go - 为什么不更改 gxui 中进度条的映射？

Question

我想使用 gxui 中的进度条，但没有达到我的预期。example正常工作，但改变它我没有成功。这是代码:

package main

import (
    "fmt"
    "io/ioutil"
    "log"
    "net/http"
    "time"

    "github.com/google/gxui"
    "github.com/google/gxui/drivers/gl"
    "github.com/google/gxui/math"
    "github.com/google/gxui/samples/flags"
)

func appMain(driver gxui.Driver) {
    theme := flags.CreateTheme(driver)

    layout := theme.CreateLinearLayout()
    layout.SetHorizontalAlignment(gxui.AlignCenter)

    progressBar := theme.CreateProgressBar()
    progressBar.SetDesiredSize(math.Size{W: 480, H: 60})

    button := theme.CreateButton()
    button.SetText("Start")
    t0 := time.Now()
    button.OnClick(func(gxui.MouseEvent) {
        progressBar.SetTarget(100)
        N := 100

        for count := 0; count < N; count++ {
            resp, err := http.Get("http://example.com")
            if err != nil {
                log.Fatal(err)
            }
            defer resp.Body.Close()

            if count%10 == 0 {

                go func() {
                    driver.Call(func() {
                        fmt.Println("Tuk")
                        progressBar.SetProgress(count * 100 / N)
                    })
                }()
                fmt.Println(count)
                fmt.Println(ioutil.ReadAll(resp.Body))
                fmt.Printf("Elapsed time: %v\n", time.Since(t0))
            }
        }
        progressBar.SetProgress(50)
    })

    layout.AddChild(button)
    layout.AddChild(progressBar)

    window := theme.CreateWindow(500, 100, "Test")
    window.SetScale(flags.DefaultScaleFactor)
    window.AddChild(layout)
    window.OnClose(driver.Terminate)
}

func main() {
    gl.StartDriver(appMain)
}

由于我使用了goroutine，假设输出文本会交替，但是所有goroutine只在主线程之后才执行打印。我做错了什么以及如何解决？

Answer 1

不同之处在于你的 goroutine 进入执行 UI 例程的队列，如 documentation 中所写:

// Call queues f to be run on the UI go-routine, returning before f may have been called.

UI-routine 执行一个循环，所以不能同时处理变化磁带进度条。为了获得期望的结果，有必要在单独的 goroutine 中运行处理函数。修改代码:

package main

import (
    "fmt"
    "io/ioutil"
    "log"
    "net/http"
    "time"

    "github.com/google/gxui"
    "github.com/google/gxui/drivers/gl"
    "github.com/google/gxui/math"
    "github.com/google/gxui/samples/flags"
)

func appMain(driver gxui.Driver) {
    theme := flags.CreateTheme(driver)

    layout := theme.CreateLinearLayout()
    layout.SetHorizontalAlignment(gxui.AlignCenter)

    progressBar := theme.CreateProgressBar()
    progressBar.SetDesiredSize(math.Size{W: 480, H: 60})
    progressBar.SetTarget(100)
    button := theme.CreateButton()
    button.SetText("Start")
    t0 := time.Now()
    button.OnClick(func(gxui.MouseEvent) {
        go func() {
            N := 100
            for count := 0; count < N; count++ {
                resp, err := http.Get("http://example.com")
                if err != nil {
                    log.Fatal(err)
                }
                defer resp.Body.Close()

                driver.Call(func() {
                    progressBar.SetProgress(count * 100 / N)
                })

                fmt.Println(count)
                fmt.Println(ioutil.ReadAll(resp.Body))
                fmt.Printf("Elapsed time: %v\n", time.Since(t0))

            }
            progressBar.SetTarget(100)
        }()
    })

    layout.AddChild(button)
    layout.AddChild(progressBar)

    window := theme.CreateWindow(500, 100, "Test")
    window.SetScale(flags.DefaultScaleFactor)
    window.AddChild(layout)
    window.OnClose(driver.Terminate)

}

func main() {
    gl.StartDriver(appMain)
}