// What it does:
//
// This example uses the Window class to open an image file, and then display
// the image in a Window class.
//
// How to run:
//
// go run ./cmd/showimage/main.go /home/ron/Pictures/mcp23017.jpg
//
// +build example

package main

import (
 "fmt"
 "image"
 "image/color"
 "os"

 "gocv.io/x/gocv"
)

func main() {
 if len(os.Args) < 2 {
 fmt.Println("How to run:\n\tshowimage [imgfile]")
 return
 }

 filename := os.Args[1]
 window := gocv.NewWindow("Hello")
 img := gocv.IMRead(filename, gocv.IMReadColor)
 grayImage := gocv.NewMat()
 defer grayImage.Close()

 gocv.CvtColor(img, &grayImage, gocv.ColorBGRToGray)
 destImage := gocv.NewMat()
 gocv.Threshold(grayImage, &destImage, 100, 255, gocv.ThresholdBinaryInv)
 resultImage := gocv.NewMatWithSize(500, 400, gocv.MatTypeCV8U)

 gocv.Resize(destImage, &resultImage, image.Pt(resultImage.Rows(), resultImage.Cols()), 0, 0, gocv.InterpolationCubic)
 gocv.Dilate(resultImage, &resultImage, gocv.NewMat())
 gocv.GaussianBlur(resultImage, &resultImage, image.Pt(5, 5), 0, 0, gocv.BorderWrap)
 results := gocv.FindContours(resultImage, gocv.RetrievalTree, gocv.ChainApproxSimple)
 imageForShowing := gocv.NewMatWithSize(resultImage.Rows(), resultImage.Cols(), gocv.MatChannels4)
 for index, element := range results {
 fmt.Println(index)
 gocv.DrawContours(&imageForShowing, results, index, color.RGBA{R: 0, G: 0, B: 255, A: 255}, 1)
 gocv.Rectangle(&imageForShowing,
 gocv.BoundingRect(element),
 color.RGBA{R: 0, G: 255, B: 0, A: 100}, 1)
 }

 if img.Empty() {
 fmt.Println("Error reading image from: %v", filename)
 return
 }

 for {
 window.IMShow(imageForShowing)
 if window.WaitKey(1) >= 0 {
 break
 }
 }
}