Add support for canvas and multipart

Quite incomplete canvas implementation. Crucially, the layout engine
can't do much with whatever is drawn because it doesn't support images
yet.

I've re-introduced multipart as well, with the FormData API. For the
append function I've also introduced a hack to the JS binding generator
that allows requesting the JSContext pointer in nim procs. Really I
should just fix the union generator thing and add support for overloading.

In conclusion, for now the only thing canvas can be used for is exporting
it as PNG and uploading it somewhere. Also, we now have PNG encoding and
decoding too. (Now if only we had sixels as well...)

3 files changed, 20 insertions, 25 deletions

diff --git a/src/css/cascade.nim b/src/css/cascade.nim
index 0cea87b7..7aac213f 100644
--- a/src/css/cascade.nim
+++ b/src/css/cascade.nim
@@ -127,17 +127,17 @@ func calcPresentationalHints(element: Element): CSSComputedValues =
     if c.isSome:
       set_cv "color", c.get
   template map_colspan =
-    let colspan = element.attrigz("colspan")
+    let colspan = element.attrulgz("colspan")
     if colspan.isSome:
       let i = colspan.get
       if i <= 1000:
-        set_cv "-cha-colspan", i
+        set_cv "-cha-colspan", int(i)
   template map_rowspan =
-    let rowspan = element.attrigez("rowspan")
+    let rowspan = element.attrul("rowspan")
     if rowspan.isSome:
       let i = rowspan.get
       if i <= 65534:
-        set_cv "-cha-rowspan", i
+        set_cv "-cha-rowspan", int(i)
 
   case element.tagType
   of TAG_DIV:
@@ -170,8 +170,8 @@ func calcPresentationalHints(element: Element): CSSComputedValues =
     map_text
   of TAG_TEXTAREA:
     let textarea = HTMLTextAreaElement(element)
-    let cols = textarea.attri("cols").get(20)
-    let rows = textarea.attri("rows").get(1)
+    let cols = textarea.attrul("cols").get(20)
+    let rows = textarea.attrul("rows").get(1)
     set_cv "width", CSSLength(unit: UNIT_CH, num: float64(cols))
     set_cv "height", CSSLength(unit: UNIT_EM, num: float64(rows))
   of TAG_FONT:
diff --git a/src/css/cssparser.nim b/src/css/cssparser.nim
index 9c8328de..57cfc87e 100644
--- a/src/css/cssparser.nim
+++ b/src/css/cssparser.nim
@@ -867,10 +867,10 @@ proc parseAnB*(state: var CSSParseState): Option[CSSAnB] =
       return none(CSSAnB)
   template parse_sub_int(sub: string, skip: int): int =
     let s = sub.substr(skip)
-    for c in s:
-      if c notin AsciiDigit:
-        return none(CSSAnB)
-    parseInt32(s)
+    let x = parseInt32(s)
+    if x.isNone:
+      return none(CSSAnB)
+    x.get
   template fail_non_integer(tok: CSSToken, res: Option[CSSAnB]) =
     if tok.tokenType != CSS_NUMBER_TOKEN:
       state.reconsume()
diff --git a/src/css/values.nim b/src/css/values.nim
index c786e47e..dd3f2df4 100644
--- a/src/css/values.nim
+++ b/src/css/values.nim
@@ -493,7 +493,7 @@ func skipWhitespace(vals: seq[CSSComponentValue], i: var int) =
       break
     inc i
 
-func cssColor(val: CSSComponentValue): RGBAColor =
+func cssColor*(val: CSSComponentValue): RGBAColor =
   if val of CSSToken:
     let tok = CSSToken(val)
     case tok.tokenType
@@ -525,23 +525,15 @@ func cssColor(val: CSSComponentValue): RGBAColor =
           commaMode = true
         elif commaMode:
           raise newException(CSSValueError, "Invalid color")
-        if slash:
+        elif slash:
           if f.value[i] != CSS_DELIM_TOKEN or CSSToken(f.value[i]).rvalue != Rune('/'):
             raise newException(CSSValueError, "Invalid color")
           inc i
           f.value.skipWhitespace(i)
-      check_err
+      if not slash:
+        check_err
     case f.name
-    of "rgb":
-      f.value.skipWhitespace(i)
-      check_err
-      let r = CSSToken(f.value[i]).nvalue
-      next_value true
-      let g = CSSToken(f.value[i]).nvalue
-      next_value
-      let b = CSSToken(f.value[i]).nvalue
-      return rgba(int(r), int(g), int(b), 255)
-    of "rgba":
+    of "rgb", "rgba":
       f.value.skipWhitespace(i)
       check_err
       let r = CSSToken(f.value[i]).nvalue
@@ -550,8 +542,11 @@ func cssColor(val: CSSComponentValue): RGBAColor =
       next_value
       let b = CSSToken(f.value[i]).nvalue
       next_value false, true
-      let a = CSSToken(f.value[i]).nvalue
-      return rgba(int(r), int(g), int(b), int(a))
+      let a = if i < f.value.len:
+        CSSToken(f.value[i]).nvalue
+      else:
+        1
+      return rgba(int(r), int(g), int(b), int(a * 255))
     else: discard
   raise newException(CSSValueError, "Invalid color")