av/filter/debug.go

// +build debug

/*
DESCRIPTION
  Displays debug information for the motion filters.

AUTHORS
  Scott Barnard <scott@ausocean.org>

LICENSE
  This file is Copyright (C) 2020 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  in gpl.txt.  If not, see http://www.gnu.org/licenses.
*/

package filter

import (
	"fmt"
	"image"
	"image/color"
	"image/jpeg"
	"io"
	"os"
	"strconv"

	"golang.org/x/image/font"
	"golang.org/x/image/font/basicfont"
	"golang.org/x/image/math/fixed"
)

// debugFile is used for sending debug information to a file.
type debugFile struct {
	bwImg *image.RGBA
	file  io.WriteCloser
}

// newDebugFile creates a file for saving debugging frames to.
func newDebugFile() debugFile {
	const debugfile = "motion.mjpeg"

	file, err := os.Create(debugfile)
	if err != nil {
		panic(fmt.Sprintf("could not create debug file: %w", err))
	}

	return debugFile{
		bwImg: image.NewRGBA(image.Rect(0, 0, 0, 0)),
		file:  file,
	}
}

// close closes files used for debugging purposes.
func (d *debugFile) close() error {
	err := d.file.Close()
	if err != nil {
		return fmt.Errorf("file cannot be closed: %w", err)
	}
	return nil
}

// draw draws debugging information to a frame.
func (d *debugFile) draw(i, j int, val uint8) {
	d.bwImg.SetRGBA(i, j, color.RGBA{val, val, val, 0xff})
}

// saveFrame writes a frame showing motion to a file.
func (d *debugFile) saveFrame(motion, pix int) error {
	col := color.RGBA{200, 100, 0, 255} // Red text.

	var s string
	if motion > pix {
		s = strconv.Itoa(motion) + " Motion"
	} else {
		s = strconv.Itoa(motion)
	}

	(&font.Drawer{
		Dst:  d.bwImg,
		Src:  image.NewUniform(col),
		Face: basicfont.Face7x13,
		Dot:  fixed.P(20, 30),
	}).DrawString(s)

	return jpeg.Encode(d.file, d.bwImg, nil)
}

// resetFrame makes an image of given dimensions.
func (d *debugFile) resetFrame(w, h int) {
	d.bwImg = image.NewRGBA(image.Rect(0, 0, w, h))
}