update docs and improve compatibility

10 files changed, 59 insertions, 67 deletions

diff --git a/drawing.go b/drawing.go
index 3ce1282..5e5bba9 100644
--- a/drawing.go
+++ b/drawing.go
@@ -1001,8 +1001,6 @@ func (f *File) drawPlotAreaValAx(formatSet *formatChart) []*cAxs {
 		max = nil
 	}
 	var logBase *attrValFloat
-	// Follow OOXML requirements on
-	// [https://github.com/sc34wg4/OOXMLSchemas/blob/2b074ca2c5df38b18ac118646b329b508b5bdecc/Part1/OfficeOpenXML-XMLSchema-Strict/dml-chart.xsd#L1142-L1147]
 	if formatSet.YAxis.LogBase >= 2 && formatSet.YAxis.LogBase <= 1000 {
 		logBase = &attrValFloat{Val: float64Ptr(formatSet.YAxis.LogBase)}
 	}
diff --git a/lib_test.go b/lib_test.go
index 229412c..e4ccdcc 100644
--- a/lib_test.go
+++ b/lib_test.go
@@ -95,6 +95,9 @@ func TestColumnNumberToName_Error(t *testing.T) {
 	if assert.Error(t, err) {
 		assert.Equal(t, "", out)
 	}
+
+	_, err = ColumnNumberToName(TotalColumns + 1)
+	assert.EqualError(t, err, "column number exceeds maximum limit")
 }
 
 func TestSplitCellName_OK(t *testing.T) {
diff --git a/picture.go b/picture.go
index 0e9e3bb..c7f6e27 100644
--- a/picture.go
+++ b/picture.go
@@ -549,11 +549,12 @@ func (f *File) getPictureFromWsDr(row, col int, drawingRelationships string, wsD
 	for _, anchor = range wsDr.TwoCellAnchor {
 		if anchor.From != nil && anchor.Pic != nil {
 			if anchor.From.Col == col && anchor.From.Row == row {
-				drawRel = f.getDrawingRelationships(drawingRelationships,
-					anchor.Pic.BlipFill.Blip.Embed)
-				if _, ok = supportImageTypes[filepath.Ext(drawRel.Target)]; ok {
-					ret, buf = filepath.Base(drawRel.Target), f.XLSX[strings.Replace(drawRel.Target, "..", "xl", -1)]
-					return
+				if drawRel = f.getDrawingRelationships(drawingRelationships,
+					anchor.Pic.BlipFill.Blip.Embed); drawRel != nil {
+					if _, ok = supportImageTypes[filepath.Ext(drawRel.Target)]; ok {
+						ret, buf = filepath.Base(drawRel.Target), f.XLSX[strings.Replace(drawRel.Target, "..", "xl", -1)]
+						return
+					}
 				}
 			}
 		}
diff --git a/picture_test.go b/picture_test.go
index 015d854..f6f716e 100644
--- a/picture_test.go
+++ b/picture_test.go
@@ -152,6 +152,11 @@ func TestGetPicture(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Empty(t, file)
 	assert.Empty(t, raw)
+	f, err = prepareTestBook1()
+	assert.NoError(t, err)
+	f.XLSX["xl/drawings/drawing1.xml"] = MacintoshCyrillicCharset
+	_, _, err = f.getPicture(20, 5, "xl/drawings/drawing1.xml", "xl/drawings/_rels/drawing2.xml.rels")
+	assert.EqualError(t, err, "xml decode error: XML syntax error on line 1: invalid UTF-8")
 }
 
 func TestAddDrawingPicture(t *testing.T) {
diff --git a/rows_test.go b/rows_test.go
index fd7196d..14537eb 100644
--- a/rows_test.go
+++ b/rows_test.go
@@ -169,6 +169,8 @@ func TestSharedStringsReader(t *testing.T) {
 	f := NewFile()
 	f.XLSX["xl/sharedStrings.xml"] = MacintoshCyrillicCharset
 	f.sharedStringsReader()
+	si := xlsxSI{}
+	assert.EqualValues(t, "", si.String())
 }
 
 func TestRowVisibility(t *testing.T) {
diff --git a/stream.go b/stream.go
index 81dea1e..bdc0d26 100644
--- a/stream.go
+++ b/stream.go
@@ -72,7 +72,7 @@ type StreamWriter struct {
 //
 func (f *File) NewStreamWriter(sheet string) (*StreamWriter, error) {
 	sheetID := f.getSheetID(sheet)
-	if sheetID == 0 {
+	if sheetID == -1 {
 		return nil, fmt.Errorf("sheet %s is not exist", sheet)
 	}
 	sw := &StreamWriter{
diff --git a/xmlStyles.go b/xmlStyles.go
index 07413dd..2884800 100644
--- a/xmlStyles.go
+++ b/xmlStyles.go
@@ -13,9 +13,7 @@ package excelize
 
 import "encoding/xml"
 
-// xlsxStyleSheet directly maps the stylesheet element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxStyleSheet is the root element of the Styles part.
 type xlsxStyleSheet struct {
 	XMLName      xml.Name          `xml:"http://schemas.openxmlformats.org/spreadsheetml/2006/main styleSheet"`
 	NumFmts      *xlsxNumFmts      `xml:"numFmts,omitempty"`
@@ -55,9 +53,7 @@ type xlsxProtection struct {
 	Locked bool `xml:"locked,attr"`
 }
 
-// xlsxLine directly maps the line style element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxLine expresses a single set of cell border.
 type xlsxLine struct {
 	Style string     `xml:"style,attr,omitempty"`
 	Color *xlsxColor `xml:"color,omitempty"`
@@ -119,13 +115,10 @@ type xlsxFill struct {
 	GradientFill *xlsxGradientFill `xml:"gradientFill,omitempty"`
 }
 
-// xlsxPatternFill directly maps the patternFill element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need. This element is
-// used to specify cell fill information for pattern and solid color cell fills.
-// For solid cell fills (no pattern), fgColor is used. For cell fills with
-// patterns specified, then the cell fill color is specified by the bgColor
-// element.
+// xlsxPatternFill is used to specify cell fill information for pattern and
+// solid color cell fills. For solid cell fills (no pattern), fgColor is used.
+// For cell fills with patterns specified, then the cell fill color is
+// specified by the bgColor element.
 type xlsxPatternFill struct {
 	PatternType string    `xml:"patternType,attr,omitempty"`
 	FgColor     xlsxColor `xml:"fgColor,omitempty"`
@@ -303,7 +296,7 @@ type xlsxNumFmts struct {
 // format properties which indicate how to format and render the numeric value
 // of a cell.
 type xlsxNumFmt struct {
-	NumFmtID   int    `xml:"numFmtId,attr,omitempty"`
+	NumFmtID   int    `xml:"numFmtId,attr"`
 	FormatCode string `xml:"formatCode,attr,omitempty"`
 }
 
diff --git a/xmlTheme.go b/xmlTheme.go
index 2f181e2..e3588dc 100644
--- a/xmlTheme.go
+++ b/xmlTheme.go
@@ -123,9 +123,9 @@ type xlsxBgFillStyleLst struct {
 	BgFillStyleLst string `xml:",innerxml"`
 }
 
-// xlsxClrScheme maps to children of the clrScheme element in the namespace
-// http://schemas.openxmlformats.org/drawingml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxClrScheme specifies the theme color, stored in the document's Theme
+// part to which the value of this theme color shall be mapped. This mapping
+// enables multiple theme colors to be chained together.
 type xlsxClrSchemeEl struct {
 	XMLName xml.Name
 	SysClr  *xlsxSysClr    `xml:"sysClr"`
diff --git a/xmlWorkbook.go b/xmlWorkbook.go
index 733eb57..89cacd9 100644
--- a/xmlWorkbook.go
+++ b/xmlWorkbook.go
@@ -27,9 +27,9 @@ type xlsxRelationship struct {
 	TargetMode string `xml:",attr,omitempty"`
 }
 
-// xlsxWorkbook directly maps the workbook element from the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxWorkbook contains elements and attributes that encompass the data
+// content of the workbook. The workbook's child elements each have their own
+// subclause references.
 type xlsxWorkbook struct {
 	XMLName             xml.Name                 `xml:"http://schemas.openxmlformats.org/spreadsheetml/2006/main workbook"`
 	FileVersion         *xlsxFileVersion         `xml:"fileVersion"`
@@ -153,7 +153,7 @@ type xlsxSheets struct {
 type xlsxSheet struct {
 	Name    string `xml:"name,attr,omitempty"`
 	SheetID int    `xml:"sheetId,attr,omitempty"`
-	ID      string `xml:"http://schemas.openxmlformats.org/officeDocument/2006/relationships id,attr,omitempty"`
+	ID      string `xml:"http://schemas.openxmlformats.org/officeDocument/2006/relationships id,attr"`
 	State   string `xml:"state,attr,omitempty"`
 }
 
diff --git a/xmlWorksheet.go b/xmlWorksheet.go
index 03b1a71..7cd73c4 100644
--- a/xmlWorksheet.go
+++ b/xmlWorksheet.go
@@ -165,25 +165,20 @@ type xlsxSheetFormatPr struct {
 	OutlineLevelCol  uint8    `xml:"outlineLevelCol,attr,omitempty"`
 }
 
-// xlsxSheetViews directly maps the sheetViews element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - Worksheet views
-// collection.
+// xlsxSheetViews represents worksheet views collection.
 type xlsxSheetViews struct {
 	XMLName   xml.Name        `xml:"sheetViews"`
 	SheetView []xlsxSheetView `xml:"sheetView"`
 }
 
-// xlsxSheetView directly maps the sheetView element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need. A single sheet
-// view definition. When more than one sheet view is defined in the file, it
-// means that when opening the workbook, each sheet view corresponds to a
-// separate window within the spreadsheet application, where each window is
-// showing the particular sheet containing the same workbookViewId value, the
-// last sheetView definition is loaded, and the others are discarded. When
-// multiple windows are viewing the same sheet, multiple sheetView elements
-// (with corresponding workbookView entries) are saved.
-// See https://docs.microsoft.com/en-us/dotnet/api/documentformat.openxml.spreadsheet.sheetview
+// xlsxSheetView represents a single sheet view definition. When more than one
+// sheet view is defined in the file, it means that when opening the workbook,
+// each sheet view corresponds to a separate window within the spreadsheet
+// application, where each window is showing the particular sheet containing
+// the same workbookViewId value, the last sheetView definition is loaded, and
+// the others are discarded. When multiple windows are viewing the same sheet,
+// multiple sheetView elements (with corresponding workbookView entries) are
+// saved.
 type xlsxSheetView struct {
 	WindowProtection         bool             `xml:"windowProtection,attr,omitempty"`
 	ShowFormulas             bool             `xml:"showFormulas,attr,omitempty"`
@@ -245,31 +240,27 @@ type xlsxSheetPr struct {
 	PageSetUpPr                       *xlsxPageSetUpPr `xml:"pageSetUpPr,omitempty"`
 }
 
-// xlsxOutlinePr maps to the outlinePr element
-// SummaryBelow allows you to adjust the direction of grouper controls
+// xlsxOutlinePr maps to the outlinePr element. SummaryBelow allows you to
+// adjust the direction of grouper controls.
 type xlsxOutlinePr struct {
 	SummaryBelow bool `xml:"summaryBelow,attr"`
 }
 
-// xlsxPageSetUpPr directly maps the pageSetupPr element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - Page setup
-// properties of the worksheet.
+// xlsxPageSetUpPr expresses page setup properties of the worksheet.
 type xlsxPageSetUpPr struct {
 	AutoPageBreaks bool `xml:"autoPageBreaks,attr,omitempty"`
-	FitToPage      bool `xml:"fitToPage,attr,omitempty"` // Flag indicating whether the Fit to Page print option is enabled.
+	FitToPage      bool `xml:"fitToPage,attr,omitempty"`
 }
 
-// xlsxTabColor directly maps the tabColor element in the namespace currently I
-// have not checked it for completeness - it does as much as I need.
+// xlsxTabColor represents background color of the sheet tab.
 type xlsxTabColor struct {
 	RGB   string  `xml:"rgb,attr,omitempty"`
 	Theme int     `xml:"theme,attr,omitempty"`
 	Tint  float64 `xml:"tint,attr,omitempty"`
 }
 
-// xlsxCols directly maps the cols element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxCols defines column width and column formatting for one or more columns
+// of the worksheet.
 type xlsxCols struct {
 	XMLName xml.Name  `xml:"cols"`
 	Col     []xlsxCol `xml:"col"`
@@ -293,18 +284,18 @@ type xlsxCol struct {
 // xlsxDimension directly maps the dimension element in the namespace
 // http://schemas.openxmlformats.org/spreadsheetml/2006/main - This element
 // specifies the used range of the worksheet. It specifies the row and column
-// bounds of used cells in the worksheet. This is optional and is not required.
-// Used cells include cells with formulas, text content, and cell formatting.
-// When an entire column is formatted, only the first cell in that column is
-// considered used.
+// bounds of used cells in the worksheet. This is optional and is not
+// required. Used cells include cells with formulas, text content, and cell
+// formatting. When an entire column is formatted, only the first cell in that
+// column is considered used.
 type xlsxDimension struct {
 	XMLName xml.Name `xml:"dimension"`
 	Ref     string   `xml:"ref,attr"`
 }
 
-// xlsxSheetData directly maps the sheetData element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxSheetData collection represents the cell table itself. This collection
+// expresses information about each cell, grouped together by rows in the
+// worksheet.
 type xlsxSheetData struct {
 	XMLName xml.Name  `xml:"sheetData"`
 	Row     []xlsxRow `xml:"row"`
@@ -440,9 +431,9 @@ type DataValidation struct {
 	Formula2         string  `xml:",innerxml"`
 }
 
-// xlsxC directly maps the c element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxC collection represents a cell in the worksheet. Information about the
+// cell's location (reference), value, data type, formatting, and formula is
+// expressed here.
 //
 // This simple type is restricted to the values listed in the following table:
 //
@@ -472,9 +463,8 @@ func (c *xlsxC) hasValue() bool {
 	return c.S != 0 || c.V != "" || c.F != nil || c.T != ""
 }
 
-// xlsxF directly maps the f element in the namespace
-// http://schemas.openxmlformats.org/spreadsheetml/2006/main - currently I have
-// not checked it for completeness - it does as much as I need.
+// xlsxF represents a formula for the cell. The formula expression is
+// contained in the character node of this element.
 type xlsxF struct {
 	Content string `xml:",chardata"`
 	T       string `xml:"t,attr,omitempty"`   // Formula type