pdf417: fix left row indicator for rows using cluster 0 symbol characters

pdf417/encoder.go

@@ -101,7 +101,7 @@ func getLeftCodeWord(rowNum int, rows int, columns int, securityLevel byte) int
 
 	switch tableId {
 	case 0:
-		x = (rows - 3) / 3
+		x = (rows - 1) / 3
 	case 1:
 		x = int(securityLevel) * 3
 		x += (rows - 1) % 3

pdf417/encoder_test.go

@@ -0,0 +1,43 @@
+package pdf417
+
+import "testing"
+
+func TestRowIndicatorCodewords(t *testing.T) {
+	tests := []struct {
+		name          string
+		rowNum        int
+		rows          int
+		columns       int
+		securityLevel byte
+		wantLeft      int
+		wantRight     int
+	}{
+		{"table0/group0", 0, 17, 6, 3, 5, 5},
+		{"table1/group0", 1, 17, 6, 3, 10, 5},
+		{"table2/group0", 2, 17, 6, 3, 5, 10},
+		{"table0/group1", 3, 17, 6, 3, 35, 35},
+		{"table1/group1", 4, 17, 6, 3, 40, 35},
+		{"table2/group1", 5, 17, 6, 3, 35, 40},
+		{"table1/group5", 16, 17, 6, 3, 160, 155},
+		{"table0/rowsMod1", 0, 16, 6, 3, 5, 5},
+		{"table0/maxParams", 0, maxRows, maxCols, 8, 9, 29},
+		{"table1/maxParams", 1, maxRows, maxCols, 8, 26, 9},
+		{"table2/maxParams", 2, maxRows, maxCols, 8, 29, 26},
+		{"table0/lastRow", maxRows - 3, maxRows, maxCols, 8, 279, 299},
+		{"table1/lastRow", maxRows - 2, maxRows, maxCols, 8, 296, 279},
+		{"table2/lastRow", maxRows - 1, maxRows, maxCols, 8, 299, 296},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := getLeftCodeWord(tt.rowNum, tt.rows, tt.columns, tt.securityLevel); got != tt.wantLeft {
+				t.Errorf("getLeftCodeWord(rowNum=%d, rows=%d, columns=%d, securityLevel=%d) = %d, want %d",
+					tt.rowNum, tt.rows, tt.columns, tt.securityLevel, got, tt.wantLeft)
+			}
+			if got := getRightCodeWord(tt.rowNum, tt.rows, tt.columns, tt.securityLevel); got != tt.wantRight {
+				t.Errorf("getRightCodeWord(rowNum=%d, rows=%d, columns=%d, securityLevel=%d) = %d, want %d",
+					tt.rowNum, tt.rows, tt.columns, tt.securityLevel, got, tt.wantRight)
+			}
+		})
+	}
+}