gtk.NewMenuItemWithMnemonic("_File")
 66 | 	menubar.Append(filemenu)
 67 | 	filesubmenu := gtk.NewMenu()
 68 | 	filemenu.SetSubmenu(filesubmenu)
 69 | 
 70 | 	aboutmenuitem := gtk.NewMenuItemWithMnemonic("_About")
 71 | 	aboutmenuitem.Connect("activate", func() {
 72 | 		messagedialog := gtk.NewMessageDialog(
 73 | 			window.GetTopLevelAsWindow(),
 74 | 			gtk.DIALOG_MODAL,
 75 | 			gtk.MESSAGE_INFO,
 76 | 			gtk.BUTTONS_OK,
 77 | 			"Simple Go Calculator")
 78 | 		messagedialog.Response(func() {}, nil)
 79 | 		messagedialog.Run()
 80 | 		messagedialog.Destroy()
 81 | 	},
 82 | 		nil)
 83 | 	filesubmenu.Append(aboutmenuitem)
 84 | 
 85 | 	resetmenuitem := gtk.NewMenuItemWithMnemonic("_Reset")
 86 | 	resetmenuitem.Connect("activate", func() { Reset(); display.SetText("0") }, nil)
 87 | 	filesubmenu.Append(resetmenuitem)
 88 | 
 89 | 	exitmenuitem := gtk.NewMenuItemWithMnemonic("E_xit")
 90 | 	exitmenuitem.Connect("activate", Quit, nil)
 91 | 	filesubmenu.Append(exitmenuitem)
 92 | 
 93 | 	// Vertical box containing all buttons
 94 | 	buttons := gtk.NewVBox(false, 5)
 95 | 
 96 | 	for i := 0; i < 4; i++ {
 97 | 		hbox := gtk.NewHBox(false, 5) // a horizontal box for each 4 buttons
 98 | 		for j := 0; j < 4; j++ {
 99 | 			b := gtk.NewButtonWithLabel(string(nums[i*4+j]))
100 | 			b.Clicked(Input(b), nil) //add click event
101 | 			hbox.Add(b)
102 | 		}
103 | 		buttons.Add(hbox) // add horizonatal box to vertical buttons' box
104 | 	}
105 | 
106 | 	vbox.Add(buttons)
107 | 
108 | 	window.Add(vbox)
109 | 	window.SetSizeRequest(250, 250)
110 | 	window.ShowAll()
111 | 	gtk.Main()
112 | }
113 | 


--------------------------------------------------------------------------------