From 857725be79d76b26ce84fd62f8fd5cf90be5a70d Mon Sep 17 00:00:00 2001
From: David Oram <david.oram99@gmail.com>
Date: Mon, 14 Sep 2015 17:21:21 +1200
Subject: [PATCH] Added sequence, curve and contour related functions

---
 opencv/cxcore.go       | 12 ++++++++++++
 opencv/cxtype.go       | 27 ++++++++++++++++++++++++++
 opencv/imgproc.go      | 44 ++++++++++++++++++++++++++++++++++++++++++
 opencv/imgproc_test.go |  7 +++----
 4 files changed, 86 insertions(+), 4 deletions(-)

diff --git a/opencv/cxcore.go b/opencv/cxcore.go
index e4bff18..dacd0ba 100644
--- a/opencv/cxcore.go
+++ b/opencv/cxcore.go
@@ -553,6 +553,18 @@ func (seq *Seq) Total() int {
 	return (int)(seq.total)
 }
 
+func (seq *Seq) HNext() *Seq {
+	return (*Seq)(seq.h_next)
+}
+
+func (seq *Seq) VNext() *Seq {
+	return (*Seq)(seq.v_next)
+}
+
+func (seq *Seq) Storage() *MemStorage {
+	return (*MemStorage)(seq.storage)
+}
+
 /****************************************************************************************\
 *                                     Drawing                                 *
 \****************************************************************************************/
diff --git a/opencv/cxtype.go b/opencv/cxtype.go
index 984baa4..6f250e4 100644
--- a/opencv/cxtype.go
+++ b/opencv/cxtype.go
@@ -595,6 +595,18 @@ type Box2D struct {
 	angle  float32
 }
 
+func (box *Box2D) Size() Size2D32f {
+	return box.size
+}
+
+func (box *Box2D) Center() Point2D32f {
+	return box.center
+}
+
+func (box *Box2D) Angle() float32 {
+	return box.angle
+}
+
 type LineIterator C.CvLineIterator
 
 /************************************* CvSlice ******************************************/
@@ -605,6 +617,12 @@ const (
 	CV_WHOLE_SEQ_END_INDEX = C.CV_WHOLE_SEQ_END_INDEX
 )
 
+/* Equivalent to the C constant CV_WHOLE_SEQ */
+func WholeSeq() Slice {
+	slice := C.cvSlice(C.int(0), C.CV_WHOLE_SEQ_END_INDEX)
+	return (Slice)(slice)
+}
+
 /************************************* CvScalar *****************************************/
 
 type Scalar C.CvScalar
@@ -706,6 +724,15 @@ const (
 
 type AttrList C.CvAttrList
 
+/****************************************************************************************/
+/*                  Structural Analysis and Shape Descriptors                           */
+/****************************************************************************************/
+
+/* For use in ApproxPoly */
+const (
+	CV_POLY_APPROX_DP = C.CV_POLY_APPROX_DP
+)
+
 /*****************************************************************************\
 *                                 --- END ---                                 *
 \*****************************************************************************/
diff --git a/opencv/imgproc.go b/opencv/imgproc.go
index 8861bab..53aca58 100644
--- a/opencv/imgproc.go
+++ b/opencv/imgproc.go
@@ -83,3 +83,47 @@ func DrawContours(image *IplImage, contours *Seq, externalColor, holeColor Scala
 		C.int(lineType),
 		C.cvPoint(C.int(offset.X), C.int(offset.Y)))
 }
+
+// CvSeq* cvApproxPoly(const void* src_seq, int header_size, CvMemStorage* storage, int method, double eps, int recursive=0 )
+func ApproxPoly(src *Seq, header_size int, storage *MemStorage, method int, eps float64, recursive int) *Seq {
+	seq := C.cvApproxPoly(
+		unsafe.Pointer(src),
+		C.int(header_size),
+		(*C.CvMemStorage)(storage),
+		C.int(method),
+		C.double(eps),
+		C.int(recursive))
+	return (*Seq)(seq)
+}
+
+// cvArcLength(const void* curve, CvSlice slice=CV_WHOLE_SEQ, int is_closed=-1 )
+func ArcLength(curve *Seq, slice Slice, is_closed bool) float64 {
+	is_closed_int := 0
+	if is_closed {
+		is_closed_int = 1
+	}
+	return float64(C.cvArcLength(unsafe.Pointer(curve),
+		(C.CvSlice)(slice),
+		C.int(is_closed_int)))
+}
+
+func ContourPerimeter(curve *Seq) float64 {
+	return ArcLength(curve, WholeSeq(), true)
+}
+
+// double cvContourArea(const CvArr* contour, CvSlice slice=CV_WHOLE_SEQ, int oriented=0 )
+func ContourArea(contour *Seq, slice Slice, oriented int) float64 {
+	return float64(C.cvContourArea(
+		unsafe.Pointer(contour),
+		(C.CvSlice)(slice),
+		C.int(oriented)))
+}
+
+/* points can be either CvSeq* or CvMat* */
+func FitEllipse2(points unsafe.Pointer) Box2D {
+	box := C.cvFitEllipse2(points)
+	center := Point2D32f{float32(box.center.x), float32(box.center.y)}
+	size := Size2D32f{float32(box.size.width), float32(box.size.height)}
+	angle := float32(box.angle)
+	return Box2D{center, size, angle}
+}
diff --git a/opencv/imgproc_test.go b/opencv/imgproc_test.go
index 9f4509b..037ce28 100644
--- a/opencv/imgproc_test.go
+++ b/opencv/imgproc_test.go
@@ -1,11 +1,11 @@
 package opencv
 
 import (
+	"os"
 	"path"
 	"runtime"
-	"os"
-	"testing"
 	"syscall"
+	"testing"
 )
 
 func TestResize(t *testing.T) {
@@ -72,7 +72,6 @@ func TestFindContours(t *testing.T) {
 	CvtColor(image, grayscale, CV_BGR2GRAY)
 	defer grayscale.Release()
 
-
 	edges := CreateImage(grayscale.Width(), grayscale.Height(), grayscale.Depth(), grayscale.Channels())
 	defer edges.Release()
 	Canny(grayscale, edges, 50, 200, 3)
@@ -87,7 +86,7 @@ func TestFindContours(t *testing.T) {
 	black := NewScalar(0, 0, 0, 0)
 	red := NewScalar(0, 255, 0, 0)
 
-	for ; seq != nil; seq = (*Seq)(seq.h_next) {
+	for ; seq != nil; seq = seq.HNext() {
 		DrawContours(contours, seq, red, black, 0, 2, 8, Point{0, 0})
 	}