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| 1 | //go:build ignore |
| 2 | |
| 3 | // Re-encode an opaque icon as RGB PNG; Chromium may retain an unused alpha channel. |
| 4 | package main |
| 5 | |
| 6 | import ( |
| 7 | "bytes" |
| 8 | "fmt" |
| 9 | "image/png" |
| 10 | "io" |
| 11 | "os" |
| 12 | ) |
| 13 | |
| 14 | func main() { |
| 15 | if err := run(); err != nil { |
| 16 | fmt.Fprintln(os.Stderr, err) |
| 17 | os.Exit(1) |
| 18 | } |
| 19 | } |
| 20 | |
| 21 | func run() error { |
| 22 | raw, err := io.ReadAll(io.LimitReader(os.Stdin, 8<<20)) |
| 23 | if err != nil || len(raw) == 8<<20 { |
| 24 | return fmt.Errorf("icon PNG exceeds input limit") |
| 25 | } |
| 26 | cfg, err := png.DecodeConfig(bytes.NewReader(raw)) |
| 27 | if err != nil || cfg.Width != 1024 || cfg.Height != 1024 { |
| 28 | return fmt.Errorf("icon must be a 1024-pixel PNG") |
| 29 | } |
| 30 | img, err := png.Decode(bytes.NewReader(raw)) |
| 31 | if err != nil { |
| 32 | return err |
| 33 | } |
| 34 | opaque, ok := img.(interface{ Opaque() bool }) |
| 35 | if !ok || !opaque.Opaque() { |
| 36 | return fmt.Errorf("iPhone icon must be fully opaque") |
| 37 | } |
| 38 | // The standard encoder omits alpha when every pixel is opaque. |
| 39 | return png.Encode(os.Stdout, img) |
| 40 | } |
| 41 | |
amadan