2024-07-02 07:36:18 +00:00
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package main
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import (
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"bytes"
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2024-07-02 07:58:14 +00:00
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"encoding/base64"
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2024-07-02 07:36:18 +00:00
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"errors"
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"fmt"
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"image"
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"image/gif"
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"image/jpeg"
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"image/png"
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"io"
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"log"
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"math/rand"
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"net/http"
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"strconv"
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"strings"
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"sync"
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"time"
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h2m "github.com/JohannesKaufmann/html-to-markdown"
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"github.com/JohannesKaufmann/html-to-markdown/plugin"
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"github.com/nfnt/resize"
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"github.com/yuin/goldmark"
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"github.com/yuin/goldmark/ast"
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"github.com/yuin/goldmark/extension"
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"github.com/yuin/goldmark/parser"
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"github.com/yuin/goldmark/text"
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"github.com/yuin/goldmark/util"
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"golang.org/x/image/webp"
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)
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var imgStor imageStore
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2024-07-02 07:46:24 +00:00
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const imgZpfx = "/imgz/"
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2024-07-02 07:36:18 +00:00
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func init() {
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imgStor.img = make(map[string]imageContainer)
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// TODO: add garbage collector
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// think about how to remove old images
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// if removed from cache how to download them later if a browser goes back?
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// browser should cache on it's own... but it may request it, what then?
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}
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type imageContainer struct {
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data []byte
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url string
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added time.Time
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}
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type imageStore struct {
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img map[string]imageContainer
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sync.Mutex
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}
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func (i *imageStore) add(id, url string, img []byte) {
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i.Lock()
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defer i.Unlock()
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i.img[id] = imageContainer{data: img, url: url, added: time.Now()}
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}
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func (i *imageStore) get(id string) ([]byte, error) {
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i.Lock()
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defer i.Unlock()
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img, ok := i.img[id]
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if !ok {
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return nil, errors.New("not found")
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}
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return img.data, nil
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}
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func (i *imageStore) del(id string) {
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i.Lock()
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defer i.Unlock()
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delete(i.img, id)
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}
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2024-07-02 08:14:24 +00:00
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func grabImage(id, url string) error {
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log.Printf("Downloading IMGZ URL=%q for ID=%q", url, id)
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var img []byte
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var err error
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switch url[:4] {
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case "http":
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r, err := http.Get(url) // TODO: possibly set a header "referer" here
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if err != nil {
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return fmt.Errorf("Error downloading %q: %v", url, err)
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}
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defer r.Body.Close()
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img, err = io.ReadAll(r.Body)
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if err != nil {
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return fmt.Errorf("Error reading %q: %v", url, err)
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}
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case "data":
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idx := strings.Index(url, ",")
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if idx < 1 {
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return fmt.Errorf("image is embeded but unable to find coma: %q", url)
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}
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img, err = base64.StdEncoding.DecodeString(url[idx+1:])
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if err != nil {
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return fmt.Errorf("error decoding image from url embed: %q: %v", url, err)
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}
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}
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gif, err := smallGif(img)
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if err != nil {
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return fmt.Errorf("Error scaling down image: %v", err)
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}
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imgStor.add(id, url, gif)
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return nil
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}
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type astTransformer struct{}
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func (t *astTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
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ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
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if link, ok := n.(*ast.Link); ok && entering {
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link.Destination = append([]byte("?t=txt&url="), link.Destination...)
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}
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if img, ok := n.(*ast.Image); ok && entering {
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id := fmt.Sprintf("txt%05d.gif", rand.Intn(99999)) // atomic.AddInt64 could be better here
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2024-07-02 08:19:19 +00:00
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err := grabImage(id, string(img.Destination)) // TODO: use goroutines with waitgroup
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if err != nil {
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log.Print(err)
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n.Parent().RemoveChildren(n)
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return ast.WalkContinue, nil
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}
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img.Destination = []byte(imgZpfx + id)
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}
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return ast.WalkContinue, nil
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})
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}
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func (rq *wrpReq) captureMarkdown() {
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log.Printf("Processing Markdown conversion request for %v", rq.url)
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// TODO: bug - DomainFromURL always prefixes with http:// instead of https
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// this causes issues on some websites, fix or write a smarter DomainFromURL
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c := h2m.NewConverter(h2m.DomainFromURL(rq.url), true, nil)
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c.Use(plugin.GitHubFlavored())
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md, err := c.ConvertURL(rq.url) // We could also get inner html from chromedp
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if err != nil {
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http.Error(rq.w, err.Error(), http.StatusInternalServerError)
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return
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}
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log.Printf("Got %v bytes md from %v", len(md), rq.url)
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t := &astTransformer{}
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gm := goldmark.New(
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goldmark.WithExtensions(extension.GFM),
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goldmark.WithParserOptions(parser.WithASTTransformers(util.Prioritized(t, 100))),
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)
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var ht bytes.Buffer
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err = gm.Convert([]byte(md), &ht)
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if err != nil {
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http.Error(rq.w, err.Error(), http.StatusInternalServerError)
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return
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}
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log.Printf("Rendered %v bytes html for %v", len(ht.String()), rq.url)
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rq.printHTML(printParams{
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text: string(asciify([]byte(ht.String()))),
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})
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}
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func imgServerZ(w http.ResponseWriter, r *http.Request) {
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log.Printf("%s IMGZ Request for %s", r.RemoteAddr, r.URL.Path)
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id := strings.Replace(r.URL.Path, imgZpfx, "", 1)
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img, err := imgStor.get(id)
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if err != nil {
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http.Error(w, err.Error(), http.StatusInternalServerError)
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log.Printf("%s IMGZ error for %s: %v", r.RemoteAddr, r.URL.Path, err)
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return
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}
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imgStor.del(id)
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w.Header().Set("Content-Type", "image/gif")
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w.Header().Set("Content-Length", strconv.Itoa(len(img)))
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// TODO: we may want to let the client browser cache images
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w.Header().Set("Cache-Control", "max-age=0")
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w.Header().Set("Expires", "-1")
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w.Header().Set("Pragma", "no-cache")
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w.Write(img)
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w.(http.Flusher).Flush()
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}
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func smallGif(src []byte) ([]byte, error) {
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t := http.DetectContentType(src)
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var err error
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var img image.Image
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switch t {
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case "image/png":
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img, err = png.Decode(bytes.NewReader(src))
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case "image/gif":
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img, err = gif.Decode(bytes.NewReader(src))
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case "image/jpeg":
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img, err = jpeg.Decode(bytes.NewReader(src))
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case "image/webp":
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img, err = webp.Decode(bytes.NewReader(src))
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default: // TODO: also add svg
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err = errors.New("unknown content type: " + t)
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}
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if err != nil {
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return nil, fmt.Errorf("image decode problem: %v", err)
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}
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2024-07-02 08:21:22 +00:00
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if img.Bounds().Max.X-img.Bounds().Min.X > *txtImgSize {
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img = resize.Resize(uint(*txtImgSize), 0, img, resize.NearestNeighbor)
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2024-07-02 08:05:07 +00:00
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}
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var gifBuf bytes.Buffer
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2024-07-02 08:05:07 +00:00
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err = gif.Encode(&gifBuf, gifPalette(img, 216), &gif.Options{})
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2024-07-02 07:36:18 +00:00
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if err != nil {
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return nil, fmt.Errorf("gif encode problem: %v", err)
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}
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return gifBuf.Bytes(), nil
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}
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