epd

// Make sure periph is initialized.
if _, err := host.Init(); err != nil {
	log.Fatal(err)
}

// Use spireg SPI bus registry to find the first available SPI bus.
b, err := spireg.Open("")
if err != nil {
	log.Fatal(err)
}
defer b.Close()

dev, err := epd.NewSPIHat(b, &epd.EPD2in13) // Display config and size
if err != nil {
	log.Fatalf("failed to initialize epd: %v", err)
}

// Draw on it.
img := image1bit.NewVerticalLSB(dev.Bounds())
// Note: this code is commented out so periph does not depend on:
//    "golang.org/x/image/font"
//    "golang.org/x/image/font/basicfont"
//    "golang.org/x/image/math/fixed"
//
// f := basicfont.Face7x13
// drawer := font.Drawer{
// 	Dst:  img,
// 	Src:  &image.Uniform{image1bit.On},
// 	Face: f,
// 	Dot:  fixed.P(0, img.Bounds().Dy()-1-f.Descent),
// }
// drawer.DrawString("Hello from periph!")

if err := dev.Draw(dev.Bounds(), img, image.Point{}); err != nil {
	log.Fatal(err)
}
dev.DisplayFrame() // After drawing on the display, you have to show the frame

// Make sure periph is initialized.
if _, err := host.Init(); err != nil {
	log.Fatal(err)
}

// Use spireg SPI bus registry to find the first available SPI bus.
b, err := spireg.Open("")
if err != nil {
	log.Fatal(err)
}
defer b.Close()

dev, err := epd.NewSPIHat(b, &epd.EPD2in13) // Display config and size
if err != nil {
	log.Fatalf("failed to initialize epd: %v", err)
}

var img image.Image
// Note: this code is commented out so periph does not depend on:
//    "github.com/fogleman/gg"
//    "github.com/golang/freetype/truetype"
//    "golang.org/x/image/font/gofont/goregular"
//
// bounds := dev.Bounds()
// w := bounds.Dx()
// h := bounds.Dy()
// dc := gg.NewContext(w, h)
// im, err := gg.LoadPNG("gopher.png")
// if err != nil {
// 	panic(err)
// }
// dc.SetRGB(1, 1, 1)
// dc.Clear()
// dc.SetRGB(0, 0, 0)
// dc.Rotate(gg.Radians(90))
// dc.Translate(0.0, -float64(h/2))
// font, err := truetype.Parse(goregular.TTF)
// if err != nil {
// 	panic(err)
// }
// face := truetype.NewFace(font, &truetype.Options{
// 	Size: 16,
// })
// dc.SetFontFace(face)
// text := "Hello from periph!"
// tw, th := dc.MeasureString(text)
// dc.DrawImage(im, 120, 30)
// padding := 8.0
// dc.DrawRoundedRectangle(padding*2, padding*2, tw+padding*2, th+padding, 10)
// dc.Stroke()
// dc.DrawString(text, padding*3, padding*2+th)
// for i := 0; i < 10; i++ {
// 	dc.DrawCircle(float64(30+(10*i)), 100, 5)
// }
// for i := 0; i < 10; i++ {
// 	dc.DrawRectangle(float64(30+(10*i)), 80, 5, 5)
// }
// dc.Fill()
// img = dc.Image()
if err := dev.Draw(dev.Bounds(), img, image.Point{}); err != nil {
	log.Fatal(err)
}
dev.DisplayFrame() // After drawing on the display, you have to show the frame