Move CascadeClassifier into proper objdetect group

Signed-off-by: deadprogram <ron@hybridgroup.com>

objdetect.go

@@ -0,0 +1,63 @@
+package opencv3
+
+/*
+#cgo linux pkg-config: opencv
+#cgo darwin pkg-config: opencv
+#include <stdlib.h>
+#include "objdetect.h"
+*/
+import "C"
+import (
+	"reflect"
+	"unsafe"
+)
+
+// CascadeClassifier is a bind of `cv::CascadeClassifier`
+type CascadeClassifier struct {
+	p C.CascadeClassifier
+}
+
+// NewCascadeClassifier returns a new CascadeClassifier.
+func NewCascadeClassifier() CascadeClassifier {
+	return CascadeClassifier{p: C.CascadeClassifier_New()}
+}
+
+// Delete CascadeClassifier's pointer.
+func (c *CascadeClassifier) Delete() {
+	C.CascadeClassifier_Delete(c.p)
+	c.p = nil
+}
+
+// Load cascade configuration file to classifier.
+func (c *CascadeClassifier) Load(name string) bool {
+	cName := C.CString(name)
+	defer C.free(unsafe.Pointer(cName))
+	return C.CascadeClassifier_Load(c.p, cName) != 0
+}
+
+// DetectMultiScale detects something which is decided by loaded file. Returns
+// multi results addressed with rectangle.
+func (c *CascadeClassifier) DetectMultiScale(img MatVec3b) []Rect {
+	ret := C.CascadeClassifier_DetectMultiScale(c.p, img.p)
+	defer C.Rects_Delete(ret)
+
+	cArray := ret.rects
+	length := int(ret.length)
+	hdr := reflect.SliceHeader{
+		Data: uintptr(unsafe.Pointer(cArray)),
+		Len:  length,
+		Cap:  length,
+	}
+	goSlice := *(*[]C.Rect)(unsafe.Pointer(&hdr))
+
+	rects := make([]Rect, length)
+	for i, r := range goSlice {
+		rects[i] = Rect{
+			X:      int(r.x),
+			Y:      int(r.y),
+			Width:  int(r.width),
+			Height: int(r.height),
+		}
+	}
+	return rects
+}