display

Documentation

Overview

Package display implements interfaces for visual output devices. These can be pixel or text based.

Index

• type Drawer

Examples

• Drawer

Types

type Drawer

type Drawer interface {
	conn.Resource

	// ColorModel returns the device native color model.
	ColorModel() color.Model
	// Bounds returns the size of the output device.
	//
	// Generally displays should have Min at {0, 0} but this is not guaranteed in
	// multiple displays setup or when an instance of this interface represents a
	// section of a larger logical display.
	Bounds() image.Rectangle
	// Draw updates the display with this image.
	//
	// Only the pixels within the display boundary are updated. Partial update is
	// supported.
	//
	// Coordinates are top-left 0,0.
	//
	// dstRect aligns the the drawing operation in the display, enabling partial
	// update.
	//
	// srcPts aligns the image at this offset, enabling using a subset of the
	// source image. use image.Point{} to take the image at its origin.
	Draw(dstRect image.Rectangle, src image.Image, srcPts image.Point) error
}

Drawer represents a context to display pixels on an output device. It is a write-only interface.

What Drawer represents can be as varied as a 1 bit OLED display or a strip of LED lights. The implementation keeps a single frame buffer, so that partial updates can be done.

Example

package main

import (
	"image"
	"log"

	"periph.io/x/periph/conn/display"
	"periph.io/x/periph/host"
)

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

	// Get a display output device, like an apa102 or ssd1306. For example:
	//   s, _ := spireg.Open("")
	//   d, _ := apa102.New(s, &apa102.DefaultOpts)
	var d display.Drawer

	// Get an image. You could load a PNG. Resize it to the device display size.
	img := image.NewNRGBA(d.Bounds())

	// Render the image. The normal use case is:
	// - Use d.Bounds() as the dstRect, to cover the whole screen.
	// - Use image.Point{} as 'srcPts' unless you want to offset inside
	//   the image.
	if err := d.Draw(d.Bounds(), img, image.Point{}); err != nil {
		log.Fatal(err)
	}
}