main.go

package main

import (
	"log"

	"gopkg.in/gographics/imagick.v2/imagick"
)

func mainInternal() error {
	pdfName := "test.pdf"
	imageName := "test.jpg"
	imagick.Initialize()
	defer imagick.Terminate()

	mw := imagick.NewMagickWand()
	defer mw.Destroy()

	// Must be *before* ReadImageFile
	// Make sure our image is high quality
	if err := mw.SetResolution(300, 300); err != nil {
		return err
	}

	// Load the image file into imagick
	if err := mw.ReadImage(pdfName); err != nil {
		return err
	}

	// Must be *after* ReadImageFile
	// Flatten image and remove alpha channel, to prevent alpha turning black in jpg
	if err := mw.SetImageAlphaChannel(imagick.ALPHA_CHANNEL_FLATTEN); err != nil {
		return err
	}

	// Set any compression (100 = max quality)
	if err := mw.SetCompressionQuality(95); err != nil {
		return err
	}

	// Select only first page of pdf
	mw.SetIteratorIndex(0)
	w := mw.GetImageWidth()
	h := mw.GetImageHeight()
	if err := mw.ThumbnailImage(700, h*700/w); err != nil {
		return err
	}
	err := mw.CropImage(700, 700, 0, 0)
	if err != nil {
		return err
	}
	// Convert into JPG
	if err := mw.SetFormat("jpg"); err != nil {
		return err
	}

	// Save File
	return mw.WriteImage(imageName)
}

func main() {
	if err := mainInternal(); err != nil {
		log.Fatal(err)
	}
}