waveshare2in13v2: add example (#8)

go.mod

@@ -7,6 +7,9 @@ module periph.io/x/devices/v3
 go 1.13
 
 require (
+	github.com/fogleman/gg v1.3.0
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
+	golang.org/x/image v0.0.0-20210220032944-ac19c3e999fb
 	periph.io/x/conn/v3 v3.6.7
 	periph.io/x/host/v3 v3.6.7
 )

go.sum

@@ -1,3 +1,10 @@
+github.com/fogleman/gg v1.3.0 h1:/7zJX8F6AaYQc57WQCyN9cAIz+4bCJGO9B+dyW29am8=
+github.com/fogleman/gg v1.3.0/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
+golang.org/x/image v0.0.0-20210220032944-ac19c3e999fb h1:fqpd0EBDzlHRCjiphRR5Zo/RSWWQlWv34418dnEixWk=
+golang.org/x/image v0.0.0-20210220032944-ac19c3e999fb/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 periph.io/x/conn/v3 v3.6.7 h1:hem/gzoUI0tnvdJOJAk+XLBhqBGX9sHkwShBXRGGy0k=
 periph.io/x/conn/v3 v3.6.7/go.mod h1:3OD27w9YVa5DS97VsUxsPGzD9Qrm5Ny7cF5b6xMMIWg=
 periph.io/x/host/v3 v3.6.7 h1:hUVkGKJ235XocQIRiITxSmP8TT8f27oiN7R2dJkomIE=

waveshare2in13v2/example_test.go

@@ -0,0 +1,120 @@
+// Copyright 2021 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package waveshare2in13v2_test
+
+import (
+	"image"
+	"image/draw"
+	"log"
+
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/basicfont"
+	"golang.org/x/image/math/fixed"
+
+	"github.com/fogleman/gg"
+	"github.com/golang/freetype/truetype"
+	"golang.org/x/image/font/gofont/goregular"
+
+	"periph.io/x/conn/v3/spi/spireg"
+	"periph.io/x/devices/v3/ssd1306/image1bit"
+	"periph.io/x/devices/v3/waveshare2in13v2"
+	"periph.io/x/host/v3"
+)
+
+func Example() {
+	// 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 := waveshare2in13v2.NewHat(b, &waveshare2in13v2.EPD2in13v2) // Display config and size
+	if err != nil {
+		log.Fatalf("failed to initialize epd: %v", err)
+	}
+
+	// Draw on it. Black text on a white background.
+	img := image1bit.NewVerticalLSB(dev.Bounds())
+	draw.Draw(img, img.Bounds(), &image.Uniform{image1bit.On}, image.Point{}, draw.Src)
+	f := basicfont.Face7x13
+	drawer := font.Drawer{
+		Dst:  img,
+		Src:  &image.Uniform{image1bit.Off},
+		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)
+	}
+}
+
+func Example_other() {
+	// 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 := waveshare2in13v2.NewHat(b, &waveshare2in13v2.EPD2in13v2) // Display config and size
+	if err != nil {
+		log.Fatalf("failed to initialize epd: %v", err)
+	}
+
+	var img image.Image
+	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)
+	}
+}