From 6e55ecc7d4bfcabc0aabe3e42cdace97f8aae59b Mon Sep 17 00:00:00 2001
From: Ryan Oldenburg <guzba8@gmail.com>
Date: Sun, 13 Dec 2020 02:21:18 -0600
Subject: [PATCH] svg no more asserts

---
 src/pixie/fileformats/svg.nim | 120 ++++++++++++++++++----------------
 1 file changed, 63 insertions(+), 57 deletions(-)

diff --git a/src/pixie/fileformats/svg.nim b/src/pixie/fileformats/svg.nim
index 5e72284..13c8b65 100644
--- a/src/pixie/fileformats/svg.nim
+++ b/src/pixie/fileformats/svg.nim
@@ -5,72 +5,78 @@ import chroma, pixie/images, pixie/common, pixie/paths, vmath, xmlparser, xmltre
 
 const svgSignature* = "<?xml"
 
+template failInvalid() =
+  raise newException(PixieError, "Invalid SVG data")
+
 proc draw(img: Image, matStack: var seq[Mat3], xml: XmlNode) =
-  case xml.tag:
-    of "g":
-      let
-        fill = xml.attr("fill")
-        stroke = xml.attr("stroke")
-        strokeWidth = xml.attr("stroke-width")
-        transform = xml.attr("transform")
+  if xml.tag != "g":
+    raise newException(PixieError, "Unsupported SVG tag: " & xml.tag & ".")
 
-      if transform != "":
-        if transform.startsWith("matrix("):
-          let arr = transform[7..^2].split(",")
-          assert arr.len == 6
-          var m = mat3()
-          m[0] = parseFloat(arr[0])
-          m[1] = parseFloat(arr[1])
-          m[3] = parseFloat(arr[2])
-          m[4] = parseFloat(arr[3])
-          m[6] = parseFloat(arr[4])
-          m[7] = parseFloat(arr[5])
-          matStack.add(matStack[^1] * m)
-        else:
-          raise newException(
-            PixieError, "Unsupported SVG transform: " & transform & ".")
-
-      for child in xml:
-        if child.tag == "path":
-          let d = child.attr("d")
-
-          if fill != "none" and fill != "":
-            let fillColor = parseHtmlColor(fill).rgba
-            let (bounds, fillImg) =
-              fillPathBounds(d, fillColor, mat = matStack[^1])
-            img.draw(fillImg, bounds.xy)
-
-          if stroke != "none" and stroke != "":
-            let strokeColor = parseHtmlColor(stroke).rgba
-            let strokeWidth =
-              if strokeWidth == "": 1.0 # Default stroke width is 1px
-              else: parseFloat(strokeWidth)
-            let (bounds, strokeImg) =
-              strokePathBounds(d, strokeColor, strokeWidth, mat = matStack[^1])
-            img.draw(strokeImg, bounds.xy)
-
-        else:
-          img.draw(matStack, child)
-
-      if transform != "":
-        discard matStack.pop()
+  let
+    fill = xml.attr("fill")
+    stroke = xml.attr("stroke")
+    strokeWidth = xml.attr("stroke-width")
+    transform = xml.attr("transform")
 
+  if transform != "":
+    if transform.startsWith("matrix("):
+      let arr = transform[7..^2].split(",")
+      if arr.len != 6:
+        failInvalid()
+      var m = mat3()
+      m[0] = parseFloat(arr[0])
+      m[1] = parseFloat(arr[1])
+      m[3] = parseFloat(arr[2])
+      m[4] = parseFloat(arr[3])
+      m[6] = parseFloat(arr[4])
+      m[7] = parseFloat(arr[5])
+      matStack.add(matStack[^1] * m)
     else:
-      raise newException(PixieError, "Unsupported SVG tag: " & xml.tag & ".")
+      raise newException(
+        PixieError, "Unsupported SVG transform: " & transform & ".")
+
+  for child in xml:
+    if child.tag == "path":
+      let d = child.attr("d")
+
+      if fill != "none" and fill != "":
+        let
+          fillColor = parseHtmlColor(fill).rgba
+          (bounds, fillImg) = fillPathBounds(d, fillColor, matStack[^1])
+        img.draw(fillImg, bounds.xy)
+
+      if stroke != "none" and stroke != "":
+        let
+          strokeColor = parseHtmlColor(stroke).rgba
+          strokeWidth =
+            if strokeWidth == "": 1.0 # Default stroke width is 1px
+            else: parseFloat(strokeWidth)
+          (bounds, strokeImg) =
+            strokePathBounds(d, strokeColor, strokeWidth, matStack[^1])
+        img.draw(strokeImg, bounds.xy)
+    else:
+      img.draw(matStack, child)
+
+  if transform != "":
+    discard matStack.pop()
 
 proc decodeSvg*(data: string): Image =
   ## Render SVG file and return the image.
   try:
-    var xml = parseXml(data)
-    assert xml.tag == "svg"
-    var viewBox = xml.attr "viewBox"
-    let box = viewBox.split(" ")
-    assert parseInt(box[0]) == 0
-    assert parseInt(box[1]) == 0
-    let w = parseInt(box[2])
-    let h = parseInt(box[3])
-    result = newImage(w, h)
+    let xml = parseXml(data)
+    if xml.tag != "svg":
+      failInvalid()
 
+    let
+      viewBox = xml.attr("viewBox")
+      box = viewBox.split(" ")
+    if parseInt(box[0]) != 0 or parseInt(box[1]) != 0:
+      failInvalid()
+
+    let
+      width = parseInt(box[2])
+      height = parseInt(box[3])
+    result = newImage(width, height)
     var matStack = @[mat3()]
     for n in xml:
       result.draw(matStack, n)