patch of ico: add module to deal with ico files · round #0 · pull #936 · tangled.org/core

the ico file format is quite straightforward, it contains a few headers followed by any number of full PNG/BMP images. for our usecase, we only need to be able to embed a single favicon an ico file, this module handles just the conversion of an image.Image to the ico format.

Signed-off-by: oppiliappan me@oppi.li

+4 -4

appview/ogcard/card.go

··· 453 453 454 454 // Handle SVG separately 455 455 if contentType == "image/svg+xml" || strings.HasSuffix(url, ".svg") { 456 - return c.convertSVGToPNG(bodyBytes) 456 + return convertSVGToPNG(bodyBytes) 457 457 } 458 458 459 459 // Support content types are in-sync with the allowed custom avatar file types ··· 493 493 } 494 494 495 495 // convertSVGToPNG converts SVG data to a PNG image 496 - func (c *Card) convertSVGToPNG(svgData []byte) (image.Image, bool) { 496 + func convertSVGToPNG(svgData []byte) (image.Image, bool) { 497 497 // Parse the SVG 498 498 icon, err := oksvg.ReadIconStream(bytes.NewReader(svgData)) 499 499 if err != nil { ··· 547 547 draw.CatmullRom.Scale(scaledImg, scaledImg.Bounds(), img, srcBounds, draw.Src, nil) 548 548 549 549 // Draw the image with circular clipping 550 - for cy := 0; cy < size; cy++ { 551 - for cx := 0; cx < size; cx++ { 550 + for cy := range size { 551 + for cx := range size { 552 552 // Calculate distance from center 553 553 dx := float64(cx - center) 554 554 dy := float64(cy - center)

+88

ico/ico.go

··· 1 + package ico 2 + 3 + import ( 4 + "bytes" 5 + "encoding/binary" 6 + "fmt" 7 + "image" 8 + "image/png" 9 + ) 10 + 11 + type IconDir struct { 12 + Reserved uint16 // must be 0 13 + Type uint16 // 1 for ICO, 2 for CUR 14 + Count uint16 // number of images 15 + } 16 + 17 + type IconDirEntry struct { 18 + Width uint8 // 0 means 256 19 + Height uint8 // 0 means 256 20 + ColorCount uint8 21 + Reserved uint8 // must be 0 22 + ColorPlanes uint16 // 0 or 1 23 + BitsPerPixel uint16 24 + SizeInBytes uint32 25 + Offset uint32 26 + } 27 + 28 + func ImageToIco(img image.Image) ([]byte, error) { 29 + // encode image as png 30 + var pngBuf bytes.Buffer 31 + if err := png.Encode(&pngBuf, img); err != nil { 32 + return nil, fmt.Errorf("failed to encode PNG: %w", err) 33 + } 34 + pngData := pngBuf.Bytes() 35 + 36 + // get image dimensions 37 + bounds := img.Bounds() 38 + width := bounds.Dx() 39 + height := bounds.Dy() 40 + 41 + // prepare output buffer 42 + var icoBuf bytes.Buffer 43 + 44 + iconDir := IconDir{ 45 + Reserved: 0, 46 + Type: 1, // ICO format 47 + Count: 1, // One image 48 + } 49 + 50 + w := uint8(width) 51 + h := uint8(height) 52 + 53 + // width/height of 256 should be stored as 0 54 + if width == 256 { 55 + w = 0 56 + } 57 + if height == 256 { 58 + h = 0 59 + } 60 + 61 + iconDirEntry := IconDirEntry{ 62 + Width: w, 63 + Height: h, 64 + ColorCount: 0, // 0 for PNG (32-bit) 65 + Reserved: 0, 66 + ColorPlanes: 1, 67 + BitsPerPixel: 32, // PNG with alpha 68 + SizeInBytes: uint32(len(pngData)), 69 + Offset: 6 + 16, // Size of ICONDIR + ICONDIRENTRY 70 + } 71 + 72 + // write IconDir 73 + if err := binary.Write(&icoBuf, binary.LittleEndian, iconDir); err != nil { 74 + return nil, fmt.Errorf("failed to write ICONDIR: %w", err) 75 + } 76 + 77 + // write IconDirEntry 78 + if err := binary.Write(&icoBuf, binary.LittleEndian, iconDirEntry); err != nil { 79 + return nil, fmt.Errorf("failed to write ICONDIRENTRY: %w", err) 80 + } 81 + 82 + // write PNG data directly 83 + if _, err := icoBuf.Write(pngData); err != nil { 84 + return nil, fmt.Errorf("failed to write PNG data: %w", err) 85 + } 86 + 87 + return icoBuf.Bytes(), nil 88 + }