373 lines
10 KiB
Nim
373 lines
10 KiB
Nim
## Load SVG files.
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import chroma, pixie/common, pixie/images, pixie/paths, strutils, vmath,
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xmlparser, xmltree
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const
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xmlSignature* = "<?xml"
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svgSignature* = "<svg"
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type Ctx = object
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fillRule: WindingRule
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fill, stroke: ColorRGBA
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strokeWidth: float32
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strokeLineCap: LineCap
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strokeLineJoin: LineJoin
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transform: Mat3
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shouldStroke: bool
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template failInvalid() =
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raise newException(PixieError, "Invalid SVG data")
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proc attrOrDefault(node: XmlNode, name, default: string): string =
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result = node.attr(name)
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if result.len == 0:
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result = default
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proc initCtx(): Ctx =
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result.fill = parseHtmlColor("black").rgba
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result.stroke = parseHtmlColor("black").rgba
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result.strokeWidth = 1
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result.transform = mat3()
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proc decodeCtx(inherited: Ctx, node: XmlNode): Ctx =
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result = inherited
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var
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fillRule = node.attr("fill-rule")
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fill = node.attr("fill")
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stroke = node.attr("stroke")
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strokeWidth = node.attr("stroke-width")
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strokeLineCap = node.attr("stroke-linecap")
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strokeLineJoin = node.attr("stroke-linejoin")
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transform = node.attr("transform")
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style = node.attr("style")
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let pairs = style.split(';')
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for pair in pairs:
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let parts = pair.split(':')
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if parts.len == 2:
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# Do not override element properties
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case parts[0].strip():
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of "fill":
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if fill.len == 0:
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fill = parts[1].strip()
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of "stroke":
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if stroke.len == 0:
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stroke = parts[1].strip()
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of "stroke-linecap":
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if strokeLineCap.len == 0:
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strokeLineCap = parts[1].strip()
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of "stroke-linejoin":
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if strokeLineJoin.len == 0:
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strokeLineJoin = parts[1].strip()
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of "stroke-width":
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if strokeWidth.len == 0:
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strokeWidth = parts[1].strip()
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if fillRule == "":
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discard # Inherit
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elif fillRule == "nonzero":
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result.fillRule = wrNonZero
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elif fillRule == "evenodd":
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result.fillRule = wrEvenOdd
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else:
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raise newException(
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PixieError, "Invalid fill-rule value " & fillRule
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)
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if fill == "" or fill == "currentColor":
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discard # Inherit
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elif fill == "none":
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result.fill = ColorRGBA()
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else:
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result.fill = parseHtmlColor(fill).rgba
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if stroke == "":
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discard # Inherit
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elif stroke == "currentColor":
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result.shouldStroke = true
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elif stroke == "none":
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result.stroke = ColorRGBA()
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else:
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result.stroke = parseHtmlColor(stroke).rgba
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result.shouldStroke = true
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if strokeWidth == "":
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discard # Inherit
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else:
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if strokeWidth.endsWith("px"):
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strokeWidth = strokeWidth[0 .. ^3]
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result.strokeWidth = parseFloat(strokeWidth)
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result.shouldStroke = true
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if result.stroke == ColorRGBA() or result.strokeWidth <= 0:
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result.shouldStroke = false
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if strokeLineCap == "":
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discard # Inherit
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else:
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case strokeLineCap:
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of "butt":
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result.strokeLineCap = lcButt
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of "round":
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result.strokeLineCap = lcRound
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of "square":
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result.strokeLineCap = lcSquare
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of "inherit":
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discard
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else:
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raise newException(
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PixieError, "Invalid stroke-linecap value " & strokeLineCap
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)
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if strokeLineJoin == "":
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discard # Inherit
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else:
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case strokeLineJoin:
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of "miter":
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result.strokeLineJoin = ljMiter
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of "round":
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result.strokeLineJoin = ljRound
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of "bevel":
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result.strokeLineJoin = ljBevel
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of "inherit":
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discard
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else:
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raise newException(
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PixieError, "Invalid stroke-linejoin value " & strokeLineJoin
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)
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if transform == "":
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discard # Inherit
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else:
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template failInvalidTransform(transform: string) =
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raise newException(
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PixieError, "Unsupported SVG transform: " & transform & "."
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)
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var remaining = transform
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while remaining.len > 0:
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let index = remaining.find(")")
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if index == -1:
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failInvalidTransform(transform)
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let f = remaining[0 .. index].strip()
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remaining = remaining[index + 1 .. ^1]
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if f.startsWith("matrix("):
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let arr =
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if f.contains(","):
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f[7 .. ^2].split(",")
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else:
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f[7 .. ^2].split(" ")
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if arr.len != 6:
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failInvalidTransform(transform)
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var m = mat3()
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m[0] = parseFloat(arr[0].strip())
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m[1] = parseFloat(arr[1].strip())
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m[3] = parseFloat(arr[2].strip())
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m[4] = parseFloat(arr[3].strip())
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m[6] = parseFloat(arr[4].strip())
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m[7] = parseFloat(arr[5].strip())
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result.transform = result.transform * m
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elif f.startsWith("translate("):
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let
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components = f[10 .. ^2].split(" ")
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tx = parseFloat(components[0].strip())
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ty =
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if components[1].len == 0:
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0.0
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else:
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parseFloat(components[1].strip())
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result.transform = result.transform * translate(vec2(tx, ty))
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elif f.startsWith("rotate("):
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let
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values = f[7 .. ^2].split(" ")
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angle = parseFloat(values[0].strip()) * -PI / 180
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var cx, cy: float32
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if values.len > 1:
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cx = parseFloat(values[1].strip())
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if values.len > 2:
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cy = parseFloat(values[2].strip())
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let center = vec2(cx, cy)
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result.transform = result.transform *
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translate(center) * rotationMat3(angle) * translate(-center)
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else:
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failInvalidTransform(transform)
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proc draw(img: Image, node: XmlNode, ctxStack: var seq[Ctx]) =
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if node.kind != xnElement:
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# Skip <!-- comments -->
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return
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case node.tag:
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of "title", "desc", "defs":
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discard
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of "g":
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let ctx = decodeCtx(ctxStack[^1], node)
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ctxStack.add(ctx)
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for child in node:
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img.draw(child, ctxStack)
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discard ctxStack.pop()
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of "path":
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let
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d = node.attr("d")
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ctx = decodeCtx(ctxStack[^1], node)
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path = parsePath(d)
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if ctx.fill != ColorRGBA():
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img.fillPath(path, ctx.fill, ctx.transform, ctx.fillRule)
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if ctx.shouldStroke:
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img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
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of "line":
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let
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ctx = decodeCtx(ctxStack[^1], node)
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x1 = parseFloat(node.attrOrDefault("x1", "0"))
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y1 = parseFloat(node.attrOrDefault("y1", "0"))
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x2 = parseFloat(node.attrOrDefault("x2", "0"))
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y2 = parseFloat(node.attrOrDefault("y2", "0"))
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var path: Path
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path.moveTo(x1, y1)
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path.lineTo(x2, y2)
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path.closePath()
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if ctx.fill != ColorRGBA():
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img.fillPath(path, ctx.fill, ctx.transform)
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if ctx.shouldStroke:
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img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
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of "polyline", "polygon":
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let
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ctx = decodeCtx(ctxStack[^1], node)
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points = node.attr("points")
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var vecs: seq[Vec2]
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if points.contains(","):
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for pair in points.split(" "):
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let parts = pair.split(",")
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if parts.len != 2:
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failInvalid()
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vecs.add(vec2(parseFloat(parts[0]), parseFloat(parts[1])))
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else:
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let points = points.split(" ")
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if points.len mod 2 != 0:
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failInvalid()
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for i in countup(0, points.len - 2, 2):
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vecs.add(vec2(parseFloat(points[i]), parseFloat(points[i + 1])))
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if vecs.len == 0:
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failInvalid()
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var path: Path
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path.moveTo(vecs[0])
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for i in 1 ..< vecs.len:
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path.lineTo(vecs[i])
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# The difference between polyline and polygon is whether we close the path
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if node.tag == "polygon":
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path.closePath()
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if ctx.fill != ColorRGBA():
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img.fillPath(path, ctx.fill, ctx.transform)
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if ctx.shouldStroke:
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img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
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of "rect":
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let
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ctx = decodeCtx(ctxStack[^1], node)
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x = parseFloat(node.attrOrDefault("x", "0"))
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y = parseFloat(node.attrOrDefault("y", "0"))
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width = parseFloat(node.attr("width"))
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height = parseFloat(node.attr("height"))
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var
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rx = max(parseFloat(node.attrOrDefault("rx", "0")), 0)
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ry = max(parseFloat(node.attrOrDefault("ry", "0")), 0)
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var path: Path
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if rx > 0 or ry > 0:
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if rx == 0:
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rx = ry
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elif ry == 0:
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ry = rx
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rx = min(rx, width / 2)
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ry = min(ry, height / 2)
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path.moveTo(x + rx, y)
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path.lineTo(x + width - rx, y)
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path.ellipticalArcTo(rx, ry, 0, false, true, x + width, y + ry)
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path.lineTo(x + width, y + height - ry)
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path.ellipticalArcTo(rx, ry, 0, false, true, x + width - rx, y + height)
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path.lineTo(x + rx, y + height)
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path.ellipticalArcTo(rx, ry, 0, false, true, x, y + height - ry)
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path.lineTo(x, y + ry)
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path.ellipticalArcTo(rx, ry, 0, false, true, x + rx, y)
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else:
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path.rect(x, y, width, height)
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if ctx.fill != ColorRGBA():
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img.fillPath(path, ctx.fill, ctx.transform)
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if ctx.shouldStroke:
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img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
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of "circle", "ellipse":
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let
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ctx = decodeCtx(ctxStack[^1], node)
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cx = parseFloat(node.attrOrDefault("cx", "0"))
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cy = parseFloat(node.attrOrDefault("cy", "0"))
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var rx, ry: float32
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if node.tag == "circle":
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rx = parseFloat(node.attr("r"))
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ry = rx
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else:
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rx = parseFloat(node.attrOrDefault("rx", "0"))
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ry = parseFloat(node.attrOrDefault("ry", "0"))
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var path: Path
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path.ellipse(cx, cy, rx, ry)
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if ctx.fill != ColorRGBA():
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img.fillPath(path, ctx.fill, ctx.transform)
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if ctx.shouldStroke:
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img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
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else:
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raise newException(PixieError, "Unsupported SVG tag: " & node.tag & ".")
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proc decodeSvg*(data: string, width = 0, height = 0): Image =
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## Render SVG file and return the image. Defaults to the SVG's view box size.
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try:
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let root = parseXml(data)
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if root.tag != "svg":
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failInvalid()
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let
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viewBox = root.attr("viewBox")
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box = viewBox.split(" ")
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viewBoxWidth = parseInt(box[2])
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viewBoxHeight = parseInt(box[3])
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var rootCtx = initCtx()
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rootCtx = decodeCtx(rootCtx, root)
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if width == 0 and height == 0: # Default to the view box size
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result = newImage(viewBoxWidth, viewBoxHeight)
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else:
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result = newImage(width, height)
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let
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scaleX = width.float32 / viewBoxWidth.float32
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scaleY = height.float32 / viewBoxHeight.float32
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rootCtx.transform = scale(vec2(scaleX, scaleY))
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var ctxStack = @[rootCtx]
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for node in root:
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result.draw(node, ctxStack)
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except PixieError as e:
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raise e
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except:
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raise newException(PixieError, "Unable to load SVG")
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