expose control menu type and step size via public API (#62)

examples/getcontrols/getcontrols.go

@@ -35,6 +35,6 @@ func main() {
 	cmap := cam.GetControls()
 	fmt.Println("Available controls: ")
 	for id, c := range cmap {
-		fmt.Printf("ID:%08x %-32s  Min: %4d  Max: %5d\n", id, c.Name, c.Min, c.Max)
+		fmt.Printf("ID:%08x %-32s Type: %1d Min: %6d Max: %6d Step: %6d\n", id, c.Name, c.Type, c.Min, c.Max, c.Step)
 	}
 }

v4l2.go

@@ -28,6 +28,7 @@ type control struct {
 	id     uint32
 	name   string
 	c_type controlType
+	step   int32
 	min    int32
 	max    int32
 }
@@ -654,6 +655,7 @@ func queryControls(fd uintptr) []control {
 			c.name = CToGoString(query.name[:])
 			c.min = query.minimum
 			c.max = query.maximum
+			c.step = query.step
 			controls = append(controls, c)
 		}
 	}

webcam.go

@@ -25,6 +25,8 @@ type Control struct {
 	Name string
 	Min  int32
 	Max  int32
+	Type int32
+	Step int32
 }
 
 // Open a webcam with a given path
@@ -179,7 +181,13 @@ func (w *Webcam) SetBufferCount(count uint32) error {
 func (w *Webcam) GetControls() map[ControlID]Control {
 	cmap := make(map[ControlID]Control)
 	for _, c := range queryControls(w.fd) {
-		cmap[ControlID(c.id)] = Control{c.name, c.min, c.max}
+		cmap[ControlID(c.id)] = Control{
+			Name: c.name,
+			Min:  c.min,
+			Max:  c.max,
+			Type: int32(c.c_type),
+			Step: c.step,
+		}
 	}
 	return cmap
 }