zntg/ui/label.go

package ui

import (
	"opslag.de/schobers/geom"
)

type Label struct {
	ControlBase

	Text string

	init bool
	size *Cache
}

func BuildLabel(text string, fn func(*Label)) *Label {
	var l = &Label{Text: text}
	if fn != nil {
		fn(l)
	}
	return l
}

func (l *Label) initialize() {
	if l.init {
		return
	}
	l.size = NewCacheContext(l.desiredSize, l.hashContent)
	l.init = true
}

func (l *Label) hashContent(ctx Context) string {
	return l.FontName(ctx) + l.Text
}

func (l *Label) desiredSize(ctx Context) interface{} {
	fontName := l.FontName(ctx)
	font := ctx.Fonts().Font(fontName)
	width := font.WidthOf(l.Text)
	height := font.Height()
	pad := ctx.Style().Dimensions.TextPadding
	return geom.PtF32(width+pad*2, height+pad*2)
}

func (l *Label) DesiredSize(ctx Context) geom.PointF32 {
	l.initialize()
	return l.size.Get(ctx).(geom.PointF32)
}

func (l *Label) Render(ctx Context) {
	l.RenderBackground(ctx)
	fontColor := l.TextColor(ctx)
	fontName := l.FontName(ctx)
	pad := ctx.Style().Dimensions.TextPadding
	bounds := l.bounds.Inset(pad)
	switch l.TextAlignment {
	case AlignLeft:
		ctx.Fonts().TextAlign(fontName, bounds.Min, fontColor, l.Text, l.TextAlignment)
	case AlignRight:
		ctx.Fonts().TextAlign(fontName, geom.PtF32(bounds.Max.X, bounds.Min.Y), fontColor, l.Text, l.TextAlignment)
	case AlignCenter:
		ctx.Fonts().TextAlign(fontName, geom.PtF32(.5*(bounds.Min.X+bounds.Max.X), bounds.Min.Y), fontColor, l.Text, l.TextAlignment)
	}
}