Bug 720697 - Provide internal API to get canvas image data as nsIInputStream; r=khuey

content/html/content/src/nsHTMLCanvasElement.cpp

@@ -216,6 +216,28 @@ nsHTMLCanvasElement::ToDataURL(const nsAString& aType, nsIVariant* aParams,
   return ToDataURLImpl(aType, aParams, aDataURL);
 }
 
+// nsHTMLCanvasElement::mozFetchAsStream
+
+NS_IMETHODIMP
+nsHTMLCanvasElement::MozFetchAsStream(nsIInputStreamCallback *aCallback,
+                                      const nsAString& aType)
+{
+  if (!nsContentUtils::IsCallerChrome())
+    return NS_ERROR_FAILURE;
+
+  nsresult rv;
+  bool fellBackToPNG = false;
+  nsCOMPtr<nsIInputStream> inputData;
+
+  rv = ExtractData(aType, EmptyString(), getter_AddRefs(inputData), fellBackToPNG);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIAsyncInputStream> asyncData = do_QueryInterface(inputData, &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return aCallback->OnInputStreamReady(asyncData);
+}
+
 nsresult
 nsHTMLCanvasElement::ExtractData(const nsAString& aType,
                                  const nsAString& aOptions,

dom/interfaces/html/nsIDOMHTMLCanvasElement.idl

@@ -54,6 +54,7 @@
 
 interface nsIDOMFile;
 interface nsIVariant;
+interface nsIInputStreamCallback;
 
 [scriptable, uuid(8cddbc86-f384-40ac-835b-fe3e00630cad)]
 interface nsIDOMHTMLCanvasElement : nsIDOMHTMLElement
@@ -82,5 +83,10 @@ interface nsIDOMHTMLCanvasElement : nsIDOMHTMLElement
   // A Mozilla-only extension to get a canvas context backed by double-buffered
   // shared memory. Only privileged callers can call this.
   nsISupports MozGetIPCContext(in DOMString contextId);
+
+  // A Mozilla-only extension that returns the canvas' image data as a data
+  // stream in the desired image format.
+  void mozFetchAsStream(in nsIInputStreamCallback callback,
+                                        [optional] in DOMString type);
 };
 

xpcom/io/nsIAsyncInputStream.idl

@@ -124,7 +124,7 @@ interface nsIAsyncInputStream : nsIInputStream
 /**
  * This is a companion interface for nsIAsyncInputStream::asyncWait.
  */
-[scriptable, uuid(d1f28e94-3a6e-4050-a5f5-2e81b1fc2a43)]
+[function, scriptable, uuid(d1f28e94-3a6e-4050-a5f5-2e81b1fc2a43)]
 interface nsIInputStreamCallback : nsISupports
 {
     /**