zntg/ui/checkbox.go

package ui

import (
	"fmt"
	"image/color"

	"github.com/llgcode/draw2d/draw2dimg"
	"github.com/llgcode/draw2d/draw2dkit"
	"opslag.de/schobers/galleg/allegro5"
	"opslag.de/schobers/geom"
)

type CheckboxValueChangedFn func(bool)

func drawCheckedBitmap(fill, stroke color.Color) *allegro5.Bitmap {
	return drawBitmap(checkboxSize, checkboxSize, func(gc *draw2dimg.GraphicContext) {
		var size = float64(checkboxSize)
		var margin = float64(checkboxMargin)

		gc.SetFillColor(fill)
		draw2dkit.RoundedRectangle(gc, margin, margin, size-margin, size-margin, margin, margin)
		gc.Fill()

		gc.SetStrokeColor(stroke)
		gc.SetLineWidth(1.5)
		gc.MoveTo(7, 12)
		gc.LineTo(10.5, 15.5)
		gc.LineTo(17, 9)
		gc.Stroke()
	})
}

func drawUncheckedBitmap(fill, stroke color.Color) *allegro5.Bitmap {
	return drawBitmap(checkboxSize, checkboxSize, func(gc *draw2dimg.GraphicContext) {
		var size = float64(checkboxSize)
		var margin = float64(checkboxMargin)

		gc.SetLineWidth(2)
		gc.SetStrokeColor(stroke)
		draw2dkit.RoundedRectangle(gc, margin+1, margin+1, size-margin-1, size-margin-1, margin-1, margin-1)
		gc.Stroke()
	})
}

type Checkbox struct {
	ControlBase
	Value     bool
	Text      string
	OnChanged CheckboxValueChangedFn
	checked   *allegro5.Bitmap
	unchecked *allegro5.Bitmap
}

func (c *Checkbox) Created(ctx Context, p Container) error {
	var err = c.ControlBase.Created(ctx, p)
	if nil != err {
		return err
	}
	var plt = ctx.Palette()
	c.checked = drawCheckedBitmap(plt.Primary(), plt.Lightest())
	c.unchecked = drawUncheckedBitmap(plt.Lightest(), plt.Darkest())
	if nil == c.checked || nil == c.unchecked {
		return fmt.Errorf("error creating checkboxes")
	}
	return nil
}

func (c *Checkbox) Handle(ctx Context, ev allegro5.Event) {
	var pressed = c.IsPressed
	c.ControlBase.Handle(ctx, ev)
	switch ev.(type) {
	case *allegro5.MouseButtonUpEvent:
		if !c.Disabled && pressed && c.IsOver {
			c.Value = !c.Value
			var onChanged = c.OnChanged
			if nil != onChanged {
				onChanged(c.Value)
			}
		}
	}
}

func (c *Checkbox) DesiredSize(ctx Context) geom.PointF {
	var fonts = ctx.Fonts()
	var fnt = fonts.Get("default")
	var w = fnt.TextWidth(c.Text)
	return geom.PtF(float64(w+checkboxSize+leftMargin), checkboxSize)
}

func (c *Checkbox) box() *allegro5.Bitmap {
	if c.Value {
		return c.checked
	}
	return c.unchecked
}

func (c *Checkbox) Render(ctx Context) {
	var fonts = ctx.Fonts()

	var min = c.Bounds.Min.To32()
	var fnt = fonts.Get("default")

	fnt.Draw(min.X+checkboxSize, min.Y-.67*fnt.Ascent()+.5*checkboxSize, ctx.Palette().Darkest(), allegro5.AlignLeft, c.Text)
	if c.Disabled {
		var disabled = ctx.Palette().Disabled()
		c.box().DrawOptions(min.X, min.Y, allegro5.DrawOptions{Tint: &disabled})
	} else {
		c.box().Draw(min.X, min.Y)
	}

	c.ControlBase.Render(ctx)
}