make setting up apple mail clients easier by providing .mobileconfig device management profiles

including showing a qr code to easily get the file on iphones.
the profile is currently in the "account" page.

idea by x8x in issue #65

vendor/rsc.io/qr/qr.go

@@ -0,0 +1,116 @@
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package qr encodes QR codes.
+*/
+package qr // import "rsc.io/qr"
+
+import (
+	"errors"
+	"image"
+	"image/color"
+
+	"rsc.io/qr/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
+}