diff --git a/debug.go b/debug.go
index 680111f..8e30560 100644
--- a/debug.go
+++ b/debug.go
@@ -81,7 +81,7 @@ func debugDrawTo(w io.Writer, mat Matrix) error {
 	// background
 	rectangle(0, 0, width, height, img, color.Gray16{Y: 0xff12})
 
-	mat.Iterate(IterDirection_COLUMN, func(x int, y int, v qrvalue) {
+	mat.iter(IterDirection_COLUMN, func(x int, y int, v qrvalue) {
 		sx := x*blockWidth + padding
 		sy := y*blockWidth + padding
 		es := (x+1)*blockWidth + padding
diff --git a/mask.go b/mask.go
index cdee293..97b6b97 100644
--- a/mask.go
+++ b/mask.go
@@ -75,7 +75,7 @@ func (m *mask) masking() {
 		panic("impossible panic, contact maintainer plz")
 	}
 
-	m.mat.Iterate(IterDirection_COLUMN, func(x, y int, s qrvalue) {
+	m.mat.iter(IterDirection_COLUMN, func(x, y int, s qrvalue) {
 		// skip the function modules
 		if v, _ := m.mat.at(x, y); v.qrtype() != QRType_INIT {
 			_ = m.mat.set(x, y, QRValue_INIT_V0)
diff --git a/mask_test.go b/mask_test.go
index 2c314de..691a775 100644
--- a/mask_test.go
+++ b/mask_test.go
@@ -15,7 +15,7 @@ func TestMask(t *testing.T) {
 	require.NoError(t, err)
 
 	var stateInitCnt int
-	qrc.mat.Iterate(IterDirection_COLUMN, func(x, y int, s qrvalue) {
+	qrc.mat.iter(IterDirection_COLUMN, func(x, y int, s qrvalue) {
 		if s.qrtype() == QRType_INIT {
 			stateInitCnt++
 		}
diff --git a/matrix.go b/matrix.go
index ae38922..5fb9559 100644
--- a/matrix.go
+++ b/matrix.go
@@ -49,7 +49,7 @@ func (m *Matrix) init() {
 
 // print to stdout
 func (m *Matrix) print() {
-	m.Iterate(IterDirection_ROW, func(x, y int, s qrvalue) {
+	m.iter(IterDirection_ROW, func(x, y int, s qrvalue) {
 		fmt.Printf("%s ", s)
 		if (x + 1) == m.width {
 			fmt.Println()
@@ -96,7 +96,7 @@ func (m *Matrix) set(w, h int, c qrvalue) error {
 	return nil
 }
 
-// at state qrbool from matrix with position {x, y}
+// at state qrvalue from matrix with position {x, y}
 func (m *Matrix) at(w, h int) (qrvalue, error) {
 	if w >= m.width || w < 0 {
 		return QRValue_INIT_V0, ErrorOutRangeOfW
@@ -120,26 +120,28 @@ const (
 
 // Iterate the Matrix with loop direction IterDirection_ROW major or IterDirection_COLUMN major.
 // IterDirection_COLUMN is recommended.
-func (m *Matrix) Iterate(dir iterDirection, f func(int, int, qrvalue)) {
+func (m *Matrix) Iterate(direction iterDirection, fn func(x, y int, s QRValue)) {
+	m.iter(direction, fn)
+}
+
+func (m *Matrix) iter(dir iterDirection, visitFn func(x int, y int, v qrvalue)) {
 	// row direction first
 	if dir == IterDirection_ROW {
 		for h := 0; h < m.height; h++ {
 			for w := 0; w < m.width; w++ {
-				f(w, h, m.mat[w][h])
+				visitFn(w, h, m.mat[w][h])
 			}
 		}
 		return
 	}
 
 	// column direction first
-	if dir == IterDirection_COLUMN {
-		for w := 0; w < m.width; w++ {
-			for h := 0; h < m.height; h++ {
-				f(w, h, m.mat[w][h])
-			}
+	for w := 0; w < m.width; w++ {
+		for h := 0; h < m.height; h++ {
+			visitFn(w, h, m.mat[w][h])
 		}
-		return
 	}
+	return
 }
 
 // Row return a row of matrix, cur should be y dimension.
diff --git a/matrix_test.go b/matrix_test.go
index 86417df..ed524e6 100644
--- a/matrix_test.go
+++ b/matrix_test.go
@@ -1,7 +1,6 @@
 package qrcode
 
 import (
-	"reflect"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -41,25 +40,16 @@ func TestMatrix_Copy(t *testing.T) {
 
 	// change origin
 	_ = m1.set(2, 2, QRValue_DATA_V1)
+	assert.Equal(t, m2, got)
 
-	// compare copy of the matrix
-	if !reflect.DeepEqual(got, m2) {
-		t.Errorf("Matrix.Copy() = %v, want %v", got, m2)
-		t.Fail()
-	}
-
-	if s, err := m1.at(2, 2); err != nil {
-		t.Errorf("Matrix.at() = %v, want %v", QRValue_DATA_V1, s)
-		t.Fail()
-	} else if s != QRValue_DATA_V1 {
-		t.Errorf("Matrix.Copy() = %v, want %v", QRValue_DATA_V1, s)
-		t.Fail()
-	}
+	s, err := m1.at(2, 2)
+	assert.NoError(t, err)
+	assert.Equal(t, QRValue_DATA_V1, s)
 
-	if s, _ := got.at(2, 2); s != QRValue_DATA_V1 {
-		t.Errorf("Matrix.Copy() = %v, want %v", QRValue_DATA_V1, s)
-		t.Fail()
-	}
+	s, err = got.at(2, 2)
+	assert.NoError(t, err)
+	assert.NotEqual(t, QRValue_DATA_V1, s)
+	assert.Equal(t, QRValue_INIT_V0, s)
 }
 
 //func Test_stateSliceMatched(t *testing.T) {
@@ -99,7 +89,7 @@ func TestMatrix_Copy(t *testing.T) {
 //}
 
 // go test -run=NONE -bench Benchmark_Iterate -count 10 > old.txt
-// after change to `m.Iterate(IterDirection_COLUMN, rowIteration)`
+// after change to `m.iter(IterDirection_COLUMN, rowIteration)`
 // go test -run=NONE -bench Benchmark_Iterate -count 10 > new.txt
 // benchstat old.txt new.txt
 func Benchmark_Iterate(b *testing.B) {
@@ -119,8 +109,8 @@ func Benchmark_Iterate(b *testing.B) {
 	}
 
 	for i := 0; i < b.N; i++ {
-		//m.Iterate(IterDirection_ROW, rowIteration)
-		m.Iterate(IterDirection_COLUMN, rowIteration)
+		//m.iter(IterDirection_ROW, rowIteration)
+		m.iter(IterDirection_COLUMN, rowIteration)
 	}
 }
 
diff --git a/matrix_type.go b/matrix_type.go
index 434483c..9f97d74 100644
--- a/matrix_type.go
+++ b/matrix_type.go
@@ -1,5 +1,7 @@
 package qrcode
 
+type QRType = qrtype
+
 // qrtype
 type qrtype uint8
 
@@ -43,6 +45,16 @@ func (s qrtype) String() string {
 	return "?"
 }
 
+type QRValue = qrvalue
+
+func (v QRValue) Type() qrtype {
+	return v.qrtype()
+}
+
+func (v QRValue) IsSet() bool {
+	return v.qrbool()
+}
+
 // qrvalue represents the value of the matrix, it is composed of the qrtype(7bits) and the value(1bits).
 // such as: 0b0000,0011 (QRValue_DATA_V1) represents the qrtype is QRType_DATA and the value is 1.
 type qrvalue uint8
diff --git a/qrcode.go b/qrcode.go
index 5cc8cc7..68980cf 100644
--- a/qrcode.go
+++ b/qrcode.go
@@ -664,7 +664,7 @@ func (q *QRCode) masking() {
 
 // all mask patter and check the maskScore choose the lowest mask result
 func (q *QRCode) xorMask(m *Matrix, mask *mask) {
-	mask.mat.Iterate(IterDirection_COLUMN, func(x, y int, v qrvalue) {
+	mask.mat.iter(IterDirection_COLUMN, func(x, y int, v qrvalue) {
 		// skip the empty place
 		if v.qrtype() == QRType_INIT {
 			return
diff --git a/utilities.go b/utilities.go
index 45b2966..5ec026a 100644
--- a/utilities.go
+++ b/utilities.go
@@ -3,7 +3,7 @@ package qrcode
 // samestate judge two matrix qrtype is same with binary semantic.
 // QRValue_DATA_V0/QRType_INIT only equal to QRValue_DATA_V0, other state are equal to each other.
 func samestate(s1, s2 qrvalue) bool {
-	return s1.qrbool() && s2.qrbool()
+	return s1.qrbool() == s2.qrbool()
 }
 
 func abs(x int) int {