From 8b24624eabb95554b3d0dcf9594b9166a7688d1f Mon Sep 17 00:00:00 2001
From: Tj Holowaychuk <tj@vision-media.ca>
Date: Fri, 29 Oct 2010 14:44:17 -0700
Subject: [PATCH] Added QuadraticCurveTo() using the libsvg-cairo
 implementation. Closes #10

---
 src/CanvasRenderingContext2d.cc | 34 +++++++++++++++++++++++++++++++++
 src/CanvasRenderingContext2d.h  |  1 +
 2 files changed, 35 insertions(+)

diff --git a/src/CanvasRenderingContext2d.cc b/src/CanvasRenderingContext2d.cc
index 27c62c0..d85ebc9 100644
--- a/src/CanvasRenderingContext2d.cc
+++ b/src/CanvasRenderingContext2d.cc
@@ -91,6 +91,7 @@ Context2d::Initialize(Handle<Object> target) {
   NODE_SET_PROTOTYPE_METHOD(t, "moveTo", MoveTo);
   NODE_SET_PROTOTYPE_METHOD(t, "lineTo", LineTo);
   NODE_SET_PROTOTYPE_METHOD(t, "bezierCurveTo", BezierCurveTo);
+  NODE_SET_PROTOTYPE_METHOD(t, "quadraticCurveTo", QuadraticCurveTo);
   NODE_SET_PROTOTYPE_METHOD(t, "beginPath", BeginPath);
   NODE_SET_PROTOTYPE_METHOD(t, "closePath", ClosePath);
   NODE_SET_PROTOTYPE_METHOD(t, "arc", Arc);
@@ -547,6 +548,39 @@ Context2d::BezierCurveTo(const Arguments &args) {
   return Undefined();
 }
 
+/*
+ * Quadratic curve approximation from libsvg-cairo.
+ */
+
+Handle<Value>
+Context2d::QuadraticCurveTo(const Arguments &args) {
+  HandleScope scope;
+
+  if (!args[0]->IsNumber()
+    ||!args[1]->IsNumber()
+    ||!args[2]->IsNumber()
+    ||!args[3]->IsNumber()) return Undefined();
+
+  Context2d *context = ObjectWrap::Unwrap<Context2d>(args.This());
+  cairo_t *ctx = context->getContext();
+
+  double x, y
+    , x1 = args[0]->NumberValue()
+    , y1 = args[1]->NumberValue()
+    , x2 = args[2]->NumberValue()
+    , y2 = args[3]->NumberValue();
+
+  cairo_get_current_point(ctx, &x, &y);
+
+  cairo_curve_to(ctx
+    , x  + 2.0 / 3.0 * (x1 - x),  y  + 2.0 / 3.0 * (y1 - y)
+    , x2 + 2.0 / 3.0 * (x1 - x2), y2 + 2.0 / 3.0 * (y1 - y2)
+    , x2
+    , y2);
+
+  return Undefined();
+}
+
 /*
  * Save state.
  */
diff --git a/src/CanvasRenderingContext2d.h b/src/CanvasRenderingContext2d.h
index 35929cd..ac52868 100644
--- a/src/CanvasRenderingContext2d.h
+++ b/src/CanvasRenderingContext2d.h
@@ -65,6 +65,7 @@ class Context2d: public node::ObjectWrap {
     static Handle<Value> SetFillPattern(const Arguments &args);
     static Handle<Value> SetStrokePattern(const Arguments &args);
     static Handle<Value> BezierCurveTo(const Arguments &args);
+    static Handle<Value> QuadraticCurveTo(const Arguments &args);
     static Handle<Value> LineTo(const Arguments &args);
     static Handle<Value> MoveTo(const Arguments &args);
     static Handle<Value> FillRect(const Arguments &args);