face.go

package main

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

    "gocv.io/x/gocv"
)
// How to run:
//    for human faces
// 		go run ./counter/main.go 0 haarcascade_frontalface_default
//    for cat faces
// 		go run ./counter/main.go 0 haarcascade_frontalcatface_default

func main() {
    if len(os.Args) < 3 {
        fmt.Println("How to run:\n\tfacedetect [camera ID] [classifier XML file]")
        return
    }

    // parse args
    deviceID, _ := strconv.Atoi(os.Args[1])
    xmlFile := os.Args[2]

    // open webcam
    webcam, err := gocv.VideoCaptureDevice(int(deviceID))
    if err != nil {
        fmt.Println(err)
        return
    }
    defer webcam.Close()

    // open display window
    window := gocv.NewWindow("Face Detect")
    defer window.Close()

    // prepare image matrix
    img := gocv.NewMat()
    defer img.Close()

    // color for the rect when faces detected
    blue := color.RGBA{0, 0, 255, 0}

    // load classifier to recognize faces
    classifier := gocv.NewCascadeClassifier()
    defer classifier.Close()

    if !classifier.Load(xmlFile) {
        fmt.Printf("Error reading cascade file: %v\n", xmlFile)
        return
    }

    fmt.Printf("start reading camera device: %v\n", deviceID)
    for {
        if ok := webcam.Read(&img); !ok {
            fmt.Printf("cannot read device %d\n", deviceID)
            return
        }
        if img.Empty() {
            continue
        }

        // detect faces
        rects := classifier.DetectMultiScale(img)
        fmt.Printf("found %d faces\n", len(rects))

        // draw a rectangle around each face on the original image,
        // along with text identifying as "Human"
        for _, r := range rects {
            gocv.Rectangle(&img, r, blue, 3)

            size := gocv.GetTextSize("Human", gocv.FontHersheyPlain, 1.2, 2)
            pt := image.Pt(r.Min.X+(r.Min.X/2)-(size.X/2), r.Min.Y-2)
            gocv.PutText(&img, "Human", pt, gocv.FontHersheyPlain, 1.2, blue, 2)
        }

        // show the image in the window, and wait 1 millisecond
        window.IMShow(img)
        if window.WaitKey(1) >= 0 {
            break
        }
    }
}