Support to create of 17 kinds of fill variants styles

- Update the unit tests
- Update the `SetHeaderFooter` function parameters name
- Update document for the `SetDocProps` and `SetCellHyperLink` functions

cell.go

@@ -835,7 +835,7 @@ type HyperlinkOpts struct {
 //
 //	display, tooltip := "https://github.com/xuri/excelize", "Excelize on GitHub"
 //	if err := f.SetCellHyperLink("Sheet1", "A3",
-//	    "https://github.com/xuri/excelize", "External", excelize.HyperlinkOpts{
+//	    display, "External", excelize.HyperlinkOpts{
 //	        Display: &display,
 //	        Tooltip: &tooltip,
 //	    }); err != nil {

docProps.go

@@ -120,39 +120,45 @@ func (f *File) GetAppProps() (ret *AppProperties, err error) {
 // properties that can be set are:
 //
 //	 Property       | Description
-//	----------------+-----------------------------------------------------------------------------
+//	----------------+-----------------------------------------------------------
 //	 Title          | The name given to the resource.
 //	                |
 //	 Subject        | The topic of the content of the resource.
 //	                |
-//	 Creator        | An entity primarily responsible for making the content of the resource.
+//	 Creator        | An entity primarily responsible for making the content of
+//	                | the resource.
 //	                |
-//	 Keywords       | A delimited set of keywords to support searching and indexing. This is
-//	                | typically a list of terms that are not available elsewhere in the properties.
+//	 Keywords       | A delimited set of keywords to support searching and
+//	                | indexing. This is typically a list of terms that are not
+//	                | available elsewhere in the properties.
 //	                |
 //	 Description    | An explanation of the content of the resource.
 //	                |
-//	 LastModifiedBy | The user who performed the last modification. The identification is
-//	                | environment-specific.
+//	 LastModifiedBy | The user who performed the last modification. The
+//	                | identification is environment-specific.
 //	                |
 //	 Language       | The language of the intellectual content of the resource.
 //	                |
-//	 Identifier     | An unambiguous reference to the resource within a given context.
+//	 Identifier     | An unambiguous reference to the resource within a given
+//	                | context.
 //	                |
 //	 Revision       | The topic of the content of the resource.
 //	                |
-//	 ContentStatus  | The status of the content. For example: Values might include "Draft",
-//	                | "Reviewed" and "Final"
+//	 ContentStatus  | The status of the content. For example: Values might
+//	                | include "Draft", "Reviewed" and "Final"
 //	                |
 //	 Category       | A categorization of the content of this package.
 //	                |
-//	 Version        | The version number. This value is set by the user or by the application.
+//	 Version        | The version number. This value is set by the user or by
+//	                | the application.
 //	                |
-//	 Modified       | The created time of the content of the resource which
-//	                | represent in ISO 8601 UTC format, for example "2019-06-04T22:00:10Z".
+//	 Created        | The created time of the content of the resource which
+//	                | represent in ISO 8601 UTC format, for example
+//	                | "2019-06-04T22:00:10Z".
 //	                |
 //	 Modified       | The modified time of the content of the resource which
-//	                | represent in ISO 8601 UTC format, for example "2019-06-04T22:00:10Z".
+//	                | represent in ISO 8601 UTC format, for example
+//	                | "2019-06-04T22:00:10Z".
 //	                |
 //
 // For example:

sheet.go

@@ -1183,17 +1183,17 @@ func attrValToBool(name string, attrs []xml.Attr) (val bool, err error) {
 // that same page
 //
 // - No footer on the first page
-func (f *File) SetHeaderFooter(sheet string, settings *HeaderFooterOptions) error {
+func (f *File) SetHeaderFooter(sheet string, opts *HeaderFooterOptions) error {
 	ws, err := f.workSheetReader(sheet)
 	if err != nil {
 		return err
 	}
-	if settings == nil {
+	if opts == nil {
 		ws.HeaderFooter = nil
 		return err
 	}
 
-	v := reflect.ValueOf(*settings)
+	v := reflect.ValueOf(*opts)
 	// Check 6 string type fields: OddHeader, OddFooter, EvenHeader, EvenFooter,
 	// FirstFooter, FirstHeader
 	for i := 4; i < v.NumField()-1; i++ {
@@ -1202,16 +1202,16 @@ func (f *File) SetHeaderFooter(sheet string, settings *HeaderFooterOptions) erro
 		}
 	}
 	ws.HeaderFooter = &xlsxHeaderFooter{
-		AlignWithMargins: settings.AlignWithMargins,
-		DifferentFirst:   settings.DifferentFirst,
-		DifferentOddEven: settings.DifferentOddEven,
-		ScaleWithDoc:     settings.ScaleWithDoc,
-		OddHeader:        settings.OddHeader,
-		OddFooter:        settings.OddFooter,
-		EvenHeader:       settings.EvenHeader,
-		EvenFooter:       settings.EvenFooter,
-		FirstFooter:      settings.FirstFooter,
-		FirstHeader:      settings.FirstHeader,
+		AlignWithMargins: opts.AlignWithMargins,
+		DifferentFirst:   opts.DifferentFirst,
+		DifferentOddEven: opts.DifferentOddEven,
+		ScaleWithDoc:     opts.ScaleWithDoc,
+		OddHeader:        opts.OddHeader,
+		OddFooter:        opts.OddFooter,
+		EvenHeader:       opts.EvenHeader,
+		EvenFooter:       opts.EvenFooter,
+		FirstFooter:      opts.FirstFooter,
+		FirstHeader:      opts.FirstHeader,
 	}
 	return err
 }

styles.go

@@ -1145,9 +1145,9 @@ func parseFormatStyleSet(style *Style) (*Style, error) {
 //
 //	 Index | Style           | Index | Style
 //	-------+-----------------+-------+-----------------
-//	 0     | Horizontal      | 3     | Diagonal down
-//	 1     | Vertical        | 4     | From corner
-//	 2     | Diagonal Up     | 5     | From center
+//	 0-2   | Horizontal      | 9-11  | Diagonal down
+//	 3-5   | Vertical        | 12-15 | From corner
+//	 6-8   | Diagonal Up     | 16    | From center
 //
 // The following table shows the pattern styles used in 'Fill.Pattern' supported
 // by excelize index number:
@@ -2459,41 +2459,38 @@ func newFills(style *Style, fg bool) *xlsxFill {
 		"gray125",
 		"gray0625",
 	}
-
-	variants := []float64{
-		90,
-		0,
-		45,
-		135,
+	variants := []xlsxGradientFill{
+		{Degree: 90, Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Degree: 270, Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Degree: 90, Stop: []*xlsxGradientFillStop{{}, {Position: 0.5}, {Position: 1}}},
+		{Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Degree: 180, Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Stop: []*xlsxGradientFillStop{{}, {Position: 0.5}, {Position: 1}}},
+		{Degree: 45, Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Degree: 255, Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Degree: 45, Stop: []*xlsxGradientFillStop{{}, {Position: 0.5}, {Position: 1}}},
+		{Degree: 135, Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Degree: 315, Stop: []*xlsxGradientFillStop{{}, {Position: 1}}},
+		{Degree: 135, Stop: []*xlsxGradientFillStop{{}, {Position: 0.5}, {Position: 1}}},
+		{Stop: []*xlsxGradientFillStop{{}, {Position: 1}}, Type: "path"},
+		{Stop: []*xlsxGradientFillStop{{}, {Position: 1}}, Type: "path", Left: 1, Right: 1},
+		{Stop: []*xlsxGradientFillStop{{}, {Position: 1}}, Type: "path", Bottom: 1, Top: 1},
+		{Stop: []*xlsxGradientFillStop{{}, {Position: 1}}, Type: "path", Bottom: 1, Left: 1, Right: 1, Top: 1},
+		{Stop: []*xlsxGradientFillStop{{}, {Position: 1}}, Type: "path", Bottom: 0.5, Left: 0.5, Right: 0.5, Top: 0.5},
 	}
 
 	var fill xlsxFill
 	switch style.Fill.Type {
 	case "gradient":
-		if len(style.Fill.Color) != 2 {
+		if len(style.Fill.Color) != 2 || style.Fill.Shading < 0 || style.Fill.Shading > 16 {
 			break
 		}
-		var gradient xlsxGradientFill
-		switch style.Fill.Shading {
-		case 0, 1, 2, 3:
-			gradient.Degree = variants[style.Fill.Shading]
-		case 4:
-			gradient.Type = "path"
-		case 5:
-			gradient.Type = "path"
-			gradient.Bottom = 0.5
-			gradient.Left = 0.5
-			gradient.Right = 0.5
-			gradient.Top = 0.5
+		gradient := variants[style.Fill.Shading]
+		gradient.Stop[0].Color.RGB = getPaletteColor(style.Fill.Color[0])
+		gradient.Stop[1].Color.RGB = getPaletteColor(style.Fill.Color[1])
+		if len(gradient.Stop) == 3 {
+			gradient.Stop[2].Color.RGB = getPaletteColor(style.Fill.Color[0])
 		}
-		var stops []*xlsxGradientFillStop
-		for index, color := range style.Fill.Color {
-			var stop xlsxGradientFillStop
-			stop.Position = float64(index)
-			stop.Color.RGB = getPaletteColor(color)
-			stops = append(stops, &stop)
-		}
-		gradient.Stop = stops
 		fill.GradientFill = &gradient
 	case "pattern":
 		if style.Fill.Pattern > 18 || style.Fill.Pattern < 0 {

styles_test.go

@@ -223,6 +223,13 @@ func TestUnsetConditionalFormat(t *testing.T) {
 
 func TestNewStyle(t *testing.T) {
 	f := NewFile()
+	for i := 0; i < 18; i++ {
+		_, err := f.NewStyle(&Style{
+			Fill: Fill{Type: "gradient", Color: []string{"#FFFFFF", "#4E71BE"}, Shading: i},
+		})
+		assert.NoError(t, err)
+	}
+	f = NewFile()
 	styleID, err := f.NewStyle(&Style{Font: &Font{Bold: true, Italic: true, Family: "Times New Roman", Size: 36, Color: "#777777"}})
 	assert.NoError(t, err)
 	styles, err := f.stylesReader()