Add new exported `ColorMappingType` used for color transformation

Using `ColorMappingType` color transformation types enumeration for tab color index, ref #1285

3 files changed, 25 insertions, 22 deletions

diff --git a/sheetpr.go b/sheetpr.go
index cc4e4a9..0e3cb9b 100644
--- a/sheetpr.go
+++ b/sheetpr.go
@@ -47,23 +47,6 @@ type (
 	OutlineSummaryBelow bool
 )
 
-const (
-	TabColorThemeLight1 int = iota // Inverted compared to the spec because that's how Excel maps them
-	TabColorThemeDark1
-	TabColorThemeLight2
-	TabColorThemeDark2
-	TabColorThemeAccent1
-	TabColorThemeAccent2
-	TabColorThemeAccent3
-	TabColorThemeAccent4
-	TabColorThemeAccent5
-	TabColorThemeAccent6
-	TabColorThemeHyperlink
-	TabColorThemeFollowedHyperlink
-
-	TabColorUnsetValue int = -1
-)
-
 // setSheetPrOption implements the SheetPrOption interface.
 func (o OutlineSummaryBelow) setSheetPrOption(pr *xlsxSheetPr) {
 	if pr.OutlinePr == nil {
@@ -165,7 +148,7 @@ func (o TabColorIndexed) setSheetPrOption(pr *xlsxSheetPr) {
 // TabColor Indexed. Defaults to -1 if no indexed has been set.
 func (o *TabColorIndexed) getSheetPrOption(pr *xlsxSheetPr) {
 	if pr == nil || pr.TabColor == nil {
-		*o = TabColorIndexed(TabColorUnsetValue)
+		*o = TabColorIndexed(ColorMappingTypeUnset)
 		return
 	}
 	*o = TabColorIndexed(pr.TabColor.Indexed)
@@ -206,7 +189,7 @@ func (o TabColorTheme) setSheetPrOption(pr *xlsxSheetPr) {
 // TabColor Theme. Defaults to -1 if no theme has been set.
 func (o *TabColorTheme) getSheetPrOption(pr *xlsxSheetPr) {
 	if pr == nil || pr.TabColor == nil {
-		*o = TabColorTheme(TabColorUnsetValue)
+		*o = TabColorTheme(ColorMappingTypeUnset)
 		return
 	}
 	*o = TabColorTheme(pr.TabColor.Theme)
diff --git a/sheetpr_test.go b/sheetpr_test.go
index 000b33a..65ab196 100644
--- a/sheetpr_test.go
+++ b/sheetpr_test.go
@@ -15,7 +15,7 @@ var _ = []SheetPrOption{
 	FitToPage(true),
 	TabColorIndexed(42),
 	TabColorRGB("#FFFF00"),
-	TabColorTheme(TabColorThemeLight2),
+	TabColorTheme(ColorMappingTypeLight2),
 	TabColorTint(0.5),
 	AutoPageBreaks(true),
 	OutlineSummaryBelow(true),
@@ -45,7 +45,7 @@ func ExampleFile_SetSheetPrOptions() {
 		FitToPage(true),
 		TabColorIndexed(42),
 		TabColorRGB("#FFFF00"),
-		TabColorTheme(TabColorThemeLight2),
+		TabColorTheme(ColorMappingTypeLight2),
 		TabColorTint(0.5),
 		AutoPageBreaks(true),
 		OutlineSummaryBelow(false),
@@ -124,7 +124,7 @@ func TestSheetPrOptions(t *testing.T) {
 		{new(FitToPage), FitToPage(true)},
 		{new(TabColorIndexed), TabColorIndexed(42)},
 		{new(TabColorRGB), TabColorRGB("FFFF00")},
-		{new(TabColorTheme), TabColorTheme(TabColorThemeLight2)},
+		{new(TabColorTheme), TabColorTheme(ColorMappingTypeLight2)},
 		{new(TabColorTint), TabColorTint(0.5)},
 		{new(AutoPageBreaks), AutoPageBreaks(true)},
 		{new(OutlineSummaryBelow), OutlineSummaryBelow(false)},
diff --git a/xmlDrawing.go b/xmlDrawing.go
index 3e54b72..8c3d734 100644
--- a/xmlDrawing.go
+++ b/xmlDrawing.go
@@ -120,6 +120,26 @@ const (
 	pivotTableVersion = 3
 )
 
+// ColorMappingType is the type of color transformation.
+type ColorMappingType byte
+
+// Color transformation types enumeration.
+const (
+	ColorMappingTypeLight1 ColorMappingType = iota
+	ColorMappingTypeDark1
+	ColorMappingTypeLight2
+	ColorMappingTypeDark2
+	ColorMappingTypeAccent1
+	ColorMappingTypeAccent2
+	ColorMappingTypeAccent3
+	ColorMappingTypeAccent4
+	ColorMappingTypeAccent5
+	ColorMappingTypeAccent6
+	ColorMappingTypeHyperlink
+	ColorMappingTypeFollowedHyperlink
+	ColorMappingTypeUnset int = -1
+)
+
 // supportedImageTypes defined supported image types.
 var supportedImageTypes = map[string]string{".gif": ".gif", ".jpg": ".jpeg", ".jpeg": ".jpeg", ".png": ".png", ".tif": ".tiff", ".tiff": ".tiff", ".emf": ".emf", ".wmf": ".wmf"}