Fix error with caputre and window interfaces

platforms/opencv/camera_driver.go

@@ -11,6 +11,11 @@ import (
 
 var _ gobot.Driver = (*CameraDriver)(nil)
 
+type capture interface {
+	RetrieveFrame(int) *cv.IplImage
+	GrabFrame() bool
+}
+
 type CameraDriver struct {
 	name     string
 	camera   capture

platforms/opencv/helpers_test.go

@@ -2,11 +2,6 @@ package opencv
 
 import cv "github.com/hybridgroup/go-opencv/opencv"
 
-type capture interface {
-	RetrieveFrame(int) *cv.IplImage
-	GrabFrame() bool
-}
-
 type testCapture struct{}
 
 func (c *testCapture) RetrieveFrame(i int) *cv.IplImage {
@@ -17,10 +12,6 @@ func (c *testCapture) GrabFrame() bool {
 	return true
 }
 
-type window interface {
-	ShowImage(*cv.IplImage)
-}
-
 type testWindow struct{}
 
 func (w *testWindow) ShowImage(i *cv.IplImage) { return }

platforms/opencv/window_driver.go

@@ -7,6 +7,10 @@ import (
 
 var _ gobot.Driver = (*WindowDriver)(nil)
 
+type window interface {
+	ShowImage(*cv.IplImage)
+}
+
 type WindowDriver struct {
 	name   string
 	window window