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103 lines
2.7 KiB
Go
103 lines
2.7 KiB
Go
// Copyright 2021 The Periph Authors. All rights reserved.
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// Use of this source code is governed under the Apache License, Version 2.0
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// that can be found in the LICENSE file.
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// Package videosink provides a display driver implementing an HTTP request
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// handler. Client requests get an initial snapshot of the graphics buffer and
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// are updated further on every change.
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//
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// The primary use case is the development of display outputs on a host
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// machine. Additionally devices with network connectivity can use this driver
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// to provide a copy of their local display via a web interface.
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//
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// The protocol used is "MJPEG" (https://en.wikipedia.org/wiki/Motion_JPEG)
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// which is often used by IP cameras. Because of its better suitability for
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// computer-drawn graphics the PNG image format is used by default. JPEG as
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// a format can be selected via Options.Format or using the "format" URL
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// parameter.
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package videosink
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import (
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"image"
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"image/color"
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"image/draw"
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"net/http"
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"sync"
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"periph.io/x/conn/v3/display"
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)
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// Options for videosink devices.
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type Options struct {
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// Width and height of the image buffer.
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Width, Height int
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// Format specifies the image format to send to clients.
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Format ImageFormat
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// TODO: Add options for JPEG and PNG encoder settings
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}
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type Display struct {
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defaultFormat ImageFormat
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mu sync.Mutex
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buffer *image.RGBA
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clients map[*client]struct{}
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snapshot map[imageConfig][]byte
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}
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var _ display.Drawer = (*Display)(nil)
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var _ http.Handler = (*Display)(nil)
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// New creates a new videosink device instance.
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func New(opt *Options) *Display {
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buffer := image.NewRGBA(image.Rect(0, 0, opt.Width, opt.Height))
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// By default the alpha channel is set to full transparency. The following
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// draw operation makes it opaque.
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draw.Draw(buffer, buffer.Bounds(), image.Black, image.Point{}, draw.Src)
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return &Display{
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buffer: buffer,
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clients: map[*client]struct{}{},
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snapshot: map[imageConfig][]byte{},
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defaultFormat: opt.Format,
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}
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}
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// String returns the name of the device.
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func (d *Display) String() string {
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return "VideoSink"
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}
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// Halt implements conn.Resource and terminates all running client requests
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// asynchronously.
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func (d *Display) Halt() error {
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d.mu.Lock()
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d.terminateClientsLocked()
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d.mu.Unlock()
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return nil
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}
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// ColorModel implements display.Drawer.
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func (d *Display) ColorModel() color.Model {
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return d.buffer.ColorModel()
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}
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// Bounds implements display.Drawer.
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func (d *Display) Bounds() image.Rectangle {
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return d.buffer.Bounds()
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}
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// Draw implements display.Drawer.
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func (d *Display) Draw(dstRect image.Rectangle, src image.Image, srcPts image.Point) error {
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d.mu.Lock()
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draw.Draw(d.buffer, dstRect, src, srcPts, draw.Src)
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d.bufferChangedLocked()
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d.mu.Unlock()
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return nil
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}
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