Fix #469

pkg/api/test/stamp_test.go

@@ -548,3 +548,29 @@ func TestStampingLifecyle(t *testing.T) {
 		t.Fatalf("Watermarks found: %s\n", outFile)
 	}
 }
+
+func TestRecycleWM(t *testing.T) {
+	msg := "TestRecycleWM"
+	inFile := filepath.Join(inDir, "Test.pdf")
+	outFile := filepath.Join("..", "..", "samples", "watermark", "text", "TextRecycled.pdf")
+	onTop := false // we are testing watermarks
+
+	desc := "pos:tl, points:22, rot:0, scale:1 abs, off:0 -5, opacity:0.3"
+	wm, err := api.TextWatermark("This is a watermark", desc, onTop, false, pdfcpu.POINTS)
+	if err != nil {
+		t.Fatalf("%s %s: %v\n", msg, outFile, err)
+	}
+
+	if err = api.AddWatermarksFile(inFile, outFile, nil, wm, nil); err != nil {
+		t.Fatalf("%s %s: %v\n", msg, outFile, err)
+	}
+
+	wm.Recycle()
+
+	// Shift down watermark.
+	wm.Dy = -55
+
+	if err = api.AddWatermarksFile(outFile, outFile, nil, wm, nil); err != nil {
+		t.Fatalf("%s %s: %v\n", msg, outFile, err)
+	}
+}

pkg/pdfcpu/stamp.go

@@ -248,6 +248,11 @@ func DefaultWatermarkConfig() *Watermark {
 	}
 }
 
+func (wm *Watermark) Recycle() {
+	wm.objs = IntSet{}
+	wm.fCache = formCache{}
+}
+
 func (wm Watermark) typ() string {
 	if wm.isImage() {
 		return "image"
@@ -324,17 +329,6 @@ func (wm Watermark) multiStamp() bool {
 	return wm.Page == 0
 }
 
-// func (wm Watermark) calcMaxTextWidth() float64 {
-// 	var maxWidth float64
-// 	for _, l := range wm.TextLines {
-// 		w := font.TextWidth(l, wm.FontName, wm.ScaledFontSize)
-// 		if w > maxWidth {
-// 			maxWidth = w
-// 		}
-// 	}
-// 	return maxWidth
-// }
-
 func ResolveWMTextString(text, timeStampFormat string, pageNr, pageCount int) (string, bool) {
 	// replace  %p with pageNr
 	//			%P with pageCount