golang学习之go fyne GUI编程

一、fyne 项目搭建

1、fyne初始化

新建项目目录 fyne

go mod init fyne

2、fyne依赖安装

go get fyne.io/fyne/v2

go mod tidy

3、gcc安装

fyne包含c/c++代码需要gcc编译，下载TDM-GCC，安装成功后默认设置了环境变量。

二、Hello World

fyne默认没有中文字体，中文乱码。从系统目录C:\Windows\Fonts拷贝中文字体到fyne开发目录，并设置fyne字体 fyne_font。

package main

import (
	"os"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/widget"
)

func main() {
	// 设置中文字体，不然中文乱码
	os.Setenv("FYNE_FONT", "msyhl.ttc")
	a := app.New()
	//创建一个窗口
	w := a.NewWindow("gui编程")
	//设置窗口内显示内容，需要中文字体
	w.SetContent(widget.NewLabel("go GUI 编程"))
	// 设置窗口大小
	w.Resize(fyne.NewSize(400, 400))
	// 窗口居中
	w.CenterOnScreen()
	//展示窗口 并运行程序
	w.ShowAndRun()
}

go run main.go

三、fyne 时钟

fyne 绘制图像界面时钟

package main

import (
	"fmt"
	"image/color"
	"math"
	"time"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/canvas"
	"fyne.io/fyne/v2/container"
)

const (
	secondHandLenth float64 = 180.0
	minuteHandLenth float64 = 120.0
	hourHandLenth   float64 = 80.0
)

func main() {
	clockApp := app.New()
	window := clockApp.NewWindow("时钟")
	window.SetPadded(false)

	yellow := color.RGBA{R: 0xff, G: 0xff, B: 0xcc, A: 0xff}
	circle := canvas.NewCircle(yellow)
	circle.StrokeWidth = 1
	circle.StrokeColor = color.Black
	// 圆所在正方形的左上角坐标
	circle.Position1.X = 0
	circle.Position1.Y = 0
	// 圆所在正方形的右下角坐标
	circle.Position2.X = 400
	circle.Position2.Y = 400
	layout := container.NewWithoutLayout(circle)

// 刻度
	for i := 1; i <= 12; i++ {
		scale := canvas.NewText(fmt.Sprint(i), color.Black)
		scale.Alignment = fyne.TextAlignCenter
		size := scale.MinSize()
		// 根据字体大小计算刻度位置偏移量
		h := size.Height / 2
		//w := size.Width
		
		// 移动刻度至合适位置
		scale.Move(fyne.NewPos(getX(i*5, secondHandLenth), getY(i*5, secondHandLenth)-h))
		layout.Add(scale)
	}

	now := time.Now()

	second := now.Second()
	secondHand := drawPointer(second, secondHandLenth)
	layout.Add(secondHand)

	minute := now.Minute()
	minuteHand := drawPointer(minute, minuteHandLenth)
	layout.Add(minuteHand)

	hour := now.Hour() * 5
	hourHand := drawPointer(hour, hourHandLenth)
	layout.Add(hourHand)

	window.SetContent(layout)

	go func() {
		for {
			time.Sleep(1 * time.Second)
			now := time.Now()

			second := now.Second()
			secondHand.Position2.X = getX(second, secondHandLenth)
			secondHand.Position2.Y = getY(second, secondHandLenth)
			secondHand.Refresh()

			minute := now.Minute()
			minuteHand.Position2.X = getX(minute, minuteHandLenth)
			minuteHand.Position2.Y = getY(minute, minuteHandLenth)
			minuteHand.Refresh()

			hour := now.Hour() * 5
			hourHand.Position2.X = getX(hour, hourHandLenth)
			hourHand.Position2.Y = getY(hour, hourHandLenth)
			hourHand.Refresh()
		}
	}()

	window.Resize(fyne.NewSize(400, 400))
	window.CenterOnScreen()
	window.ShowAndRun()
}
// 绘制时钟指针
func drawPointer(second int, pointerLen float64) *canvas.Line {
	pointerHand := canvas.NewLine(color.Black)
	pointerHand.Position1.X = 200
	pointerHand.Position1.Y = 200
	pointerHand.Position2.X = getX(second, pointerLen)
	pointerHand.Position2.Y = getY(second, pointerLen)

	return pointerHand
}

func getX(second int, pointerLen float64) float32 {
	return float32(200 + pointerLen*math.Cos(float64((math.Pi/float64(30))*float64(second)-(math.Pi/2))))
}

func getY(second int, pointerLen float64) float32 {
	return float32(200 + pointerLen*math.Sin(float64((math.Pi/float64(30))*float64(second)-(math.Pi/2))))
}

运行结果如下图所示：