add auto fit columns function

col.go

@@ -479,9 +479,15 @@ func (f *File) SetColWidth(sheet, startCol, endCol string, width float64) error
 	if err != nil {
 		return err
 	}
+
+	return f.setColWidth(sheet, min, max, width)
+}
+
+func (f *File) setColWidth(sheet string, min, max int, width float64) error {
 	if width > MaxColumnWidth {
 		return ErrColumnWidth
 	}
+
 	ws, err := f.workSheetReader(sheet)
 	if err != nil {
 		return err
@@ -512,6 +518,61 @@ func (f *File) SetColWidth(sheet, startCol, endCol string, width float64) error
 	return err
 }
 
+// AutoFitColWidth provides a function to autofit columns according to
+// their text content
+// Note: this only works on the column with cells which not contains
+// formula cell and style with a number format.
+//
+// For example set column of column H on Sheet1:
+//
+// err = f.AutoFitColWidth("Sheet1", "H")
+//
+// Set style of columns C:F on Sheet1:
+//
+// err = f.AutoFitColWidth("Sheet1", "C:F", style)
+func (f *File) AutoFitColWidth(sheetName string, columns string) error {
+	startColIdx, endColIdx, err := f.parseColRange(columns)
+	if err != nil {
+		return err
+	}
+
+	cols, err := f.Cols(sheetName)
+	if err != nil {
+		return err
+	}
+
+	colIdx := 1
+	for cols.Next() {
+		if colIdx >= startColIdx && colIdx <= endColIdx {
+			rowCells, _ := cols.Rows()
+			max := defaultColWidth
+			for i := range rowCells {
+				rowCell := rowCells[i]
+				cellWidth := float64(len(rowCell) + 3) // + 3 for margin
+
+				if cellWidth > max && cellWidth < MaxColumnWidth {
+					max = cellWidth
+				} else if cellWidth >= MaxColumnWidth {
+					max = MaxColumnWidth
+				}
+			}
+
+			if err := f.setColWidth(sheetName, colIdx, colIdx, max); err != nil {
+				return err
+			}
+		}
+
+		// fast go away
+		if colIdx == endColIdx {
+			break
+		}
+
+		colIdx++
+	}
+
+	return nil
+}
+
 // flatCols provides a method for the column's operation functions to flatten
 // and check the worksheet columns.
 func flatCols(col xlsxCol, cols []xlsxCol, replacer func(fc, c xlsxCol) xlsxCol) []xlsxCol {

col_test.go

@@ -1,6 +1,7 @@
 package excelize
 
 import (
+	"math/rand"
 	"path/filepath"
 	"testing"
 
@@ -360,6 +361,65 @@ func TestColWidth(t *testing.T) {
 	convertRowHeightToPixels(0)
 }
 
+func TestAutoFitColWidth(t *testing.T) {
+	randStr := func(n int) string {
+		var letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+		b := make([]rune, n)
+		for i := range b {
+			b[i] = letterRunes[rand.Intn(len(letterRunes))]
+		}
+		return string(b)
+	}
+
+	f := NewFile()
+	// Test null data columns
+	assert.NoError(t, f.AutoFitColWidth("Sheet1", "A"))
+	width, err := f.GetColWidth("Sheet1", "A")
+	assert.Equal(t, defaultColWidth, width)
+	assert.NoError(t, err)
+
+	// Test some data
+	for _, max := range []int{1, 10, 100, 1000} {
+		f.SetCellValue("Sheet1", "B2", randStr(max/2))
+		f.SetCellValue("Sheet1", "B3", randStr(max))
+		assert.NoError(t, f.AutoFitColWidth("Sheet1", "B:A"))
+		width, err = f.GetColWidth("Sheet1", "A")
+		assert.Equal(t, defaultColWidth, width)
+		assert.NoError(t, err)
+
+		width, err = f.GetColWidth("Sheet1", "B")
+		if float64(max) < defaultColWidth {
+			assert.Equal(t, defaultColWidth, width)
+		} else if max > MaxColumnWidth {
+			assert.Equal(t, float64(MaxColumnWidth), width)
+		} else {
+			assert.Equal(t, float64(max+3), width)
+		}
+		assert.NoError(t, err)
+	}
+
+	// Test All columns
+	f.SetCellValue("sheet1", "C2", randStr(10))
+	f.SetCellValue("sheet1", "D2", randStr(20))
+	f.SetCellValue("sheet1", "E2", randStr(30))
+	assert.NoError(t, f.AutoFitColWidth("Sheet1", "XFD:D"))
+	width, err = f.GetColWidth("Sheet1", "C")
+	assert.Equal(t, defaultColWidth, width)
+	assert.NoError(t, err)
+
+	width, err = f.GetColWidth("Sheet1", "D")
+	assert.Equal(t, float64(23), width)
+	assert.NoError(t, err)
+
+	width, err = f.GetColWidth("Sheet1", "E")
+	assert.Equal(t, float64(33), width)
+	assert.NoError(t, err)
+
+	assert.NoError(t, f.SaveAs(filepath.Join("test", "TestAutoColWidth.xlsx")))
+	convertRowHeightToPixels(0)
+}
+
 func TestGetColStyle(t *testing.T) {
 	f := NewFile()
 	styleID, err := f.GetColStyle("Sheet1", "A")