package qr

Import Path
	rsc.io/qr (on go.dev)

Dependency Relation
	imports 8 packages, and imported by one package

Involved Source Files

	    png.go
	  d qr.go
		Package qr encodes QR codes.
Package-Level Type Names (total 6, in which 2 are exported)

	/* sort exporteds by: alphabet | popularity */
	 type Code (struct)
		A Code is a square pixel grid.
		It implements image.Image and direct PNG encoding.

		Fields (total 4, all are exported)
			Bitmap []byte
				// 1 is black, 0 is white

			Scale int
				// number of image pixels per QR pixel

			Size int
				// number of pixels on a side

			Stride int
				// number of bytes per row

		Methods (total 3, all are exported)
			(*Code) Black(x, y int) bool
				Black returns true if the pixel at (x,y) is black.

			(*Code) Image() image.Image
				Image returns an Image displaying the code.

			(*Code) PNG() []byte
				PNG returns a PNG image displaying the code.
				
				PNG uses a custom encoder tailored to QR codes.
				Its compressed size is about 2x away from optimal,
				but it runs about 20x faster than calling png.Encode
				on c.Image().

		As Outputs Of (at least one exported)
			func Encode(text string, level Level) (*Code, error)

	 type Level int (basic type)
		A Level denotes a QR error correction level.
		From least to most tolerant of errors, they are L, M, Q, H.

		As Inputs Of (at least 2, both are exported)
			func Encode(text string, level Level) (*Code, error)
			func github.com/gotd/td/telegram/auth/qrlogin.Token.Image(level Level) (image.Image, error)
		As Types Of (total 4, all are exported)
			const H
			const L
			const M
			const Q

	/* 4 unexporteds ... *//* 4 unexporteds: */
	 type adigest (struct)

		Fields (total 2, neither is exported)
			/* 2 unexporteds ... *//* 2 unexporteds: */
			a uint32
			b uint32
		Methods (total 4, all are exported)
			(*adigest) Reset()
			(*adigest) Sum32() uint32
			(*adigest) WriteN(p []byte, n int)
			(*adigest) WriteNByte(pi byte, n int)

	 type bitWriter (struct)
		A bitWriter is a write buffer for bit-oriented data like deflate.

		Fields (total 5, none are exported)
			/* 5 unexporteds ... *//* 5 unexporteds: */
			adler32 adigest
			bit uint32
			bytes bytes.Buffer
			nbit uint
			tmp [4]byte
		Methods (total 9, none are exported)
			/* 9 unexporteds ... *//* 9 unexporteds: */
			(*bitWriter) byte(x byte)
			(*bitWriter) codex(c int, val int, nx uint)
			(*bitWriter) flushBits()
			(*bitWriter) hcode(v int)
			(*bitWriter) repeat(n, d int)
			(*bitWriter) repeat1(n, d int)
			(*bitWriter) run(v byte, n int)
			(*bitWriter) writeBits(bit uint32, nbit uint, rev bool)
			(*bitWriter) writeCode(c *Code)

	 type codeImage (struct)
		codeImage implements image.Image

		Fields (total 5, all are exported)
			Code *Code
			Code.Bitmap []byte
				// 1 is black, 0 is white

			Code.Scale int
				// number of image pixels per QR pixel

			Code.Size int
				// number of pixels on a side

			Code.Stride int
				// number of bytes per row

		Methods (total 6, all are exported)
			(*codeImage) At(x, y int) color.Color
			( codeImage) Black(x, y int) bool
				Black returns true if the pixel at (x,y) is black.

			(*codeImage) Bounds() image.Rectangle
			(*codeImage) ColorModel() color.Model
			( codeImage) Image() image.Image
				Image returns an Image displaying the code.

			( codeImage) PNG() []byte
				PNG returns a PNG image displaying the code.
				
				PNG uses a custom encoder tailored to QR codes.
				Its compressed size is about 2x away from optimal,
				but it runs about 20x faster than calling png.Encode
				on c.Image().

		Implements (at least one exported)
			*codeImage : image.Image

	 type pngWriter (struct)

		Fields (total 5, none are exported)
			/* 5 unexporteds ... *//* 5 unexporteds: */
			buf bytes.Buffer
			crc hash.Hash32
			tmp [16]byte
			wctmp [4]byte
			zlib bitWriter
		Methods (total 2, neither is exported)
			/* 2 unexporteds ... *//* 2 unexporteds: */
			(*pngWriter) encode(c *Code) []byte
			(*pngWriter) writeChunk(name string, data []byte)


Package-Level Functions (total 3, in which 1 is exported)

	 func Encode(text string, level Level) (*Code, error)
		Encode returns an encoding of text at the given error correction level.

	/* 2 unexporteds ... *//* 2 unexporteds: */
	 func afinish(a, b uint32) uint32
	 func aupdate(a, b uint32, pi byte, n int) (aa, bb uint32)
Package-Level Variables (total 4, none are exported)

	/* 4 unexporteds ... *//* 4 unexporteds: */
	  var blackColor color.Color
	  var comment []byte
	  var pngHeader []byte
	  var whiteColor color.Color
Package-Level Constants (total 5, in which 4 are exported)

	const H Level = 3 // 65% redundant
	const L Level = 0 // 20% redundant
	const M Level = 1 // 38% redundant
	const Q Level = 2 // 55% redundant
	/* one unexported ... *//* one unexported: */
	const amod = 65521

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