[librsvg] shapes.rs: NodeCircle fully implemented in Rust!

[Federico Mena Quintero <federico src gnome org>]

commit e36a432082d2e6c281891c9b5832c30ac3f7089d
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Feb 20 18:07:04 2017 -0600

    shapes.rs: NodeCircle fully implemented in Rust!

 rsvg-base.c        |    2 +-
 rsvg-shapes.c      |   94 ----------------------------------------------------
 rsvg-shapes.h      |    6 ++-
 rust/src/lib.rs    |    1 +
 rust/src/shapes.rs |   83 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 89 insertions(+), 97 deletions(-)
---
diff --git a/rsvg-base.c b/rsvg-base.c
index 9671d63..df3119b 100644
--- a/rsvg-base.c
+++ b/rsvg-base.c
@@ -260,7 +260,7 @@ static const NodeCreator node_creators[] = {
     /* "animateColor",       FALSE, */
     /* "animateMotion",      FALSE, */
     /* "animateTransform",   FALSE, */
-    { "circle",              TRUE,  rsvg_new_circle },
+    { "circle",              TRUE,  rsvg_node_circle_new },
     { "clipPath",            TRUE,  rsvg_new_clip_path },
     /* "color-profile",      FALSE, */
     { "conicalGradient",     TRUE,  rsvg_new_radial_gradient },
diff --git a/rsvg-shapes.c b/rsvg-shapes.c
index 5ba3f59..0a74f58 100644
--- a/rsvg-shapes.c
+++ b/rsvg-shapes.c
@@ -167,100 +167,6 @@ rsvg_new_polyline (const char *element_name, RsvgNode *parent)
     return rsvg_new_any_poly (RSVG_NODE_TYPE_POLYLINE, parent);
 }
 
-typedef struct _RsvgNodeCircle RsvgNodeCircle;
-
-struct _RsvgNodeCircle {
-    RsvgLength cx, cy, r;
-};
-
-static void
-rsvg_node_circle_set_atts (RsvgNode *node, gpointer impl, RsvgHandle *handle, RsvgPropertyBag *atts)
-{
-    RsvgNodeCircle *circle = impl;
-    const char *value;
-
-    if ((value = rsvg_property_bag_lookup (atts, "cx")))
-        circle->cx = rsvg_length_parse (value, LENGTH_DIR_HORIZONTAL);
-    if ((value = rsvg_property_bag_lookup (atts, "cy")))
-        circle->cy = rsvg_length_parse (value, LENGTH_DIR_VERTICAL);
-    if ((value = rsvg_property_bag_lookup (atts, "r")))
-        circle->r = rsvg_length_parse (value, LENGTH_DIR_BOTH);
-}
-
-static void
-rsvg_node_circle_draw (RsvgNode *node, gpointer impl, RsvgDrawingCtx *ctx, int dominate)
-{
-    RsvgNodeCircle *circle = impl;
-    double cx, cy, r;
-    RsvgPathBuilder *builder;
-
-    cx = rsvg_length_normalize (&circle->cx, ctx);
-    cy = rsvg_length_normalize (&circle->cy, ctx);
-    r = rsvg_length_normalize (&circle->r, ctx);
-
-    if (r <= 0)
-        return;
-
-    /* approximate a circle using 4 bezier curves */
-
-    builder = rsvg_path_builder_new ();
-
-    rsvg_path_builder_move_to (builder, cx + r, cy);
-
-    rsvg_path_builder_curve_to (builder,
-                                cx + r, cy + r * RSVG_ARC_MAGIC,
-                                cx + r * RSVG_ARC_MAGIC, cy + r,
-                                cx, cy + r);
-
-    rsvg_path_builder_curve_to (builder,
-                                cx - r * RSVG_ARC_MAGIC, cy + r,
-                                cx - r, cy + r * RSVG_ARC_MAGIC,
-                                cx - r, cy);
-
-    rsvg_path_builder_curve_to (builder,
-                                cx - r, cy - r * RSVG_ARC_MAGIC,
-                                cx - r * RSVG_ARC_MAGIC, cy - r,
-                                cx, cy - r);
-
-    rsvg_path_builder_curve_to (builder,
-                                cx + r * RSVG_ARC_MAGIC, cy - r,
-                                cx + r, cy - r * RSVG_ARC_MAGIC,
-                                cx + r, cy);
-
-    rsvg_path_builder_close_path (builder);
-
-    rsvg_state_reinherit_top (ctx, rsvg_node_get_state (node), dominate);
-
-    rsvg_render_path_builder (ctx, builder);
-
-    rsvg_path_builder_destroy (builder);
-}
-
-static void
-rsvg_node_circle_free (gpointer impl)
-{
-    RsvgNodeCircle *circle = impl;
-
-    g_free (circle);
-}
-
-RsvgNode *
-rsvg_new_circle (const char *element_name, RsvgNode *parent)
-{
-    RsvgNodeCircle *circle;
-
-    circle = g_new0 (RsvgNodeCircle, 1);
-    circle->cx = circle->cy = circle->r = rsvg_length_parse ("0", LENGTH_DIR_BOTH);
-
-    return rsvg_rust_cnode_new (RSVG_NODE_TYPE_CIRCLE,
-                                parent,
-                                rsvg_state_new (),
-                                circle,
-                                rsvg_node_circle_set_atts,
-                                rsvg_node_circle_draw,
-                                rsvg_node_circle_free);
-}
-
 typedef struct _RsvgNodeEllipse RsvgNodeEllipse;
 
 struct _RsvgNodeEllipse {
diff --git a/rsvg-shapes.h b/rsvg-shapes.h
index b7cef55..3d21ee4 100644
--- a/rsvg-shapes.h
+++ b/rsvg-shapes.h
@@ -48,13 +48,15 @@ RsvgNode *rsvg_node_line_new (const char *element_name, RsvgNode *parent);
 G_GNUC_INTERNAL
 RsvgNode *rsvg_node_rect_new (const char *element_name, RsvgNode *parent);
 
+/* Implemented in rust/src/shapes.rs */
+G_GNUC_INTERNAL
+RsvgNode *rsvg_node_circle_new (const char *element_name, RsvgNode *parent);
+
 G_GNUC_INTERNAL
 RsvgNode *rsvg_new_polygon (const char *element_name, RsvgNode *parent);
 G_GNUC_INTERNAL
 RsvgNode *rsvg_new_polyline (const char *element_name, RsvgNode *parent);
 G_GNUC_INTERNAL
-RsvgNode *rsvg_new_circle (const char *element_name, RsvgNode *parent);
-G_GNUC_INTERNAL
 RsvgNode *rsvg_new_ellipse (const char *element_name, RsvgNode *parent);
 
 G_END_DECLS
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 1ceb665..e0047da 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -79,6 +79,7 @@ pub use pattern::{
 };
 
 pub use shapes::{
+    rsvg_node_circle_new,
     rsvg_node_line_new,
     rsvg_node_path_new,
     rsvg_node_rect_new,
diff --git a/rust/src/shapes.rs b/rust/src/shapes.rs
index 830a81e..b91da3d 100644
--- a/rust/src/shapes.rs
+++ b/rust/src/shapes.rs
@@ -346,6 +346,81 @@ impl NodeTrait for NodeRect {
     }
 }
 
+/***** NodeCircle *****/
+
+struct NodeCircle {
+    cx: Cell<RsvgLength>,
+    cy: Cell<RsvgLength>,
+    r:  Cell<RsvgLength>
+}
+
+impl NodeCircle {
+    fn new () -> NodeCircle {
+        NodeCircle {
+            cx: Cell::new (RsvgLength::default ()),
+            cy: Cell::new (RsvgLength::default ()),
+            r:  Cell::new (RsvgLength::default ()),
+        }
+    }
+}
+
+impl NodeTrait for NodeCircle {
+    fn set_atts (&self, _: &RsvgNode, _: *const RsvgHandle, pbag: *const RsvgPropertyBag) {
+        self.cx.set (property_bag::lookup (pbag, "cx").map_or (RsvgLength::default (),
+                                                              |v| RsvgLength::parse (&v, 
LengthDir::Horizontal)));
+
+        self.cy.set (property_bag::lookup (pbag, "cy").map_or (RsvgLength::default (),
+                                                               |v| RsvgLength::parse (&v, 
LengthDir::Vertical)));
+
+        self.r.set (property_bag::lookup (pbag, "r").map_or (RsvgLength::default (),
+                                                             |v| RsvgLength::parse (&v, LengthDir::Both)));
+    }
+
+    fn draw (&self, node: &RsvgNode, draw_ctx: *const RsvgDrawingCtx, dominate: i32) {
+        let cx = self.cx.get ().normalize (draw_ctx);
+        let cy = self.cy.get ().normalize (draw_ctx);
+        let r = self.r.get ().normalize (draw_ctx);
+
+        // Per the spec, r must be nonnegative
+        if r <= 0.0 {
+            return;
+        }
+
+        // 4/3 * (1-cos 45°)/sin 45° = 4/3 * sqrt(2) - 1
+        let arc_magic: f64 = 0.5522847498;
+
+        // approximate a circle using 4 Bézier curves
+
+        let mut builder = RsvgPathBuilder::new ();
+
+        builder.move_to (cx + r, cy);
+
+        builder.curve_to (cx + r, cy + r * arc_magic,
+                          cx + r * arc_magic, cy + r,
+                          cx, cy + r);
+
+        builder.curve_to (cx - r * arc_magic, cy + r,
+                          cx - r, cy + r * arc_magic,
+                          cx - r, cy);
+
+        builder.curve_to (cx - r, cy - r * arc_magic,
+                          cx - r * arc_magic, cy - r,
+                          cx, cy - r);
+
+        builder.curve_to (cx + r * arc_magic, cy - r,
+                          cx + r, cy - r * arc_magic,
+                          cx + r, cy);
+
+        builder.close_path ();
+
+        render_path_builder (&builder, draw_ctx, node.get_state (), dominate, false);
+    }
+
+    fn get_c_impl (&self) -> *const RsvgCNodeImpl {
+        ptr::null ()
+    }
+}
+
 /***** C Prototypes *****/
 
 #[no_mangle]
@@ -371,3 +446,11 @@ pub extern fn rsvg_node_rect_new (_: *const libc::c_char, raw_parent: *const Rsv
                                   drawing_ctx::state_new (),
                                   Box::new (NodeRect::new ()))))
 }
+
+#[no_mangle]
+pub extern fn rsvg_node_circle_new (_: *const libc::c_char, raw_parent: *const RsvgNode) -> *const RsvgNode {
+    box_node (Rc::new (Node::new (NodeType::Circle,
+                                  parent_ptr_to_weak (raw_parent),
+                                  drawing_ctx::state_new (),
+                                  Box::new (NodeCircle::new ()))))
+}