🎨 桌面端支持搜索图片中的文本 Fix https://github.com/siyuan-note/siyuan/issues/3470

kernel/treenode/node.go

@@ -18,10 +18,11 @@ package treenode
 
 import (
 	"bytes"
-	"github.com/88250/gulu"
+	"path/filepath"
 	"strings"
 	"sync"
 
+	"github.com/88250/gulu"
 	"github.com/88250/lute"
 	"github.com/88250/lute/ast"
 	"github.com/88250/lute/editor"
@@ -31,6 +32,7 @@ import (
 	"github.com/88250/lute/render"
 	"github.com/88250/lute/util"
 	"github.com/siyuan-note/logging"
+	util2 "github.com/siyuan-note/siyuan/kernel/util"
 )
 
 func GetBlockRef(n *ast.Node) (blockRefID, blockRefText, blockRefSubtype string) {
@@ -107,6 +109,19 @@ func NodeStaticContent(node *ast.Node, excludeTypes []string) string {
 		switch n.Type {
 		case ast.NodeLinkText:
 			buf.Write(n.Tokens)
+
+			if nil != n.Parent && ast.NodeImage == n.Parent.Type {
+				destNode := n.Parent.ChildByType(ast.NodeLinkDest)
+				if nil != destNode {
+					// 桌面端支持搜索图片中的文本 https://github.com/siyuan-note/siyuan/issues/3470
+					// 尝试 OCR 识别图片中的文字并作为图片的 alt
+					if text := util2.Tesseract(filepath.Join(util2.DataDir, destNode.TokensStr())); "" != text {
+						buf.WriteByte(' ')
+						buf.WriteString(text)
+					}
+				}
+			}
+
 			buf.WriteByte(' ')
 		case ast.NodeLinkDest:
 			buf.Write(n.Tokens)

kernel/util/ocr.go

@@ -0,0 +1,105 @@
+// SiYuan - Build Your Eternal Digital Garden
+// Copyright (c) 2020-present, b3log.org
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package util
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/88250/gulu"
+	"github.com/dgraph-io/ristretto"
+	"github.com/siyuan-note/logging"
+)
+
+var tesseractEnabled bool
+
+func initTesseract() {
+	ver := getTesseractVer()
+	if "" == ver {
+		return
+	}
+
+	logging.LogInfof("tesseract-ocr enabled [ver=%s]", ver)
+}
+
+func getTesseractVer() (ret string) {
+	cmd := exec.Command("tesseract", "--version")
+	gulu.CmdAttr(cmd)
+	data, err := cmd.CombinedOutput()
+	if nil == err && strings.HasPrefix(string(data), "tesseract v") {
+		parts := bytes.Split(data, []byte("\n"))
+		if 0 < len(parts) {
+			ret = strings.TrimPrefix(string(parts[0]), "tesseract ")
+			ret = strings.TrimSpace(ret)
+			tesseractEnabled = true
+		}
+		return
+	}
+	return
+}
+
+var ocrResultCache, _ = ristretto.NewCache(&ristretto.Config{
+	NumCounters: 100000,
+	MaxCost:     1000 * 1000 * 64,
+	BufferItems: 64,
+})
+
+func Tesseract(imgAbsPath string) string {
+	if ContainerStd != Container || !tesseractEnabled {
+		return ""
+	}
+
+	info, err := os.Stat(imgAbsPath)
+	if nil != err {
+		return ""
+	}
+
+	cached, ok := ocrResultCache.Get(imgAbsPath)
+	if ok {
+		return cached.(string)
+	}
+
+	defer logging.Recover()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, "tesseract", "-c", "debug_file=/dev/null", imgAbsPath, "stdout", "-l", "chi_sim+eng")
+	gulu.CmdAttr(cmd)
+	output, err := cmd.CombinedOutput()
+	if ctx.Err() == context.DeadlineExceeded {
+		logging.LogWarnf("tesseract [path=%s, size=%d] timeout", imgAbsPath, info.Size())
+		return ""
+	}
+
+	if nil != err {
+		logging.LogWarnf("tesseract [path=%s, size=%d] failed: %s", imgAbsPath, info.Size(), err)
+		return ""
+	}
+
+	ret := string(output)
+	reg := regexp.MustCompile("\\s+")
+	ret = reg.ReplaceAllString(ret, "")
+	logging.LogInfof("tesseract [path=%s, size=%d]: %s", imgAbsPath, info.Size(), ret)
+	ocrResultCache.Set(imgAbsPath, ret, info.Size())
+	return ret
+}

kernel/util/working.go

@@ -113,6 +113,7 @@ func Boot() {
 
 	initPathDir()
 	go initPandoc()
+	go initTesseract()
 
 	bootBanner := figure.NewColorFigure("SiYuan", "isometric3", "green", true)
 	logging.LogInfof("\n" + bootBanner.String())