crates/svg-filters/src/main.rs

@@ -1,6 +1,20 @@
-use svg_filters::{types::nodes::primitives::color_matrix::ColorMatrixType, Edge, Filter, Node};
+use svg_filters::{
+    types::nodes::{primitives::color_matrix::ColorMatrixType, standard_input::StandardInput},
+    Edge, Filter, Node,
+};
 
 fn main() {
+    let mut supersimple = Filter::new();
+
+    let cm = supersimple.add_node(Node::color_matrix(ColorMatrixType::Matrix(Box::new([
+        1., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 1., 0.,
+    ]))));
+
+    supersimple
+        .graph
+        .extend_with_edges(&[(supersimple.source_graphic(), cm)]);
+    dbg!(supersimple.to_svg());
+
     let mut filter = Filter::new();
 
     // <filter id="chromabb" >
@@ -50,5 +64,5 @@ fn main() {
         (chan_g, composite_final, Edge::in_idx(1)),
     ]);
 
-    println!("{filter:#?}")
+    println!("Result: {}", filter.to_svg())
 }

crates/svg-filters/src/types.rs

@@ -1,8 +1,15 @@
-use std::collections::HashMap;
+use std::{borrow::Cow, collections::HashMap, fmt::Debug, io::BufWriter, primitive};
 
 use petgraph::{
-    adj::EdgeIndex, data::Build, graph::DiGraph, graphmap::DiGraphMap, prelude::NodeIndex,
+    adj::EdgeIndex,
+    algo::{toposort, DfsSpace},
+    data::{Build, DataMap},
+    graph::DiGraph,
+    graphmap::DiGraphMap,
+    prelude::NodeIndex,
+    visit::NodeIndexable,
 };
+use quick_xml::{events::attributes::Attribute, name::QName, ElementWriter};
 
 pub mod length;
 pub mod nodes;
@@ -11,7 +18,10 @@ use crate::types::nodes::primitives::color_matrix::{ColorMatrix, ColorMatrixType
 
 use self::{
     length::{Coordinate, Length},
-    nodes::Node,
+    nodes::{
+        primitives::{FePrimitive, WriteElement},
+        Node,
+    },
 };
 
 #[derive(Debug)]
@@ -40,6 +50,52 @@ impl Filter<'_> {
     pub fn source_graphic(&self) -> NodeIndex {
         self.source_graphic_idx
     }
+
+    pub fn to_svg(&self) -> String {
+        let mut result = Vec::new();
+        let mut writer = quick_xml::Writer::new(&mut result);
+
+        let mut dfs_space = DfsSpace::new(&self.graph);
+        let sorted = toposort(&self.graph, Some(&mut dfs_space)).expect("No cycles! Bad user!");
+
+        sorted
+            .into_iter()
+            .filter_map(|node_idx| {
+                let node = self
+                    .graph
+                    .node_weight(node_idx)
+                    .expect("toposorting will not return invalid indices");
+
+                if let Node::Primitive {
+                    primitive,
+                    common_attrs,
+                } = node
+                {
+                    Some((node_idx, primitive, common_attrs))
+                } else {
+                    None
+                }
+            })
+            .fold(
+                &mut writer,
+                |writer, (node_idx, primitive, common_attrs)| {
+                    let el_writer = primitive.element_writer(writer);
+                    create_input_elements(
+                        &self.graph,
+                        el_writer,
+                        node_idx,
+                        self.graph
+                            .node_weight(node_idx)
+                            .expect("cannot get invalid node_idx from toposort")
+                            .input_count(),
+                    )
+                    .write_empty()
+                    .expect("should write successfully")
+                },
+            );
+
+        String::from_utf8_lossy(&result).to_string()
+    }
 }
 
 impl Default for Filter<'_> {
@@ -50,10 +106,10 @@ impl Default for Filter<'_> {
 
 #[derive(Debug, Clone)]
 pub struct Edge<'a> {
-    edge_type: EdgeType<'a>,
+    pub edge_type: EdgeType<'a>,
     /// the index of the `in` attribute on the target element
     /// if None, just `in`
-    in_idx: Option<u8>,
+    pub in_idx: Option<u8>,
 }
 
 impl Edge<'_> {
@@ -72,9 +128,60 @@ impl Edge<'_> {
     }
 }
 
+impl Default for Edge<'_> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum EdgeType<'a> {
     Named(&'a str),
     /// For standard inputs such as SourceGraphic etc., which we'll just be representing as nodes for simplicity
     Unnamed,
 }
+fn create_input_elements<'a>(
+    g: &'a DiGraph<Node, Edge<'_>>,
+    mut el_writer: ElementWriter<'a, &'a mut Vec<u8>>,
+    node_idx: NodeIndex,
+    input_count: u8,
+) -> ElementWriter<'a, &'a mut Vec<u8>> {
+    let inputs = g
+        .neighbors_directed(node_idx, petgraph::Direction::Incoming)
+        .collect::<Vec<NodeIndex>>();
+
+    if inputs.len() != input_count as usize {
+        // TODO: better error handling
+        panic!("input couns didnt match");
+    }
+
+    inputs
+        .into_iter()
+        .enumerate()
+        .fold(el_writer, |el_writer, (i, incoming_idx)| {
+            let incoming_node = g.node_weight(incoming_idx).expect("cannot fail here");
+
+            // find incoming edge and get weight
+            let Edge { edge_type, in_idx } = g
+                .edge_weight(
+                    g.find_edge(incoming_idx, node_idx)
+                        .expect("there should always be an edge"),
+                )
+                .expect("once again, should always exist");
+
+            let in_attr_name = match in_idx {
+                None | Some(0) => "in".to_owned(),
+                Some(n) => format!("in{}", n + 1),
+            };
+
+            let v = match incoming_node {
+                Node::StdInput(std_in) => format!("{std_in:?}"),
+                Node::Primitive {
+                    primitive,
+                    common_attrs,
+                } => todo!(),
+            };
+
+            el_writer.with_attribute((in_attr_name.as_str(), v.as_str()))
+        })
+}

crates/svg-filters/src/types/nodes.rs

@@ -1,3 +1,7 @@
+use core::panic;
+
+use quick_xml::events::attributes::Attribute;
+
 use self::{
     primitives::{
         blend::{Blend, BlendMode},
@@ -31,7 +35,7 @@ impl Default for Node {
 }
 
 #[derive(Default, Debug)]
-struct CommonAttrs {
+pub(crate) struct CommonAttrs {
     x: Coordinate,
     y: Coordinate,
     width: Length,

crates/svg-filters/src/types/nodes/primitives.rs

@@ -1,3 +1,5 @@
+use quick_xml::{events::attributes::Attribute, ElementWriter, Writer};
+
 use crate::types::length::{Coordinate, Length};
 
 use self::blend::BlendMode;
@@ -21,6 +23,19 @@ pub mod specular_lighting;
 pub mod tile;
 pub mod turbulence;
 
+pub trait WriteElement {
+    fn attrs(&self) -> Vec<Attribute>;
+    fn tag_name(&self) -> &'static str;
+    fn element_writer<'writer, 'result>(
+        &self,
+        writer: &'writer mut Writer<&'result mut Vec<u8>>,
+    ) -> ElementWriter<'writer, &'result mut Vec<u8>> {
+        writer
+            .create_element(self.tag_name())
+            .with_attributes(self.attrs())
+    }
+}
+
 /// svg filter effects primitives
 #[derive(Debug)]
 pub enum FePrimitive {
@@ -42,3 +57,47 @@ pub enum FePrimitive {
     Tile(tile::Tile),
     Turbulence(turbulence::Turbulence),
 }
+
+impl WriteElement for FePrimitive {
+    fn attrs(&self) -> std::vec::Vec<quick_xml::events::attributes::Attribute<'_>> {
+        match self {
+            FePrimitive::Blend(_) => todo!(),
+            FePrimitive::ColorMatrix(cm) => cm.attrs(),
+            FePrimitive::ComponentTransfer(_) => todo!(),
+            FePrimitive::Composite(_) => todo!(),
+            FePrimitive::ConvolveMatrix(_) => todo!(),
+            FePrimitive::DiffuseLighting(_) => todo!(),
+            FePrimitive::DisplacementMap(_) => todo!(),
+            FePrimitive::Flood(_) => todo!(),
+            FePrimitive::GaussianBlur(_) => todo!(),
+            FePrimitive::Image(_) => todo!(),
+            FePrimitive::Merge(_) => todo!(),
+            FePrimitive::Morphology(_) => todo!(),
+            FePrimitive::Offset(_) => todo!(),
+            FePrimitive::SpecularLighting(_) => todo!(),
+            FePrimitive::Tile(_) => todo!(),
+            FePrimitive::Turbulence(_) => todo!(),
+        }
+    }
+
+    fn tag_name(&self) -> &'static str {
+        match self {
+            FePrimitive::Blend(_) => todo!(),
+            FePrimitive::ColorMatrix(cm) => cm.tag_name(),
+            FePrimitive::ComponentTransfer(_) => todo!(),
+            FePrimitive::Composite(_) => todo!(),
+            FePrimitive::ConvolveMatrix(_) => todo!(),
+            FePrimitive::DiffuseLighting(_) => todo!(),
+            FePrimitive::DisplacementMap(_) => todo!(),
+            FePrimitive::Flood(_) => todo!(),
+            FePrimitive::GaussianBlur(_) => todo!(),
+            FePrimitive::Image(_) => todo!(),
+            FePrimitive::Merge(_) => todo!(),
+            FePrimitive::Morphology(_) => todo!(),
+            FePrimitive::Offset(_) => todo!(),
+            FePrimitive::SpecularLighting(_) => todo!(),
+            FePrimitive::Tile(_) => todo!(),
+            FePrimitive::Turbulence(_) => todo!(),
+        }
+    }
+}

crates/svg-filters/src/types/nodes/primitives/blend.rs

@@ -1,6 +1,6 @@
 /// [feBlend](https://www.w3.org/TR/SVG11/filters.html#feBlendElement)
 #[derive(Debug)]
-pub(in crate::types::nodes) struct Blend {
+pub struct Blend {
     mode: BlendMode,
 }
 

crates/svg-filters/src/types/nodes/primitives/color_matrix.rs

@@ -1,3 +1,9 @@
+use std::borrow::Cow;
+
+use quick_xml::{events::attributes::Attribute, name::QName, se::to_string};
+
+use super::WriteElement;
+
 /// [feColorMatrix](https://www.w3.org/TR/SVG11/filters.html#feColorMatrixElement)
 #[derive(Debug)]
 pub struct ColorMatrix {
@@ -10,6 +16,34 @@ impl ColorMatrix {
     }
 }
 
+impl WriteElement for ColorMatrix {
+    fn attrs(&self) -> Vec<quick_xml::events::attributes::Attribute> {
+        match &self.cm_type {
+            ColorMatrixType::Matrix(v) => vec![Attribute {
+                key: QName(b"values"),
+                value: Cow::from(
+                    v.iter()
+                        .map(|v| v.to_string())
+                        .reduce(|mut acc, e| {
+                            acc.push(' ');
+                            acc.push_str(&e);
+                            acc
+                        })
+                        .expect("Should be able to concatenate the thingies")
+                        .into_bytes(),
+                ),
+            }],
+            ColorMatrixType::Saturate(v) => todo!(),
+            ColorMatrixType::HueRotate(v) => todo!(),
+            ColorMatrixType::LuminanceToAlpha => todo!(),
+        }
+    }
+
+    fn tag_name(&self) -> &'static str {
+        "feColorMatrix"
+    }
+}
+
 #[derive(Debug)]
 pub enum ColorMatrixType {
     Matrix(Box<[f32; 20]>),