screenshot golang osx

screenshot.go

package main

import (
	"encoding/base64"
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"sync"

	chrome "github.com/mkenney/go-chrome/tot"
	"github.com/mkenney/go-chrome/tot/emulation"
	"github.com/mkenney/go-chrome/tot/page"
	"github.com/mkenney/go-chrome/tot/socket"
)

func main() {

	// Define a chrome instance with remote debugging enabled.
	browser := chrome.New(
		// See https://developers.google.com/web/updates/2017/04/headless-chrome#cli
		// for details about startup flags
		&chrome.Flags{
			"addr":               "localhost",
			"disable-extensions": nil,
			"disable-gpu":        nil,
			"headless":           nil,
			"hide-scrollbars":    nil,
			"no-first-run":       nil,
			"no-sandbox":         nil,
			"port":               9222,
			"remote-debugging-address": "0.0.0.0",
			"remote-debugging-port":    9222,
		},
		"/Applications/Google Chrome.app/Contents/MacOS/Google Chrome", // Path to Chromeium binary
		"/tmp",      // Set the Chromium working directory
		"/dev/null", // Ignore internal Chromium output, set to empty string for os.Stdout
		"/dev/null", // Ignore internal Chromium errors, set to empty string for os.Stderr
	)

	// Start the chrome process.
	if err := browser.Launch(); nil != err {
		panic(err)
	}

	wg := &sync.WaitGroup{}
	for i := 0; i < 10; i++ {
		wg.Add(1)
		p := os.TempDir() + fmt.Sprintf("%d", i) + "example.png"
		go func() {
			defer wg.Done()
			// Open a tab and navigate to the URL you want to screenshot.
			tab, err := browser.NewTab("https://d1u06kz0k4cl3m.cloudfront.net/04a327.svg")
			if nil != err {
				panic(err)
			}

			// Enable Page events for this tab.
			if enableResult := <-tab.Page().Enable(); nil != enableResult.Err {
				panic(enableResult.Err)
			}

			// Create a channel to receive the screenshot data generated by the
			// event handler.
			results := make(chan *page.CaptureScreenshotResult)

			// Create an event handler that executes when the page load event is
			// received.
			loadEventHandler := socket.NewEventHandler(
				"Page.loadEventFired",

				// This function will generate a screenshot and write the data
				// to the results channel.
				func(response *socket.Response) {

					// Set the device emulation parameters.
					overrideResult := <-tab.Emulation().SetDeviceMetricsOverride(
						&emulation.SetDeviceMetricsOverrideParams{
							Width:  1440,
							Height: 1440,
							ScreenOrientation: &emulation.ScreenOrientation{
								Type:  emulation.OrientationType.PortraitPrimary,
								Angle: 90,
							},
						},
					)
					if nil != overrideResult.Err {
						panic(overrideResult.Err)
					}

					// Capture a screenshot of the current state of the current
					// page.
					screenshotResult := <-tab.Page().CaptureScreenshot(
						&page.CaptureScreenshotParams{
							Format: page.Format.Png,
						},
					)
					if nil != screenshotResult.Err {
						return
					}

					results <- screenshotResult
				},
			)

			// Add the handler to the stack for this tab. Multiple handlers can
			// listen to the same event.
			tab.AddEventHandler(loadEventHandler)

			// Wait for the handler to fire
			result := <-results

			// Decode the base64 encoded image data
			data, err := base64.StdEncoding.DecodeString(result.Data)
			if nil != err {
				panic(err)
			}

			// Write the generated image to a file
			err = ioutil.WriteFile(p, data, 0644)
			if nil != err {
				panic(err)
			}

			exec.Command("open", p).Run()
			fmt.Println("Finished rendering example.jpg")
		}()
	}
	wg.Wait()
}