zntg/ui/images.go

package ui

import "github.com/nfnt/resize"

func ScaleImage(render Renderer, im Image, scale float32) Image {
	w := uint(im.Width() * scale)
	if w == 0 {
		return nil
	}
	scaled := resize.Resize(w, 0, im.Image(), resize.Bilinear)
	res, err := render.CreateImage(scaled)
	if err != nil {
		return nil
	}
	return res
}

type Images struct {
	render Renderer
	ims    map[string]Image
	scaled map[Image]ScaledImages
}

func NewImages(render Renderer) *Images {
	return &Images{render, map[string]Image{}, map[Image]ScaledImages{}}
}

func (i *Images) AddImage(name string, im Image) {
	curr := i.ims[name]
	if curr != nil {
		curr.Destroy()
	}
	i.ims[name] = im
}

func (i *Images) Destroy() {
	for _, im := range i.ims {
		im.Destroy()
	}
	i.ims = nil
	for _, ims := range i.scaled {
		ims.Destroy()
	}
	i.scaled = nil
}

func (i *Images) Image(name string) Image {
	im, ok := i.ims[name]
	if ok {
		return im
	}
	return nil
}

func (i *Images) Scaled(im Image, scale float32) Image {
	if scale <= 0 {
		return nil
	}
	if scale == 1 {
		return im
	}
	ims := i.scaled[im]
	if ims == nil {
		ims = make(ScaledImages)
	} else {
		scaled := ims[scale]
		if scaled != nil {
			return scaled
		}
	}
	scaled := ScaleImage(i.render, im, scale)
	ims[scale] = scaled
	i.scaled[im] = ims
	return scaled
}

func (i *Images) ScaledByName(name string, scale float32) Image {
	im := i.Image(name)
	if im == nil {
		return nil
	}
	return i.Scaled(im, scale)
}

type ScaledImages map[float32]Image

func (i ScaledImages) Destroy() {
	for _, im := range i {
		im.Destroy()
	}
}