Merge pull request #204 from guzba/master

context and svg: miterLimit, line dashes

src/pixie.nim

@@ -1,8 +1,7 @@
 import bumpy, chroma, flatty/binny, os, pixie/blends, pixie/common,
     pixie/context, pixie/fileformats/bmp, pixie/fileformats/gif,
     pixie/fileformats/jpg, pixie/fileformats/png, pixie/fileformats/svg,
-    pixie/fonts, pixie/images, pixie/masks, pixie/paints, pixie/paths, strutils,
-    vmath
+    pixie/fonts, pixie/images, pixie/masks, pixie/paints, pixie/paths, strutils, vmath
 
 export blends, bumpy, chroma, common, context, fonts, images, masks, paints,
     paths, vmath

src/pixie/context.nim

@@ -11,11 +11,13 @@ type
     image*: Image
     fillStyle*, strokeStyle*: Paint
     lineWidth*: float32
+    miterLimit*: float32
     lineCap*: LineCap
     lineJoin*: LineJoin
     font*: Font
     textAlign*: HAlignMode
     path: Path
+    lineDash: seq[float32]
     mat: Mat3
     mask: Mask
     layer: Image
@@ -24,10 +26,12 @@ type
   ContextState = object
     fillStyle, strokeStyle: Paint
     lineWidth: float32
+    miterLimit: float32
     lineCap: LineCap
     lineJoin: LineJoin
     font: Font
     textAlign: HAlignMode
+    lineDash: seq[float32]
     mat: Mat3
     mask: Mask
     layer: Image
@@ -41,6 +45,7 @@ proc newContext*(image: Image): Context =
   result.image = image
   result.mat = mat3()
   result.lineWidth = 1
+  result.miterLimit = 10
   result.fillStyle = Paint(kind: pkSolid, color: rgbx(0, 0, 0, 255))
   result.strokeStyle = Paint(kind: pkSolid, color: rgbx(0, 0, 0, 255))
 
@@ -52,26 +57,31 @@ proc state(ctx: Context): ContextState =
   result.fillStyle = ctx.fillStyle
   result.strokeStyle = ctx.strokeStyle
   result.lineWidth = ctx.lineWidth
+  result.miterLimit = ctx.miterLimit
   result.lineCap = ctx.lineCap
   result.lineJoin = ctx.lineJoin
   result.font = ctx.font
   result.textAlign = ctx.textAlign
+  result.lineDash = ctx.lineDash
   result.mat = ctx.mat
   result.mask = if ctx.mask != nil: ctx.mask.copy() else: nil
 
 proc save*(ctx: Context) {.inline.} =
-  ## Saves the entire state of the canvas by pushing the current state onto
+  ## Saves the entire state of the context by pushing the current state onto
   ## a stack.
   ctx.stateStack.add(ctx.state())
 
 proc saveLayer*(ctx: Context) =
+  ## Saves the entire state of the context by pushing the current state onto
+  ## a stack and allocates a new image layer for subsequent drawing. Calling
+  ## restore blends the current layer image onto the prior layer or root image.
   var state = ctx.state()
   state.layer = ctx.layer
   ctx.stateStack.add(state)
   ctx.layer = newImage(ctx.image.width, ctx.image.height)
 
 proc restore*(ctx: Context) =
-  ## Restores the most recently saved canvas state by popping the top entry
+  ## Restores the most recently saved context state by popping the top entry
   ## in the drawing state stack. If there is no saved state, this method does
   ## nothing.
   if ctx.stateStack.len == 0:
@@ -85,10 +95,12 @@ proc restore*(ctx: Context) =
   ctx.fillStyle = state.fillStyle
   ctx.strokeStyle = state.strokeStyle
   ctx.lineWidth = state.lineWidth
+  ctx.miterLimit = state.miterLimit
   ctx.lineCap = state.lineCap
   ctx.lineJoin = state.lineJoin
   ctx.font = state.font
   ctx.textAlign = state.textAlign
+  ctx.lineDash = state.lineDash
   ctx.mat = state.mat
   ctx.mask = state.mask
   ctx.layer = state.layer
@@ -118,7 +130,9 @@ proc stroke(ctx: Context, image: Image, path: Path) {.inline.} =
     ctx.mat,
     ctx.lineWidth,
     ctx.lineCap,
-    ctx.lineJoin
+    ctx.lineJoin,
+    ctx.miterLimit,
+    ctx.lineDash
   )
 
 proc fillText(ctx: Context, image: Image, text: string, at: Vec2) {.inline.} =
@@ -155,7 +169,9 @@ proc strokeText(ctx: Context, image: Image, text: string, at: Vec2) {.inline.} =
     ctx.lineWidth,
     hAlign = ctx.textAlign,
     lineCap = ctx.lineCap,
-    lineJoin = ctx.lineJoin
+    lineJoin = ctx.lineJoin,
+    miterLimit = ctx.miterLimit,
+    dashes = ctx.lineDash
   )
 
 proc beginPath*(ctx: Context) {.inline.} =
@@ -289,13 +305,13 @@ proc clearRect*(ctx: Context, rect: Rect) =
   if ctx.layer != nil:
     ctx.layer.fillPath(
       path,
-      Paint(kind: pkSolid, color:rgbx(0, 0, 0, 0), blendMode: bmOverwrite),
+      Paint(kind: pkSolid, color: rgbx(0, 0, 0, 0), blendMode: bmOverwrite),
       ctx.mat
     )
   else:
     ctx.image.fillPath(
       path,
-      Paint(kind: pkSolid, color:rgbx(0, 0, 0, 0), blendMode: bmOverwrite),
+      Paint(kind: pkSolid, color: rgbx(0, 0, 0, 0), blendMode: bmOverwrite),
       ctx.mat
     )
 
@@ -368,6 +384,12 @@ proc measureText*(ctx: Context, text: string): TextMetrics =
   let bounds = typeset(ctx.font, text).computeBounds()
   result.width = bounds.x
 
+proc getLineDash*(ctx: Context): seq[float32] {.inline.} =
+  ctx.lineDash
+
+proc setLineDash*(ctx: Context, lineDash: seq[float32]) {.inline.} =
+  ctx.lineDash = lineDash
+
 proc getTransform*(ctx: Context): Mat3 {.inline.} =
   ## Retrieves the current transform matrix being applied to the context.
   ctx.mat
@@ -399,12 +421,12 @@ proc translate*(ctx: Context, x, y: float32) {.inline.} =
   ctx.mat = ctx.mat * translate(vec2(x, y))
 
 proc scale*(ctx: Context, v: Vec2) {.inline.} =
-  ## Adds a scaling transformation to the canvas units horizontally and/or
+  ## Adds a scaling transformation to the context units horizontally and/or
   ## vertically.
   ctx.mat = ctx.mat * scale(v)
 
 proc scale*(ctx: Context, x, y: float32) {.inline.} =
-  ## Adds a scaling transformation to the canvas units horizontally and/or
+  ## Adds a scaling transformation to the context units horizontally and/or
   ## vertically.
   ctx.mat = ctx.mat * scale(vec2(x, y))
 

src/pixie/demo.nim

@@ -1,7 +1,6 @@
-import opengl, pixie, pixie/context
-import staticglfw except Image
-export pixie
-export staticglfw except Image
+import opengl, pixie, pixie/context, staticglfw except Image
+
+export pixie, staticglfw except Image
 
 var
   dpi: float32 = 1.0

src/pixie/fileformats/svg.nim

@@ -1,7 +1,7 @@
 ## Load SVG files.
 
-import chroma, pixie/common, pixie/images, pixie/paths, pixie/paints, strutils, vmath,
-    xmlparser, xmltree
+import chroma, pixie/common, pixie/images, pixie/paints, pixie/paths, strutils,
+    vmath, xmlparser, xmltree
 
 const
   xmlSignature* = "<?xml"
@@ -13,6 +13,8 @@ type Ctx = object
   strokeWidth: float32
   strokeLineCap: LineCap
   strokeLineJoin: LineJoin
+  strokeMiterLimit: float32
+  strokeDashArray: seq[float32]
   transform: Mat3
   shouldStroke: bool
 
@@ -29,6 +31,7 @@ proc initCtx(): Ctx =
   result.stroke = parseHtmlColor("black").rgbx
   result.strokeWidth = 1
   result.transform = mat3()
+  result.strokeMiterLimit = defaultMiterLimit
 
 proc decodeCtx(inherited: Ctx, node: XmlNode): Ctx =
   result = inherited
@@ -40,6 +43,8 @@ proc decodeCtx(inherited: Ctx, node: XmlNode): Ctx =
     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")
 
@@ -64,6 +69,12 @@ proc decodeCtx(inherited: Ctx, node: XmlNode): Ctx =
       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()
 
   if fillRule == "":
     discard # Inherit
@@ -138,6 +149,18 @@ proc decodeCtx(inherited: Ctx, node: XmlNode): Ctx =
         PixieError, "Invalid stroke-linejoin value " & strokeLineJoin
       )
 
+  if strokeMiterLimit == "":
+    discard
+  else:
+    result.strokeMiterLimit = parseFloat(strokeMiterLimit)
+
+  if strokeDashArray == "":
+    discard
+  else:
+    var values = strokeDashArray.replace(',', ' ').split(' ')
+    for value in values:
+      result.strokeDashArray.add(parseFloat(value))
+
   if transform == "":
     discard # Inherit
   else:
@@ -210,6 +233,19 @@ proc decodeCtx(inherited: Ctx, node: XmlNode): Ctx =
       else:
         failInvalidTransform(transform)
 
+proc fill(img: Image, ctx: Ctx, path: Path) {.inline.} =
+  img.fillPath(path, ctx.fill, ctx.transform, ctx.fillRule)
+
+proc stroke(img: Image, ctx: Ctx, path: Path) {.inline.} =
+  img.strokePath(
+    path,
+    ctx.stroke,
+    ctx.transform,
+    ctx.strokeWidth,
+    miterLimit = ctx.strokeMiterLimit,
+    dashes = ctx.strokeDashArray
+  )
+
 proc draw(img: Image, node: XmlNode, ctxStack: var seq[Ctx]) =
   if node.kind != xnElement:
     # Skip <!-- comments -->
@@ -232,9 +268,9 @@ proc draw(img: Image, node: XmlNode, ctxStack: var seq[Ctx]) =
       ctx = decodeCtx(ctxStack[^1], node)
       path = parsePath(d)
     if ctx.fill != ColorRGBX():
-      img.fillPath(path, ctx.fill, ctx.transform, ctx.fillRule)
+      img.fill(ctx, path)
     if ctx.shouldStroke:
-      img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
+      img.stroke(ctx, path)
 
   of "line":
     let
@@ -247,12 +283,9 @@ proc draw(img: Image, node: XmlNode, ctxStack: var seq[Ctx]) =
     var path: Path
     path.moveTo(x1, y1)
     path.lineTo(x2, y2)
-    path.closePath()
 
-    if ctx.fill != ColorRGBX():
-      img.fillPath(path, ctx.fill, ctx.transform)
     if ctx.shouldStroke:
-      img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
+      img.stroke(ctx, path)
 
   of "polyline", "polygon":
     let
@@ -282,13 +315,15 @@ proc draw(img: Image, node: XmlNode, ctxStack: var seq[Ctx]) =
       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()
 
-    if ctx.fill != ColorRGBX():
-      img.fillPath(path, ctx.fill, ctx.transform)
+      if ctx.fill != ColorRGBX():
+        img.fill(ctx, path)
+
     if ctx.shouldStroke:
-      img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
+      img.stroke(ctx, path)
 
   of "rect":
     let
@@ -324,9 +359,9 @@ proc draw(img: Image, node: XmlNode, ctxStack: var seq[Ctx]) =
       path.rect(x, y, width, height)
 
     if ctx.fill != ColorRGBX():
-      img.fillPath(path, ctx.fill, ctx.transform)
+      img.fill(ctx, path)
     if ctx.shouldStroke:
-      img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
+      img.stroke(ctx, path)
 
   of "circle", "ellipse":
     let
@@ -346,9 +381,9 @@ proc draw(img: Image, node: XmlNode, ctxStack: var seq[Ctx]) =
     path.ellipse(cx, cy, rx, ry)
 
     if ctx.fill != ColorRGBX():
-      img.fillPath(path, ctx.fill, ctx.transform)
+      img.fill(ctx, path)
     if ctx.shouldStroke:
-      img.strokePath(path, ctx.stroke, ctx.transform, ctx.strokeWidth)
+      img.stroke(ctx, path)
 
   else:
     raise newException(PixieError, "Unsupported SVG tag: " & node.tag & ".")

src/pixie/fonts.nim

@@ -442,7 +442,9 @@ proc strokeText*(
   transform: Vec2 | Mat3 = vec2(0, 0),
   strokeWidth = 1.0,
   lineCap = lcButt,
-  lineJoin = ljMiter
+  lineJoin = ljMiter,
+  miterLimit = defaultMiterLimit,
+  dashes: seq[float32] = @[]
 ) =
   ## Strokes the text arrangement.
   for spanIndex, (start, stop) in arrangement.spans:
@@ -455,10 +457,25 @@ proc strokeText*(
       )
       when type(target) is Image:
         target.strokePath(
-          path, font.paint, transform, strokeWidth, lineCap, lineJoin
+          path,
+          font.paint,
+          transform,
+          strokeWidth,
+          lineCap,
+          lineJoin,
+          miterLimit,
+          dashes
         )
       else: # target is Mask
-        target.strokePath(path, transform, strokeWidth, lineCap, lineJoin)
+        target.strokePath(
+          path,
+          transform,
+          strokeWidth,
+          lineCap,
+          lineJoin,
+          miterLimit,
+          dashes
+        )
 
 proc strokeText*(
   target: Image | Mask,
@@ -470,7 +487,9 @@ proc strokeText*(
   hAlign = haLeft,
   vAlign = vaTop,
   lineCap = lcButt,
-  lineJoin = ljMiter
+  lineJoin = ljMiter,
+  miterLimit = defaultMiterLimit,
+  dashes: seq[float32] = @[]
 ) {.inline.} =
   ## Typesets and strokes the text. Optional parameters:
   ## transform: translation or matrix to apply
@@ -485,5 +504,7 @@ proc strokeText*(
     transform,
     strokeWidth,
     lineCap,
-    lineJoin
+    lineJoin,
+    miterLimit,
+    dashes
   )

src/pixie/paths.nim

@@ -36,7 +36,9 @@ type
 
   SomePath* = Path | string | seq[seq[Vec2]]
 
-const epsilon = 0.0001 * PI ## Tiny value used for some computations.
+const
+  epsilon = 0.0001 * PI ## Tiny value used for some computations.
+  defaultMiterLimit*: float32 = 4
 
 when defined(release):
   {.push checks: off.}
@@ -1422,15 +1424,16 @@ proc strokeShapes(
           shape[0]
         ))
 
+    var dashes = dashes
+    if dashes.len mod 2 != 0:
+      dashes.add(dashes)
+
     for i in 1 ..< shape.len:
       let
         pos = shape[i]
         prevPos = shape[i - 1]
 
       if dashes.len > 0:
-        var dashes = dashes
-        if dashes.len mod 2 != 0:
-          dashes.add(dashes[^1])
         var distance = dist(prevPos, pos)
         let dir = dir(pos, prevPos)
         var currPos = prevPos
@@ -1546,8 +1549,8 @@ proc strokePath*(
   strokeWidth = 1.0,
   lineCap = lcButt,
   lineJoin = ljMiter,
-  miterLimit: float32 = 4,
-  dashes: seq[float32] = @[],
+  miterLimit = defaultMiterLimit,
+  dashes: seq[float32] = @[]
 ) =
   ## Strokes a path.
   var strokeShapes = strokeShapes(
@@ -1569,7 +1572,7 @@ proc strokePath*(
   strokeWidth = 1.0,
   lineCap = lcButt,
   lineJoin = ljMiter,
-  miterLimit: float32 = 4,
+  miterLimit = defaultMiterLimit,
   dashes: seq[float32] = @[]
 ) =
   ## Strokes a path.

tests/images/svg/dashes.svg

@@ -0,0 +1,20 @@
+<svg viewBox="0 0 600 200" transform="scale(20, 20)" xmlns="http://www.w3.org/2000/svg">
+  <!-- No dashes nor gaps -->
+  <line x1="0" y1="1" x2="30" y2="1" stroke="black" />
+
+  <!-- Dashes and gaps of the same size -->
+  <line x1="0" y1="3" x2="30" y2="3" stroke="black"
+          stroke-dasharray="4" />
+
+  <!-- Dashes and gaps of different sizes -->
+  <line x1="0" y1="5" x2="30" y2="5" stroke="black"
+          stroke-dasharray="4 1" />
+
+  <!-- Dashes and gaps of various sizes with an odd number of values -->
+  <line x1="0" y1="7" x2="30" y2="7" stroke="black"
+          stroke-dasharray="4 1 2" />
+
+  <!-- Dashes and gaps of various sizes with an even number of values -->
+  <line x1="0" y1="9" x2="30" y2="9" stroke="black"
+          stroke-dasharray="4 1 2 3" />
+</svg>

tests/images/svg/miterlimit.svg

@@ -0,0 +1,27 @@
+<svg viewBox="0 0 760 600" transform="scale(20, 20)" xmlns="http://www.w3.org/2000/svg">
+  <!-- Impact of the default miter limit -->
+  <path stroke="black" fill="none" stroke-linejoin="miter" id="p1" d="M1,9 l7   ,-3 l7   ,3
+           m2,0 l3.5 ,-3 l3.5 ,3
+           m2,0 l2   ,-3 l2   ,3
+           m2,0 l0.75,-3 l0.75,3
+           m2,0 l0.5 ,-3 l0.5 ,3"></path>
+
+  <!-- Impact of the smallest miter limit (1) -->
+  <path stroke="black" fill="none" stroke-linejoin="miter" stroke-miterlimit="1" id="p2" d="M1,19 l7   ,-3 l7   ,3
+           m2, 0 l3.5 ,-3 l3.5 ,3
+           m2, 0 l2   ,-3 l2   ,3
+           m2, 0 l0.75,-3 l0.75,3
+           m2, 0 l0.5 ,-3 l0.5 ,3"></path>
+
+  <!-- Impact of a large miter limit (8) -->
+  <path stroke="black" fill="none" stroke-linejoin="miter" stroke-miterlimit="8" id="p3" d="M1,29 l7   ,-3 l7   ,3
+           m2, 0 l3.5 ,-3 l3.5 ,3
+           m2, 0 l2   ,-3 l2   ,3
+           m2, 0 l0.75,-3 l0.75,3
+           m2, 0 l0.5 ,-3 l0.5 ,3"></path>
+
+  <!-- the following pink lines highlight the position of the path for each stroke -->
+  <path stroke="pink" fill="none" stroke-width="0.05" d="M1, 9 l7,-3 l7,3 m2,0 l3.5,-3 l3.5,3 m2,0 l2,-3 l2,3 m2,0 l0.75,-3 l0.75,3 m2,0 l0.5,-3 l0.5,3
+           M1,19 l7,-3 l7,3 m2,0 l3.5,-3 l3.5,3 m2,0 l2,-3 l2,3 m2,0 l0.75,-3 l0.75,3 m2,0 l0.5,-3 l0.5,3
+           M1,29 l7,-3 l7,3 m2,0 l3.5,-3 l3.5,3 m2,0 l2,-3 l2,3 m2,0 l0.75,-3 l0.75,3 m2,0 l0.5,-3 l0.5,3"></path>
+</svg>

tests/test_context.nim

@@ -408,7 +408,6 @@ block:
 
   ctx.image.writeFile("tests/images/context/clip_1e.png")
 
-
 block:
   let ctx = newContext(newImage(300, 150))
 
@@ -491,3 +490,28 @@ block:
 
   let metrics = ctx.measureText("Hello world")
   doAssert metrics.width == 61
+
+block:
+  let
+    image = newImage(300, 150)
+    ctx = newContext(image)
+
+  var y = 15.float32
+
+  proc drawDashedLine(pattern: seq[float32]) =
+    ctx.beginPath();
+    ctx.setLineDash(pattern);
+    ctx.moveTo(0, y);
+    ctx.lineTo(300, y);
+    ctx.stroke();
+    y += 20;
+
+  drawDashedLine(@[]);
+  drawDashedLine(@[1.float32, 1]);
+  drawDashedLine(@[10.float32, 10]);
+  drawDashedLine(@[20.float32, 5]);
+  drawDashedLine(@[15.float32, 3, 3, 3]);
+  drawDashedLine(@[20.float32, 3, 3, 3, 3, 3, 3, 3]);
+  drawDashedLine(@[12.float32, 3, 3]);
+
+  image.writeFile("tests/images/context/setLineDash_1.png")

tests/test_paths.nim

@@ -47,7 +47,7 @@ block:
     image = newImage(100, 100)
     pathStr = "M 10 10 L 90 90"
     color = rgba(255, 0, 0, 255)
-  image.strokePath(pathStr, color, strokeWidth=10)
+  image.strokePath(pathStr, color, strokeWidth = 10)
   image.writeFile("tests/images/paths/pathStroke1.png")
 
 block:
@@ -55,7 +55,7 @@ block:
     image = newImage(100, 100)
     pathStr = "M 10 10 L 50 60 90 90"
     color = rgba(255, 0, 0, 255)
-  image.strokePath(pathStr, color, strokeWidth=10)
+  image.strokePath(pathStr, color, strokeWidth = 10)
   image.writeFile("tests/images/paths/pathStroke2.png")
 
 block:
@@ -268,12 +268,12 @@ block:
 
   image.strokePath(
     path, rgba(0, 0, 0, 255), vec2(5, 25), 10, lcButt, ljBevel,
-    dashes = @[2.float32,2]
+    dashes = @[2.float32, 2]
   )
 
   image.strokePath(
     path, rgba(0, 0, 0, 255), vec2(5, 45), 10, lcButt, ljBevel,
-    dashes = @[4.float32,4]
+    dashes = @[4.float32, 4]
   )
 
   image.strokePath(

tests/test_svg.nim

@@ -11,7 +11,9 @@ const files = [
   "triangle01",
   "quad01",
   "Ghostscript_Tiger",
-  "scale"
+  "scale",
+  "miterlimit",
+  "dashes"
 ]
 
 for file in files: