Add webcam example

samples/webcam.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+  "fmt"
+	"os"
+  //"path"
+  //"runtime"
+
+  //"github.com/lazywei/go-opencv/opencv"
+	"../opencv" // can be used in forks, comment in real application
+)
+
+func main() {
+	win := opencv.NewWindow("Go-OpenCV Webcam")
+	defer win.Destroy()
+
+  cap := opencv.NewCameraCapture(0)
+	if cap == nil {
+		panic("can not open camera")
+	}
+  defer cap.Release()
+
+  win.CreateTrackbar("Thresh", 1, 100, func(pos int, param ...interface{}) {
+    for {
+      if cap.GrabFrame() {
+        img := cap.RetrieveFrame(1)
+        if img != nil {
+          ProcessImage(img, win, pos)
+        } else {
+          fmt.Println("Image ins nil")
+        }
+      }
+
+      if key := opencv.WaitKey(10); key == 27 {
+        os.Exit(0)
+      }
+    }
+  })
+  opencv.WaitKey(0)
+}
+
+func ProcessImage(img *opencv.IplImage, win *opencv.Window, pos int) error {
+	w := img.Width()
+	h := img.Height()
+
+	// Create the output image
+	cedge := opencv.CreateImage(w, h, opencv.IPL_DEPTH_8U, 3)
+	defer cedge.Release()
+
+	// Convert to grayscale
+	gray := opencv.CreateImage(w, h, opencv.IPL_DEPTH_8U, 1)
+	edge := opencv.CreateImage(w, h, opencv.IPL_DEPTH_8U, 1)
+	defer gray.Release()
+	defer edge.Release()
+
+	opencv.CvtColor(img, gray, opencv.CV_BGR2GRAY)
+
+  opencv.Smooth(gray, edge, opencv.CV_BLUR, 3, 3, 0, 0)
+  opencv.Not(gray, edge)
+
+  // Run the edge detector on grayscale
+  opencv.Canny(gray, edge, float64(pos), float64(pos*3), 3)
+
+  opencv.Zero(cedge)
+  // copy edge points
+  opencv.Copy(img, cedge, edge)
+
+  win.ShowImage(cedge)
+  return nil
+}