implement vertical baseline alignment for text

2 files changed, 53 insertions, 23 deletions

diff --git a/fpdf.go b/fpdf.go
index 6eae426..fd0c91f 100644
--- a/fpdf.go
+++ b/fpdf.go
@@ -1376,6 +1376,16 @@ func (f *Fpdf) AddFont(familyStr, styleStr, fileStr string) {
 	f.AddFontFromReader(familyStr, styleStr, file)
 }
 
+// getFontKey is used by AddFontFromReader and GetFontDesc
+func getFontKey(familyStr, styleStr string) string {
+	familyStr = strings.ToLower(familyStr)
+	styleStr = strings.ToUpper(styleStr)
+	if styleStr == "IB" {
+		styleStr = "BI"
+	}
+	return familyStr + styleStr
+}
+
 // AddFontFromReader imports a TrueType, OpenType or Type1 font and makes it
 // available using a reader that satisifies the io.Reader interface. See
 // AddFont for details about familyStr and styleStr.
@@ -1385,12 +1395,7 @@ func (f *Fpdf) AddFontFromReader(familyStr, styleStr string, r io.Reader) {
 	}
 	// dbg("Adding family [%s], style [%s]", familyStr, styleStr)
 	var ok bool
-	familyStr = strings.ToLower(familyStr)
-	styleStr = strings.ToUpper(styleStr)
-	if styleStr == "IB" {
-		styleStr = "BI"
-	}
-	fontkey := familyStr + styleStr
+	fontkey := getFontKey(familyStr, styleStr)
 	_, ok = f.fonts[fontkey]
 	if ok {
 		return
@@ -1434,8 +1439,7 @@ func (f *Fpdf) AddFontFromReader(familyStr, styleStr string, r io.Reader) {
 // documentation about the font descriptor.
 // See AddFont for details about familyStr and styleStr.
 func (f *Fpdf) GetFontDesc(familyStr, styleStr string) FontDescType {
-	fontkey := familyStr + styleStr // see AddFontFromReader
-	return f.fonts[fontkey].Desc
+	return f.fonts[getFontKey(familyStr, styleStr)].Desc
 }
 
 // SetFont sets the font used to print character strings. It is mandatory to
@@ -1686,8 +1690,8 @@ func (f *Fpdf) SetAcceptPageBreakFunc(fnc func() bool) {
 // alignStr specifies how the text is to be positionined within the cell.
 // Horizontal alignment is controlled by including "L", "C" or "R" (left,
 // center, right) in alignStr. Vertical alignment is controlled by including
-// "T", "M" or "B" (top, middle, bottom) in alignStr. The default alignment is
-// left middle.
+// "T", "M", "B" or "A" (top, middle, bottom, baseline) in alignStr. The default
+// alignment is left middle.
 //
 // fill is true to paint the cell background or false to leave it transparent.
 //
@@ -1778,6 +1782,16 @@ func (f *Fpdf) CellFormat(w, h float64, txtStr string, borderStr string, ln int,
 			dy = (f.fontSize - h) / 2.0
 		} else if strings.Index(alignStr, "B") != -1 {
 			dy = (h - f.fontSize) / 2.0
+		} else if strings.Index(alignStr, "A") != -1 {
+			var descent float64
+			d := f.currentFont.Desc
+			if d.Descent == 0 {
+				// not defined (standard font?), use average of 19%
+				descent = -0.19 * f.fontSize
+			} else {
+				descent = float64(d.Descent) * f.fontSize / float64(d.Ascent-d.Descent)
+			}
+			dy = (h-f.fontSize)/2.0 - descent
 		} else {
 			dy = 0
 		}
diff --git a/fpdf_test.go b/fpdf_test.go
index fdc3334..63d4655 100644
--- a/fpdf_test.go
+++ b/fpdf_test.go
@@ -1175,25 +1175,41 @@ func ExampleFpdf_CellFormat_2() {
 		recType{"BC", "bottom center"},
 		recType{"BR", "bottom right"},
 	}
-	pdf := gofpdf.New("P", "mm", "A4", "") // A4 210.0 x 297.0
-	pdf.SetFont("Helvetica", "", 16)
-	linkStr := ""
-	for pageJ := 0; pageJ < 2; pageJ++ {
-		pdf.AddPage()
-		pdf.SetMargins(10, 10, 10)
-		pdf.SetAutoPageBreak(false, 0)
-		borderStr := "1"
-		for _, rec := range recList {
-			pdf.SetXY(20, 20)
-			pdf.CellFormat(170, 257, rec.txt, borderStr, 0, rec.align, false, 0, linkStr)
-			borderStr = ""
+	recListBaseline := []recType{
+		recType{"AL", "baseline left"},
+		recType{"AC", "baseline center"},
+		recType{"AR", "baseline right"},
+	}
+	var formatRect = func(pdf *gofpdf.Fpdf, recList []recType) {
+		linkStr := ""
+		for pageJ := 0; pageJ < 2; pageJ++ {
+			pdf.AddPage()
+			pdf.SetMargins(10, 10, 10)
+			pdf.SetAutoPageBreak(false, 0)
+			borderStr := "1"
+			for _, rec := range recList {
+				pdf.SetXY(20, 20)
+				pdf.CellFormat(170, 257, rec.txt, borderStr, 0, rec.align, false, 0, linkStr)
+				borderStr = ""
+			}
+			linkStr = "https://github.com/jung-kurt/gofpdf"
 		}
-		linkStr = "https://github.com/jung-kurt/gofpdf"
 	}
+	pdf := gofpdf.New("P", "mm", "A4", "") // A4 210.0 x 297.0
+	pdf.SetFont("Helvetica", "", 16)
+	formatRect(pdf, recList)
+	formatRect(pdf, recListBaseline)
+	var fr fontResourceType
+	pdf.SetFontLoader(fr)
+	pdf.AddFont("Calligrapher", "", "calligra.json")
+	pdf.SetFont("Calligrapher", "", 16)
+	formatRect(pdf, recListBaseline)
 	fileStr := exampleFilename("Fpdf_CellFormat_2_align")
 	err := pdf.OutputFileAndClose(fileStr)
 	summary(err, fileStr)
 	// Output:
+	// Generalized font loader reading calligra.json
+	// Generalized font loader reading calligra.z
 	// Successfully generated pdf/Fpdf_CellFormat_2_align.pdf
 }