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svg.go
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svg.go
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// svg.go
// This file is part of hcontours -- HarrisContours.
// Copyright (C) 2024 Chris Dennis, [email protected]
//
// hcontours is free software: you can redistribute it and/or modify
// it 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.
//
// This program 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
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"fmt"
"log"
"math"
"os"
"path"
"strconv"
"strings"
)
type SVGfile struct {
currentLayer int
file *os.File
filename string
pathCounter int
polygonCounter int
polylineCounter int
thresholds []int // [0] is the background, so other indexes are bumped up by 1
colours []string // SVGColourM // indexed by threshold
}
func (svg *SVGfile) write(s string) {
fmt.Fprint(svg.file, s)
}
func (svg *SVGfile) writeComment(s string) {
svg.write("<!-- " + s + " -->\n")
}
// Not used:
func (svg *SVGfile) line(fromX, fromY, toX, toY float64) {
// Write a line path; coordinates are ... scaling is done in svg.openStart
svg.write(fmt.Sprintf("<path id=\"%d\" d=\"M %6.3f,%6.3f L %6.3f,%6.3f\" />\n", svg.pathCounter, fromX, fromY, toX, toY))
svg.pathCounter += 1
}
func (svg *SVGfile) polygon(contour ContourT, args string) {
// Single polygon -- assume the contour is closed
// e.g. <polygon points="100,100 150,25 150,75 200,0" fill="none" stroke="black" />
//svg.write(fmt.Sprintf("<!-- contour: %v -->\n", contour))
//fmt.Printf("polygon: %v\n", contour)
svg.write(fmt.Sprintf("<polygon id=\"%d\" %s points=\"", svg.polygonCounter, args))
svg.polygonCounter += 1
for _, p := range contour {
svg.write(fmt.Sprintf("%.2f,%.2f ", p.x, p.y))
}
//svg.write(fmt.Sprint("\" fill=\"none\" stroke=\"black\" stroke-width=\"0.1mm\" />\n"))
svg.write(fmt.Sprint("\" />\n"))
}
// Find the intercept between the line through p1 and p2 and the vertical line at x
func interceptX(p1, p2 Point64T, x float64) Point64T {
m := (p2.y - p1.y) / (p2.x - p1.x)
c := p1.y - m*p1.x
y := m*x + c
//fmt.Printf("iX: p1=%v p2=%v x=%v m=%v c=%v y=%v\n", p1, p2, x, m, c, y)
return Point64T{x, y}
}
// Find the intercept between the line through p1 and p2 and the horizontal line at y
func interceptY(p1, p2 Point64T, y float64) Point64T {
m := (p2.y - p1.y) / (p2.x - p1.x)
c := p1.y - m*p1.x
x := (y - c) / m
return Point64T{x, y}
}
// Find the point on the edge of the image where the line
// from p1 to p2 crosses the edge.
// Assumes p1 is without the image, p2 is within it.
// NOTE to match with offImage() below, the edge is actually
// 1 pixel in.
func edgePoint(outPoint, inPoint Point64T, width, height int) Point64T {
if outPoint.x < 0 {
outPoint = interceptX(inPoint, outPoint, 0)
}
if outPoint.x > float64(width) {
outPoint = interceptX(inPoint, outPoint, float64(width))
}
if outPoint.y < 0 {
outPoint = interceptY(inPoint, outPoint, 0)
}
if outPoint.y > float64(height) {
outPoint = interceptY(inPoint, outPoint, float64(height))
}
return outPoint
}
// 'off the image' includes contours around shapes that hit the edge.
// Because values have already been increased by 0.5 (in PointWeightedAvg()),
// choose anything here that's within 1 pixel of the edge.
// FIXME move this -- it's not an SVG thing
// FIXME limit is now 0.0
func offImage(p Point64T, width, height int) bool {
const limit = 0.0 //1.0
if p.x < limit || p.y < limit || p.x > float64(width)-limit || p.y > float64(height)-limit {
return true
}
return false
}
// Given a contour (a slice of coordinates), make them into a polyline
func (svg *SVGfile) polyline(contour ContourT) {
//fmt.Printf("polyline: %v\n", contour)
svg.write(fmt.Sprintf("<polyline id=\"%d\" points=\"", svg.polylineCounter))
svg.polylineCounter += 1
for _, p := range contour {
svg.write(fmt.Sprintf("%.2f,%.2f ", p.x, p.y))
}
svg.write(fmt.Sprint("\" />\n"))
}
// Polygon, or polyline if not closed
func (svg *SVGfile) polyshape(contour ContourT) {
ccontour := contour.Compress()
if ccontour[0].Equal(ccontour[len(ccontour)-1]) {
svg.polygon(ccontour, "")
} else {
svg.polyline(ccontour)
}
}
// Plot a contour onto the SVG file: as a polygon unless it goes off the
// edge of the image, in which case it becomes one or more polylines.
func (svg *SVGfile) plotContour(contour ContourT, width, height int) {
lineOpen := false
//fmt.Printf("plotC: contour=%v\n", contour)
var subContour ContourT // may not be the whole contour
for i, p := range contour {
if offImage(p, width, height) {
//fmt.Printf("plotC: offImage at %v lineOpen=%v\n", p, lineOpen)
if lineOpen {
// stop the line - end right at the edge(s)
edgeP := edgePoint(p, contour[i-1], width, height)
subContour = append(subContour, edgeP)
//fmt.Printf("plotC: stopping c-1=%v p=%v w=%v h=%v edgeP=%v subC=%v\n", contour[i-1], p, width, height, edgeP, subContour)
svg.polyshape(subContour)
subContour = nil
lineOpen = false
} else {
//fmt.Printf("plotC: skipping %v\n", p)
// line already closed -- skip the point
// But wait! what if we've gone over a corner? FIXME TODO
// Edge case (literally) -- line that starts and ends off-image -- see test11.png
}
} else {
//fmt.Printf("plotC: on Image at %v lineOpen=%v\n", p, lineOpen)
if !lineOpen {
// start a new line
subContour = make(ContourT, 0, 10)
if i > 0 {
// Not the first point -- we've come back from off-image, so start on the edge
edgeP := edgePoint(contour[i-1], p, width, height)
//fmt.Printf("plotC: starting at edgeP %v\n", edgeP)
subContour = append(subContour, edgeP)
} else {
//fmt.Printf("plotC: starting on image\n")
}
lineOpen = true
}
//fmt.Printf("plotC: adding %v\n", p)
subContour = append(subContour, p)
}
}
if lineOpen {
// stop the line
//fmt.Printf("plotC: final close\n")
svg.polyshape(subContour)
subContour = nil
}
}
func (svg *SVGfile) closedPathStart(args string) {
svg.write(fmt.Sprintf("<path id=\"%d\" clip-path=\"url(#clip1)\" %s d=\"", svg.pathCounter, args))
svg.pathCounter += 1
}
func (svg *SVGfile) closedPathStop() {
svg.write(fmt.Sprint("\" />\n"))
}
// Write one contour's worth of points to an already started path.
// e.g. M 10,20 L 20,20, L 20,10 Z
func (svg *SVGfile) closedPathLoop(contour ContourT, args string) {
cmd := "M"
for _, p := range contour {
svg.write(fmt.Sprintf("%s %.2f,%.2f ", cmd, p.x, p.y))
cmd = "L"
}
svg.write("Z ")
}
// Alternative strategy to plot a contour, using clipping instead of broken paths.
// This will allow filling, but won't work with AxiDraw.
func (svg *SVGfile) plotContourClip(contour ContourT, width, height int) {
const args = "clip-path=\"url(#clip1)\""
ccontour := contour.Compress()
svg.closedPathLoop(ccontour, args)
}
func calcSizes(image RectangleT, margin float64, paper RectangleT, framewidth float64) (RectangleT, float64) {
//g := fmt.Sprintf("<g transform=\"translate(%g,%g) scale(%g)\" stroke=\"black\" stroke-width=\"1\" stroke-linecap=\"round\" stroke-linejoin=\"round\" fill=\"none\">\n",
printWidth := paper.width - 2*margin - 2*framewidth
printHeight := paper.height - 2*margin - 2*framewidth
imageAspect := float64(image.width) / float64(image.height)
printAspect := printWidth / printHeight
//fmt.Printf("print %g x %g image %g x %g pA %g iA %g\n", printWidth, printHeight, image.width, image.height, printAspect, imageAspect)
var scale float64
var translate RectangleT
if imageAspect > printAspect {
scale = printWidth / float64(image.width)
//fmt.Println("scaling width")
translate.width = margin + framewidth
translate.height = (paper.height - float64(image.height)*scale) / 2
} else {
scale = printHeight / float64(image.height)
//fmt.Println("scaling height")
translate.width = (paper.width - float64(image.width)*scale) / 2
translate.height = margin + framewidth
}
//fmt.Printf("translate = %g,%g scale=%g\n", translate.width, translate.height, scale)
return translate, scale
}
// Parse the colour string, e.g. "00ff00" or "123456,abcdef,ff7700" or "222222-eeeeee"
// into a slice of such values.
// The input has already been validated by regexp, so no error checking done here.
// Assumes svg.thresholds has already be set up.
func (svg *SVGfile) setColours(colourString string) {
if colourString == "" {
return
}
colourString = strings.ToLower(colourString)
if len(colourString) == 6 {
// Single colour -- treat as two (one for contour, one for background)
svg.colours = []string{colourString, colourString}
return
}
if colourString[6:7] == "," {
// List of colours
svg.colours = strings.Split(colourString, ",")
return
}
// Range of colours 123456-abcdef
svg.colours = make([]string, len(svg.thresholds))
hex0 := colourString[:6]
hex1 := colourString[7:]
// first contour gets first colour
svg.colours[0] = hex0
tcount := len(svg.thresholds) // including 1 for the background
if tcount > 2 {
r0, _ := strconv.ParseInt(colourString[0:2], 16, 0)
g0, _ := strconv.ParseInt(colourString[2:4], 16, 0)
b0, _ := strconv.ParseInt(colourString[4:6], 16, 0)
r1, _ := strconv.ParseInt(colourString[7:9], 16, 0)
g1, _ := strconv.ParseInt(colourString[9:11], 16, 0)
b1, _ := strconv.ParseInt(colourString[11:13], 16, 0)
rStep := float64(r1-r0) / float64(tcount-1)
gStep := float64(g1-g0) / float64(tcount-1)
bStep := float64(b1-b0) / float64(tcount-1)
//fmt.Printf("input=%s t's=%v %02x %02x %02x %02x %02x %02x step: %v %v %v\n", colourString, svg.thresholds, r0, g0, b0, r1, g1, b1, rStep, gStep, bStep)
for i := 1; i < tcount; i++ {
r := r0 + int64(math.Round(float64(i)*rStep))
g := g0 + int64(math.Round(float64(i)*gStep))
b := b0 + int64(math.Round(float64(i)*bStep))
svg.colours[i] = fmt.Sprintf("%02x%02x%02x", r, g, b)
}
}
// background counts as last threshold
svg.colours[len(svg.colours)-1] = hex1
//fmt.Printf("setColours: %#v\n", svg.colours)
}
func (svg *SVGfile) open(filename string) {
svg.filename = filename
fh, err := os.Create(svg.filename)
if err != nil {
log.Fatalf("Unable to open SVG file %q - %s", svg.filename, err)
}
svg.file = fh
svg.write("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n") // needed so that next line can be a comment
}
func (svg *SVGfile) start(opts OptsT) (scale float64) {
svg.currentLayer = -1 // no layer open
svg.thresholds = append([]int{0}, opts.thresholds...) // the background counts as threshold 0
svg.setColours(opts.colours)
// write the wrapper SVG with background colour first
viewbox := fmt.Sprintf("viewBox=\"0 0 %g %g\"", opts.paperSize.width, opts.paperSize.height)
// Set background via style rather than filling an oversized rect (which upsets Axidraw)
// (The style seems to be ignored by gThumb)
bg := fmt.Sprintf("style=\"background-color:%s\"", "white")
xmlns := "xmlns=\"http://www.w3.org/2000/svg\" xmlns:inkscape=\"http://www.inkscape.org/namespaces/inkscape\""
svgElement := fmt.Sprintf("<svg width=\"%gmm\" height=\"%gmm\" %s %s %s encoding=\"UTF-8\" >\n",
opts.paperSize.width, opts.paperSize.height, viewbox, bg, xmlns)
svg.write(svgElement)
// Debug only: show paper limits
if opts.debug {
paperBox := fmt.Sprintf("<rect id=\"papersize\" width=\"%g\" height=\"%g\" stroke=\"blue\" stroke-dasharray=\"4\" fill=\"none\"/>\n", opts.paperSize.width, opts.paperSize.height)
svg.write(paperBox)
}
translate, scale := calcSizes(RectangleT{float64(opts.width), float64(opts.height)}, opts.margin, opts.paperSize, opts.framewidth)
// Debug only: show plot limits
if opts.debug {
plotBox := fmt.Sprintf("<rect id=\"plotsize\" width=\"%g\" height=\"%g\" x=\"%g\" y=\"%g\" stroke=\"green\" stroke-dasharray=\"3\" fill=\"none\"/>\n",
float64(opts.width)*scale, float64(opts.height)*scale, translate.width, translate.height)
svg.write(plotBox)
}
transform := fmt.Sprintf("transform=\"translate(%.4f,%.4f) scale(%.4f)\"", translate.width, translate.height, scale)
// Main group -- scaled to fit paper
// stroke-width is 'descaled' to result in what the user asked for
g := fmt.Sprintf("<g stroke=\"black\" stroke-width=\"%.4f\" stroke-linecap=\"round\" stroke-linejoin=\"round\" fill=\"none\" %s>\n", opts.linewidth/scale, transform)
svg.write(g)
// Clippage is the amount to be taken off the edge of the image to hide the off-image
// parts of contour polygons (while still allowing them to be filled with colour).
// Ideally, clippage would be used in calcSizes, but that goes circular.
// It's only an issue with very wide contour lines.
clippage := 0.0
if opts.clip {
clippage = opts.linewidth / 2 / scale
}
if opts.clip { // inside the transformed group
clipString := fmt.Sprintf("<defs><clipPath id=\"clip1\" ><rect id=\"cliprect\" width=\"%.4f\" height=\"%.4f\" x=\"%.4f\" y=\"%.4f\" /></clipPath></defs>\n", float64(opts.width)-clippage*2, float64(opts.height)-clippage*2, clippage, clippage)
svg.write(clipString)
}
// Background layer for various reasons -- for clip because might have fill colours
svg.layer(0, "background", len(svg.thresholds)-1)
if opts.image {
// CHECK clip image same as plot?
imageString := fmt.Sprintf("<image id=\"background\" href=\"%s\" width=\"%d\" height=\"%d\" clip-path=\"url(#clip1)\" />\n", path.Base(opts.infile), opts.width, opts.height)
//fmt.Print(imageString)
svg.write(imageString)
}
// If colouring, need a background rect to be filled by the first colour
if len(svg.colours) > 0 {
rect := fmt.Sprintf("<rect id=\"plotsize\" width=\"%g\" height=\"%g\" stroke=\"none\" />\n",
float64(opts.width), float64(opts.height))
svg.write(rect)
}
//fmt.Printf("lw=%v scale=%v clippage=%v\n", opts.linewidth, scale, clippage)
if opts.framewidth > 0.0 {
// stroke-width is 'descaled' to result in what the user asked for:
fwdescaled := opts.framewidth / scale
w := float64(opts.width) + fwdescaled
h := float64(opts.height) + fwdescaled
// frame is outside the image, so shifted up and left a bit:
x := -fwdescaled / 2
y := -fwdescaled / 2
if opts.clip {
// adjust frame size and position to fit clipped image
w -= 2 * clippage
h -= 2 * clippage
x += clippage
y += clippage
}
//frame := fmt.Sprintf("<rect id=\"frame\" width=\"%d\" height=\"%d\" stroke-width=\"%.4f\" />\n", opts.width, opts.height, opts.framewidth/scale)
frameString := fmt.Sprintf("<rect id=\"frame\" width=\"%.4f\" height=\"%.4f\" x=\"%.4f\" y=\"%.4f\" stroke-width=\"%.4f\" />\n", w, h, x, y, fwdescaled)
//fmt.Print(frameString)
svg.write(frameString)
}
return scale
}
func (svg *SVGfile) stopSave() {
svg.endLayer()
svg.write("</g>\n</svg>\n")
svg.file.Close()
fmt.Printf("Created SVG file %q\n", svg.filename)
}
func (svg *SVGfile) startLayer(l int, label string, colourIdx int) {
fill := ""
if len(svg.colours) > 0 {
//fmt.Printf("svg.sL: contour fill: l=%d svg.colours[%d]=%v\n", l, colourIdx, svg.colours[colourIdx%len(svg.colours)])
fill = fmt.Sprintf("fill=\"#%s\"", svg.colours[colourIdx%len(svg.colours)])
}
svg.write(fmt.Sprintf("<g inkscape:groupmode=\"layer\" inkscape:label=\"%d %s\" stroke=\"black\" %s >\n", svg.thresholds[l], label, fill))
svg.currentLayer = l
}
func (svg *SVGfile) endLayer() {
if svg.currentLayer >= 0 {
svg.write("</g>\n") // end of stroke and layer group
}
svg.currentLayer = -1
}
func (svg *SVGfile) layer(l int, label string, colourIdx int) {
//fmt.Printf("svg.l: cL=%d l=%d label=%s\n", svg.currentLayer, l, label)
if l == svg.currentLayer {
// nothing to do
} else {
svg.endLayer()
svg.startLayer(l, label, colourIdx)
}
}