1 files changed, 207 insertions, 0 deletions
diff --git a/cmd/pggraph/main.go b/cmd/pggraph/main.go
new file mode 100644
index 0000000..9d9d26c
--- /dev/null
+++ b/cmd/pggraph/main.go
@@ -0,0 +1,207 @@
+// Copyright 2020 Nick White.
+// Use of this source code is governed by the GPLv3
+// license that can be found in the LICENSE file.
+
+// pggraph creates a graph showing the proportion of black pixels
+// for slices through an image. This is useful to determine
+// appropriate parameters to pass to the wipe functions in this
+// module.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"image"
+	"image/draw"
+	_ "image/png"
+	_ "image/jpeg"
+	"io"
+	"log"
+	"os"
+	"sort"
+
+	"rescribe.xyz/integralimg"
+	chart "github.com/wcharczuk/go-chart"
+)
+
+const usage = `Usage: pggraph [-vertical] [-width] inimg graphname
+
+Creates a graph showing the proportion of black pixels
+for slices through an image. This is useful to determine
+appropriate parameters to pass to the wipe functions in
+this module.
+`
+
+const middlePercent = 20
+const tickEvery = 30
+
+// sideways flips an image sideways
+func sideways(img *image.Gray) *image.Gray {
+	b := img.Bounds()
+	newb := image.Rect(b.Min.Y, b.Min.X, b.Max.Y, b.Max.X)
+	new := image.NewGray(newb)
+	for x := b.Min.X; x < b.Max.X; x++ {
+		for y := b.Min.Y; y < b.Max.Y; y++ {
+			new.SetGray(y, x, img.GrayAt(x, y))
+		}
+	}
+	return new
+}
+
+func graph(title string, points map[int]float64, w io.Writer) error {
+	var xvals, yvals []float64
+	var xs []int
+	var midxvals, midyvals []float64
+	var midxs []int
+
+	if len(points) < 2 {
+		return fmt.Errorf("Not enough points to graph, only %d\n", len(points))
+	}
+
+	for x, _ := range points {
+		xs = append(xs, x)
+	}
+	sort.Ints(xs)
+
+	for _, x := range xs {
+		xvals = append(xvals, float64(x))
+		yvals = append(yvals, points[x])
+	}
+
+	mainSeries := chart.ContinuousSeries{
+		Style: chart.Style{
+			StrokeColor: chart.ColorBlue,
+			FillColor:   chart.ColorAlternateBlue,
+		},
+		XValues: xvals,
+		YValues: yvals,
+	}
+
+	numAroundMiddle := int(middlePercent / 2 * float64(len(xs)) / float64(100))
+	if numAroundMiddle > 1 {
+		for i := (len(xs) / 2) - numAroundMiddle; i < (len(xs) / 2) + numAroundMiddle; i++ {
+			midxs = append(midxs, xs[i])
+		}
+	} else {
+		midxs = xs
+	}
+
+	for _, x := range midxs {
+		midxvals = append(midxvals, float64(x))
+		midyvals = append(midyvals, points[x])
+	}
+
+	middleSeries := chart.ContinuousSeries{
+		XValues: midxvals,
+		YValues: midyvals,
+	}
+
+	minSeries := &chart.MinSeries{
+		Style: chart.Style{
+			StrokeColor: chart.ColorAlternateGray,
+			StrokeDashArray: []float64{5.0, 5.0},
+		},
+		InnerSeries: middleSeries,
+	}
+
+	maxSeries := &chart.MaxSeries{
+		Style: chart.Style{
+			StrokeColor: chart.ColorAlternateGray,
+			StrokeDashArray: []float64{5.0, 5.0},
+		},
+		InnerSeries: middleSeries,
+	}
+
+	width := xs[1]
+	var ticks []chart.Tick
+	// if width is larger than tickEvery, just have a tick for each point,
+	// otherwise have a tick every tickEvery period
+	if width > tickEvery {
+		for _, v := range xs {
+			ticks = append(ticks, chart.Tick{float64(v), fmt.Sprintf("%d", v)})
+		}
+	} else {
+		for i := 0; i < len(xs) - 1; i += tickEvery {
+			ticks = append(ticks, chart.Tick{float64(xs[i]), fmt.Sprintf("%d", xs[i])})
+		}
+		if len(ticks) > 1 {
+			lastx := xs[len(xs) - 1]
+			ticks[len(ticks) - 1] = chart.Tick{float64(lastx), fmt.Sprintf("%d", lastx)}
+		}
+	}
+
+	graph := chart.Chart{
+		Title: title,
+		Width: 1920,
+		Height: 800,
+		XAxis: chart.XAxis{
+			Name: "Pixel number",
+			Ticks: ticks,
+		},
+		YAxis: chart.YAxis{
+			Name: "Proportion of black pixels",
+		},
+		Series: []chart.Series{
+			mainSeries,
+			minSeries,
+			maxSeries,
+			chart.LastValueAnnotationSeries(minSeries),
+			chart.LastValueAnnotationSeries(maxSeries),
+		},
+	}
+
+	return graph.Render(chart.PNG, w)
+}
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(flag.CommandLine.Output(), usage)
+		flag.PrintDefaults()
+	}
+	vertical := flag.Bool("vertical", false, "Slice image vertically (from top to bottom) rather than horizontally")
+	width := flag.Int("width", 5, "Width of slice in pixels (height if in vertical mode)")
+	flag.Parse()
+	if flag.NArg() < 2 {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	f, err := os.Open(flag.Arg(0))
+	defer f.Close()
+	if err != nil {
+		log.Fatalf("Could not open file %s: %v\n", flag.Arg(0), err)
+	}
+	img, _, err := image.Decode(f)
+	if err != nil {
+		log.Fatalf("Could not decode image: %v\n", err)
+	}
+	b := img.Bounds()
+	gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
+	draw.Draw(gray, b, img, b.Min, draw.Src)
+	if *vertical {
+		gray = sideways(gray)
+	}
+	integral := integralimg.ToIntegralImg(gray)
+
+	points := make(map[int]float64)
+	maxx := len(integral[0]) -1
+	for x := 0; x + *width < maxx; x += *width {
+		w := integral.GetVerticalWindow(x, *width)
+		points[x] = w.Proportion()
+	}
+
+	f, err = os.Create(flag.Arg(1))
+	defer f.Close()
+	if err != nil {
+		log.Fatalf("Could not create file %s: %v\n", flag.Arg(1), err)
+	}
+
+	title := fmt.Sprintf("Proportion of black pixels over %s (width %d)", flag.Arg(0), *width)
+	if *vertical {
+		title += " (vertical)"
+	}
+	err = graph(title, points, f)
+	if err != nil {
+		log.Fatalf("Could not create graph: %v\n", err)
+	}
+}