ico

type BitmapFileHeader struct {
	Type       [2]byte // The header field used to identify the BMP and DIB file is 0x42 0x4D in hexadecimal, same as BM in ASCII.
	Size       uint32  // The size of the BMP file in bytes
	Reserved1  uint16  // Reserved; actual value depends on the application that creates the image, if created manually can be 0
	Reserved2  uint16  // Reserved; actual value depends on the application that creates the image, if created manually can be 0
	OffsetBits uint32  // The offset, i.e. starting address, of the byte where the bitmap image data (pixel array) can be found.
}

type BitmapInfoHeader struct {
	Size     uint32 // the size of this header, in bytes (40)
	Width    int32  // the bitmap width in pixels (signed integer)
	Height   int32  // the bitmap width in pixels (signed integer)
	Planes   uint16 // the number of color planes (must be 1)
	BitCount uint16 // the number of bits per pixel, which is the color depth of the image. Typical values are 1, 4, 8, 16, 24 and 32.
	// Note for ico files the fields below can be zero
	Compression     uint32 // the compression method being used. See the next table for a list of possible values
	SizeImage       uint32 // the image size. This is the size of the raw bitmap data; a dummy 0 can be given for BI_RGB bitmaps.
	XPixelsPerMeter int32  // the horizontal resolution of the image. (pixel per metre, signed integer)
	YPixelsPerMeter int32  // the vertical resolution of the image. (pixel per metre, signed integer)
	ColorsUsed      uint32 // the number of colors in the color palette, or 0 to default to 2n
	ColorsImportant uint8  // the number of important colors used, or 0 when every color is important; generally ignored
}

type IconDirectoryEntry struct {
	Width       uint8  // Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
	Height      uint8  // Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.
	ColorCount  uint8  // Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
	Reserved    uint8  // Reserved. Should be 0
	Planes      uint16 // Specifies color planes. Should be 0 or 1.
	BitCount    uint16 // Specifies bits per pixel.
	BytesInRes  uint32 // Specifies the size of the image's data in bytes.
	ImageOffset uint32 // Specifies the offset of BMP or PNG data from the beginning of the ICO/CUR file
}

type IconHeader struct {
	Reserved uint16 // Reserved. Must always be 0.
	Type     uint16 // Specifies image type: 1 for icon (.ICO) image, 2 for cursor (.CUR) image. Other values are invalid.
	Count    uint16 // Specifies the number of iconDirectoryEntry
}