tins2020/label.go

package tins2020

import (
	"strings"
)

type Label struct {
	ControlBase

	Text      string
	Alignment TextAlignment
}

func (l *Label) Render(ctx *Context) {
	font := ctx.Fonts.Font(l.ActualFontName())
	color := l.ActualForeground()
	bottom := l.Bounds.Y + l.Bounds.H
	switch l.Alignment {
	case TextAlignmentCenter:
		font.RenderCopyAlign(ctx.Renderer, l.Text, Pt(l.Bounds.X+l.Bounds.W/2, bottom), color, TextAlignmentCenter)
	case TextAlignmentLeft:
		font.RenderCopyAlign(ctx.Renderer, l.Text, Pt(l.Bounds.X, bottom), color, TextAlignmentLeft)
	case TextAlignmentRight:
		font.RenderCopyAlign(ctx.Renderer, l.Text, Pt(l.Bounds.X+l.Bounds.W, bottom), color, TextAlignmentRight)
	}
}

type Paragraph struct {
	Label
}

func (p *Paragraph) Render(ctx *Context) {
	font := ctx.Fonts.Font(p.ActualFontName())
	color := p.ActualForeground()
	fontHeight := int32(font.Height())
	lines := strings.Split(p.Text, "\n")

	measure := func(s string) int32 {
		w, _, _ := font.SizeUTF8(s)
		return int32(w)
	}

	spaces := func(s string) []int {
		var spaces []int
		offset := 0
		for {
			space := strings.Index(s[offset:], " ")
			if space == -1 {
				return spaces
			}
			offset += space
			spaces = append(spaces, offset)
			offset++
		}
	}

	fit := func(s string) string {
		if measure(s) < p.Bounds.W {
			return s
		}
		spaces := spaces(s)
		for split := len(spaces) - 1; split >= 0; split-- {
			clipped := s[:spaces[split]]
			if measure(clipped) < p.Bounds.W {
				return clipped
			}
		}
		return s
	}

	offset := p.Bounds.Y
	for _, line := range lines {
		if len(line) == 0 {
			offset += fontHeight
			continue
		}

		for len(line) > 0 {
			offset += fontHeight
			clipped := fit(line)
			line = strings.TrimLeft(line[len(clipped):], " ")
			font.RenderCopy(ctx.Renderer, clipped, Pt(p.Bounds.X, offset), color)
		}
	}
}