[dev] decode is now good

README.md

@@ -1,2 +1,15 @@
 # qrcode-api
 A simple API service for QR Code generation/recognition
+
+# Compile
+
+Install and compile ZBar:
+
+```bash
+wget https://downloads.sourceforge.net/project/zbar/zbar/0.10/zbar-0.10.tar.bz2
+tar -xf zbar-0.10.tar.bz2
+cd zbar-0.10
+export CFLAGS=""
+./configure --disable-video --without-imagemagick --without-qt --without-python --without-gtk --without-x --disable-pthread
+make install
+```

cmd/api/build.sh

@@ -3,4 +3,7 @@
 VERSION=`git describe --tags --dirty`
 BUILD=`date +%FT%T%z`
 
-go build -ldflags "-s -w -X main.Version=$VERSION -X main.BuildDate=$BUILD" -o qrcode-api
+# can not build statically safely
+# see https://stackoverflow.com/questions/8140439/why-would-it-be-impossible-to-fully-statically-link-an-application
+export LD_LIBRARY_PATH=/usr/local/lib
+go build -ldflags '-s -w -X main.Version=$VERSION -X main.BuildDate=$BUILD' -o qrcode-api

cmd/api/main.go

@@ -28,6 +28,9 @@ var (
 	BuildDate string
 )
 
+// maxDecodeFileByte is MaxDecodeFileSize's byte version
+var maxDecodeFileByte int64
+
 func init() {
 	w := common.NewBufferedLumberjack(&lumberjack.Logger{
 		Filename:   "qrcode-api.log",
@@ -48,6 +51,7 @@ func main() {
 	defer logger.Sync()
 	defer func() {
 		if err != nil {
+			fmt.Println(err)
 			logger.Fatal("fatal error",
 				zap.Error(err),
 			)
@@ -67,6 +71,8 @@ built on %s
 		return
 	}
 
+	maxDecodeFileByte = int64(C.MaxDecodeFileSize << 10)
+
 	router := setupRouter()
 	startAPI(router, C.Port)
 }

cmd/api/router.go

@@ -11,13 +11,21 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"image"
+	"io"
 	"net/http"
 	"os"
 	"os/signal"
 	"sync/atomic"
 	"syscall"
 	"time"
 
+	"github.com/pkg/errors"
+
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+
 	"github.com/nanmu42/qrcode-api"
 
 	"go.uber.org/zap"
@@ -47,6 +55,7 @@ func setupRouter() (router *gin.Engine) {
 
 	// setup routes
 	router.GET("/encode", EncodeQRCode)
+	router.POST("/decode", DecodeQRCode)
 	return
 }
 
@@ -134,15 +143,15 @@ func EncodeQRCode(c *gin.Context) {
 	encoder, err := ParseEncodeRequest(c.Request.URL.Query())
 	if err != nil {
 		c.Error(err)
-		c.String(http.StatusBadRequest, "%s", err.Error())
+		c.String(http.StatusBadRequest, err.Error())
 		return
 	}
 
 	var buf bytes.Buffer
 	gotType, err := encoder.Encode(&buf)
 	if err != nil {
 		c.Error(err)
-		c.String(http.StatusInternalServerError, "%s", err.Error())
+		c.String(http.StatusInternalServerError, err.Error())
 		return
 	}
 
@@ -155,3 +164,75 @@ func EncodeQRCode(c *gin.Context) {
 
 	return
 }
+
+// DecodeQRCode controller to decode QR Code
+func DecodeQRCode(c *gin.Context) {
+	var err error
+
+	// avoid too big image
+	if c.Request.ContentLength >= maxDecodeFileByte {
+		err = errors.New("request is too big(content-length)")
+		c.Error(err)
+		c.JSON(http.StatusOK, DecodeResponse{
+			OK:      false,
+			Desc:    "request is too big",
+			Content: nil,
+		})
+		return
+	}
+	var buf bytes.Buffer
+	_, readErr := io.CopyN(&buf, c.Request.Body, maxDecodeFileByte)
+	if readErr == nil {
+		err = errors.New("request is too big(actually read)")
+		c.Error(err)
+		c.JSON(http.StatusOK, DecodeResponse{
+			OK:      false,
+			Desc:    "request is too big",
+			Content: nil,
+		})
+		return
+	}
+	if readErr != io.EOF {
+		err = errors.Wrap(readErr, "body read error")
+		c.Error(err)
+		c.JSON(http.StatusOK, DecodeResponse{
+			OK:      false,
+			Desc:    err.Error(),
+			Content: nil,
+		})
+		return
+	}
+
+	// decode image
+	input, _, err := image.Decode(&buf)
+	if err != nil {
+		err = errors.Wrap(err, "file decoding error")
+		c.Error(err)
+		c.JSON(http.StatusOK, DecodeResponse{
+			OK:      false,
+			Desc:    err.Error(),
+			Content: nil,
+		})
+		return
+	}
+
+	contents, err := qrcode.DecodeQRCode(input)
+	if err != nil {
+		err = errors.Wrap(err, "QR Code scanning error")
+		c.Error(err)
+		c.JSON(http.StatusOK, DecodeResponse{
+			OK:      false,
+			Desc:    err.Error(),
+			Content: nil,
+		})
+		return
+	}
+
+	c.JSON(http.StatusOK, DecodeResponse{
+		OK:      true,
+		Desc:    "",
+		Content: contents,
+	})
+
+	return
+}

cmd/api/run.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+LD_LIBRARY_PATH=/usr/local/lib ./qrcode-api

cmd/api/type.go

@@ -39,3 +39,10 @@ func ParseEncodeRequest(values url.Values) (encoder qrcode.QREncoder, err error)
 	encoder.Type = values.Get(typeField)
 	return
 }
+
+// DecodeResponse content holder for response
+type DecodeResponse struct {
+	OK      bool     `json:"ok"`
+	Desc    string   `json:"desc"`
+	Content []string `json:"content"`
+}

decode.go

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2018 LI Zhennan
+ *
+ * Use of this work is governed by an MIT License.
+ * You may find a license copy in project root.
+ */
+
+package qrcode
+
+import (
+	"errors"
+	"image"
+
+	"github.com/PeterCxy/gozbar"
+)
+
+// DecodeQRCode decodes QR Code content from image
+//
+// content contains multiple string if there are more than one QR Code
+// got decoded.
+// content and err are both nil when no QR Code found.
+func DecodeQRCode(img image.Image) (content []string, err error) {
+	input := zbar.FromImage(img)
+
+	s := zbar.NewScanner()
+	s.SetConfig(zbar.QRCODE, zbar.CFG_ENABLE, 1)
+	result := s.Scan(input)
+
+	if result < 0 {
+		err = errors.New("error occurred when scanning")
+		return
+	}
+
+	input.First().Each(func(item string) {
+		content = append(content, item)
+	})
+
+	return
+}

go.mod

@@ -1,6 +1,7 @@
 module github.com/nanmu42/qrcode-api
 
 require (
+	github.com/PeterCxy/gozbar v0.0.0-20151016114418-0b38584c8ebd
 	github.com/gin-contrib/sse v0.0.0-20170109093832-22d885f9ecc7 // indirect
 	github.com/gin-gonic/gin v1.3.0
 	github.com/golang/protobuf v1.2.0 // indirect

go.sum

@@ -1,3 +1,5 @@
+github.com/PeterCxy/gozbar v0.0.0-20151016114418-0b38584c8ebd h1:sokLkqqCxrUcnf+Ptl42sqBdg7z5+u/GdKOWH9WCvDY=
+github.com/PeterCxy/gozbar v0.0.0-20151016114418-0b38584c8ebd/go.mod h1:zZuJKy6Ywgi7DSwgUn0UMhiaNMt2rXW5kCQESjg7YKw=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV9I=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=