Add TOCLine component

pdf/creator/styled_paragraph.go

@@ -63,6 +63,9 @@ type StyledParagraph struct {
 
 	// Text chunk lines after wrapping to available width.
 	lines [][]TextChunk
+
+	// Before render callback
+	beforeRender func(p *StyledParagraph, ctx DrawContext)
 }
 
 // NewStyledParagraph creates a new styled paragraph.
@@ -104,6 +107,23 @@ func (p *StyledParagraph) Append(text string, style TextStyle) {
 	p.wrapText()
 }
 
+// Insert adds a new text chunk at the specified position in the paragraph.
+func (p *StyledParagraph) Insert(index uint, text string, style TextStyle) {
+	l := uint(len(p.chunks))
+	if index > l {
+		index = l
+	}
+
+	chunk := TextChunk{
+		Text:  text,
+		Style: style,
+	}
+	chunk.Style.Font.SetEncoder(p.encoder)
+
+	p.chunks = append(p.chunks[:index], append([]TextChunk{chunk}, p.chunks[index:]...)...)
+	p.wrapText()
+}
+
 // Reset sets the entire text and also the style of the paragraph
 // to those specified. It behaves as if the paragraph was a new one.
 func (p *StyledParagraph) Reset(text string, style TextStyle) {
@@ -238,6 +258,41 @@ func (p *StyledParagraph) getTextWidth() float64 {
 	return width
 }
 
+// getTextLineWidth calculates the text width of a provided collection of text chunks
+func (p *StyledParagraph) getTextLineWidth(line []TextChunk) float64 {
+	var width float64
+	for _, chunk := range line {
+		style := &chunk.Style
+
+		for _, rune := range chunk.Text {
+			glyph, found := p.encoder.RuneToGlyph(rune)
+			if !found {
+				common.Log.Debug("Error! Glyph not found for rune: %s\n", rune)
+
+				// XXX/FIXME: return error.
+				return -1
+			}
+
+			// Ignore newline for this.. Handles as if all in one line.
+			if glyph == "controlLF" {
+				continue
+			}
+
+			metrics, found := style.Font.GetGlyphCharMetrics(glyph)
+			if !found {
+				common.Log.Debug("Glyph char metrics not found! %s\n", glyph)
+
+				// XXX/FIXME: return error.
+				return -1
+			}
+
+			width += style.FontSize * metrics.Wx
+		}
+	}
+
+	return width
+}
+
 // getTextHeight calculates the text height as if all in one line (not taking wrapping into account).
 func (p *StyledParagraph) getTextHeight() float64 {
 	var height float64
@@ -415,6 +470,10 @@ func (p *StyledParagraph) GeneratePageBlocks(ctx DrawContext) ([]*Block, DrawCon
 		ctx.Y = p.yPos
 	}
 
+	if p.beforeRender != nil {
+		p.beforeRender(p, ctx)
+	}
+
 	// Place the Paragraph on the template at position (x,y) based on the ctx.
 	ctx, err := drawStyledParagraphOnBlock(blk, p, ctx)
 	if err != nil {

pdf/creator/text_chunk.go

@@ -0,0 +1,15 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
+package creator
+
+// TextChunk represents a chunk of text along with a particular style.
+type TextChunk struct {
+	// The text that is being rendered in the PDF.
+	Text string
+
+	// The style of the text being rendered.
+	Style TextStyle
+}

pdf/creator/text_style.go

@@ -35,9 +35,3 @@ func NewTextStyle() TextStyle {
 		FontSize: 10,
 	}
 }
-
-// TextChunk represents a chunk of text along with a particular style.
-type TextChunk struct {
-	Text  string
-	Style TextStyle
-}

pdf/creator/toc_line.go

@@ -0,0 +1,129 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
+package creator
+
+import (
+	"strings"
+)
+
+type TOCLine struct {
+	sp *StyledParagraph
+
+	number    TextChunk
+	title     TextChunk
+	page      TextChunk
+	separator TextChunk
+
+	level       uint
+	levelOffset float64
+}
+
+func NewTOCLine(number, title, page string, level uint) *TOCLine {
+	style := NewTextStyle()
+
+	return NewStyledTOCLine(
+		TextChunk{Text: number, Style: style},
+		TextChunk{Text: title, Style: style},
+		TextChunk{Text: page, Style: style},
+		level,
+	)
+}
+
+func NewStyledTOCLine(number, title, page TextChunk, level uint) *TOCLine {
+	style := NewTextStyle()
+
+	sp := NewStyledParagraph("", style)
+	sp.SetEnableWrap(true)
+	sp.SetTextAlignment(TextAlignmentLeft)
+
+	tl := &TOCLine{
+		sp:     sp,
+		number: number,
+		title:  title,
+		page:   page,
+		separator: TextChunk{
+			Text:  ".",
+			Style: style,
+		},
+		level:       level,
+		levelOffset: 10,
+	}
+
+	sp.margins.left = float64(level) * tl.levelOffset
+	sp.beforeRender = tl.prepareParagraph
+	return tl
+}
+
+func (tl *TOCLine) prepareParagraph(sp *StyledParagraph, ctx DrawContext) {
+	if tl.number.Text != "" {
+		tl.title.Text = " " + tl.title.Text
+	}
+	tl.title.Text += " "
+
+	if tl.page.Text != "" {
+		tl.page.Text = " " + tl.page.Text
+	}
+
+	sp.chunks = []TextChunk{
+		tl.number,
+		tl.title,
+		tl.page,
+	}
+	sp.SetEncoder(sp.encoder)
+	sp.wrapText()
+
+	l := len(sp.lines)
+	if l == 0 {
+		return
+	}
+
+	// Insert separator
+	availWidth := ctx.Width*1000 - sp.getTextLineWidth(sp.lines[l-1])
+	sepWidth := sp.getTextLineWidth([]TextChunk{tl.separator})
+	sepCount := int(availWidth / sepWidth)
+	sepText := strings.Repeat(tl.separator.Text, sepCount)
+
+	sp.Insert(2, sepText, tl.separator.Style)
+
+	// Push page numbers to the end of the line
+	availWidth = availWidth - float64(sepCount)*sepWidth
+	if availWidth > 500 {
+		spaceMetrics, found := tl.separator.Style.Font.GetGlyphCharMetrics("space")
+		if found && availWidth > spaceMetrics.Wx {
+			spaces := int(availWidth / spaceMetrics.Wx)
+			if spaces > 0 {
+				style := tl.separator.Style
+				style.FontSize = 1
+				sp.Insert(2, strings.Repeat(" ", spaces), style)
+			}
+		}
+	}
+}
+
+func (tl *TOCLine) GeneratePageBlocks(ctx DrawContext) ([]*Block, DrawContext, error) {
+	origCtx := ctx
+
+	blocks, ctx, err := tl.sp.GeneratePageBlocks(ctx)
+	if err != nil {
+		return blocks, ctx, err
+	}
+	if len(blocks) > 1 {
+		// Did not fit, moved to new Page block.
+		ctx.Page++
+	}
+
+	if tl.sp.positioning.isRelative() {
+		// Move back X to same start of line.
+		ctx.X = origCtx.X
+	}
+
+	if tl.sp.positioning.isAbsolute() {
+		// If absolute: return original context.
+		return blocks, origCtx, nil
+	}
+
+	return blocks, ctx, nil
+}