From 3e839726060964e2e5b049232a79962ce0aa16ae Mon Sep 17 00:00:00 2001
From: Raph Levien <raph.levien@gmail.com>
Date: Thu, 28 May 2020 11:48:36 -0700
Subject: [PATCH] Improve SVG parsing

WIP
---
 piet-gpu/src/pico_svg.rs | 88 ++++++++++++++++++++++++++++++++--------
 1 file changed, 71 insertions(+), 17 deletions(-)

diff --git a/piet-gpu/src/pico_svg.rs b/piet-gpu/src/pico_svg.rs
index a4c92d0..7b52f5a 100644
--- a/piet-gpu/src/pico_svg.rs
+++ b/piet-gpu/src/pico_svg.rs
@@ -2,7 +2,7 @@
 
 use std::str::FromStr;
 
-use roxmltree::Document;
+use roxmltree::{Document, Node};
 
 use piet::kurbo::{Affine, BezPath};
 
@@ -28,27 +28,18 @@ pub struct FillItem {
     path: BezPath,
 }
 
+struct Parser<'a> {
+    items: &'a mut Vec<Item>,
+}
+
 impl PicoSvg {
     pub fn load(xml_string: &str, scale: f64) -> Result<PicoSvg, Box<dyn std::error::Error>> {
         let doc = Document::parse(xml_string)?;
         let root = doc.root_element();
-        let g = root.first_element_child().ok_or("no root element")?;
         let mut items = Vec::new();
-        for el in g.children() {
-            if el.is_element() {
-                let d = el.attribute("d").ok_or("missing 'd' attribute")?;
-                let bp = BezPath::from_svg(d)?;
-                let path = Affine::scale(scale) * bp;
-                if let Some(fill_color) = el.attribute("fill") {
-                    let color = parse_color(fill_color);
-                    items.push(Item::Fill(FillItem { color, path: path.clone() }));
-                }
-                if let Some(stroke_color) = el.attribute("stroke") {
-                    let width = f64::from_str(el.attribute("stroke-width").ok_or("missing width")?)?;
-                    let color = parse_color(stroke_color);
-                    items.push(Item::Stroke(StrokeItem { width, color, path }));
-                }
-            }
+        let mut parser = Parser::new(&mut items);
+        for node in root.children() {
+            parser.rec_parse(node)?;
         }
         Ok(PicoSvg { items })
     }
@@ -67,6 +58,49 @@ impl PicoSvg {
     }
 }
 
+impl<'a> Parser<'a> {
+    fn new(items: &'a mut Vec<Item>) -> Parser<'a> {
+        Parser {
+            items
+        }
+    }
+
+    fn rec_parse(&mut self, node: Node) -> Result<(), Box<dyn std::error::Error>> {
+        if node.is_element() {
+            match node.tag_name().name() {
+                "g" => {
+                    for child in node.children() {
+                        self.rec_parse(child)?;
+                    }
+                }
+                "path" => {
+                    let d = node.attribute("d").ok_or("missing 'd' attribute")?;
+                    let bp = BezPath::from_svg(d)?;
+                    let path = Affine::new([1.5, 0.0, 0.0, -1.5, 0.0, 1500.0]) * bp;
+                    // TODO: default fill color is black, but this is overridden in tiger to this logic.
+                    if let Some(fill_color) = node.attribute("fill") {
+                        if fill_color != "none" {
+                            let color = parse_color(fill_color);
+                            let color = modify_opacity(color, "fill-opacity", node);
+                            self.items.push(Item::Fill(FillItem { color, path: path.clone() }));
+                        }
+                    }
+                    if let Some(stroke_color) = node.attribute("stroke") {
+                        if stroke_color != "none" {
+                            let width = 1.5 * f64::from_str(node.attribute("stroke-width").ok_or("missing width")?)?;
+                            let color = parse_color(stroke_color);
+                            let color = modify_opacity(color, "stroke-opacity", node);
+                            self.items.push(Item::Stroke(StrokeItem { width, color, path }));
+                        }
+                    }
+                }
+                _ => (),
+            }
+        }
+        Ok(())
+    }
+}
+
 fn parse_color(color: &str) -> Color {
     if color.as_bytes()[0] == b'#' {
         let mut hex = u32::from_str_radix(&color[1..], 16).unwrap();
@@ -74,7 +108,27 @@ fn parse_color(color: &str) -> Color {
             hex = (hex >> 8) * 0x110000 + ((hex >> 4) & 0xf) * 0x1100 + (hex & 0xf) * 0x11;
         }
         Color::from_rgba32_u32((hex << 8) + 0xff)
+    } else if color.starts_with("rgb(") {
+        let mut iter = color[4..color.len() - 1].split(',');
+        let r = u8::from_str(iter.next().unwrap()).unwrap();
+        let g = u8::from_str(iter.next().unwrap()).unwrap();
+        let b = u8::from_str(iter.next().unwrap()).unwrap();
+        Color::rgb8(r, g, b)
     } else {
         Color::from_rgba32_u32(0xff00ff80)
     }
 }
+
+fn modify_opacity(color: Color, attr_name: &str, node: Node) -> Color {
+    if let Some(opacity) = node.attribute(attr_name) {
+        let alpha = if opacity.ends_with("%") {
+            let pctg = opacity[..opacity.len() - 1].parse().unwrap_or(100.0);
+            pctg * 0.01
+        } else {
+            opacity.parse().unwrap_or(1.0)
+        };
+        color.with_alpha(alpha)
+    } else {
+        color
+    }
+}