zntg/ui/controlbase.go

package ui

import (
	"image/color"

	"opslag.de/schobers/geom"
)

type ClickFn func(ctx Context, c Control, pos geom.PointF32, btn MouseButton)
type DragEndFn func(ctx Context, c Control, start, end geom.PointF32)
type DragMoveFn func(ctx Context, c Control, start, move geom.PointF32)
type DragStartFn func(ctx Context, c Control, start geom.PointF32)
type MouseEnterFn func(ctx Context, c Control)
type MouseLeaveFn func(ctx Context, c Control)

var _ Control = &ControlBase{}

type ControlBase struct {
	bounds    geom.RectangleF32
	offset    geom.PointF32
	dragStart *geom.PointF32
	over      bool
	pressed   bool

	onClick     ClickFn
	onDragEnd   DragEndFn
	onDragMove  DragMoveFn
	onDragStart DragStartFn

	Background color.Color
	FontName   string
	FontColor  color.Color
}

func (c *ControlBase) Arrange(ctx Context, bounds geom.RectangleF32, offset geom.PointF32) {
	c.bounds = bounds
	c.offset = offset
}

func (c *ControlBase) Bounds() geom.RectangleF32 {
	return c.bounds
}

func (c *ControlBase) DesiredSize(Context) geom.PointF32 {
	return geom.ZeroPtF32
}

func (c *ControlBase) Handle(ctx Context, e Event) {
	var pos = func(e MouseEvent) geom.PointF32 { return e.Pos().Sub(c.offset) }
	var over = func(e MouseEvent) bool {
		c.over = pos(e).In(c.bounds)
		return c.over
	}
	switch e := e.(type) {
	case *MouseMoveEvent:
		over(e.MouseEvent)
		if c.pressed {
			if c.dragStart == nil {
				var start = pos(e.MouseEvent)
				c.dragStart = &start
				if c.onDragStart != nil {
					c.onDragStart(ctx, c, start)
				}
			} else {
				var start = *c.dragStart
				var move = pos(e.MouseEvent)
				if c.onDragMove != nil {
					c.onDragMove(ctx, c, start, move)
				}
			}
		}
	case *MouseButtonDownEvent:
		if over(e.MouseEvent) && 1 == e.Button {
			c.pressed = true
		}
	case *MouseButtonUpEvent:
		if 1 == e.Button {
			if c.dragStart != nil {
				var start = *c.dragStart
				var end = pos(e.MouseEvent)
				c.dragStart = nil
				if c.onDragEnd != nil {
					c.onDragEnd(ctx, c, start, end)
				}
			}
			if c.pressed {
				if c.onClick != nil {
					c.onClick(ctx, c, pos(e.MouseEvent), e.Button)
				}
			}
			c.pressed = false
		}
	}
}

func (c *ControlBase) IsOver() bool { return c.over }

func (c *ControlBase) IsPressed() bool { return c.pressed }

func (c *ControlBase) Offset() geom.PointF32 { return c.offset }

func (c *ControlBase) OnClick(fn ClickFn) {
	c.onClick = fn
}

func (c *ControlBase) OnDragStart(fn DragStartFn) {
	c.onDragStart = fn
}

func (c *ControlBase) OnDragMove(fn DragMoveFn) {
	c.onDragMove = fn
}

func (c *ControlBase) OnDragEnd(fn DragEndFn) {
	c.onDragEnd = fn
}

func (c *ControlBase) RenderBackground(ctx Context) {
	if c.Background != nil {
		ctx.Renderer().FillRectangle(c.bounds, c.Background)
	}
}

func (c *ControlBase) Render(Context) {
}

func (c *ControlBase) fontName(ctx Context) string {
	var name = c.FontName
	if len(name) == 0 {
		name = ctx.Style().Fonts.Default
	}
	return name
}