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favicon.go
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favicon.go
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package common
import (
"bytes"
"encoding/binary"
)
const (
ICO_CONTENT_TYPE = "image/x-icon"
)
type IcoHeader struct {
Reserved uint16
ImageType uint16
NumberOfImages uint16
}
func (icoHeader IcoHeader) IsValid() bool {
return icoHeader.Reserved == 0
}
func (icoHeader IcoHeader) IsIco() bool {
return icoHeader.ImageType == 1
}
func (icoHeader IcoHeader) IsCursor() bool {
return icoHeader.ImageType == 2
}
type ImageEntry struct {
Width byte
Height byte
NumberOfColors byte
Reserved byte
ColorPlanes uint16
BitsPerPixel uint16
ImageSize uint32
ImageOffset uint32
}
type BitmapInfoHeader struct {
HeaderSize uint32
Width uint32
Height uint32
ColorPlanes uint16
BitsPerPixel uint16
CompressionMethod uint32
ImageSize uint32
HorizontalResolution uint32
VerticalResolution uint32
NumberOfColors uint32
NumberOfImportantColorsUsed uint32
}
func (bitmapInfoHeader BitmapInfoHeader) IsCompressed() bool {
return bitmapInfoHeader.CompressionMethod != 0
}
type PixelData struct {
Blue byte
Green byte
Red byte
Alpha byte
}
type FaviconIco struct {
Header IcoHeader
ImageEntries []ImageEntry
BitmapInfoHeaders []BitmapInfoHeader
Pixels [][]PixelData
}
func (favicon *FaviconIco) CreateImage(color uint32, width uint32, height uint32) {
//ICO header
favicon.Header.Reserved = 0
favicon.Header.ImageType = 1
favicon.Header.NumberOfImages = 1
//ICO parameters
var imageEntry ImageEntry
imageEntry.Width = byte(width)
imageEntry.Height = byte(height)
imageEntry.NumberOfColors = 0
imageEntry.Reserved = 0
imageEntry.ColorPlanes = 1
imageEntry.BitsPerPixel = 32
imageEntry.ImageSize = (width * height * uint32(imageEntry.BitsPerPixel/8)) + 40
imageEntry.ImageOffset = 22 //Size of two headers
favicon.ImageEntries = append(favicon.ImageEntries, imageEntry)
//Bitmap info header
var bitmapInfoHeader BitmapInfoHeader
bitmapInfoHeader.HeaderSize = 40
bitmapInfoHeader.Width = width
bitmapInfoHeader.Height = height * 2
bitmapInfoHeader.ColorPlanes = 1
bitmapInfoHeader.BitsPerPixel = 32
bitmapInfoHeader.CompressionMethod = 0
bitmapInfoHeader.ImageSize = (width * height * uint32(imageEntry.BitsPerPixel/8))
bitmapInfoHeader.HorizontalResolution = 2834
bitmapInfoHeader.VerticalResolution = 2834
bitmapInfoHeader.NumberOfColors = 0
bitmapInfoHeader.NumberOfImportantColorsUsed = 0
favicon.BitmapInfoHeaders = append(favicon.BitmapInfoHeaders, bitmapInfoHeader)
//Pixels
numOfPixels := bitmapInfoHeader.ImageSize / uint32(bitmapInfoHeader.BitsPerPixel/8)
var pixels []PixelData
for iter := uint32(0); iter < numOfPixels; iter++ {
var pixel PixelData
pixel.Red = byte((color >> 24) & 0xff)
pixel.Green = byte((color >> 16) & 0xff)
pixel.Blue = byte((color >> 8) & 0xff)
pixel.Alpha = byte(color & 0xff)
pixels = append(pixels, pixel)
}
favicon.Pixels = append(favicon.Pixels, pixels)
}
func (favicon FaviconIco) GetImageData() []byte {
var buffer bytes.Buffer
binary.Write(&buffer, binary.LittleEndian, favicon.Header)
for iter := uint16(0); iter < favicon.Header.NumberOfImages; iter++ {
binary.Write(&buffer, binary.LittleEndian, favicon.ImageEntries[iter])
binary.Write(&buffer, binary.LittleEndian, favicon.BitmapInfoHeaders[iter])
binary.Write(&buffer, binary.LittleEndian, favicon.Pixels[iter])
}
return buffer.Bytes()
}