添加pdf水印

services/file.go

@@ -12,7 +12,6 @@ import (
 	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/model"
 	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/types"
 	"io"
-	"math"
 	"mime/multipart"
 	"os"
 	"os/exec"
@@ -191,6 +190,7 @@ func GetResourceUrlBySvgImg(imgData string) (resourceUrl string, err error, errM
 func GeneralWaterMarkPdf(pdfPath, waterMarkStr string) (f2 *bytes.Buffer, err error) {
 	onTop := true
 	update := false
+	desc := "fo:SimHei, points:24, col: 0.75 0.75 0.75, scale:1 abs, opacity:0.3"
 	//fontDir := `C:\Users\123\go\src\eta\eta_api\static`
 	fontDir := `static`
 	font.UserFontDir = fontDir
@@ -211,54 +211,73 @@ func GeneralWaterMarkPdf(pdfPath, waterMarkStr string) (f2 *bytes.Buffer, err er
 	defer func() {
 		_ = f1.Close()
 	}()
-
+	fmt.Println(len(waterMarkStr))
 	f2 = &bytes.Buffer{}
-	points := "24" //字号大小
-	rows := 6      //行数
-	// 处理文字
-	textLen := len(waterMarkStr)
-	count := int(math.Round(250.0 / (float64(textLen) + 18)))
-	if textLen > 102 {
-		count = 1
+	wm, tmpErr := api.TextWatermark(waterMarkStr, desc, onTop, update, types.POINTS)
+	if tmpErr != nil {
+		fmt.Println("TextWatermark err:", tmpErr)
+		return
 	}
-	if textLen > 210 {
-		points = "20"
-		rows = 7
+	wm.Pos = types.TopCenter
+	realFontSize := wm.ScaledFontSize
+	if realFontSize <= 0 {
+		realFontSize = wm.FontSize
 	}
-	var sb1 strings.Builder
-	for i := 0; i < count; i++ {
-		sb1.WriteString(waterMarkStr)
+	targetLineWidth := font.TextWidth(waterMarkStr, wm.FontName, realFontSize)
+	targetText := waterMarkStr
+	var ctxCpu *model.Context
+	ctxCpu, err = api.ReadValidateAndOptimize(f1, api.LoadConfiguration())
+	if err != nil {
+		return nil, err
+	}
+	var dms []types.Dim
+	dms, err = ctxCpu.PageDims()
+	if err != nil {
+		return nil, err
 	}
 
-	//单行文字制作完成
-	sb1Str := sb1.String()
-	//拼接成多行文字
+	dm := dms[0]
+	fmt.Println("targetLineWidth", targetLineWidth)
+	if targetLineWidth*2 > dm.Width {
+		targetText += "  "
+		for _, v := range waterMarkStr {
+			if dm.Width <= targetLineWidth {
+				break
+			}
+			targetText += fmt.Sprintf("%c", v)
+			targetLineWidth = font.TextWidth(targetText, wm.FontName, realFontSize)
+		}
+	} else {
+		for dm.Width >= targetLineWidth {
+			targetText += "  " + waterMarkStr
+			targetLineWidth = font.TextWidth(targetText, wm.FontName, realFontSize)
+		}
+	}
+
+	fmt.Println("dm.Width", dm.Width, " dm.Height", dm.Height)
 	var sb2 strings.Builder
 	lineSpace := "\n \n \n \n \n \n"
-
+	rows := 6
 	for i := 0; i < rows; i++ {
-		sb2.WriteString(sb1Str)
+		sb2.WriteString(targetText)
 		if i < rows-1 {
 			sb2.WriteString(lineSpace)
 		}
-
 	}
+	fmt.Println(sb2.String())
 	wmList := make([]*model.Watermark, 0)
-	//for i := types.TopLeft; i <= 9; i++ {
-	wm, tmpErr := api.TextWatermark(sb2.String(), "fo:SimHei, points:"+points+", col: 0.75 0.75 0.75, scale:1 abs, opacity:0.3", onTop, update, types.POINTS)
+	wm, tmpErr = api.TextWatermark(sb2.String(), "fo:SimHei, points:38, col: 0.75 0.75 0.75, scale:1 abs, opacity:0.3", onTop, update, types.POINTS)
 	if tmpErr != nil {
 		fmt.Println("TextWatermark err:", tmpErr)
 		return
 	}
-	//wm.Pos = types.Center
 	wm.Pos = types.TopCenter
 	wmList = append(wmList, wm)
-	//}
 
 	err = AddWatermarks(f1, f2, nil, wmList, nil)
-
 	return
 }
+
 func AddWatermarks(rs io.ReadSeeker, w io.Writer, selectedPages []string, wmList []*model.Watermark, conf *model.Configuration) error {
 	if rs == nil {
 		return errors.New("pdfcpu: AddWatermarks: missing rs")