wrap vpx_image into a struct

pkg/codec/vpx/vpx_decoder.go

@@ -97,9 +97,10 @@ func (d *Decoder) Decode(data []byte) {
 	}
 }
 
-func (d *Decoder) GetFrame() *C.vpx_image_t {
+func (d *Decoder) GetFrame() *VpxImage {
 	iter := C.newIter()
-	return C.getFrame(d.codec, iter)
+	img := C.getFrame(d.codec, iter)
+	return &VpxImage{img: img}
 }
 
 func (d *Decoder) FreeDecoderCtx() {

pkg/codec/vpx/vpx_image.go

@@ -0,0 +1,40 @@
+package vpx
+
+/*
+#cgo pkg-config: vpx
+#include <vpx/vpx_image.h>
+*/
+import "C"
+import "unsafe"
+
+type VpxImage struct {
+	img *C.vpx_image_t
+}
+
+func NewImageFromPtr(ptr *C.vpx_image_t) *VpxImage {
+	return &VpxImage{img: ptr}
+}
+
+func (i *VpxImage) Width() int {
+	return int(i.img.d_w)
+}
+
+func (i *VpxImage) Height() int {
+	return int(i.img.d_h)
+}
+
+func (i *VpxImage) YStride() int {
+	return int(i.img.stride[0])
+}
+
+func (i *VpxImage) UStride() int {
+	return int(i.img.stride[1])
+}
+
+func (i *VpxImage) VStride() int {
+	return int(i.img.stride[2])
+}
+
+func (i *VpxImage) Plane(n int) unsafe.Pointer {
+	return unsafe.Pointer(i.img.planes[n])
+}