gopkg/image/gif.go

// Package image ...
//
// Description : GIF相关操作
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2021-11-29 12:43 下午
package image

import (
	"errors"
	"image"
	"image/color"
	"image/color/palette"
	"image/draw"
	"image/gif"
	"image/jpeg"
	"image/png"
	"os"

	"git.zhangdeman.cn/zhangdeman/gopkg/util"
)

var (
	// GIF ...
	GIF *GIFConvert
)

func init() {
	GIF = &GIFConvert{}
}

// GIFConvert gif转换
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 12:44 下午 2021/11/29
type GIFConvert struct {
}

// Generate 生成
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2:13 下午 2021/11/29
func (g *GIFConvert) Generate(sourceImageList []string, savePath string) error {
	if len(sourceImageList) == 0 {
		return errors.New("source image list is empty")
	}
	var (
		err           error
		formatImgList []ImgInfo
		disposals     []byte
		images        []*image.Paletted
		// 播放速度设置 , 100 次多少秒
		delays []int
	)
	if formatImgList, err = g.checkImageType(sourceImageList); nil != err {
		return err
	}

	for _, imgInfo := range formatImgList {
		img, gErr := g.loadImage(imgInfo)
		if nil != gErr {
			return gErr
		}
		cp := g.getPalette(img)
		//cp:=append(palette.WebSafe,color.Transparent)
		disposals = append(disposals, gif.DisposalBackground) //透明图片需要设置
		p := image.NewPaletted(image.Rect(0, 0, 640, 996), cp)
		draw.Draw(p, p.Bounds(), img, image.ZP, draw.Src)
		images = append(images, p)
		delays = append(delays, 100)
	}
	gifInstance := &gif.GIF{
		Image:     images,
		Delay:     delays,
		LoopCount: -1,
		Disposal:  disposals,
	}
	f, fErr := os.Create(savePath)
	if fErr != nil {
		return fErr
	}
	defer func() { _ = f.Close() }()
	return gif.EncodeAll(f, gifInstance)
}

// checkImageType 检测图片类型
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2:16 下午 2021/11/29
func (g *GIFConvert) checkImageType(sourceImageList []string) ([]ImgInfo, error) {
	result := make([]ImgInfo, 0)
	for _, item := range sourceImageList {
		imgType := util.GetFileType(item)
		if len(imgType) == 0 {
			return result, errors.New(item + " parse img type fail!")
		}
		result = append(result, ImgInfo{
			Path: item,
			Type: imgType,
		})
	}
	return result, nil
}

// loadImage 加载图片内容
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2:52 下午 2021/11/29
func (g *GIFConvert) loadImage(imgInfo ImgInfo) (image.Image, error) {
	var (
		err error
		f   *os.File
	)
	if f, err = os.Open(imgInfo.Path); nil != err {
		return nil, err
	}

	defer func() {
		_ = f.Close()
	}()

	switch imgInfo.Type {
	case TypePNG:
		if img, imgErr := png.Decode(f); nil != err {
			return nil, imgErr
		} else {
			return img, nil
		}
	case TypeJPEG:
		fallthrough
	case TypeJPG:
		if img, imgErr := jpeg.Decode(f); nil != err {
			return nil, imgErr
		} else {
			return img, nil
		}
	case TypeGIF:
		if img, imgErr := gif.Decode(f); nil != err {
			return nil, imgErr
		} else {
			return img, nil
		}
	default:
		return nil, errors.New(imgInfo.Type + " is not support!")
	}
}

// getPalette ...
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 3:01 下午 2021/11/29
func (g *GIFConvert) getPalette(m image.Image) color.Palette {
	p := color.Palette{color.RGBA{0x00, 0x00, 0x00, 0x00}}
	p9 := color.Palette(palette.Plan9)
	b := m.Bounds()
	black := false
	for y := b.Min.Y; y < b.Max.Y; y++ {
		for x := b.Min.X; x < b.Max.X; x++ {
			c := m.At(x, y)
			cc := p9.Convert(c)
			if cc == p9[0] {
				black = true
			}
			if g.isInPalette(p, cc) == -1 {
				p = append(p, cc)
			}
		}
	}
	if len(p) < 256 && black == true {
		p[0] = color.RGBA{0x00, 0x00, 0x00, 0x00} // transparent
		p = append(p, p9[0])
	}
	return p
}

// isInPalette ...
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 3:01 下午 2021/11/29
func (g *GIFConvert) isInPalette(p color.Palette, c color.Color) int {
	ret := -1
	for i, v := range p {
		if v == c {
			return i
		}
	}
	return ret
}