syncthing/vendor/github.com/vitrun/qart/qr/qr.go
Jakob Borg 65aaa607ab Use Go 1.5 vendoring instead of Godeps
Change made by:

- running "gvt fetch" on each of the packages mentioned in
  Godeps/Godeps.json
- `rm -rf Godeps`
- tweaking the build scripts to not mention Godeps
- tweaking the build scripts to test `./lib/...`, `./cmd/...` explicitly
  (to avoid testing vendor)
- tweaking the build scripts to not juggle GOPATH for Godeps and instead
  set GO15VENDOREXPERIMENT.

This also results in some updated packages at the same time I bet.

Building with Go 1.3 and 1.4 still *works* but won't use our vendored
dependencies - the user needs to have the actual packages in their
GOPATH then, which they'll get with a normal "go get". Building with Go
1.6+ will get our vendored dependencies by default even when not using
our build script, which is nice.

By doing this we gain some freedom in that we can pick and choose
manually what to include in vendor, as it's not based on just dependency
analysis of our own code. This is also a risk as we might pick up
dependencies we are unaware of, as the build may work locally with those
packages present in GOPATH. On the other hand the build server will
detect this as it has no packages in it's GOPATH beyond what is included
in the repo.

Recommended tool to manage dependencies is github.com/FiloSottile/gvt.
2016-03-05 21:21:24 +01:00

110 lines
2.3 KiB
Go

package qr
import (
"errors"
"image"
"image/color"
"github.com/vitrun/qart/coding"
)
// A Level denotes a QR error correction level.
// From least to most tolerant of errors, they are L, M, Q, H.
type Level int
const (
L Level = iota // 20% redundant
M // 38% redundant
Q // 55% redundant
H // 65% redundant
)
// Encode returns an encoding of text at the given error correction level.
func Encode(text string, level Level) (*Code, error) {
// Pick data encoding, smallest first.
// We could split the string and use different encodings
// but that seems like overkill for now.
var enc coding.Encoding
switch {
case coding.Num(text).Check() == nil:
enc = coding.Num(text)
case coding.Alpha(text).Check() == nil:
enc = coding.Alpha(text)
default:
enc = coding.String(text)
}
// Pick size.
l := coding.Level(level)
var v coding.Version
for v = coding.MinVersion; ; v++ {
if v > coding.MaxVersion {
return nil, errors.New("text too long to encode as QR")
}
if enc.Bits(v) <= v.DataBytes(l)*8 {
break
}
}
// Build and execute plan.
p, err := coding.NewPlan(v, l, 0)
if err != nil {
return nil, err
}
cc, err := p.Encode(enc)
if err != nil {
return nil, err
}
// TODO: Pick appropriate mask.
return &Code{cc.Bitmap, cc.Size, cc.Stride, 8}, nil
}
// A Code is a square pixel grid.
// It implements image.Image and direct PNG encoding.
type Code struct {
Bitmap []byte // 1 is black, 0 is white
Size int // number of pixels on a side
Stride int // number of bytes per row
Scale int // number of image pixels per QR pixel
}
// Black returns true if the pixel at (x,y) is black.
func (c *Code) Black(x, y int) bool {
return 0 <= x && x < c.Size && 0 <= y && y < c.Size &&
c.Bitmap[y*c.Stride+x/8]&(1<<uint(7-x&7)) != 0
}
// Image returns an Image displaying the code.
func (c *Code) Image() image.Image {
return &codeImage{c}
}
// codeImage implements image.Image
type codeImage struct {
*Code
}
var (
whiteColor color.Color = color.Gray{0xFF}
blackColor color.Color = color.Gray{0x00}
)
func (c *codeImage) Bounds() image.Rectangle {
d := (c.Size + 8) * c.Scale
return image.Rect(0, 0, d, d)
}
func (c *codeImage) At(x, y int) color.Color {
if c.Black(x, y) {
return blackColor
}
return whiteColor
}
func (c *codeImage) ColorModel() color.Model {
return color.GrayModel
}