Support checking cell value length with multi-bytes characters (#1517)

cell.go

@@ -20,6 +20,7 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"unicode/utf8"
 )
 
 // CellType is the type of cell value type.
@@ -397,8 +398,8 @@ func (f *File) SetCellStr(sheet, cell, value string) error {
 // setCellString provides a function to set string type to shared string
 // table.
 func (f *File) setCellString(value string) (t, v string, err error) {
-	if len(value) > TotalCellChars {
+	if utf8.RuneCountInString(value) > TotalCellChars {
-		value = value[:TotalCellChars]
+		value = string([]rune(value)[:TotalCellChars])
 	}
 	t = "s"
 	var si int
@@ -458,8 +459,8 @@ func (f *File) setSharedString(val string) (int, error) {
 
 // trimCellValue provides a function to set string type to cell.
 func trimCellValue(value string) (v string, ns xml.Attr) {
-	if len(value) > TotalCellChars {
+	if utf8.RuneCountInString(value) > TotalCellChars {
-		value = value[:TotalCellChars]
+		value = string([]rune(value)[:TotalCellChars])
 	}
 	if len(value) > 0 {
 		prefix, suffix := value[0], value[len(value)-1]

cell_test.go

@@ -176,6 +176,19 @@ func TestSetCellFloat(t *testing.T) {
 	assert.EqualError(t, f.SetCellFloat("Sheet:1", "A1", 123.42, -1, 64), ErrSheetNameInvalid.Error())
 }
 
+func TestSetCellValuesMultiByte(t *testing.T) {
+	value := strings.Repeat("\u042B", TotalCellChars+1)
+
+	f := NewFile()
+	err := f.SetCellValue("Sheet1", "A1", value)
+	assert.NoError(t, err)
+
+	v, err := f.GetCellValue("Sheet1", "A1")
+	assert.NoError(t, err)
+	assert.NotEqual(t, value, v)
+	assert.Equal(t, TotalCellChars, len([]rune(v)))
+}
+
 func TestSetCellValue(t *testing.T) {
 	f := NewFile()
 	assert.EqualError(t, f.SetCellValue("Sheet1", "A", time.Now().UTC()), newCellNameToCoordinatesError("A", newInvalidCellNameError("A")).Error())