captcha init

Author: feiin

.gitignore

@@ -0,0 +1 @@
+test.png

canvas.go

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+package captcha
+
+import (
+	// "fmt"
+
+	"embed"
+	// "fmt"
+	"github.com/golang/freetype"
+	"github.com/golang/freetype/truetype"
+	"image"
+	"image/color"
+	// "math"
+	"math/rand"
+	"time"
+)
+
+//go:embed fonts/*
+var fontFS embed.FS
+
+var defaultFont *truetype.Font
+
+func init() {
+
+	fontdata, _ := fontFS.ReadFile("fonts/SourceHanSerifCN-Light.ttf")
+	defaultFont, _ = freetype.ParseFont(fontdata)
+
+	rand.Seed(time.Now().UnixNano())
+
+	// fmt.Printf("defaultFont %+v :err:%+v", defaultFont, err)
+}
+
+type Canvas struct {
+	*image.NRGBA
+	Width  int
+	Height int
+}
+
+func (c *Canvas) DrawLines(lineCount int) {
+
+	for lineCount > 0 {
+
+		p1 := Point{X: rand.Intn(c.Width), Y: rand.Intn(c.Height)}
+		p2 := Point{X: rand.Intn(c.Width), Y: rand.Intn(c.Height)}
+
+		c.DrawLine(p1, p2, randomColor())
+		lineCount--
+	}
+}
+
+//DrawLine 画干扰线
+func (c *Canvas) DrawLine(p1, p2 Point, color color.Color) {
+
+	var k float64 = 0
+	b := p1.Y
+	if (p2.X - p1.X) != 0 {
+		k = float64(p2.Y-p1.Y) / float64(p2.X-p1.X)
+	}
+
+	b = p1.Y - int(k*float64(p1.X))
+
+	sx := 1
+	offsetX := p1.X
+
+	if p2.X < p1.X {
+		sx = -1
+	}
+
+	for {
+
+		offsetY := int(k*float64(offsetX)) + b
+		c.Set(offsetX, offsetY, color)
+
+		if offsetX == p2.X {
+			break
+		}
+		offsetX = offsetX + sx
+
+	}
+}
+
+func (c *Canvas) DrawString(text string) {
+
+	for _, ch := range text {
+
+		dc := freetype.NewContext()
+		dc.SetDPI(float64(72))
+		dc.SetFont(defaultFont)
+		dc.SetClip(c.Bounds())
+		dc.SetDst(c)
+
+		// 文字大小
+		dc.SetFontSize(float64(56))
+
+		// 文字颜色
+		fontColor := image.NewUniform(randomColor())
+		dc.SetSrc(fontColor)
+
+		pos := c.randomFontPosition(56)
+		// 画文本
+		pt := freetype.Pt(pos.X, pos.Y) // 字出现的位置
+		_, err := dc.DrawString(string(ch), pt)
+		if err != nil {
+			panic(err)
+		}
+	}
+
+}
+
+func (c *Canvas) randomFontPosition(fontSize int) Point {
+	minX := fontSize
+	minY := fontSize
+
+	maxX := c.Width - fontSize
+	maxY := c.Height - fontSize
+
+	x := randomInt(minX, maxX)
+	y := randomInt(minY, maxY)
+
+	return Point{x, y}
+
+}
+
+//randomInt 返回随机数 [min,max)
+func randomInt(min, max int) int {
+	if min >= max || max == 0 {
+		return max
+	}
+	return rand.Intn(max-min) + min
+}
+
+func randomColor() color.RGBA {
+	red := rand.Intn(256)
+	green := rand.Intn(256)
+	blue := rand.Intn(256)
+
+	return color.RGBA{R: uint8(red), G: uint8(green), B: uint8(blue), A: uint8(255)}
+}
+
+//DrawCircles 随机产生circleCount干扰点
+func (c *Canvas) DrawCircles(circleCount int) {
+
+	for circleCount > 0 {
+
+		cc := randomColor()
+		x := rand.Intn(c.Width)
+		y := rand.Intn(c.Height)
+
+		r := rand.Intn(3)
+
+		fillCircle := rand.Intn(5) > 1
+
+		c.DrawCircle(x, y, r, fillCircle, cc)
+
+		circleCount = circleCount - 1
+
+	}
+
+}
+
+func (c *Canvas) drawCircle8(xc, yc, x, y int, cc color.Color) {
+	c.Set(xc+x, yc+y, cc)
+	c.Set(xc-x, yc+y, cc)
+	c.Set(xc+x, yc-y, cc)
+	c.Set(xc-x, yc-y, cc)
+	c.Set(xc+y, yc+x, cc)
+	c.Set(xc-y, yc+x, cc)
+	c.Set(xc+y, yc-x, cc)
+	c.Set(xc-y, yc-x, cc)
+}
+
+// DrawCircle 画圆
+func (c *Canvas) DrawCircle(xc, yc, r int, fill bool, cc color.Color) {
+	size := c.Bounds().Size()
+	if xc+r < 0 || xc-r >= size.X || yc+r < 0 || yc-r >= size.Y {
+		return
+	}
+	x, y, d := 0, r, 3-2*r
+	for x <= y {
+		if fill {
+			for yi := x; yi <= y; yi++ {
+				c.drawCircle8(xc, yc, x, yi, cc)
+			}
+		} else {
+			c.drawCircle8(xc, yc, x, y, cc)
+		}
+		if d < 0 {
+			d = d + 4*x + 6
+		} else {
+			d = d + 4*(x-y) + 10
+			y--
+		}
+		x++
+	}
+}

captcha.go

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+package captcha
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"image"
+	// "image/color"
+	"image/png"
+	"os"
+)
+
+type Captcha struct {
+	Width  int
+	Height int
+}
+
+func NewCaptcha(width, height int) *Captcha {
+	return &Captcha{Width: width, Height: height}
+}
+
+func (cp *Captcha) GenCaptchaImage() (string, error) {
+	c := Canvas{
+		Width:  cp.Width,
+		Height: cp.Height,
+		NRGBA:  image.NewNRGBA(image.Rect(0, 0, cp.Width, cp.Height)),
+	}
+
+	c.DrawLines(5)
+
+	c.DrawString("测试阿斯蒂")
+
+	c.DrawCircles(120)
+
+	imageBytes, err := encodingWithPng(c)
+
+	if err != nil {
+		return "", err
+	}
+
+	writeImageFile("./test.png", imageBytes)
+	return fmt.Sprintf("data:%s;base64,%s", "image/png", base64.StdEncoding.EncodeToString(imageBytes)), nil
+
+}
+
+func encodingWithPng(img image.Image) (encodeResult []byte, err error) {
+
+	var buf bytes.Buffer
+
+	if err := png.Encode(&buf, img); err != nil {
+		return encodeResult, err
+	}
+
+	encodeResult = buf.Bytes()
+
+	buf.Reset()
+	return encodeResult, nil
+
+}
+
+func writeImageFile(filepath string, imageBytes []byte) {
+	file, err := os.OpenFile(filepath, os.O_WRONLY|os.O_CREATE, 0666)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+	file.Write(imageBytes)
+}

captcha_test.go

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+package captcha
+
+import (
+	"testing"
+)
+
+func TestGenCaptcha(t *testing.T) {
+
+	cpt := NewCaptcha(460, 200)
+	image, err := cpt.GenCaptchaImage()
+	t.Logf("GenCaptchaImage %s %+v", image, err)
+}

fonts/SourceHanSerifCN-Light.ttf

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+module github.com/feiin/go-captcha
+
+go 1.18
+
+require github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
+
+require golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9 // indirect

go.mod

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+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
+golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9 h1:LRtI4W37N+KFebI/qV0OFiLUv4GLOWeEW5hn/KEJvxE=
+golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

go.sum

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+package captcha
+
+type Point struct {
+	X int
+	Y int
+}
+
+func NewPoint(x int, y int) *Point {
+	return &Point{X: x, Y: y}
+}