Added ImagePipe

mojo/services/gfx/images/interfaces/image_pipe.mojom

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+[DartPackage="mojo_services"]
+module mojo.gfx;
+
+import "geometry/interfaces/geometry.mojom";
+import "gfx/images/interfaces/image.mojom";
+
+//The status of the last time this image was presented
+enum PresentationStatus {
+  PRESENTED = 0,
+  //Image properties are not supported by the consumer (this is not neccessarily
+  // an error, as these properties could have changed after the image was added)
+  NOT_PRESENTED_INVALID_PROPERTIES,
+  //Producer flushed the image pool
+  NOT_PRESENTED_FLUSHED,
+};
+
+//ImagePipe is a collection of semantics for streaming shared images between two
+//Mojo entities, one of which provides the image contents (the 'producer') and
+//one of which does something with the image contents (the 'consumer').
+//It operates conceptually on a pool of image descriptors that the pipe knows
+//about, allows image producers to add/remove images to/from this pool, and
+//provides mechanisms for the producer and the consumer to negotiate about who
+//owns each image in the pool at a given point in time
+interface ImagePipe {
+
+  //Add an image persistently to the pipe's image pool
+  //Adding an image that is already added, or using an ID that is already in use
+  //are both errors and will cause the connection to terminate
+  AddImage(Image image, uint32 id);
+
+  //Remove an image from the pipe's pool
+  //Use of an invalid ID will cause the connection to be terminated
+  RemoveImage(uint32 id);
+
+  //Mark the image as available for consumption by the consumer
+  //The reply will be sent when the consumer is done using this image and
+  //is ready to release ownership back to the producer.
+  //The reply will not be sent until another Image is presented to replace it
+  //presentuing an id that is added will cause the connection to terminate
+  PresentImage(uint32 id) => (uint32 id, PresentationStatus status);
+
+  //Ask the consumer to release all images in the pipe's pool
+  //this will send the presentation reply with FLUSHED on all images in the pool
+  //not being used by the consumer if the consumer is presenting this image,
+  //that image may still be presented and its Present reply will reflect that
+  FlushImages();
+
+  //Get supported propertied for images added to this pipe
+  //The reply to this method will only be sent when the values change compared
+  //to the last time they were sent (immediately for the first time they are
+  //called), so to listen for continuous updates call this method immediately
+  //after recieving the reply
+  GetSupportedImageProperties() => (SupportedImageProperties supported_properties);
+};