Different gradient fill colors return the same style index

[edwardfward]

Different gradient fills produce the same style index making it impossible to use more than one gradient fill in a workbook.

package main

import (
	"fmt"
	"github.com/xuri/excelize/v2"
)

func main() {
	f := excelize.NewFile()

	s1 := excelize.Style{
		Fill: excelize.Fill{
			Type:    "gradient",
			Pattern: 1,
			Shading: 1,
			Color:   []string{"#000000", "#FFFFFF"},
		},
	}

	s2 := excelize.Style{
		Fill: excelize.Fill{
			Type:    "gradient",
			Pattern: 1,
			Shading: 1,
			Color:   []string{"#FFFF00", "#000000"},
		},
	}

	s1Index, _ := f.NewStyle(&s1)
	s2Index, _ := f.NewStyle(&s2)

	fmt.Println("s1Index:", s1Index)
	fmt.Println("s2Index:", s2Index)
}

Describe the results you received:

s1Index: 1
s2Index: 1

Describe the results you expected:

s1Index: 1
s2Index: (Something other than 1)

Output of go version:

go version go1.22.0 darwin/arm64

Excelize version or commit ID:

github.com/xuri/excelize/v2 v2.8.0

Environment details (OS, Microsoft Excel™ version, physical, etc.):

Apple M2 Max (Mac OS 14.2.1)

[xuri]

Thanks for your issue. I have tested with the v2.8.0, and it works well. This bug was introduced by commit 9c079e5. We need to change the array variable styleFillVariants to a function to fix this:

styleFillVariants = func() []xlsxGradientFill {
    return []xlsxGradientFill{
        // ...
    }
}

Would you like to create a pull request to help us fix this problem?

[edwardfward]

I will give it a go.