Started buffer streaming

src/canvas.cc

@@ -5,6 +5,7 @@
 // Copyright (c) 2010 LearnBoost <tj@learnboost.com>
 //
 
+#include <string.h>
 #include "canvas.h"
 
 using namespace v8;
@@ -20,6 +21,7 @@ Canvas::Initialize(Handle<Object> target) {
   t->InstanceTemplate()->SetInternalFieldCount(1);
   t->SetClassName(String::NewSymbol("Canvas"));
 
+  NODE_SET_PROTOTYPE_METHOD(t, "streamPNG", StreamPNG);
   NODE_SET_PROTOTYPE_METHOD(t, "savePNG", SavePNG);
   target->Set(String::NewSymbol("Canvas"), t->GetFunction());
 }
@@ -42,6 +44,46 @@ Canvas::New(const Arguments &args) {
   return args.This();
 }
 
+typedef struct {
+  unsigned char *pos;
+  unsigned char *end;
+  Handle<Function> fn;
+} closure_t;
+
+static cairo_status_t
+writeToBuffer(void *c, const uint8_t *data, unsigned len) {
+  printf("bytes %d\n", len);
+  closure_t *closure = (closure_t *) c;
+  if (closure->pos + len > closure->end)
+    return CAIRO_STATUS_WRITE_ERROR;
+  memcpy(closure->pos, data, len);
+  Handle<Value> argv[1];
+  argv[0] = String::New("test");
+  closure->fn.Call(Context::GetCurrent()->Global(), 1, argv);
+  closure->pos += len;
+  return CAIRO_STATUS_SUCCESS;
+}
+
+/*
+ * Return a node Buffer containing PNG data.
+ */
+
+Handle<Value>
+Canvas::StreamPNG(const Arguments &args) {
+  HandleScope scope;
+  // TODO: error handling
+  if (!args[0]->IsFunction())
+    return ThrowException(Exception::TypeError(String::New("function required")));
+  Canvas *canvas = ObjectWrap::Unwrap<Canvas>(args.This());
+  closure_t closure;
+  uint8_t data[64 * 1024];
+  closure.pos = data;
+  closure.end = data + sizeof(data);
+  closure.fn = Handle<Function>::Cast(args[0]); // TODO: leakage?
+  cairo_surface_write_to_png_stream(canvas->getSurface(), writeToBuffer, &closure);
+  return Undefined();
+}
+
 /*
  * Initialize cairo surface.
  */

src/canvas.h

@@ -38,6 +38,7 @@ class Canvas: public node::ObjectWrap {
     static void Initialize(Handle<Object> target);
     static Handle<Value> New(const Arguments &args);
     static Handle<Value> SavePNG(const Arguments &args);
+    static Handle<Value> StreamPNG(const Arguments &args);
     inline cairo_surface_t *getSurface(){ return _surface; }
     Canvas(int width, int height);