Factored basic SVG path rendering, basic HTML rendering, and color routines.

1 files changed, 196 insertions, 0 deletions

diff --git a/htmlbasic.go b/htmlbasic.go
new file mode 100644
index 0000000..b2a05e5
--- /dev/null
+++ b/htmlbasic.go
@@ -0,0 +1,196 @@
+/*
+ * Copyright (c) 2014 Kurt Jung (Gmail: kurt.w.jung)
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package gofpdf
+
+import (
+	"regexp"
+	"strings"
+)
+
+type HtmlBasicSegmentType struct {
+	Cat  byte              // 'O' open tag, 'C' close tag, 'T' text
+	Str  string            // Literal text unchanged, tags are lower case
+	Attr map[string]string // Attribute keys are lower case
+}
+
+// HtmlBasicTokenize returns a list of HTML tags and literal elements. This is
+// done with regular expressions, so the result is only marginally better than
+// useless.
+func HtmlBasicTokenize(htmlStr string) (list []HtmlBasicSegmentType) {
+	// This routine is adapted from http://www.fpdf.org/
+	list = make([]HtmlBasicSegmentType, 0, 16)
+	htmlStr = strings.Replace(htmlStr, "\n", " ", -1)
+	htmlStr = strings.Replace(htmlStr, "\r", "", -1)
+	tagRe, _ := regexp.Compile(`(?U)<.*>`)
+	attrRe, _ := regexp.Compile(`([^=]+)=["']?([^"']+)`)
+	capList := tagRe.FindAllStringIndex(htmlStr, -1)
+	if capList != nil {
+		var seg HtmlBasicSegmentType
+		var parts []string
+		pos := 0
+		for _, cap := range capList {
+			if pos < cap[0] {
+				seg.Cat = 'T'
+				seg.Str = htmlStr[pos:cap[0]]
+				seg.Attr = nil
+				list = append(list, seg)
+			}
+			if htmlStr[cap[0]+1] == '/' {
+				seg.Cat = 'C'
+				seg.Str = strings.ToLower(htmlStr[cap[0]+2 : cap[1]-1])
+				seg.Attr = nil
+				list = append(list, seg)
+			} else {
+				// Extract attributes
+				parts = strings.Split(htmlStr[cap[0]+1:cap[1]-1], " ")
+				if len(parts) > 0 {
+					for j, part := range parts {
+						if j == 0 {
+							seg.Cat = 'O'
+							seg.Str = strings.ToLower(parts[0])
+							seg.Attr = make(map[string]string)
+						} else {
+							attrList := attrRe.FindAllStringSubmatch(part, -1)
+							if attrList != nil {
+								for _, attr := range attrList {
+									seg.Attr[strings.ToLower(attr[1])] = attr[2]
+								}
+							}
+						}
+					}
+					list = append(list, seg)
+				}
+			}
+			pos = cap[1]
+		}
+		if len(htmlStr) > pos {
+			seg.Cat = 'T'
+			seg.Str = htmlStr[pos:]
+			seg.Attr = nil
+			list = append(list, seg)
+		}
+	}
+	return
+}
+
+// HtmlBasicType is used for rendering a very basic subset of HTML. It supports
+// only the bold, italic and underscore attributes and hyperlinks. In the Link
+// structure, the ClrR, ClrG and ClrB fields (0 through 255) define the color
+// of hyperlinks. The Bold, Italic and Underscore values (0 for off, 1 for on)
+// define the hyperlink style.
+type HtmlBasicType struct {
+	pdf  *Fpdf
+	Link struct {
+		ClrR, ClrG, ClrB         int
+		Bold, Italic, Underscore bool
+	}
+}
+
+// HtmlBasicNew returns an instance that facilitates writing basic HTML in the
+// specified PDF file.
+func (f *Fpdf) HtmlBasicNew() (html HtmlBasicType) {
+	html.pdf = f
+	html.Link.ClrR, html.Link.ClrG, html.Link.ClrB = 0, 0, 128
+	html.Link.Bold, html.Link.Italic, html.Link.Underscore = false, false, true
+	return
+}
+
+// Write prints text from the current position using the currently selected
+// font. The text can be encoded with a basic subset of HTML that includes tags
+// for italic (I), bold (B) and underscore (U) attributes and hyperlinks. When
+// the right margin is reached a line break occurs and text continues from the
+// left margin. Upon method exit, the current position is left at the end of
+// the text.
+//
+// lineHt indicates the line height in the unit of measure specified in New().
+func (html *HtmlBasicType) Write(lineHt float64, htmlStr string) {
+	var boldLvl, italicLvl, underscoreLvl, linkBold, linkItalic, linkUnderscore int
+	var textR, textG, textB = html.pdf.GetTextColor()
+	var hrefStr string
+	if html.Link.Bold {
+		linkBold = 1
+	}
+	if html.Link.Italic {
+		linkItalic = 1
+	}
+	if html.Link.Underscore {
+		linkUnderscore = 1
+	}
+	setStyle := func(boldAdj, italicAdj, underscoreAdj int) {
+		styleStr := ""
+		boldLvl += boldAdj
+		if boldLvl > 0 {
+			styleStr += "B"
+		}
+		italicLvl += italicAdj
+		if italicLvl > 0 {
+			styleStr += "I"
+		}
+		underscoreLvl += underscoreAdj
+		if underscoreLvl > 0 {
+			styleStr += "U"
+		}
+		html.pdf.SetFont("", styleStr, 0)
+	}
+	putLink := func(urlStr, txtStr string) {
+		// Put a hyperlink
+		html.pdf.SetTextColor(html.Link.ClrR, html.Link.ClrG, html.Link.ClrB)
+		setStyle(linkBold, linkItalic, linkUnderscore)
+		html.pdf.WriteLinkString(lineHt, txtStr, urlStr)
+		setStyle(-linkBold, -linkItalic, -linkUnderscore)
+		html.pdf.SetTextColor(textR, textG, textB)
+	}
+	list := HtmlBasicTokenize(htmlStr)
+	var ok bool
+	for _, el := range list {
+		switch el.Cat {
+		case 'T':
+			if len(hrefStr) > 0 {
+				putLink(hrefStr, el.Str)
+				hrefStr = ""
+			} else {
+				html.pdf.Write(lineHt, el.Str)
+			}
+		case 'O':
+			switch el.Str {
+			case "b":
+				setStyle(1, 0, 0)
+			case "i":
+				setStyle(0, 1, 0)
+			case "u":
+				setStyle(0, 0, 1)
+			case "br":
+				html.pdf.Ln(lineHt)
+			case "a":
+				hrefStr, ok = el.Attr["href"]
+				if !ok {
+					hrefStr = ""
+				}
+			}
+		case 'C':
+			switch el.Str {
+			case "b":
+				setStyle(-1, 0, 0)
+			case "i":
+				setStyle(0, -1, 0)
+			case "u":
+				setStyle(0, 0, -1)
+
+			}
+		}
+	}
+}