freeCaculator/Application/calculator.go

package Application

import (
	"fmt"
	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/layout"
	"fyne.io/fyne/v2/widget"
	"github.com/Knetic/govaluate"
	"strconv"
	"strings"
)

/**
@author: sre
@date: 2022/8/22 0022
@desc: todo
**/

// MainShow 主界面函数
func MainShow(w fyne.Window) {
	//先创建一个widget.Entry对象，设置可显示多行：
	display := widget.NewEntry()
	display.MultiLine = true

	//其它数字和符号控件都用widget.Button来表示。
	//按钮也分为两种，一种是没有特殊效果的，点击后直接在显示框中添加对应的字符即可。
	//一种是有特殊效果的，例如清空显示框（AC）、进行计算（=）。
	//中间三行按钮都是前一种，我们使用GridLayout来布局，每行显示 4 个：
	digits := []string{
		"7", "8", "9", "×",
		"4", "5", "6", "-",
		"1", "2", "3", "+",
	}
	var digitBtns []fyne.CanvasObject
	for _, val := range digits {
		digitBtns = append(digitBtns, widget.NewButton(val, input(display, val)))
	}
	digitContainer := container.New(
		layout.NewGridLayout(4),
		digitBtns...)

	clearBtn := widget.NewButton("AC", clear(display))
	signBtn := widget.NewButton("+/-", sign(display))
	percentBtn := widget.NewButton("%", percent(display))
	divideBtn := widget.NewButton("÷", input(display, "÷"))
	clearContainer := fyne.NewContainerWithLayout(
		layout.NewGridLayout(4),
		clearBtn,
		signBtn,
		percentBtn,
		divideBtn,
	)

	zeroBtn := widget.NewButton("0", input(display, "0"))
	dotBtn := widget.NewButton(".", input(display, "."))
	equalBtn := widget.NewButton("=", equals(display))
	zeroContainer := container.New(
		layout.NewGridLayout(2),
		zeroBtn,
		container.New(
			layout.NewGridLayout(2),
			dotBtn,
			equalBtn,
		),
	)

	//最后我们将所有部分用垂直的BoxLayout组合到一起：
	container := container.New(
		layout.NewVBoxLayout(),
		display,
		clearContainer,
		digitContainer,
		zeroContainer,
		//copyright,
	)

	w.SetContent(container)
}

// clear 清空按钮响应比较简单，直接将显示框的Text设置为空即可：
func clear(display *widget.Entry) func() {
	return func() {
		display.Text = ""
		display.Refresh()
	}
}

// sign设计在显示框中显示两行，第一行是上次计算的表达式，第二行是本次的。
// 切换正负号在本次只输入一个数字时将该数字的正负号进行切换：
func sign(display *widget.Entry) func() {
	return func() {
		lines := strings.Split(display.Text, "\n")
		if len(lines) == 0 {
			return
		}

		line := lines[len(lines)-1]
		value, err := strconv.ParseInt(line, 10, 64)
		if err != nil {
			return
		}
		lines[len(lines)-1] = strconv.FormatInt(-value, 10)
		display.Text = strings.Join(lines, "\n")
	}
}

func percent(display *widget.Entry) func() {
	return func() {
		lines := strings.Split(display.Text, "\n")
		if len(lines) == 0 {
			return
		}

		line := lines[len(lines)-1]
		value, err := strconv.ParseInt(line, 10, 64)
		if err != nil {
			return
		}
		valueFloat := float64(value) / 100
		valueStr := strconv.FormatFloat(valueFloat, 'f', -1, 64)
		lines[len(lines)-1] = valueStr
		//lines[len(lines)-1] = strconv.FormatInt(-value, 10)
		display.Text = line + "%=" + strings.Join(lines, "\n")
		display.Refresh()
	}
}

// input 输入回调——将对应字符串拼接到显示框中 =号不算
func input(display *widget.Entry, value string) func() {
	return func() {
		fmt.Println("ui type value:", value)
		display.Text += value
		display.Refresh()
	}
}

// equals 计算表达式的函数 go get github.com/Knetic/govaluate
func equals(display *widget.Entry) func() {
	return func() {
		lines := strings.Split(display.Text, "\n")
		if len(lines) == 0 {
			return
		}

		line := lines[len(lines)-1]
		line = strings.Trim(line, "+÷×")
		exprLine := strings.Replace(line, "÷", "/", -1)
		exprLine = strings.Replace(line, "%", "/100", -1)
		exprLine = strings.Replace(exprLine, "×", "*", -1)
		expr, err := govaluate.NewEvaluableExpression(exprLine)
		if err != nil {
			display.Text = line + "=" + err.Error() + "\n"
			display.Refresh()
			return
		}
		result, err := expr.Evaluate(nil)
		if err != nil {
			fmt.Println(err)
			display.Text = line + "=" + err.Error() + "\n"
			display.Refresh()
			return
		}
		line = line + "=" + fmt.Sprint(result) + "\n"
		display.Text = line
		display.Refresh()

	}
}