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dolly: init dolly image generator command
given a dolly html template, this command generates pngs, svgs, icos etc
with the supplied size and color specifications.
Signed-off-by: oppiliappan <me@oppi.li>
author
oppiliappan
date
(Jan 9, 2026, 10:39 AM UTC)
commit
95e268b3
95e268b38d669dd8f98b1cc5af1cdb9b677d246a
parent
20c5bbb9
20c5bbb9862e8b53be18566ea35729867983f777
change-id
sslwwrum
sslwwrumvwuvysqzqzntkkzvnpyklxsx
+182
+182
cmd/dolly/main.go
+182
cmd/dolly/main.go
···
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package main
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import (
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"bytes"
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"flag"
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"fmt"
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"image"
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"image/color"
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"image/png"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"text/template"
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"github.com/srwiley/oksvg"
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"github.com/srwiley/rasterx"
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"golang.org/x/image/draw"
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"tangled.org/core/appview/pages"
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"tangled.org/core/ico"
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)
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func main() {
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var (
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size string
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fillColor string
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output string
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)
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flag.StringVar(&size, "size", "512x512", "Output size in format WIDTHxHEIGHT (e.g., 512x512)")
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flag.StringVar(&fillColor, "color", "#000000", "Fill color in hex format (e.g., #FF5733)")
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flag.StringVar(&output, "output", "dolly.svg", "Output file path (format detected from extension: .svg, .png, or .ico)")
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flag.Parse()
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width, height, err := parseSize(size)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error parsing size: %v\n", err)
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os.Exit(1)
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}
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// Detect format from file extension
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ext := strings.ToLower(filepath.Ext(output))
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format := strings.TrimPrefix(ext, ".")
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if format != "svg" && format != "png" && format != "ico" {
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fmt.Fprintf(os.Stderr, "Invalid file extension: %s. Must be .svg, .png, or .ico\n", ext)
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os.Exit(1)
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}
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if !isValidHexColor(fillColor) {
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fmt.Fprintf(os.Stderr, "Invalid color format: %s. Use hex format like #FF5733\n", fillColor)
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os.Exit(1)
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}
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svgData, err := dolly(fillColor)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error generating SVG: %v\n", err)
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os.Exit(1)
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}
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// Create output directory if it doesn't exist
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dir := filepath.Dir(output)
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if dir != "" && dir != "." {
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if err := os.MkdirAll(dir, 0755); err != nil {
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fmt.Fprintf(os.Stderr, "Error creating output directory: %v\n", err)
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os.Exit(1)
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}
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}
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switch format {
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case "svg":
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err = saveSVG(svgData, output, width, height)
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case "png":
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err = savePNG(svgData, output, width, height)
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case "ico":
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err = saveICO(svgData, output, width, height)
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}
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error saving file: %v\n", err)
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os.Exit(1)
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}
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fmt.Printf("Successfully generated %s (%dx%d)\n", output, width, height)
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}
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func dolly(hexColor string) ([]byte, error) {
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tpl, err := template.New("dolly").
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ParseFS(pages.Files, "templates/fragments/dolly/logo.html")
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if err != nil {
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return nil, err
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}
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var svgData bytes.Buffer
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if err := tpl.ExecuteTemplate(&svgData, "fragments/dolly/logo", pages.DollyParams{
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FillColor: hexColor,
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}); err != nil {
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return nil, err
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}
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return svgData.Bytes(), nil
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}
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func svgToImage(svgData []byte, w, h int) (image.Image, error) {
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icon, err := oksvg.ReadIconStream(bytes.NewReader(svgData))
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if err != nil {
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return nil, fmt.Errorf("error parsing SVG: %v", err)
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}
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icon.SetTarget(0, 0, float64(w), float64(h))
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rgba := image.NewRGBA(image.Rect(0, 0, w, h))
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draw.Draw(rgba, rgba.Bounds(), &image.Uniform{color.Transparent}, image.Point{}, draw.Src)
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scanner := rasterx.NewScannerGV(w, h, rgba, rgba.Bounds())
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raster := rasterx.NewDasher(w, h, scanner)
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icon.Draw(raster, 1.0)
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return rgba, nil
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}
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func parseSize(size string) (int, int, error) {
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parts := strings.Split(size, "x")
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if len(parts) != 2 {
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return 0, 0, fmt.Errorf("invalid size format, use WIDTHxHEIGHT")
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}
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width, err := strconv.Atoi(parts[0])
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if err != nil {
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return 0, 0, fmt.Errorf("invalid width: %v", err)
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}
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height, err := strconv.Atoi(parts[1])
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if err != nil {
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return 0, 0, fmt.Errorf("invalid height: %v", err)
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}
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if width <= 0 || height <= 0 {
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return 0, 0, fmt.Errorf("width and height must be positive")
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}
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return width, height, nil
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}
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func isValidHexColor(hex string) bool {
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if len(hex) != 7 || hex[0] != '#' {
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return false
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}
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_, err := strconv.ParseUint(hex[1:], 16, 32)
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return err == nil
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}
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func saveSVG(svgData []byte, filepath string, _, _ int) error {
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return os.WriteFile(filepath, svgData, 0644)
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}
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func savePNG(svgData []byte, filepath string, width, height int) error {
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img, err := svgToImage(svgData, width, height)
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if err != nil {
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return err
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}
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f, err := os.Create(filepath)
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if err != nil {
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return err
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}
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defer f.Close()
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return png.Encode(f, img)
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}
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func saveICO(svgData []byte, filepath string, width, height int) error {
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img, err := svgToImage(svgData, width, height)
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if err != nil {
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return err
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}
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icoData, err := ico.ImageToIco(img)
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if err != nil {
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return err
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}
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return os.WriteFile(filepath, icoData, 0644)
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}