tins2020/tooltip.go

package tins2020

import "github.com/veandco/go-sdl2/sdl"

type Tooltip struct {
	ControlBase

	Text string
}

const tooltipBorderThickness = 1
const tooltipHorizontalPadding = 6
const tooltipVerticalPadding = 2
const tooltipMouseDistance = 12

func (t *Tooltip) ActualFontName() string {
	if t.FontName == "" {
		return "small"
	}
	return t.FontName
}

func (t *Tooltip) Handle(ctx *Context, event sdl.Event) bool {
	if len(t.Text) == 0 {
		return false
	}

	font := ctx.Fonts.Font(t.ActualFontName())
	if font == nil {
		font = ctx.Fonts.Font("default")
	}
	windowW, windowH, err := ctx.Renderer.GetOutputSize()
	if err != nil {
		return false
	}

	labelW, labelH, err := font.SizeUTF8(t.Text)
	if err != nil {
		return false
	}

	mouse := ctx.MousePosition
	width := int32(labelW) + 2*tooltipBorderThickness + 2*tooltipHorizontalPadding
	height := int32(labelH) + 2*tooltipBorderThickness + 2*tooltipVerticalPadding

	left := mouse.X + tooltipMouseDistance
	top := mouse.Y + tooltipMouseDistance
	if left+width > windowW {
		left = mouse.X - tooltipMouseDistance - width
	}
	if top+height > windowH {
		top = mouse.Y - tooltipMouseDistance - height
	}

	t.Bounds = Rect(left, top, width, height)
	return false
}

func (t *Tooltip) Render(ctx *Context) {
	almostBlack := MustHexColor("#0000007f")
	SetDrawColor(ctx.Renderer, almostBlack)
	ctx.Renderer.FillRect(t.Bounds.SDLPtr())

	almostWhite := MustHexColor("ffffff7f")
	SetDrawColor(ctx.Renderer, almostWhite)
	ctx.Renderer.DrawRect(t.Bounds.SDLPtr())

	font := ctx.Fonts.Font(t.ActualFontName())

	bottomLeft := Pt(t.Bounds.X+tooltipBorderThickness+tooltipHorizontalPadding, t.Bounds.Y+t.Bounds.H-tooltipBorderThickness-tooltipVerticalPadding)
	font.RenderCopy(ctx.Renderer, t.Text, bottomLeft, White)
}