pixie/experiments/svg_cairo.nim
2022-02-13 20:02:37 -08:00

588 lines
16 KiB
Nim

## Load and Save SVG files.
import cairo, chroma, pixie/common, pixie/images, pixie/paints, strutils,
tables, vmath, xmlparser, xmltree
include pixie/paths
proc processCommands(
c: ptr Context, path: Path, closeSubpaths: bool, mat: Mat3
) =
let shapes = path.commandsToShapes(closeSubpaths, mat.pixelScale())
if shapes.len == 0:
return
c.newPath()
c.moveTo(shapes[0][0].x, shapes[0][0].y)
for shape in shapes:
for v in shape:
c.lineTo(v.x, v.y)
proc prepare(
c: ptr Context,
path: Path,
paint: Paint,
mat: Mat3,
closeSubpaths: bool,
windingRule = NonZero
) =
let
color = paint.color
matrix = Matrix(
xx: mat[0, 0],
yx: mat[0, 1],
xy: mat[1, 0],
yy: mat[1, 1],
x0: mat[2, 0],
y0: mat[2, 1],
)
c.setSourceRgba(color.r, color.g, color.b, color.a)
c.setMatrix(matrix.unsafeAddr)
case windingRule:
of NonZero:
c.setFillRule(FillRuleWinding)
else:
c.setFillRule(FillRuleEvenOdd)
c.processCommands(path, closeSubpaths, mat)
type
LinearGradient = object
x1, y1, x2, y2: float32
stops: seq[ColorStop]
Ctx = object
display: bool
fillRule: WindingRule
fill: Paint
stroke: ColorRGBX
strokeWidth: float32
strokeLineCap: LineCap
strokeLineJoin: LineJoin
strokeMiterLimit: float32
strokeDashArray: seq[float32]
transform: Mat3
shouldStroke: bool
opacity, strokeOpacity: float32
linearGradients: TableRef[string, LinearGradient]
template failInvalid() =
raise newException(PixieError, "Invalid SVG data")
proc attrOrDefault(node: XmlNode, name, default: string): string =
result = node.attr(name)
if result.len == 0:
result = default
proc initCtx(): Ctx =
result.display = true
try:
result.fill = parseHtmlColor("black").rgbx
result.stroke = parseHtmlColor("black").rgbx
except:
raise currentExceptionAsPixieError()
result.strokeWidth = 1
result.transform = mat3()
result.strokeMiterLimit = defaultMiterLimit
result.opacity = 1
result.strokeOpacity = 1
result.linearGradients = newTable[string, LinearGradient]()
proc decodeCtxInternal(inherited: Ctx, node: XmlNode): Ctx =
result = inherited
proc splitArgs(s: string): seq[string] =
# Handles (1,1) or (1 1) or (1, 1) or (1,1 2,2) etc
let tmp = s.replace(',', ' ').split(' ')
for entry in tmp:
if entry.len > 0:
result.add(entry)
var
fillRule = node.attr("fill-rule")
fill = node.attr("fill")
stroke = node.attr("stroke")
strokeWidth = node.attr("stroke-width")
strokeLineCap = node.attr("stroke-linecap")
strokeLineJoin = node.attr("stroke-linejoin")
strokeMiterLimit = node.attr("stroke-miterlimit")
strokeDashArray = node.attr("stroke-dasharray")
transform = node.attr("transform")
style = node.attr("style")
display = node.attr("display")
opacity = node.attr("opacity")
fillOpacity = node.attr("fill-opacity")
strokeOpacity = node.attr("stroke-opacity")
let pairs = style.split(';')
for pair in pairs:
let parts = pair.split(':')
if parts.len == 2:
# Do not override element properties
case parts[0].strip():
of "fill-rule":
if fillRule.len == 0:
fillRule = parts[1].strip()
of "fill":
if fill.len == 0:
fill = parts[1].strip()
of "stroke":
if stroke.len == 0:
stroke = parts[1].strip()
of "stroke-linecap":
if strokeLineCap.len == 0:
strokeLineCap = parts[1].strip()
of "stroke-linejoin":
if strokeLineJoin.len == 0:
strokeLineJoin = parts[1].strip()
of "stroke-width":
if strokeWidth.len == 0:
strokeWidth = parts[1].strip()
of "stroke-miterlimit":
if strokeMiterLimit.len == 0:
strokeMiterLimit = parts[1].strip()
of "stroke-dasharray":
if strokeDashArray.len == 0:
strokeDashArray = parts[1].strip()
of "display":
if display.len == 0:
display = parts[1].strip()
of "opacity":
if opacity.len == 0:
opacity = parts[1].strip()
of "fillOpacity":
if fillOpacity.len == 0:
fillOpacity = parts[1].strip()
of "strokeOpacity":
if strokeOpacity.len == 0:
strokeOpacity = parts[1].strip()
else:
discard
elif pair.len > 0:
when defined(pixieDebugSvg):
echo "Invalid style pair: ", pair
if display.len > 0:
result.display = display.strip() != "none"
if opacity.len > 0:
result.opacity = clamp(parseFloat(opacity), 0, 1)
if fillOpacity.len > 0:
result.fill.opacity = clamp(parseFloat(fillOpacity), 0, 1)
if strokeOpacity.len > 0:
result.strokeOpacity = clamp(parseFloat(strokeOpacity), 0, 1)
if fillRule == "":
discard # Inherit
elif fillRule == "nonzero":
result.fillRule = NonZero
elif fillRule == "evenodd":
result.fillRule = EvenOdd
else:
raise newException(
PixieError, "Invalid fill-rule value " & fillRule
)
if fill == "" or fill == "currentColor":
discard # Inherit
elif fill == "none":
result.fill = ColorRGBX()
elif fill.startsWith("url("):
let id = fill[5 .. ^2]
if id in result.linearGradients:
let linearGradient = result.linearGradients[id]
result.fill = newPaint(LinearGradientPaint)
result.fill.gradientHandlePositions = @[
result.transform * vec2(linearGradient.x1, linearGradient.y1),
result.transform * vec2(linearGradient.x2, linearGradient.y2)
]
result.fill.gradientStops = linearGradient.stops
else:
raise newException(PixieError, "Missing SVG resource " & id)
else:
result.fill = parseHtmlColor(fill).rgbx
if stroke == "":
discard # Inherit
elif stroke == "currentColor":
result.shouldStroke = true
elif stroke == "none":
result.stroke = ColorRGBX()
else:
result.stroke = parseHtmlColor(stroke).rgbx
result.shouldStroke = true
if strokeWidth == "":
discard # Inherit
else:
if strokeWidth.endsWith("px"):
strokeWidth = strokeWidth[0 .. ^3]
result.strokeWidth = parseFloat(strokeWidth)
result.shouldStroke = true
if result.stroke == ColorRGBX() or result.strokeWidth <= 0:
result.shouldStroke = false
if strokeLineCap == "":
discard # Inherit
else:
case strokeLineCap:
of "butt":
result.strokeLineCap = ButtCap
of "round":
result.strokeLineCap = RoundCap
of "square":
result.strokeLineCap = SquareCap
of "inherit":
discard
else:
raise newException(
PixieError, "Invalid stroke-linecap value " & strokeLineCap
)
if strokeLineJoin == "":
discard # Inherit
else:
case strokeLineJoin:
of "miter":
result.strokeLineJoin = MiterJoin
of "round":
result.strokeLineJoin = RoundJoin
of "bevel":
result.strokeLineJoin = BevelJoin
of "inherit":
discard
else:
raise newException(
PixieError, "Invalid stroke-linejoin value " & strokeLineJoin
)
if strokeMiterLimit == "":
discard
else:
result.strokeMiterLimit = parseFloat(strokeMiterLimit)
if strokeDashArray == "":
discard
else:
var values = splitArgs(strokeDashArray)
for value in values:
result.strokeDashArray.add(parseFloat(value))
if transform == "":
discard # Inherit
else:
template failInvalidTransform(transform: string) =
raise newException(
PixieError, "Unsupported SVG transform: " & transform
)
var remaining = transform
while remaining.len > 0:
let index = remaining.find(")")
if index == -1:
failInvalidTransform(transform)
let f = remaining[0 .. index].strip()
remaining = remaining[index + 1 .. ^1]
if f.startsWith("matrix("):
let arr = splitArgs(f[7 .. ^2])
if arr.len != 6:
failInvalidTransform(transform)
var m = mat3()
m[0, 0] = parseFloat(arr[0])
m[0, 1] = parseFloat(arr[1])
m[1, 0] = parseFloat(arr[2])
m[1, 1] = parseFloat(arr[3])
m[2, 0] = parseFloat(arr[4])
m[2, 1] = parseFloat(arr[5])
result.transform = result.transform * m
elif f.startsWith("translate("):
let
components = splitArgs(f[10 .. ^2])
tx = parseFloat(components[0])
ty =
if components.len == 1:
0.0
else:
parseFloat(components[1])
result.transform = result.transform * translate(vec2(tx, ty))
elif f.startsWith("rotate("):
let
values = splitArgs(f[7 .. ^2])
angle: float32 = parseFloat(values[0]) * -PI / 180
var cx, cy: float32
if values.len > 1:
cx = parseFloat(values[1])
if values.len > 2:
cy = parseFloat(values[2])
let center = vec2(cx, cy)
result.transform = result.transform *
translate(center) * rotate(angle) * translate(-center)
elif f.startsWith("scale("):
let
values = splitArgs(f[6 .. ^2])
sx: float32 = parseFloat(values[0])
sy: float32 =
if values.len > 1:
parseFloat(values[1])
else:
sx
result.transform = result.transform * scale(vec2(sx, sy))
else:
failInvalidTransform(transform)
proc decodeCtx(inherited: Ctx, node: XmlNode): Ctx =
try:
decodeCtxInternal(inherited, node)
except PixieError as e:
raise e
except:
raise currentExceptionAsPixieError()
proc cairoLineCap(lineCap: LineCap): cairo.LineCap =
case lineCap:
of ButtCap:
LineCapButt
of RoundCap:
LineCapRound
of SquareCap:
LineCapSquare
proc cairoLineJoin(lineJoin: LineJoin): cairo.LineJoin =
case lineJoin:
of MiterJoin:
LineJoinMiter
of BevelJoin:
LineJoinBevel
of RoundJoin:
LineJoinRound
proc fill(c: ptr Context, ctx: Ctx, path: Path) {.inline.} =
if ctx.display and ctx.opacity > 0:
let paint = newPaint(ctx.fill)
paint.opacity = paint.opacity * ctx.opacity
prepare(c, path, paint, ctx.transform, true, ctx.fillRule)
c.fill()
proc stroke(c: ptr Context, ctx: Ctx, path: Path) {.inline.} =
if ctx.display and ctx.opacity > 0:
let paint = newPaint(ctx.stroke)
paint.color.a *= (ctx.opacity * ctx.strokeOpacity)
prepare(c, path, paint, ctx.transform, false)
c.setLineWidth(ctx.strokeWidth)
c.setLineCap(ctx.strokeLineCap.cairoLineCap())
c.setLineJoin(ctx.strokeLineJoin.cairoLineJoin())
c.setMiterLimit(ctx.strokeMiterLimit)
c.stroke()
proc drawInternal(img: ptr Context, node: XmlNode, ctxStack: var seq[Ctx]) =
if node.kind != xnElement:
# Skip <!-- comments -->
return
case node.tag:
of "title", "desc", "defs":
discard
of "g":
let ctx = decodeCtx(ctxStack[^1], node)
ctxStack.add(ctx)
for child in node:
img.drawInternal(child, ctxStack)
discard ctxStack.pop()
of "path":
let
d = node.attr("d")
ctx = decodeCtx(ctxStack[^1], node)
path = parsePath(d)
img.fill(ctx, path)
if ctx.shouldStroke:
img.stroke(ctx, path)
of "line":
let
ctx = decodeCtx(ctxStack[^1], node)
x1 = parseFloat(node.attrOrDefault("x1", "0"))
y1 = parseFloat(node.attrOrDefault("y1", "0"))
x2 = parseFloat(node.attrOrDefault("x2", "0"))
y2 = parseFloat(node.attrOrDefault("y2", "0"))
let path = newPath()
path.moveTo(x1, y1)
path.lineTo(x2, y2)
if ctx.shouldStroke:
img.stroke(ctx, path)
of "polyline", "polygon":
let
ctx = decodeCtx(ctxStack[^1], node)
points = node.attr("points")
var vecs: seq[Vec2]
if points.contains(","):
for pair in points.split(" "):
let parts = pair.split(",")
if parts.len != 2:
failInvalid()
vecs.add(vec2(parseFloat(parts[0]), parseFloat(parts[1])))
else:
let points = points.split(" ")
if points.len mod 2 != 0:
failInvalid()
for i in 0 ..< points.len div 2:
vecs.add(vec2(parseFloat(points[i * 2]), parseFloat(points[i * 2 + 1])))
if vecs.len == 0:
failInvalid()
let path = newPath()
path.moveTo(vecs[0])
for i in 1 ..< vecs.len:
path.lineTo(vecs[i])
# The difference between polyline and polygon is whether we close the path
# and fill or not
if node.tag == "polygon":
path.closePath()
img.fill(ctx, path)
if ctx.shouldStroke:
img.stroke(ctx, path)
of "rect":
let
ctx = decodeCtx(ctxStack[^1], node)
x = parseFloat(node.attrOrDefault("x", "0"))
y = parseFloat(node.attrOrDefault("y", "0"))
width = parseFloat(node.attrOrDefault("width", "0"))
height = parseFloat(node.attrOrDefault("height", "0"))
if width == 0 or height == 0:
return
var
rx = max(parseFloat(node.attrOrDefault("rx", "0")), 0)
ry = max(parseFloat(node.attrOrDefault("ry", "0")), 0)
let path = newPath()
if rx > 0 or ry > 0:
if rx == 0:
rx = ry
elif ry == 0:
ry = rx
rx = min(rx, width / 2)
ry = min(ry, height / 2)
path.moveTo(x + rx, y)
path.lineTo(x + width - rx, y)
path.ellipticalArcTo(rx, ry, 0, false, true, x + width, y + ry)
path.lineTo(x + width, y + height - ry)
path.ellipticalArcTo(rx, ry, 0, false, true, x + width - rx, y + height)
path.lineTo(x + rx, y + height)
path.ellipticalArcTo(rx, ry, 0, false, true, x, y + height - ry)
path.lineTo(x, y + ry)
path.ellipticalArcTo(rx, ry, 0, false, true, x + rx, y)
else:
path.rect(x, y, width, height)
img.fill(ctx, path)
if ctx.shouldStroke:
img.stroke(ctx, path)
of "circle", "ellipse":
let
ctx = decodeCtx(ctxStack[^1], node)
cx = parseFloat(node.attrOrDefault("cx", "0"))
cy = parseFloat(node.attrOrDefault("cy", "0"))
var rx, ry: float32
if node.tag == "circle":
rx = parseFloat(node.attr("r"))
ry = rx
else:
rx = parseFloat(node.attrOrDefault("rx", "0"))
ry = parseFloat(node.attrOrDefault("ry", "0"))
let path = newPath()
path.ellipse(cx, cy, rx, ry)
img.fill(ctx, path)
if ctx.shouldStroke:
img.stroke(ctx, path)
else:
raise newException(PixieError, "Unsupported SVG tag: " & node.tag & ".")
proc draw(img: ptr Context, node: XmlNode, ctxStack: var seq[Ctx]) =
try:
drawInternal(img, node, ctxStack)
except PixieError as e:
raise e
except:
raise currentExceptionAsPixieError()
proc decodeSvg*(data: string, width = 0, height = 0): Image =
## Render SVG file and return the image. Defaults to the SVG's view box size.
try:
let root = parseXml(data)
if root.tag != "svg":
failInvalid()
let
viewBox = root.attr("viewBox")
box = viewBox.split(" ")
viewBoxMinX = parseInt(box[0])
viewBoxMinY = parseInt(box[1])
viewBoxWidth = parseInt(box[2])
viewBoxHeight = parseInt(box[3])
var rootCtx = initCtx()
rootCtx = decodeCtx(rootCtx, root)
if viewBoxMinX != 0 or viewBoxMinY != 0:
rootCtx.transform = rootCtx.transform * translate(
vec2(-viewBoxMinX.float32, -viewBoxMinY.float32)
)
var
width = width
height = height
surface: ptr Surface
if width == 0 and height == 0: # Default to the view box size
width = viewBoxWidth.int32
height = viewBoxHeight.int32
else:
let
scaleX = width.float32 / viewBoxWidth.float32
scaleY = height.float32 / viewBoxHeight.float32
rootCtx.transform = rootCtx.transform * scale(vec2(scaleX, scaleY))
surface = imageSurfaceCreate(FORMAT_ARGB32, width.int32, height.int32)
let c = surface.create()
var ctxStack = @[rootCtx]
for node in root:
c.draw(node, ctxStack)
surface.flush()
result = newImage(width, height)
let pixels = cast[ptr UncheckedArray[array[4, uint8]]](surface.getData())
for y in 0 ..< result.height:
for x in 0 ..< result.width:
let
bgra = pixels[result.dataIndex(x, y)]
rgba = rgba(bgra[2], bgra[1], bgra[0], bgra[3])
result.unsafe[x, y] = rgba.rgbx()
except PixieError as e:
raise e
except:
raise newException(PixieError, "Unable to load SVG")