text options!

text.go

@@ -0,0 +1,153 @@
+package chart
+
+import "strings"
+
+// TextHorizontalAlign is an enum for the horizontal alignment options.
+type textHorizontalAlign int
+
+const (
+	// TextHorizontalAlignUnset is the unset state for text horizontal alignment.
+	TextHorizontalAlignUnset textHorizontalAlign = 0
+	// TextHorizontalAlignLeft aligns a string horizontally so that it's left ligature starts at horizontal pixel 0.
+	TextHorizontalAlignLeft textHorizontalAlign = 1
+	// TextHorizontalAlignCenter left aligns a string horizontally so that there are equal pixels
+	// to the left and to the right of a string within a box.
+	TextHorizontalAlignCenter textHorizontalAlign = 2
+	// TextHorizontalAlignRight right aligns a string horizontally so that the right ligature ends at the right-most pixel
+	// of a box.
+	TextHorizontalAlignRight textHorizontalAlign = 3
+)
+
+// TextWrap is an enum for the word wrap options.
+type textWrap int
+
+const (
+	// TextWrapUnset is the unset state for text wrap options.
+	TextWrapUnset textWrap = 0
+	// TextWrapNone will spill text past horizontal boundaries.
+	TextWrapNone textWrap = 1
+	// TextWrapWord will split a string on words (i.e. spaces) to fit within a horizontal boundary.
+	TextWrapWord textWrap = 2
+	// TextWrapRune will split a string on a rune (i.e. utf-8 codepage) to fit within a horizontal boundary.
+	TextWrapRune textWrap = 3
+)
+
+// TextVerticalAlign is an enum for the vertical alignment options.
+type textVerticalAlign int
+
+const (
+	// TextVerticalAlignUnset is the unset state for vertical alignment options.
+	TextVerticalAlignUnset textVerticalAlign = 0
+	// TextVerticalAlignBaseline aligns text according to the "baseline" of the string, or where a normal ascender begins.
+	TextVerticalAlignBaseline textVerticalAlign = 1
+	// TextVerticalAlignBottom aligns the text according to the lowers pixel of any of the ligatures (ex. g or q both extend below the baseline).
+	TextVerticalAlignBottom textVerticalAlign = 2
+	// TextVerticalAlignMiddle aligns the text so that there is an equal amount of space above and below the top and bottom of the ligatures.
+	TextVerticalAlignMiddle textVerticalAlign = 3
+	// TextVerticalAlignMiddleBaseline aligns the text veritcally so that there is an equal number of pixels above and below the baseline of the string.
+	TextVerticalAlignMiddleBaseline textVerticalAlign = 4
+	// TextVerticalAlignTop alignts the text so that the top of the ligatures are at y-pixel 0 in the container.
+	TextVerticalAlignTop textVerticalAlign = 5
+)
+
+var (
+	// Text contains utilities for text.
+	Text = &text{}
+)
+
+// TextStyle encapsulates text style options.
+type TextStyle struct {
+	HorizontalAlign textHorizontalAlign
+	VerticalAlign   textVerticalAlign
+	Wrap            textWrap
+}
+
+type text struct{}
+
+func (t text) WrapFit(r Renderer, value string, width int, style Style, wrapOption textWrap) []string {
+	valueBox := r.MeasureText(value)
+	if valueBox.Width() > width {
+		switch wrapOption {
+		case TextWrapRune:
+			return t.WrapFitRune(r, value, width, style)
+		case TextWrapWord:
+			return t.WrapFitWord(r, value, width, style)
+		}
+	}
+	return []string{value}
+}
+
+func (t text) WrapFitWord(r Renderer, value string, width int, style Style) []string {
+	style.WriteToRenderer(r)
+
+	var output []string
+	var line string
+	var word string
+
+	var textBox Box
+
+	for _, c := range value {
+		if c == rune('\n') { // commit the line to output
+			output = append(output, t.Trim(line+word))
+			line = ""
+			word = ""
+			continue
+		}
+
+		textBox = r.MeasureText(line + word + string(c))
+
+		if textBox.Width() >= width {
+			output = append(output, t.Trim(line))
+			line = word
+			word = string(c)
+			continue
+		}
+
+		if c == rune(' ') || c == rune('\t') {
+			line = line + word + string(c)
+			word = ""
+			continue
+		}
+		word = word + string(c)
+	}
+
+	return append(output, t.Trim(line+word))
+}
+
+func (t text) WrapFitRune(r Renderer, value string, width int, style Style) []string {
+	style.WriteToRenderer(r)
+
+	var output []string
+	var line string
+	var textBox Box
+	for _, c := range value {
+		if c == rune('\n') {
+			output = append(output, line)
+			line = ""
+			continue
+		}
+
+		textBox = r.MeasureText(line + string(c))
+
+		if textBox.Width() >= width {
+			output = append(output, line)
+			line = string(c)
+			continue
+		}
+		line = line + string(c)
+	}
+	return t.appendLast(output, line)
+}
+
+func (t text) Trim(value string) string {
+	return strings.Trim(value, " \t\n\r")
+}
+
+func (t text) appendLast(lines []string, text string) []string {
+	if len(lines) == 0 {
+		return []string{text}
+	}
+	lastLine := lines[len(lines)-1]
+	lines[len(lines)-1] = lastLine + text
+	return lines
+}